Introduction to GPRS E-GPRS Quality of Service Monitoring - BSS Release B8 (2)

© Alcatel University - 8AS 90200 1419 VH ZZA Ed.01 Page 1.1

© Alcatel University - 8AS902001419 VTZZA1 Ed.011.1

Introductionto

GPRS & E-GPRSQuality of Service Monitoring

BSS Release B8

B8


1.2

PROGRAM

1 Role of the BSS in GPRS QoS Monitoring2 Recalls on the Main BSS GPRS Telecom Procedures3 Description of the Main BSS GPRS QoS Counters and Indicators4 Detection of the Main BSS GPRS QoS Problems5 Analysis of the Main BSS GPRS QoS Problems

B8



1 Role of the BSS in GPRS QoS monitoring

B8


1.4

1 Role of the BSS in GPRS QoS MonitoringSession Presentation

� Objective: to be able to describe the role of the BSS in the End-user GPRS QoS and the dependencies between Global(BSS+GSS) and BSS GPRS QoS on one hand and betweenBSS GSM and GPRS QoS on the other hand

� Program:1.1 Distinction between BSS/Global/End-user GPRS QoS1.2 Implementation of GPRS QoS profiles at BSS level1.3 Source of information for GPRS QoS monitoring1.4 Dependencies between BSS GSM and GPRS QoS1.5 Impact of GMM/SM signaling on BSS QoS interpretation

B8




1.1 Distinction between BSS/BSS+GSS/End-userGPRS QoS


1.6

1.1 Distinction between BSS/BSS+GSS/End-user GPRS QoSDifferent Levels of QoS

GGSN

GPRS GPRS BackboneBackbone

PacketPacketDataData

NetworkNetwork

GbGbGbGb

SGSN

A935A935A935A935MFSMFSMFSMFS

BSCBSCBSCBSC

AterAterAterAter

BTS

AbisAbisAbisAbis

BSS

GPRS QoS

GnGnGnGn GiGiGiGiUmUmUmUmRRRR

Radio QoS

User QoS

TETE

�3 types of QoS in involves in the overall analysis of the QoS of the GPRS service:�the radio QoS

�it must be considered from the R interface to the Gb interfaceit mainly belongs to the radio environment as well as the well as the proper functioning of the PCUimplemented inside the BSS�defined in terms of throughput, service precedence, RLC reliability mode, transfer delay

�The GPRS QoS�It must be considered from the R interface (MS access the GPRS) to the Gi interface (exit of the GPRSNetwork)�It includes the Radio QoS and the GSS QoS�defined in terms of service precedence, transfer delay, mean and peak throughputs and reliability

�The End-User QoS�This is the QoS as the user feels it.�It includes the GPRS QoS as well as the QoS of the external networks and their connection to the GPRSGSS�Should it not belong to the operator, it should still be monitored as it can generate customer complaints


1.7

1.1 Distinction between BSS/BSS+GSS/End-user GPRS QoSDependencies between QoS levels

End-user QoS

GPRS QoS

Radio QoS

� Bad BSS GPRS QoS (Radio QoS) will lead to bad GPRS QoS and bad End-user QoS.� Bad End-user performance can be due to bad GSS behaviour without any BSS GPRS QoS degradation.� Bad End-user QoS can also be due to bad PDN performance.


1.8

1.1 Distinction between BSS/BSS+GSS/End-user GPRS QoSImpact of UE

� Different data applications are multiplexed over the GPRS radiolayers: FTP, WEB/HTTP, WAP, MMS, etc

� Data applications have very different traffic characteristics(amount of data, duration between LLC PDUs) leading todifferent ways of triggering radio layers algorithms

� Therefore Parameters setting in the GPRS network will lead todifferent performance according to the service

� Bad end-user QoS can also be due to setting of TE protocol layers parameters which can not have optimal values to get thebest GPRS performance.


1.9

1.1 Distinction between BSS/BSS+GSS/End-user GPRS QoSImpact of UE

� Data applications use TCP/IP protocol layers which have a greatimpact on the end-user QoS

(*)

First IP router Last IP rou

GTP

relay

SNDCP

BSSGPRLC BSSGP

relay

relay

SNDCPPPP

FTP

TCP

IP

PPP

LLC

RLC

MAC

RF

MAC

RF

NS

L1

NS

L1

LLC UDP

IP-Gn

L2

L1’

UDP

IP-Gn

L2

L1’

IP

relay

IP

GTP

IP

relay

IP

relay

IP

UmRGb

Gn GiTE (PC,PDA …)

MSBSS

SGSNGGSN

Possible repartition on the end to end path of the TCP flight size

TCP data segment

TCP acknowledgement

(*) this graphical representation is used toexpress the fact that many data segments arecurrently waiting to be transmitted on therepresented link and are stored in buffers of thedevice handling the link . It doesn’t mean thatsimultaneous segments are being transmitted.

FTP above TCP/IP layers

� Bad end-user QoS can also be due to setting of TE protocol layers parameters which can not have optimal values to get thebest GPRS performance.


1.10

1.1 Distinction between BSS/BSS+GSS/End-user GPRS QoSUnderstand BSS GPRS QoS

� GPRS QoS is not an isolated topic:� It is necessary to use GSM indicators in order to complete

the analysis of GPRS QoS� It is necessary to use GSM counters in order to complete

the analysis of the impact of GPRS traffic on GSM QoS

� The BSS QoS does not allow to have a complete understandingof the end to end QoS seen by the user� Indeed, upper protocol layers (TCP for example) have a

great impact on the global QoS� The GSS also has a great impact on the global QoS




1.2 Implementation of GPRS QoS profiles at BSSlevel


1.12

Location servicesLocation servicesLocation servicesLocation services• Traffic Conditions• Itineraries• Nearest Restaurant,

Cinema, Chemist,Parking;, ATM ...

FunFunFunFun• Games (Hangman, Poker, Quiz, …)• Screen Saver• Ring Tone• Horoscope• Biorhythm

MediaAlways-on

M-commerce

Mobile OfficeMobile OfficeMobile OfficeMobile Office• Voice (!)• E-mail• Agenda• IntraNet/InterNet• Corporate Applications• Database Access

TransportationTransportationTransportationTransportation• Flight/train Schedule• reservation

Vertical applicationVertical applicationVertical applicationVertical application• Traffic Management• Automation• Mobile branches• Health

MusicMusicMusicMusic• Downloading of

music files orvideo clips

News News News News(general/specific)(general/specific)(general/specific)(general/specific)• International/National News• Local News• Sport News• Weather• Lottery Results• Finance News• Stock Quotes• Exchange Rates

PhysicalPhysicalPhysicalPhysical• on-line shopping• on-line food

Non physicalNon physicalNon physicalNon physical• on-line Banking• Ticketing• Auction• Gambling• Best Price• e-Book

DirectoriesDirectoriesDirectoriesDirectories• Yellow/White Pages• International Directories• Operator Services

1.2 Implementation of GPRS QoS Profiles at BSS LevelData Services

� Teleservices provide the full capabilities for communications by means of terminal equipment,network functions and possibly functions provided by dedicated centres.

� Multimedia teleservices support the transfer of several types of information.� M-commerce:

� Non-physical = electronic goods (e-banking, e-flight ticketing, ...)� Physical = electronic payment of physical goods (food, supplies, hardware, ...)


1.13

1.2 Implementation of GPRS QoS Profiles at BSS LevelQoS Requirements - Exercise

� Different applications require different QoS

� Exercise: find qualitatively the QoS requirements of thefollowing data services

+: low sensitivy, ++: medium, +++: high

Service Transfer Delay Throughput Reliabilitywebvideo streamingftplocation based advertisingaudio streamingemailwapfaxe-commerceinteractive gamesSMS

�Data applications have very different traffic characteristics (amount of data, duration between LLC PDU) leading to differentways of triggering of the radio layers algorithms. This has a direct impact on the follow-up of some OMC-R QoS indicators: numberof DL/UL TBF establishment requests, DL/UL TBF duration, coding scheme distribution


1.14

� 5 GPRS QoS attributes in the R’97/98 standard:

� Precedence Class: relative importance of service undercongestion; 3 values are defined

� Delay Class: total delay measured between the R or S point andthe Gi interface; 4 values are defined

� Reliability Class: mainly linked to Ack / Not Ack modes at RLCand LLC levels and within the backbone network; 5 values aredefined

� Peak Throughput Class: measured at the Gi and R referencepoints;9 values, ranging from 8 Kbit/s up to 2048 Kbit/s

� Mean Throughput Class: measured at the Gi and R referencepoints; 19 values, ranging from Best Effort up to 111 Kbit/s

1.2 Implementation of GPRS QoS Profiles at BSS LevelR’97/98 GPRS QoS Profile

�Precedence classes: high, normal, low

�Delay classes: �class 1 (average delay<0.5 sec, 95% delay<1.5 sec)�class 2 (average delay<5 sec, 95% delay<25 sec)�class 3 (average delay<50 sec, 95% delay<250 sec)�class4: not specified = “best effort

�The Mean Throughput class range is smaller than the Peak Throughput class one because�The later is considered per interface (the purpose being to maximize the use of the transmission capacity over eachinterface according to its physical characteristics)�The former is considered end to end and must take into account the weaker interface characteristics, the air interfaceone

�Reliability: Five classes are defined according to the tolerable BER (from 1 = lowest BER required to 5 = highest toleratedBER and no acknowledgement or error checking).


1.15

� ETSI R’97 principles:� GPRS QoS is negotiated between the MS and the SGSN, at

PDP context activation� The BSS is not involved in QoS negotiation� No absolute QoS can be guaranteed by the BSS� The SGSN and the GGSN play the main role in QoS

management

� But the BSS should be able to do its best...

1.2 Implementation of GPRS QoS Profiles at BSS LevelETSI Principles


1.16

GGSN

GPRS GPRS BackboneBackbone


NetworkNetwork

GbGbGbGb

SGSN

A935A935A935A935MFSMFSMFSMFS

BSCBSCBSCBSC

AterAterAterAter

BTS

AbisAbisAbisAbis

BSS

GPRS QoS

GnGnGnGn GiGiGiGiUmUmUmUmRRRR

Radio QoS

User QoS

TETE

1.2 Implementation of GPRS QoS Profiles at BSS LevelQoS Profile at BSS Level

�Throughput: not managed by Alcatel BSS in B7. The allocation strategy consists in trying to allocate to the MS as manyPDCHs as supported by its multislot class if such information is known. The operator can limit the maximum number of PDCHsallocated to a TBF through O&M configuration

�useful throughput expected on the radio interface�specified on:

�DL path: in DL BSSGP PDU header�UL path: peak throughput class in “Packet resource request” (2 phases access)

�Service precedence: not managed by Alcatel BSS in B7�defines the priority for maintaining service under congested situation�specified on:

�DL path: in DL BSSGP PDU header�UL path: radio priority in “Packet resource request” (2 phases access)

�RLC reliability mode: managed by the BSS.�RLC Ack or RLC NAck�specified on:

�DL path: in DL BSSGP PDU header�UL path: in “Packet resource request” (2 phases access)�Default mode: Ack

�Transfer delay: Best effort is supported. PDU Lifetime is taken into account for DL LLC PDU. As many TS as requestedaccording to the MS Multislot Class are allocated if possible.

�a requirement is provided for DL LLC PDU via the PDU lifetime�PDU lifetime is expected to be configured by SGSN according to GPRS transfer delay class of associated PDP context


1.17

1.2 Implementation of GPRS QoS Profiles at BSS LevelPrecedence

� Precedence:� Defines the priority for maintaining service in a congestion

situation� Specified on:

� The DL path: in the DL BSSGP PDU header� The UL path: radio priority in “Packet resource request”

(2-phase access)� Not managed in the Alcatel BSS, but the operator can

configure, in case of GPRS cell configured with a MasterPDCH the persistence level of each radio priority andtherefore control the uplink TBF establishment delay

�Service precedence:� The management of the persistence levels in the Alcatel BSS is the following. When there is a PBCCH allocated in thecell, the MFS broadcasts on PBCCH four persistence levels P(i), defined by O&M, each of them corresponding to a givenradio priority i (i = 1, 2, 3, 4), where P(i) ∈{0, 1, …14, 16}. For each access attemp, the MS draws a random value R inthe set {0, 1, …14, 15}. The MS is allowed to send a Packet Channel Request message only if the P(i), where i is theradio priority of the TBF being established, is less or equal to R. This method allows the operator to differentiate theaccess probability of the MSs as a function of their radio priority.

� There is no preemption of on-going TBF to establish a new one with higher service precedence level.


1.18

1.2 Implementation of GPRS QoS Profiles at BSS LevelThroughput

� Throughput:� Defines the data throughput requested by the user� Specified on:

� The DL path: in the DL BSSGP PDU header� The UL path: peak throughput class in “Packet resource

request” (2-phase access)� Not taken into account by the BSS� The allocation strategy consists in trying to allocate to the

MS as many PDCHs as supported by its multislot class ifknown

� Throughput:�The PDCH available throughput (in terms of RLC/MAC blocks) is equally shared between all MS allocated on it. TheBSS periodically tries to offer the best throughput to a TBF in case it has a ‘sub-optimal’ allocation, it corresponds to thedirection of the bias and a better allocation is available.� The operator can limit the maximum number of PDCHs allocated to a TBF through O&M configuration.� The maximum throughput that can be served to a MS is limited to n x 20 Kbit/s for GPRS MS or n x 59.2 Kbit/s forEGPRS MS, in case of good radio conditions (no retransmissions), n being limited by upper multislot class supported bythe network (n=5).


1.19

1.2 Implementation of GPRS QoS Profiles at BSS LevelDelay

� Delay:� Defines the end-to-end transfer delay incurred in the

transmission of SDUs through the GPRS network� Specified on:

� The DL path: through the PDU lifetime which indicatesthe latest time at when the PDU must be completelytransmitted

� The UL path: peak throughput class in “Packet resourcerequest” (2-phase access)

� Best effort is supported by the BSS:� The PDU lifetime is taken into account for a DL LLC

PDU�As many TSs as requested according to the MS

Multislot Class are allocated if possible

� Transfer delay:

� This includes the radio channel access delay (on uplink) or radio channel scheduling delay (on downlink), the radiochannel transit delay (uplink and/or downlink paths) and the GPRS-network transit delay (multiple hops). It does notinclude transfer delays in external networks.

� Delay is measured between the R or S (for MS) and Gi (for FS) reference points when applied to "MS to fixed station(FS)" or "FS to MS" transmissions.

� PDU lifetime is expected to be configured by SGSN according to GPRS transfer delay class of associated PDP context� In DL: case of unavailability of either traffic resources (TFI, TAI, throughput) or PDCH resources, DL TBFestablishments requests are queued and served according to the PDU lifetime.


1.20

1.2 Implementation of GPRS QoS Profiles at BSS LevelReliability

� Reliability:� Defines the transmission characteristics that are required by

an application in terms of SDU loss probability, duplicationof SDU, mis-sequencing of SDU or corruption of SDU

� Implemented at BSS level as RLC Acknowledged (Ack)mode or RLC Not acknowledged (Nack) mode

� Specified on� The DL path: in the DL BSSGP PDU header� The UL path: in “Packet resource request” (2-phase

access)� Default mode: Ack


1.21

1.2 Implementation of GPRS QoS Profiles at BSS LevelAlcatel QoS Offer - R’97/98 QoS Compliance

ETSI R’97/98 QoS attributes Alcatel Offer

Precedence class Mean throughput classDelay class Resulting QoS

class(4) Best Effort

1, 2 or 3

1,. 2 or 3

1,. 2 or 3

1,. 2 or 3

any

(3) Low priority

Normal, High priority

(2) Normal priority

(1) High priority

any

any

Best Effort

specified, except BE

specified, except BE

Best-Effort

Best-Effort

Best-Effort

Normal

Premium

Reliability class: as required by the MS

� These QoS attributes are associated with a PDP context performed by a R’97/98 MS

� The five QoS parameters of the standard define more than 60 combinations ! Which is too much and leeds to simplification:

� Too complex to implement,� Many of the combinations have no meaning!� The standard "allows" more simple QoS implementations.

� “-” = any value.� In bold, the main criterion for definition of the resulting QoS.

� Best effort = inexpensive, comparable to the Internet (no commitment). Ideal for foraging on the internet.

� Normal: Comparable to an intranet.

� Premium: Expensive, high performance.


1.22

� 4 UMTS QoS classes in the R’99 standard (traffic classes):

� conversational class

� video conference

� streaming class

� live video retransmission

� interactive class

�Web browsing

� background class

� email, SMS

1.2 Implementation of GPRS QoS Profiles at BSS LevelR'99 UMTS QoS Classes

� Conversational class:

� The most well known use of this scheme is telephony speech (e.g. GSM). But with Internet and multimedia a numberof new applications will require this scheme, for example voice over IP and video conferencing tools.

� Real time conversation is always performed between peers (or groups) of live (human) end users. This is the onlyscheme where the required characteristics are strictly given by human perception.

� Streaming class:

� When the user is looking at (listening to) real time video (audio) the scheme of real time streams applies. The realtime data flow is always aiming at a live (human) destination. It is a one way transport.

�Streaming class:

� When the user is looking at (listening to) real time video (audio) the scheme of real time streams applies. The realtime data flow is always aiming at a live (human) destination. It is a one way transport.

� Interactive class:

� When the end user, that is either a machine or a human, is on line requesting data from remote equipment (e.g. aserver), this scheme applies.

� Examples of human interaction with the remote equipment are: web browsing, data base retrieval, server access.Examples of machines interaction with remote equipment are: polling for measurement records and automatic database enquiries (tele-machines).

� Background class:

� When the end user, that typically is a computer, sends and receives data-files in the background, this schemeapplies.

� Examples are background delivery of E-mails, SMS, download of databases and reception of measurement records.


1.23

1.2 Implementation of GPRS QoS Profiles at BSS Level Alcatel QoS Offer - R’97/98 QoS Mapping into R'99 QoS

Traffic handling priorityR'99 Traffic class R’97/98 Bearer QoS class

Premium

Premium

Premium

Normal

Normal

conversational

streaming

interactive

interactive

interactive

-

-

1

2

3

Best Effortbackground -

� There is a mapping between R'99 Traffic class and Alcatel QoS class

� The mapping of R’97/98 QoS attributes to R'99 QoS is applicable in the following cases:

� hand-over of PDP context from GPRS R’97/R'98 SGSN to GPRS R'99 or UMTS SGSN

� when a R'99 MS performs a PDP context activation in a R'99 SGSN with a R'97/98 GGSN

� when the SGSN has received R’97/98 QoS subscribed profile, but the MS is R'99

� The mapping of R'99 QoS attributes to R'97/98 QoS is applicable in the following cases:

� PDP context is handed-over from GPRS R'99 to R'97/R'98

� when a R'99 MS performs a PDP context activation in a R'99 SGSN while the GGSN is R'97/98

� when the SGSN sends user data to the BSS for a R'99 MS

� when the SGSN has received R'99 QoS subscribed profile but the MS is R'97/98

� in the new SGSN, during an inter-SGSN RA_update procedure, or inter-system change, on receipt of the R'99 QoS

attributes from the old SGSN




1.3 Source of information for GPRS QoSmonitoring


1.25

1.3 Source of Information for GPRS QoS MonitoringTrace User Data Transfer

� Transmission plane

MAC

GSM-RF

LLC

RLC

IP/X25

SNDCP

application

MS

MAC

UmMFS

RLCrelay

BSSGP

NS

L1bis

NS

L1bis

BSSGP

Gb

LLC

SGSN

SNDCP GTP

L2

L1

IP

UDP/TCP

relay

GSM-RFrelay

Abis/Ater

L1-GCHL2-GCH

L1-GCHL2-GCH

BTS

Air Interface traces

GC

H traces

Gb traces

�For the exact purposes of the tracing, please refer to QoS part.

�It can be said from this protocol stacks diagram that after allocation of a GCH by the BSC to the MFS, the data carried overthe GCH are transparent for the BSC.

�The use of the traces will be reviewed in the last chapter of the training: “GPRS QoS Principles”�NB: the GCH traces are in fact RLC/MAC information that being traced over the Abis or Ater interface.

�The most reliable view of the overall GPRS QoS is the MS one as per the protocol stack included inside the MS.

�The RLC/MAC header is used for MS and TS multiplexing.�RLC main functions = segmentation, assembly of LLC frames + data transfer mode (ACK, NACK)�MAC main function = radio resource multiplexing (multi-slot for one MS, multi MS on 1 TS in UL)


1.26

1.3 Source of Information for GPRS QoS MonitoringTrace Signaling

� Signaling plane with CCCH use

GSM-RF

LLC

GMM/SM

MS

BSCGP

UmMFS

RRMrelay

BSSGP

NS

L1bis

Gb

GSM-RFrelay

Abis

L1-GSLL2-GSL

L1-RSLL2-RSL

BTS

L1-GSLL2-GSL

Ater

L1-RSLL2-RSL

relayRR BSCGP

RR/RRM

BSC

Air Interface traces

GC

H traces

Gb tracesG

SL traces

�2 GSL at 64kbps per BSS�RSL: refer to dimensioning rules for GSM


1.27

1.3 Source of Information for GPRS QoS MonitoringPM Counters


NetworkNetworkGPRS GPRS

BackboneBackboneSGSNGGSN

HLR

Gb

MFSBSC

BTS

BTS

COUNTERS


1.28

1.3 Source of Information for GPRS QoS MonitoringEnd-User QoS

� End-user performances are obtained through measurementscarried out for different end-user services:� Ping� FTP� WAP� WEB/HTTP

� Traces must be performed at both Air interface andApplication levels

� These performances must be interpreted with a maximum ofinformation concerning the context of the measurements

�Use of a database to register performance results


1.29

1.3 Source of Information for GPRS QoS MonitoringEnd-User QoS Measurements Principles

� GPRS performance tests performed� with PDN (real end-user QoS)� without PDN (BSS+GSS QoS: use of a local server on the

Gi interface just after the GGSN)� The use of a too old or too new mobile can be risky

�Reference mobiles are Sagem (OT96, PW959, OT190),Motorola (T260. T280), Siemens (S45)

� Use of a PC preferably with Windows 2000� Use of the Agilent software E6474A Nitro

� to pick up the transferred frames� to calculate the throughput at RLC layer

� Use of database to register performance results


1.30

1.3 Source of Information for GPRS QoS MonitoringGSS QoS

� Counters:� in the SGSN� in the GGSN� in the HLR

� Traces:� BSS-SGSN interface (Gb)� GGSN-PDN interface (Gi)� intra-GSS interface (Gn)


1.31

1.3 Source of Information for GPRS QoS MonitoringBSS QoS

� Counters:� in the MFS (specific to GPRS)� in the BSC (in relation to GSM)

� Traces:� Air interface (Um)� Ater interface (GCH)� MFS-BSC interface (GSL)� BSS-SGSN interface (Gb)


1.32

1.3 Source of Information for GPRS QoS Monitoring BSS QoS Measurements Principles

� For the Air interface trace:� Use of a too old or too new mobile can be risky

�Reference mobiles are Sagem (OT96, PW959, OT190),Motorola (T260. T280), Siemens (S45)

� Use of a PC preferably with Windows 2000� Use of the Agilent software E6474A Nitro

� For the GCH, GSL, Gb interface trace:� Use of a protocol analyzer with the Alcatel BSCGP stack

� The reference analyzer is Tektronix K1205 v2.40� Use of a post-processing tool

� The reference tool is COMPASS GPRS




1.4 Dependencies between BSS GSM and GPRSQoS


1.34

1.4 Dependencies between BSS GSM and GPRS QoSImpacts

GSM QoS

GPRS QoS

� Bad radio conditions like coverage or interference problems degrading GSM QoS will also provoke BSS GPRS QoS problems� Bad BSS GPRS performance will not always be correlated to GSM QoS problems:

� Congestion can be due to a lack of resource specific to GPRS� Low throughput can be due to a bad setting of radio algorithms specific to GPRS

� On the other hand GPRS traffic can induce or worsen GSM QoS performance:� PS traffic can increase CS congestion� PS signaling using CCCH channels can induce PS AGCH and/or PCH overload and eventually SDCCH congestion


1.35

Time allowed:10 minutes

1.4 Dependencies between BSS GSM and GPRS QoSExercise

� Among the following list of typicalproblems in a GSM network:

Find the ones having an impact onBSS GPRS QoS

Typical BSS GSM problem Impact on BSS GPRS QoSCoverageInterferencepath unbalanced at cell fringeTRX HW degradationAbis MW problemA interface congestionSDCCH congestionTCH congestionRate of LU/call too highHandover failure too high




1.5 Impact of GMM/SM signaling on BSS QoSinterpretation

B8

� This chapter is also valid for B7 release.


1.37

1.5 Impact of GMM/SM Signaling on BSS QoS Interpretation GPRS Protocol Layers

Physicallayer

L2-GCHL1-GCH

MS BTS MFS SGSN

relay

relay BSSGP

Um Abis/Ater Gb

Physical layer

Physicallayer

Framerelay

RLC

L2-GCHL1-GCH

MACMAC

RLC

Physicallayer

Framerelay

BSSGP

PCU

IP

LLC

GMMSNDCP SM

LLC

SNDCPSMGMM

User data in IP packets

SM signaling messages

GMM signaling messages

LLC frames

B8

� For PS service the BSS simply relays the LLC frames between the MS and the SGSN.� GPRS GMM/SM signaling messages are transferred through the BSS as User data.

� Therefore a BSS Data transfer procedure (called TBF) is carried out for either user data transfer or MS-SGSN signalingmessage transmission.

� BSS GPRS QoS indicators have to be carefully interpreted especially in the case of a high load of GPRSsignaling.

� BSSGP = BSS Gprs Protocol. Functions:� to relay LLC frame over the Gb, with no guarantee of integrity (relaying user data and GMM / SM messages: session,

RA_update and paging procedures).� There is 1 BSSGP frame for 1 LLC frame


1.38

1.5 Impact of GMM/SM Signaling on BSS QoS InterpretationGMM/SM Signaling Load

� There are a lot of GPRS signaling message in case of:� cell update� RA update (Normal, Periodic)

� There are less GPRS signaling message in case of :� GPRS attach� GPRS detach� PDP context activation� PDP context de-activation

B8

� BSS GPRS QoS indicators must be carefully interpreted knowing that TBF are used for both data and signaling transfer.� Gb traces might be needed for a better understanding of QoS problems.


1.39


1 Role of BSS in GPRS QoS MonitoringExercise

� A customer complains about the factthat transferring a file from his laptop tohis home computer using GPRSconnected to internet takes too muchtime.

� What will you do if you have toinvestigate this customer complaint?

B8



2 Recalls on the Main BSS GPRS TelecomProcedures

B8

� This chapter is a summary of GPRS basics. It is also valid for B7 release.


1.41

2 Recalls on the Main BSS GPRS Telecom ProceduresSession Presentation

� Objective: to be able to describe the main BSS GPRSprocedures and algorithms having an impact on QoS

� Program:� 2.1 GPRS Logical Channel� 2.2 TBF: Data Transfer Procedure between the MS and the

BSS� 2.3 Gb: BSSGP Protocol and Frame

B8




2.1 GPRS Logical Channels

B8


1.43

2.1 GPRS Logical Channels

PDCH

Master PDCH Slave PDCH

PBCCH PCCCH

PDTCH PACCH

PTCH PTCCH

Primary MPDCH

PPCH PAGCH

Secondary MPDCH

physical channel

control channel

traffic channel

signaling associated control channel

logical channel category

logical channel

B8

�




2.2 TBF: Data Transfer Procedure between theMS and the BSS

B8


1.45

2.2 TBF: Data Transfer Procedure between the MS and the BSS Radio Resources

� Temporary Block Flow (TBF): unidirectional flow of data betweenthe MS and the MFS for the transfer of one or more LLC PDUs

� Radio resources allocated to a TBF are:� DL TBF: TFi, list of PDCHs, PTCCH/PACCH TS, TAi� UL TBF: TFi, list of PDCHs, USFs, PTCCH/PACCH TS, TAi

PDCH 1

B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11

PDCH 2

B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11

PDCH 3

B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11

TBF with TFI = 5 TBF with TFI = 17 TBF with TFI = 24

B8

� A Temporary Block Flow is a temporary, unidirectional physical connection across the Um interface, between one mobile andthe BSS. The TBF is established when data units are to be transmitted across the Um interface and is released as soon as thetransmission is completed.� For UL TBF 1 USF value is assigned to each PDCH allocated to the the TBF for UL PDTCHs allocation (UL transmission ofRLC data blocks)


1.46

2.2 TBF: Data Transfer Procedure between the MS and the BSS TBF Phases

� The TBF procedure can be split as represented below

� During an on-going TBF (progress) in one direction, a TBF in theother direction can be established quicker than usually

establishment progress release

Radio resources to be usedduring the data transfer arereserved by the BSS andare assigned to the MS

Data transfer throughRLC blocks transmission

Radio resources are freed

B8

� A Temporary Block Flow is a temporary, unidirectional physical connection across the Um interface, between one mobile andthe BSS. The TBF is established when data units are to be transmitted across the Um interface and is released as soon as thetransmission is completed.� For UL TBF 1 USF value is assigned to each PDCH allocated to the the TBF for UL PDTCHs allocation (UL transmission ofRLC data blocks)


1.47

� In order to establish a DL TBF faster the release of a UL TBFcan be delayed� T_DELAYED_FINAL_PUAN is the time during which a DL TBF

can be established using the UL TBF radio resources before theyare freed

UL TBF

2.2 TBF: Data Transfer Procedure between the MS and the BSS UL TBF, Delayed Final PUAN

establishment progress release

T_DELAYED_FINAL_PUAN

B8

� T_DELAYED_FINAL_PUAN = 400 ms (default value). It is settable at OMC-R.


1.48

� The release of a DL TBF is delayed after all the DL RLC blockshave been transferred in order to be able to:� establish a UL TBF faster� resume the DL data transfer (new LLC PDU coming from the

SGSN) without having to establish a new DL TBF

DL TBF

2.2 TBF: Data Transfer Procedure between the MS and the BSS DL TBF, Delayed DL TBF Release

progress release

T_NETWORK_RESPONSE_TIME

Modified B8

TBF active TBF delayed

B8

� T_NETWORK_RESPONSE_TIME = 700 ms (default value). It is settable at OMC-R.


1.49

� A DL TBF can be re-established faster during a short time after aDL TBF release using the radio resources of the previous TBF� It is possible because the MS still monitors the radio resources

during timer T3192 after the DL TBF has been released

DL TBF

2.2 TBF: Data Transfer Procedure between the MS and the BSS DL TBF, Fast Establishment

release

T3192

TBF active TBF delayed

Fast DL TBFestablishment

on PACCH

possible

B8

� T3192 = 500 ms (default value). It is settable at OMC-R but 500 ms is the minimum allowed value.


1.50

� After T3192, a DL TBF has to be established on ControlChannels:� faster during DRX_TIMER_MAX when the MS is in Non-DRX

mode� slower afterwards when the MS is in DRX mode

DL TBF

2.2 TBF: Data Transfer Procedure between the MS and the BSS DL TBF, Establishment in DRX Mode

TBF release

DRX_TIMER_MAX

TBF active

TBF delayed

T3192

on PCHor PPCH

of MS paging group

DL TBF establishment

possible

on AGCHor

any PPCH

B8

� DRX_TIMER_MAX = 2 s (default value). It is settable at OMC-R.




2.3 Gb: BSSGP Protocol and Frame

B8


1.52

2.3 Gb: BSSGP Protocol and FrameL1bis

� Bearer Channels

L1

NS (SNS)

NS (NSC)

BSSGP

MFS

L1

NS (SNS)

NS (NSC)

BSSGP

SGSN

Gb interface

PCM BC i

BC j

PCM

BC y

BC x

B8

�The Gb physical interface consists of one or more 64 Kbit/s channels on one or more physical lines at 2048 Kbit/s�Both individual 64 Kbit/s and n*64 Kbit/s channels are supported by the MFS�A Bearer Channel (BC) is a n*64 Kbit/s channel (1 ≤ n ≤ 31)

�NB: among the 16 PCM links offered per PCU, 8 only are dedicated to the Gb interface, 4 for the upload and 4 for thedownload. The maximum transfer capacity point to point aver the Gb interface in one direction is then 31*64kbps*4 =8192kbps.


1.53

2.3 Gb: BSSGP Protocol and FrameNetwork Service 1/3

� The Sub-Network Service (SNS) sub-layer is dependent on thetransmission network and manages Permanent Virtual Channels(PVCs)

L1

NS (SNS)

NS (NSC)

BSSGP

MFS

L1

NS (SNS)

NS (NSC)

BSSGP

SGSN

Frame Relay NetworkPVCaDLCIx

PVCmDLCIαααα

PVCbDLCIy

PVCnDLCIββββ

Gb interface

B8

�Concept of PVC:�A PVC is a synchronous access line, semi-permanent connection�the PVC allows the multiplexing on a BC�it is not an end to end link between the MFS and the SGSN�at MFS side a PVC is identified by its Data Link Connection Identifier (DLCI) which is independent of theone defined at SGSN side. DLCI 0 is used for signaling�there is one PVC per BC

�SNS layer, layer 2.1 in the OSI model, offers the Frame Relay technology. The NSC layer, layer 2.2 in the OSImodel, offers the point to point data transfer in both directions.

�The PVC standards are not specific to GPRS. Please refer to the « Frame Relay Forum » organization, theCCITT and ANSI (T1S1.1 workshop) specifications.


1.54


� The Network Service Control (NSC) sub-layer is independentfrom the transmission network and manages NS VirtualConnections (NS-VCs)

L1

NS (SNS)

NS (NSC)

BSSGP

MFS

L1

NS (SNS)

NS (NSC)

BSSGP

SGSNNSVC

NSVCi=11

NSVCNSVCi=12

Gb interface

B8

�Concept of NS-VC:�a NS-VC is an end to end logical link between the MFS and the SGSN�each NS-VC is identified by its NSVCI which has an end to end significance on the Gb interface�there is a one to one relation between one NS-VC and one PVC�Sub-network service function: ordered data transfer

�The main functions of the NSC layer (2.2 layer) are: sequencing of the data transmission, flow control, lostframe management.


1.55


� Concept of NSE:� A Network Service Entity (NSE) groups several NS-VCs (at

least 2 NS-VCs per NSE) = the NSE corresponds to theresources of one GPU

� The concept of NSE is useful for the load sharing betweenthe different NS-VCs: the NS-VCs of the NSE are shared bythe BVC associated to the NSE

� The NSE is identified by an NSEI which has an end-to-endsignificance over the Gb interface

NSVCNSVCi=11

NSVCNSVCi=12L1

NS (SNS)

NS (NSC)

BSSGP

PCU

NSENSEi = 1

B8

�Note: for MM purposes, SGSN needs a 1:1 correspondence NSEI ⇔ RA

2 Mbit/s 2 Mbit/s

BC BC BC

Physical layer

PVC PVC PVCSNS sub-layer

NS-VC NS-VC NS-VC

NSE

NSC sub-layer

BVC BVC BVC sigBSSGP layer

Cell Cell

BSS


1.56

SNS

NSC

BSSGP

SGSN

2.3 Gb: BSSGP Protocol and FrameBSSGP

� BSSGP Virtual Connection (BVC): end to end link between theMFS and the SGSN

L1

SNS

NSC

BSSGP

MFS

L1

Gb interface

NSVC

BVCi=1

BVCi=2

BVCi=n BVCi=1

BVCi=2

BVCi=n

B8

�Two types of BVC:�point to point BVC dedicated to the PS traffic of one cell (BVCi ≠ 0)�signaling BVC (BVCi=0)which is the signaling circuit of all the point to point BVCs of one NSE (GPU)

� For NM reason, the duplet BVCi/NSEi must be unique within a SGSN

� To activate a new cell in a SGSN, it is only needed to add a new BVCi in a NSEi. No update of the NSEiinformation is necessary.


1.57

NSE2

SGSN

NSE1NSE1

NSE2

F.RF.RNetworkNetwork

PCM

2.3 Gb: BSSGP Protocol and Frame Gb Interface - Manageable Entities

PCM

PCM

BVCI=2

BVCI=1

BVCI=3

BVCI=5

BVCI=6BVCI=4

BSC1

BSC2

GPRS Core Network sideBSS side

BC PCMBCPVC

BC BCPVC

NSVC1

NSVC2

PCM

PCM

PCM

BC PCMBCPVC

BC BCPVC

NSVC3

NSVC4

BVCI=2BVCI=2

BVCI=1BVCI=1

BVCI=3BVCI=3

BVCI=5BVCI=5

BVCI=4BVCI=4

BVCI=6BVCI=6

� In B8 apply the followig dimensioning rules:

Gb interfaceMax. number of Gb interface physical linksper GPU

nGb nGb + nAter(mux) ≤ 16 where nAter(mux)

Max. number of Frame Relay bearerchannels per physical link

31

Max. number of Frame Relay bearerchannels per GPU board

124

Max. number of BVCs per GPU board 265 Limit due to the number of cells per BSS(264) + one signalling BVC (1)

Number of signalling BVCs per GPU 1 1 NSE is defined per GPU

Ater interfaceMaximum number of 64 kbit/s signallingchannels (GSL) per GPU

4

Number of Ater(mux) PCM links betweenone GPU and one BSC

nAter(mu

x)

nGb + nAtermux ≤ 16

Atermux sharing granularity for PS traffic g g can be set to:100 % AterMux, or75 % AterMux, or25 % AterMux, or12.5 % Atermux for GPRS traffic

Max. number of BSSs per MFS 22Max. number of GPUs per MFS 30Max. number of BSS per GPU board 1Max. number of cells per MFS 200

0Max. number of TBFs per GPU 960

Maximum number of GPU boards per BSS 6


1.58

2.3 Gb: BSSGP Protocol and Frame Gb Interface - Protocol Model and Entities

SGSNPacket Control Unit function(PCU)

BSS GPRS Protocol(BSSGP)

BSS GPRS Protocol(BSSGP)

Network Service Control(NSC)

Network Service Control(NSC)

BVCI=2BVCI=2

BVCI=1BVCI=1

BVCI=3BVCI=3

BVCI=5BVCI=5

BVCI=6BVCI=6BVCI=4BVCI=4

BSC1

BSC2

GPRS Core Network sideBSS side

Sub-Network Service(SNS)

Physical layer

Sub-Network Service(SNS)

Physical layer

Frame Relay

BVC

NS-VCNSE

PVCBC


1.59

2.3 Gb: BSSGP Protocol and FrameBSSGP Frame

� One BSSGP PDU includes one and only one LLC PDU

GPRS Traffic or signalingTLLIBVCI

LLC frame

BSSGP frame

LLC header

BSSGP header

LLC payload

B8

� In case of traffic data the LLC PDU contains a SNDCP PDU� In case of signaling the LLC PDU contains a GMM or SM message



3 Description of the Main BSS QoS Counters andIndicators

B8


1.61

3 Detection of the Main BSS QoS Counters and IndicatorsSession Presentation

� Objective: to be able to interpret the BSS GPRS QoS indicatorsattached to each BSS GPRS procedure or algorithm having animpact on QoS and to interpret the BSS GPRS PM countersused in the computation formulae of QoS indicators

� Program:� 3.1 Data Transfer Establishment� 3.2 Data Transfer Progress� 3.3 Data Transfer Release� 3.4 MS Sessions / Transfers� 3.5 Resource Usage� 3.6 CS and MCS Adaptation� 3.7 Cell Reselection

B8



3 Detection of the Main BSS QoS Counters andIndicators

3.1 Data Transfer Establishment

B8


1.63

3.1 Data Transfer EstablishmentTBF Establishments

Data Transfer establishment

UL TBF establishment DL TBF establishment

MS in PIM MS in PTM MS in PIM MS in PTM

MS in MM Ready state MS in MM Standby stateMS in MM Ready state

PS Paging

DRX

on CCCH on PCCCH

1-Phase

2-Phase

1-Phase

2-Phase

on CCCH on PCCCH

Non-DRX

DRX

Non-DRX

UL TBFrunning

DL TBFrunning

T3192running

B8

Modified B8

Modified B8

� UL TBF establishment are of 5 types:

1. On CCCH 1 Phase access: when MS is in Packet Idle Mode and no PCCCH is available in the cell and MS does notneed more than 1 PDCH and wants to transfer blocks in RLC acknowledge mode

2. On CCCH 2 Phase access: when MS is in Packet Idle Mode and no PCCCH is available in the cell and MS needsmore than 1 PDCH or wants to transfer blocks in RLC unacknowledge mode

3. On PCCCH 1 Phase access: when MS is in Packet Idle Mode and PCCCH is available in the cell and MS does notneed more than 1 PDCH and wants to transfer blocks in RLC acknowledge mode

4. On PCCCH 2 Phase access: when MS is in Packet Idle Mode and PCCCH is available in the cell and MS needsmore than 1 PDCH or wants to transfer blocks in RLC unacknowledge mode

5. During a DL TBF: when MS is in Packet Transfer Mode in DL

� DL TBF establishment are of 6 types:

1. On CCCH DRX mode: when MS is in Packet Idle Mode and no PCCCH is available in the cell and MS is listening toall AGCH channels

2. On CCCH Non-DRX: when MS is in Packet Idle Mode and no PCCCH is available in the cell and MS is listening toall PCH channels of its CS paging group

3. On PCCCH DRX mode: when MS is in Packet Idle Mode and PCCCH is available in the cell and MS is listening toall PPCH channels of its PCCCH channel

4. On PCCCH Non-DRX: when MS is in Packet Idle Mode and PCCCH is available in the cell and MS is listening to allPPCH channels of its PS paging group

5. During an UL TBF: when MS is in Packet Transfer Mode in UL

6. When T3192 is running: when a DL TBF has been released at the MS side and before the previously used radioresources are released (at T3192 expiry)


1.64

P49

3.1 Data Transfer EstablishmentUL TBF Establishment 1-Phase Access on CCCH, Success

MS BTS BSC MFS

TA calculationRACH Channel request + TA

(EGPRS Packet)Channel request

AGCHImmediate assignment

Immediate assignmentPDCH, TFI, USF, TAI, TA, CS(MCS, EGPRS window size)

MS switcheson assignedPDCH

USF Scheduling

PDTCHUSF Scheduling

RLC data block

PACCH

Packet UL Ack/Nack

PDTCH

TLLI, TFI

T_USF_Scheduling_AGCHexpiry

P62c

P30cContention

resolution

T_GPRS_ASSIGN_AGCH

RLC data block

TLLI, TFI

Packet UL Ack/Nack

P62d

GPRS EGPRS

P30d

GPRS EGPRS

PDCH & GCHallocation

B8

� In case a Channel Request or EGPRS Packet Channel Request is received from the mobile station, an ImmediateAssignment message is sent to the MS assigning the radio respources.

� In case a Channel Request is received on RACH, the BSS does not know the multislot class of the MS. Consequently,the Alcatel BSS assigns only one PDCH to the MS.

� In case an EGPRS Packet Channel Request message is received from the mobile station the EGPRS multislot class ofMS is known by the BSS. However only one PDCH is allocated due to the limitation of the Immediate Assignmentmessage.

� if the PDCH is allocated on a non-EGPRS capable TRX an Immediate Assignment message in GPRS modeis sent to the MS including PDCH id, USF value, TFI value, TAI value, TA value, GPRS coding scheme to beused.

� If the PDCH is allocated on an EGPRS capable TRX, a Immediate Assignment message in EGPRS mode issent to the MS including PDCH id, USF value, TFI value, TAI value, TA value and also EGPRS modulation andcoding scheme to be used.

� Timers� T_USF_scheduling_AGCH: Time between the sending of the Assignment Command message to the BTS and thescheduling of the first UL block on the PDCH. This internal MFS timer is always expiring in order to leave time to the MSto switch from CCCH to PDCH time slot.� T_GPRS_ASSIGN_AGCH – T_USF_scheduling_AGCH: Started at T_USF_scheduling_AGCH expiry, stopped whenreceiving the first UL block from the MS.

�T_GPRS_ASSIGN_AGCH = 0.8 s (default value) but computed as a function of the CCCH configuration inthe cell. It is not settable at OMC-R.� T_USF_scheduling_AGCH = 100 ms (default value) not settable at OMC-R

� Contention resolution procedure is used in order to avoid that two MS sending a Channel Request at the same time use thesame allocated radio resource to send data.

� each MS sends its TLLI in the first RLC Data Block� the TLLI of the MS chosen by the BSS is present in the Packet UL Ack/Nack from the MFS� the other MS will stop using the radio resource when receiving the Packet UL Ack/Nack with another TLLI

� New counters in B8: P30d, P62d.� Modified in B8: P30c, P62c, P49 take into account TBF established in EGPRS mode.


1.65

3.1 Data Transfer EstablishmentUL TBF Establishment, Fast Access Gain

UL Data

ResourceRequest toBSC forconcurrentDL TBFIMM ASS UL

CHNRQ

MS BSS Server

PDAS

DL Data

Without Immediate UL establishment

ResourceRequest toBSC forconcurrentDL TBF

IMM ASS UL

CHNRQ

MS BSS Server

UL Data

PTR

DL Data

With Immediate UL establishment

gain

EN_FAST_INITIAL_GPRS_ACCESS = disabled

No MPDCH

MIN_PDCH = 1

EN_FAST_INITIAL_GPRS_ACCESS = enabled

No MPDCH

MIN_PDCH = 1

B8

� Fast initial PS access feature is enabled if EN_FAST_INITIAL_GPRS_ACCESS = enabled

� for that MIN_PDCH > NB_TS_MPDCH is a mandatory condition

� Example: If EN_FAST_INITIAL_GPRS_ACCESS = enabled when NB_TS_MPDCH = 1 and MIN_PDCH =3 it means that 1MPDCH and 2 SPDCH channels are established permanently in the cell (corresponding PDCJ and GCH are allocated)


1.66

33.1 Data Transfer EstablishmentUL TBF Establishment 2-Phase Access on CCCH, Success

MS BTS BSC MFS




Immediate assignmentPDCH id, TBF starting time,

TA, 1 (multiple) block(s)

MS switcheson assignedPDCHs

PACCHPacket resource request

Packet UL assignmentPACCH

Packet resource request

Packet UL assignmentTLLI, PDCHs, USFs, TFI, TAI, TA, CS

(MCS, EGPRS window size)

PDTCHUSF Scheduling USF Scheduling

TLLI, MS Radio Access Capability, QoS(Additional Radio Access Capability)

RLC data blockPDTCH

P49

T_GPRS_ASSIGN_AGCH

T_ACK_WAIT

Contention

resolution

RLC data block

MS switcheson allocatedRLC block(s)

T3168

P62c P62d

GPRS EGPRS

P30c P30d

GPRS EGPRS



B8

�A two phase access is initiated:

−when an GPRS MS wants to use the TBF to send user data in RLC unacknowledged mode, or,

−when an (E)GPRS MS wants to precise QoS parameters (e.g. Peak_Throughput_Class, Radio_Priority), or,

−when an GPRS MS wants to provide the BSS with its multislot class in case of an uplink access done on CCCH, or

−when an GPRS MS wants to establish the TBF to send user data in RLC acknowledged mode and the amount of data tosend takes more than 8 RLC/MAC blocks (Note 1 and Note 2), or

−If the EGPRS PACKET CHANNEL REQUEST is not supported in the cell (Note: the Alcatel BSS always supports theEGPRS PACKET CHANNEL REQUEST), when an EGPRS MS wishes to send user data or signaling data.

−If the EGPRS PACKET CHANNEL REQUEST is supported in the cell, when an EGPRS MS wants to use the TBF to senduser data in RLC unacknowledged mode, or,

−If the EGPRS PACKET CHANNEL REQUEST is supported in the cell, when an EGPRS MS wants to establish the TBF tosend user data in RLC acknowledged mode and the amount of data to send takes more than 8 RLC/MAC blocks (Note 3 andNote 4).

Note 1: The number of blocks must be calculated assuming channel coding scheme CS-1.Note 2: The mobile station can also request one phase access.Note 3: The number of blocks must be calculated assuming modulation and channel coding scheme MCS-1.Note 4: If the cell is EGPRS capable, the mobile station can also request one phase access.

� MS Radio Access Capability IE includes the Multislot class of the MS as well as the QoS required for the transfer� Timers

� T_GPRS_ASSIGN_AGCH, controls the duration between (EGPRS Packet) Channel Request message and the UL radioblock allocated to MS� T_ACK_WAIT: Started when the first UL block is scheduled to the MS, stopped when receiving the first UL block

�T_ACK_WAIT = 1.2 s (default value) not settable at OMC-R� T3168: MS timer started when sending the Packet Resource Request message and stopped when receiving the PacketUL Assignment. It is broadcast in PSI1 message.

� T3168 = 1 s (default value) is settable at OMC-R but 1s is the minimum value� New counters in B8: P30d, P62d.� Modified in B8: P30c, P62c, P49 take into account TBF established in EGPRS mode.


1.67

3.1 Data Transfer EstablishmentUL TBF Establishment 1-Phase Access on PCCCH, Success

MS BTS BSC MFS

TA calculationPRACH (4 A.B.)

(EGPRS)Packet Channel request


Packet UL assignmentPAGCH

Packet UL assignmentPDCHs, USFs, TFI, TAI, TA, CS (MCS, EGPRS window size)


RLC data block

T_ACK_WAIT

PDTCHRLC data block

Contention

resolution

TLLI, TFI

PACCH

Packet UL Ack/Nack

TLLI, TFI

Packet UL Ack/Nack


(EGPRS) Multislot class

P30a P30d

GPRS EGPRS

P62a P62d

GPRS EGPRS


B8

� Possible causes for the one phase access for GPRS:-One phase access (MS multislot class provided)-Short access (less than 8 RLC blocks)-Paging response-Cell update-MM procedures (GPRS Attach, GPRS Detach, RA update)-Single block without TBF establishment

- Note: The access indicating “Single Block Without TBF Establishment” is supported by the Alcatel BSS: such an accessis used by the MS to report a Packet Measurement Report message or a Packet Cell Change Failure message in PacketIdle Mode

� Possible causes for the one phase access for EGPRS:-One phase access-Short access-signaling

� New counters in B8: P30d, P62d.� Modified in B8: P30a, P62a take into account TBF established in EGPRS mode.


1.68

3.1 Data Transfer EstablishmentUL TBF Establishment 2-Phases Access on PCCCH, Success

MS BTS BSC MFS

TA calculation


PACCHPacket resource request





Packet resource requestTLLI, MS Radio Access Capability, QoS(Additional Radio Access Capability)

T_ACK_WAIT

Contention

resolution

RLC data blockPDTCH

RLC data block

MS switcheson allocatedRLC block(s)

PRACH (4 A.B.)

(EGPRS)Packet Channel request (EGPRS)

Packet Channel request


Packet UL assignment

T_UL_Assign_PCCCH

PDCH id, TBF starting time, TA, 1 (multiple) block(s)



T3168

P62a P62d

GPRS EGPRS

P30a P30d

GPRS EGPRS


B8

� Timer: T_UL_ASSIGN_PCCCH controls the duration between (EGPRS) Packet Request message and the UL radio blockallocated to MS

�T_UL_ASSIGN_PCCCH = 0.4 s (default value) but is settable at OMC-R

� New counters in B8: P30d, P62d.� Modified in B8: P30a, P62a take into account TBF established in EGPRS mode.


1.69

3.1 Data Transfer EstablishmentUL TBF Establishment during a DL TBF, Success

MS BTS BSC MFS

P30b

T_ACK_WAIT

DL transfer

RLC data block, pollingRLC data blockPDTCH

Packet DL Ack/NackPACCH

(EGPRS) Packet DL Ack/Nack with Channel request


Packet UL AssignmentPDCHs, USFs, TFIUL,TAI, CS (MCS, EGPRS window size)

P62b

T3168


RLC data blockPDTCH

RLC data block

GPRS EGPRS

GPRS EGPRS


B8

� This scenario corresponds to an UL TBF establishment in PTM without Reallocation of the on-going DL TBF

� Packet UL Assignment message is repeated N_SIG_REPEAT times because if the MS did not decode the Packet UL Assignmentthen the MS will try again to establish the UL TBF only after T3168 expiry.

� N_SIG_REPEAT = 1 (default value) and is not settable at OMC-R. Therefore the Packet UL Assignment is sent 2 timesin a row.

� Modified in B8: P30b, P62b take into account TBF established in EGPRS mode.


1.70


3.1 Data Transfer EstablishmentUL TBF Establishment, Exercise

� Exercise 1: Identify the type of UL TBFestablishment procedure among theprovided traces 1, 2, 3, 4, 5

� Exercise 2: Using the trace 9 of a ULTBF establishment during a DL TBF,identify the values of:– TFIUL

– TFIDL

– PDCHs allocated for the UL TBF


1.71

3.1 Data Transfer EstablishmentUL TBF Establishment, Failures

UL TBF establishment FAILURE

BSS ResourceCongestion Radio pb BSS pb Gb pb

Radiocongestion

GPU DSPcongestion

Atercongestion

GPU CPUcongestion

�


1.72

3.1 Data Transfer EstablishmentUL TBF Establishment, Failures, BSS Resource Congestion

MS BTS BSC MFS



AGCH

Immediate assignment rejectImmediate assignment reject

Wait indication

No resource available(radio+Ater+DSP+CPU)

P27+P105h+P105d+P105f

TA calculation



No resource available(radio+Ater+DSP+CPU)

PAGCH or PACCH

Packet access reject Packet access reject

Wait indication

or Packet resource requestor Packet DL Ack/Nack with

Channel request

or Packet resource requestor Packet DL Ack/Nack with

Channel request

� The first scenario corresponds to:

� the impossibility to allocate the resources for an UL TBF establishment 1 phase access on CCCH

� the impossibility to allocate the UL block(s) for the UL TBF establishment 2 phase access on CCCH

� The second scenario corresponds to:

� the impossibility to allocate the resources for an UL TBF establishment 2 phase access on CCCH

� the impossibility to allocate the resources for an UL TBF establishment 1 phase access on PCCCH

� the impossibility to allocate the UL block(s) or the resources for an UL TBF establishment 2 phase access on PCCCH

� the impossibility to allocate the resources for an UL TBF establishment during a DL TBF


1.73

3.1 Data Transfer EstablishmentUL TBF Establishment on CCCH, Failures, Radio

MS BTS BSC MFS

TA calculationRACH

Channel request + TA(EGPRS Packet)

Channel request


Immediate assignmentPDCH, TFI, USF, TAI, TA, CS(MCS, EGPRS window size)

USF Scheduling

PDTCHUSF Scheduling

RLC data blockPDTCH

T_USF_Scheduling_AGCHexpiry

T_GPRS_ASSIGN_AGCHexpiry P28





T_ACK_WAITexpiry

P28


� a radio failure occurring an UL TBF establishment 1 phase access on CCCH


� a radio failure occurring an UL TBF establishment 2 phase access on CCCH

� If the contention resolution fails the MS will try to establish the UL TBF up to 4 more times.

� Usual radio problem counted are due to interference or bad

� but Abis microwave transmission problem or some BSS problem (RSL overload) can be counted as radio


1.74

3.1 Data Transfer EstablishmentUL TBF Establishment on PCCCH, Failures, Radio

MS BTS BSC MFS

TA calculationPRACH (4 A.B.)



Packet UL assignmentPDCHs, USFs, TFI, TAI, TA, CS (MCS, EGPRS window size)


P28T_ACK_WAITexpiry



PDTCHRLC data block





P28T_ACK_WAITexpiry


� a radio failure occurring an UL TBF establishment 1 phase access on PCCCH


� a radio failure occurring an UL TBF establishment 2 phase access on PCCCH


1.75

3.1 Data Transfer EstablishmentUL TBF Establishment during a DL TBF, Failures, Radio

MS BTS BSC MFS

P28

DL transfer / Active or Delayed phase

RLC data block, pollingRLC data blockPDTCH

Packet DL Ack/NackPACCH

(EGPRS) Packet DL Ack/Nack with Channel request


Packet UL AssignmentPDCHs, USFs, TFIUL,TAI, CS (MCS, EGPRS window size)

T3168


T_ACK_WAITexpiry

� If a DL TBF re-allocation is triggered upon UL TBF establishment:

� if the DL TBF re-allocation fails due to radio problem then counter P28 is also incremented


1.76

3.1 Data Transfer EstablishmentUL TBF Establishment, Failures, Gb, BSS

MS MFS SGSN

UL establishment requestCell identity

Cell BVCunavailable

P66

� Problem at Gb interface level� When the CELL is in the operational state “disabled” in the

BSS�O&M problem

� Problem at BSS level� which is not linked to Congestion, Radio, Gb

� no specific counter

� BSS problem can be linked to a Hardware or a Software failure


1.77

3.1 Data Transfer EstablishmentDL TBF Establishment on CCCH, MS in Ready State

MS BTS BSC MFSLLC PDU

Immediate assignmentPDCH, TFI, TAI, (EGPRS)Immediate assignment

PCH/AGCH (DRX/Non-DRX)

Packet DL assignment, polling

PDCHs, TFI, TAI, (EGPRS window size)PACCH

Packet DL assignment

PACCH (4 A.B.)Packet control Ack

Packet control AckTA calculation

Timing Advance / Power control

PACCH

TA / PC

PDTCHRLC data block


P91f, P91c

T3190

t_assign_agch_paccht_assign_pch_pacch

expiry & restart

P90f, P90c

P91g

GPRS

EGPRS

P90g

GPRSEGPRS

P53c, P49


B8

�If the MFS does not receive the Packet Control Ack message from the MS:� it sends again the Packet Downlink Assignment message up to MAX_GPRS_ASSIGN_PCH_RETRANS if MS in DRXmode or up to MAX_GPRS_ASSIGN_AGCH_RETRANS if MS in Non-DRX mode� if the Maximum number of retransmission of Packet Downlink Assignment is reached then the MSF restarts the wholeDL TBF establishment procedure up to MAX_DL_RETRANS times

�MAX_GPRS_ASSIGN_PCH_RETRANS = 3 (default value)�MAX_GPRS_ASSIGN_AGCH_RETRANS = 3 (default value)�MAX_DL_RETRANS = 3 (default value)

� Repetitions af the same TBF establishment are not counted, only first attempt is.

�Timers� T_GPRS_ASSIGN_AGCH: controls the reception of the Packet Control Ack message from MS in Non-DRX mode

�T_GPRS_ASSIGN_AGCH = 0.8 s (default value) but computed as a function of the CCCH configuration inthe cell. It is not settable at OMC-R.

�T_GPRS_ASSIGN_PCH: controls the reception of the Packet Control Ack message from MS in DRX mode�T_GPRS_ASSIGN_PCH = 1.4 s (default value) but computed as a function of the BS_PA_MFRMS CCCHparameter in the cell. It is not settable at OMC-R.

� t_assign_agch_pacch: is the time the MFS waits the Packet Control Ack message after having sent the PacketDownlink Assignment to the MS in Non-DRX mode before repeating the Packet Downlink Assignment message

�its value is computed as T_GPRS_ASSIGN_AGCH / (MAX_GPRS_ASSIGN_AGCH_RETRANS + 1)� t_assign_pch_pacch: is the time the MFS waits the Packet Control Ack message after having sent the Packet DownlinkAssignment to the MS in DRX mode before repeating the Packet Downlink Assignment message

�its value is computed as T_GPRS_ASSIGN_PCH / (MAX_GPRS_ASSIGN_PCH_RETRANS + 1)

� T3190: if this timer expires, MS returns into Packet Idle Mode.� T3190 = 5s (default value)

� New counters in B8: P90g, P91g.� Modified in B8: P90c, P90f, P91c, P91f, P53c, P49 take into account TBF established in EGPRS mode.


1.78

3.1 Data Transfer EstablishmentDL TBF Establishment on PCCCH , MS in Ready State

MS BTS BSC MFS

LLC PDU

PPCH (first/paging group)


PDCHs, TFI, TAI, (EGPRS window size)


PACCH (4 A.B.)Packet control Ack

Packet control AckTA calculation

Timing Advance / Power control

PACCH

TA / PC

PDTCHRLC data block

T3190

P90d, P90a


T_ACK_WAITT_ACK_WAIT_DRX_PCCCH

P91g

GPRS

EGPRS

P91d, P91a

P90g

GPRSEGPRS


B8

� If the MFS does not receive the Packet Control Ack message from the MS:� the MSF restarts the whole DL TBF establishment procedure up to MAX_DL_RETRANS times

� MAX_DL_RETRANS = 3 (default value)� Repetitions af the same TBF establishment are not counted, only first attempt is.

�Timers� T_ACK_WAIT: controls the reception of the Packet Control Ack message from MS in Non-DRX mode

� T_ACK_WAIT = 1.2 s (default value) and is not settable at OMC-R.� T_ACK_WAIT_DRX_PCCCH: controls the reception of the Packet Control Ack message from MS in DRX mode

� T_ACK_WAIT_DRX_PCCCH = 2.5 s (default value) and is not settable at OMC-R.


� New counters in B8: P90g, P91g.� Modified in B8: P90a, P90d, P91a, P91d take into account TBF established in EGPRS mode.


1.79

T3190

PACCHTA / PC

TA / PC

PDTCHRLC data block

RLC data blockPACCHTA / PC

TA / PC

PDTCHRLC data block

RLC data block

3.1 Data Transfer EstablishmentDL TBF Establishment during an UL TBF

MS BTS BSC MFS

UL transfer


PACCH


PDCH(s), TFIDL, TAI, (EGPRS window size)

P91b

P90b

T_ACK_WAITPacket control AckPacket control Ack

RRBP

LLC PDU

PDTCHRLC data block

RRBP+

40 ms


B8

� This scenario corresponds to a DL TBF establishment in PTM without Reallocation of the on-going UL TBF.

� Modified in B8: P90b, P91b take into account TBF established in EGPRS mode.


1.80

semantic01

The SDU contains signaling (e.g. related to GMM)The SDU contains data

coding“T bit” coding

3.1 Data Transfer EstablishmentDL TBF Establishment, Radio Resource Optimisation

MFS

BSSGP PDUn PDCHs allocated

according toMS multislot class

SGSN

(QoS profile, LLC PDU)

Only 1 PDCH allocated

n PDCHs allocatedaccording to

MS multislot class

8octet 1octet 2.2a

octet 3-4

octet 5

IEILength Indicator

Peak bit rate provided by the network, coded as the value part in Bucket Leak Rate/R IE/ GSM 08.18 a)

7 6 5 4 3 2 1

SPARE C/R T A Precedence

QoS Profile IE from BSSGP message GSM 08.18

B8

� New in B8: T bit included in QoS Profile IE of the DL BSSGP PDU is used in order to allocate only 1 PDCH in case of GPRSsignaling transfer.


1.81


3.1 Data Transfer EstablishmentDL TBF Establishment, Exercise

� Exercise 1: Identify the type of DL TBFestablishment procedure among theprovided traces 6, 7, 8 and 10

� Exercise 2: Using the trace 12 find if theDL TBF is established for data orsignaling transfer


1.82

3.1 Data Transfer EstablishmentDL TBF establishment, failures

DL TBF establishment FAILURE

BSS ResourceCongestion Radio pb BSS pb Gb pb

Radiocongestion

GPU DSPcongestion

Atercongestion

GPU CPUcongestion

�


1.83

� BSS resource congestion: radio (PDCH, TAI, TFI), Ater, GPU

� Problem at Gb interface level� When the CELL is in the operational state “disabled” in the

BSS�O&M problem

3.1 Data Transfer EstablishmentDL TBF Establishment, Failures, BSS Resource Congestion, Gb

MFS

LLC PDUs

No resource available (radio+Ater+DSP+CPU)

P14+P105g+P105c+P105e

SGSN

LLC Discarded

MFS

LLC PDUs

Cell BVC unavailableP65

SGSN

LLC Discarded


1.84

� Radio problem

� Problem at BSS level� what is not Congestion, Radio, Gb…


3.1 Data Transfer EstablishmentDL TBF Establishment, Failures, Radio

MS BTS BSC MFS

Packet control Ackt_assign_agch_pacch expiry

or t_assign_pch_pacch expiry

or T_ACK_WAIT expiryor T_ACK_WAIT_DRX_PCCCH expiry

for the last attempt of the same DL TBFestablishment


PDCHs, TFI, TAI, (EGPRS window size)


PACCH or PPCH

PACCH

P15

�If an UL TBF re-allocation is triggered upon DL TBF establishment:

� if the UL TBF re-allocation fails due to radio problem then counter P15 is also incremented


1.85

PACCHTA / PC

TA / PC

PDTCHRLC data block

RLC data blockPACCHTA / PC

TA / PC

PDTCHRLC data block

RLC data block

3.1 Data Transfer EstablishmentFast DL TBF Re-establishment, Success

T3192

MS BTS BSC MFS

DL transfer


PACCH


PDCH(s), TFIDL, TAI, (EGPRS window size)

P91e

P90e

T_ACK_WAITPacket control AckPacket control Ack

RRBP

LLC PDUSame resourcesallocation

PDTCHRLC data block

RRBP+

40 ms

end

begin

T3192&

T3192n

T3190

B8




� T_ACK_WAIT = 1.2 s (default value) and is not settable at OMC-R.


� Modified in B8: P90e, P91e take into account TBF established in EGPRS mode.


1.86

3.1 Data Transfer EstablishmentFast DL TBF Re-establishment, Failures

� All types of failures are counted in the same counters as forother kinds of DL TBF establishment� BSS resource congestion

� radio (PDCH, TAI, TFI):�Ater:�GPU

� DSP:� CPU:

� radio:� Gb:� BSS: no specific counter

P14

P105g

P105c

P105e

P15

P65




� T_ACK_WAIT = 1.2 s (default value) and is not settable at OMC-R.



1.87

3.1 Data Transfer EstablishmentPS Paging

MS BTS BSC MFS SGSN

LLC PDU

MS inStandby

PS Paging

PCH/PPCH

Paging Request/Packet Paging Request

RACH/PRACH

Channel Request/Packet Channel Requestcause =?/cause =?

AGCH/PAGCHImmediate Assignment/Packet Uplink Assignment

MS Ready

DL UNITDATA PDU

USF SchedulingPDTCH

PDTCH

Sending of an LLC PDU (RLC blocks) containing GMM Paging response message

Procedure 1 ?

Procedure 2 ?

P53a/P61a

P53b/P61b

P391a

P391b

PSPS

CSCS

� Identify the procedures 1 and 2 on the following diagram

� CS Paging Request can be sent by the SGSN to the MS through the GMM PS Paging message if GS interface exists (GPRSnetwork configured in NMO I )

� in the case of CS Paging Request sent on PCH or PPCH the MS will proceed by a CS Radio Link Establishmentprocedure


1.88


3.1 Data Transfer Establishment PS Paging, Exercise

� Exercise: Using the trace 7, find the cellin which the MS is located


1

� DL and UL TBF establishment:

TBF establishmentstart

Number of requestsNumber of successes

Success rate

Failure causes

me

TBF establishment end

Congestion

Radio

BSS

Gb

Distribution of number of TSs requested / obtained

Radio

Ater

GPU

Different cases:•DL/UL: idle & transfer mode•DL/UL: MPDCH or not•DL: DRX & non-DRX•DL: T3192 running

Allocation rate

3.1 Data Transfer EstablishmeQoS IndicatoB8

� Number of TBF establishment request gives an idea of GPRS traffic => is a KPI� Nb of Allocation success = Nb of Request - Nb of Congestion� Radio pb GPRS can be specific to GPRS (no radio pb for GSM): can be due to MS behaviour (bad handling of Polling

from BSS)� Tests on Ping have shown that RTT is varying from one MS to another. Some MS are considered as slow others as fast.


1.9

� DL and UL TBF establishment: requests/successes

Transfer phase Fast DL TBF re-establishment T3192 Non-DRX mode DRX mode

time

GPRS/EGPRSequest/success

GPRS/EGPRSequest/success

OnlyEGPRS

OnlyEGPRS

3.1 Data Transfer EstablishmenQoS Indicators, Request/Success

DL TBF establishment requests DL TBF establishment successesTransfer mode P91b Transfer mode P90bWhile T3192 running P91e While T3192 running P90eIdle mode + non-DRX mode + MPDCH P91d Idle mode + non-DRX mode + MPDCH P90dIdle mode + non-DRX mode + no MPDCH P91f Idle mode + non-DRX mode + no MPDCH P90fIdle mode + DRX mode + MPDCH P91a Idle mode + DRX mode + MPDCH P90aIdle mode + DRX mode + no MPDCH P91c Idle mode + DRX mode + no MPDCH P90cIdle mode + with / without MPDCH P91g Idle mode + with / without MPDCH P90g

UL TBF establishment requests UL TBF establishment successesIdle mode + MPDCH P62a Idle mode + MPDCH P30aIdle mode + no MPDCH P62c Idle mode + no MPDCH P30cTransfer mode P62b Transfer mode P30bIdle mode + with / without MPDCH P62d Idle mode + with / without MPDCH P30d

B8

� New counters in B8: P62d, P30d, P91g, P90g� All other counters have been modified in order to take into account EGPRS mode.


1.91

� DL and UL TBF establishment: failures

% TBF establishment failuresDownlink Uplink

Congestion rate (radio-Ater-GPU)

(P14 + P105g + P105c + P105e) / (P91a +P91b+ P91c +P91d + P91e + P91f)

Congestion (radio-Ater-GPU)rate

(P27 + P105h + P105d + P105f) / (P62a + P62b + P62c)

Radio congestion rate P14 / (P91a + P91b + P91c + P91d + P91e + P91f) Radio congestion rate P27 / (P62a + P62b + P62c)% of time during whichPDCH allocation for DL TBFis not possible due tocongestion

(P13 / 10) / GP % of time during whichPDCH allocation for UL TBFis not possible due tocongestion

(P26 / 10) / GP

ATer congestion rate P105g / (P91a + P91b + P91c + P91d + P91e + P91f) ATer congestion rate P105h / (P62a + P62b + P62c)DSP congestion rate P105c / (P91a + P91b + P91c + P91d + P91e + P91f) DSP congestion rate P105d / (P62a + P62b + P62c)CPU congestion rate P105e / (P91a + P91b + P91c + P91d + P91e + P91f) CPU congestion rate P105f / (P62a + P62b + P62c)Radio problem rate P15 / (P91a + P91b + P91c + P91d + P91e + P91f) Radio problem rate P28 / (P62a + P62b + P62c)Gb problem rate P65 / (P91a + P91b + P91c + P91d + P91e + P91f) Gb problem rate P66 / (P62a + P62b + P62c)BSS problem rate (P91a + P91b + P91c + P91d + P91e + P91f - P14 - P15

- P90a - P90b - P90c- P90d - P90e - P90f - P65 - P105e- P105c - P105g) / (P91a + P91b + P91c + P91d + P91e+ P91f)

BSS problem rate ((P62a + P62b + P62c - P27 - P28 - P30a - P30b - P30c- P66 - P105h - P105f - P105d) / (P62a + P62b + P62c)

3.1 Data Transfer EstablishmentQoS Indicators, Failure

� Per GPU a CPU load state is managed. When the CPU load state reaches the maximum (crosses a high threshold) thenno new TBF can be established on this GPU.

� Radio congestion is often low. When high it is often linked to a GPU reset or BBS Pb => Indicators based on distribution ofnb of TS allocated/requested give a better idea of the “congestion” situation

� On DL TBF establishment failure: a RADIO STATUS message is sent to the SGSN


1.92

� DL and UL TBF establishment: Partial/Optimal initial TSallocation, MS type distribution

TS distributionDL TBF establishment UL TBF establishment

Number of TBF establishments requesting 1 slotwhich are satisfied at once by the initialallocation

P160 Number of TBF establishments requesting 1 slotwhich are satisfied at once by the initialallocation

P161

Number of TBF establishments requesting 2 or 3slots which are satisfied at once by the initialallocation

P162 Number of TBF establishments requesting 2 or 3slots which are satisfied at once by the initialallocation allocation

P163

Number of TBF establishments requesting 4 or 5slots which are satisfied at once by the initialallocation

P164 Number of TBF establishments requesting 4 or 5slots which are satisfied at once by the initialallocation

P165

Number of TBF establishments requesting 2 or 3slots which are partially satisfied by the initialallocation

P166 Number of TBF establishments requesting 2 or 3slots which are partially satisfied by the initialallocation

P167

Number of TBF establishments requesting 4 or 5slots which are partially satisfied by the initialallocation

P168 Number of TBF establishments requesting 4 or 5slots which are partially satisfied by the initialallocation

P169

TBF establishments requesting 2 or 3 slots partialsuccess rate

P166 /(P162 + P166)


P167 /(P163 + P167)


P168 /(P164 + 168)


P169 /(P165 + P169)

3.1 Data Transfer EstablishmentQoS Indicators, TS Allocation

� MS on the market: 4 TS DL max, 2 TS UL max (MS class 9 & 10)


1.9

Downlink TBF establishment per MS type

0%

20%

40%

60%

80%

100%

14/08

/2003

16/08

/2003

18/08

/2003

20/08

/2003

22/08

/2003

24/08

/2003

26/08

/2003

28/08

/2003

30/08

/2003

01/09

/2003

03/09

/2003

05/09

/2003

07/09

/2003

09/09

/2003

11/09

/2003

13/09

/2003

919293949596979899

4-5 partially

2-3 partially

4 or 5 TS

2 or 3 TS

1 TS

Uplink TBF establishment per MS type

0%

20%

40%

60%

80%

100%

14/08

/2003

16/08

/2003

18/08

/2003

20/08

/2003

22/08

/2003

24/08

/2003

26/08

/2003

28/08

/2003

30/08

/2003

01/09

/2003

03/09

/2003

05/09

/2003

07/09

/2003

09/09

/2003

11/09

/2003

13/09

/2003

96.5

97

97.5

98

98.5

99

99.54-5 partially

2-3 partially

4 or 5 TS

2 or 3 TS

1 TS

3.1 Data Transfer EstablishmenQoS Indicators, TS Allocation, Graph

� Typical values of DL TBF partial establishment success rate are:� Without congestion (GSM+GPRS): less than 10% of the total of establishment successes.� With some congestion: between 10 and 20%� With high level of congestion: more than 20%

� But these values depend on the penetration rate of MS with 4 TS on the downlink (class 8,10) => Correlation needed withTBF establishment partial success rate per Nb of TS requested (see next page)

➨ Use of indicators of partial success rate according to TS distribution to assess GPRS Radio Congestion� Congestion will be reduced by reducing the GPRS signaling load (ex: Nb of RA update decreased when Suspend/Resume

is successful)


1.94

� DL and UL TBF establishment: success rate

KPI

KPI

TBF establishment requests and successesDownlink Uplink

Total number of TBFestablishmentrequests

P91a+P91b+P91c+P91d+P91e+P91f

Total number ofTBFestablishmentrequests

P62a+P62b+P62c

Total number of TBFestablishmentsuccesses

P90a+P90b+P90c+P90d+P90e+P90f

Total number ofTBF establishmentsuccesses

P30a+P30b+P30c

TBF establishmentsuccess rate

(P90a+P90b+P90c+P90d+P90e+P90f) /(P91a+P91b+P91c+P91d+P91e+P91f)

TBFestablishmentsuccess rate

(P30a+P30b+P30c) /(P62a+P62b+P62c)

TBF establishmentallocation rate

( (P91a + P91b + P91c + P91d+ P91e + P91f) - (P105c +P105e + P14 + P105g)) /(P91a + P91b + P91c + P91d+ P91e + P91f)

TBF establishmentallocation rate

((P62a + P62b + P62c) -(P105f + P27 +P105h +P105d)) / (P62a + P62b+ P62c)

3.1 Data Transfer EstablishmentQoS Indicators, KPI


1.95

� Thresholds:� Significant traffic is reached for 2000 DL TBF

requests/cell/day(less when a Delayed downlink TBF release is activated)

� A UL/DL TBF establishment success rate is seen as goodabove 95% (except if CS2 is used at the beginning of aDL TBF)

Downlink TBF Establishment

02000400060008000

10000120001400016000

14/08

/2003

16/08

/2003

18/08

/2003

20/08

/2003

22/08

/2003

24/08

/2003

26/08

/2003

28/08

/2003

30/08

/2003

01/09

/2003

03/09

/2003

05/09

/2003

07/09

/2003

09/09

/2003

11/09

/2003

13/09

/2003

90

92

94

96

98

100

102 BSS failGb failRadio failCongestionRequest% Allocated% Success

3.1 Data Transfer EstablishmentQoS Indicators, DL TBF Establishment, Graph

� TBF establishment indicators should be provided on a per DL and UL basis because the procedures are very different andQoS have to be assessed and interpreted differently

� UL TBF establishment can be degraded due to ghost RACH� Amount of bytes transferred at RLC or LLC level can be better considered as a significant traffic indicator (more Web

browsing usage than WAP)� Nb of DL TBF establishment request can be better considered as a GPRS activity indicator




3.2 Data Transfer Progress

B8


1.97

3.2 Data Transfer ProgressTBF Progress

Data Transfer established

Data Transfer released

Data transfer resumption(DL TBF only)

TBF resource re-allocation

RLCs blocks transfer

B8

Modified B8

� A TBF is considered “in progress” after is has been successfully allocated and before a release of this TBF is triggered.

� When a TBF is in progress the following processes are or can be performed:

� transfer of data is on-going

� useful RLC blocks

� LLC dummy commands (for DL TBF in Delayed phase only)

� TBF resources are re-allocated

� transfer of data is resumed (for DL TBF in Delayed phase only)


1.98DL transfer / Active phase

DL transfer / Delayed phase

3.2 Data Transfer ProgressData Transfer Resumption during a DL TBF in Delayed Phase

MS MFS

DL transfer / Active phase

last useful RLC data block, polling

(EGPRS) Packet DL Ack/Nack

one but last useful RLC data block

Dummy block, polling

Packet DL Ack/Nack

Dummy block, polling

Packet DL Ack/Nack

T_DELAYED_DL_TBF_POL_INITIAL

T_DELAYED_DL_TBF_POL


LLC PDU

SGSN

stopnew useful last RLC data block

useful last RLC data block

P422

t_delayed_dl_tbf_rel

B8

� Data transfer resumption is not a real TBF establishment since the TBF previously established with the MS being in Delayedphase is re-activated. During the Delayed DL TBF phase the BSS sends Dummy LLC UI commands to the MS leading to periodicsending of RLC blocks containing these dummy LLC data.

� As application data transfer is burstly in a GPRS network (download of a web page made of a lot of components (text, pictures) itis very important to provide the way to resume a DL transfer of LLC PDU using the same radio resources already established ratherthan re-establish again the DL TBF with the MS.

� Timers

� T_DELAYED_DL_TBF_POL_INITIAL is the duration between the last useful RLC block sent to the MS (eventuallycompleted with a Dummy UI command) and the first Dummy UI command block sent during the DL TBF delayed phase

� T_DELAYED_DL_TBF_POL_INITIAL = 100 ms (default value). It is not settable at OMC-R.

� T_DELAYED_DL_TBF_POL is the duration between the 2 consecutive Dummy UI command blocks sent during the DLTBF delayed phase

� T_DELAYED_DL_TBF_ POL = 200 ms (default value). It is not settable at OMC-R.

� t_delayed_dl_tbf_rel is the maximum time during which the DL TBF stays in Delayed phase before being actuallyreleased. It corresponds to the time duration of a typical response time of a network server as seen from this MFS

� t_delayed_dl_tbf_rel = T_NETWORK_RESPONSE_TIME = 700 ms (default value). It is settable at OMC-R.modified in B8


1.99

3.2 Data Transfer ProgressTBF Resources Re-allocation

� 4 types of TBF re-allocation cases

� T1: re-allocation to maintain a TBF in progress before aPDCH preemption is carried out

� T2: re-allocation of an on-going TBF when establishing aTBF in the opposite direction

� T3: re-allocation to offer a better throughput to an on-goingTBF

� T4: re-allocation to move a UL GPRS TBF sharing onePDCH with a DL EGPRS TBF onto PDCHs which do notsupport a DL EGPRS TBF new B8

B8

� T3 re-allocation conditions have been modified in B8� T3 trigger conditions are unchanged for TBF established in GPRS mode� one more condition is added for TBF established in EGRPS mode

� if the EDGE TBF is not established on the highest class TRX (it has been allocated the maximum number ofPDCHs according to its multislot class but which is on a TRX that does not offer the optimal throughput)

� T4 re-allocation condition is new in 8� a GPRS MS becomes candidate for a T4 re-allocation as soon as its UL GPRS TBF shares at least one PDCH with a DL EGPRS

TBF, on a 8-PSK capable TRX� The MS remains candidate for a T4 re-allocation, after an UL TBF release, if a DL TBF is still on-going.� The candidate time slot allocation does not require to offer the same number of PDCHs as the one currently served to the

MS� The candidate time slot allocation cannot contain a PDCH in the “EGPRS” state in the UL direction.


1.100

3.2 Data Transfer ProgressTBF Re-allocation of the 2 UL and DL TBFs on-going

MS_TIME_TO_SWITCH_TO_NEW_PDCH+

RRBP delay

DL:P403aUL:P404a

T1

DL:P405aUL:P406a

DL:P403cUL:P404c

T3

DL:P405cUL:P406c

DL:P403dUL:P404d

T4

DL:P405dUL:P406d

UL and DL Data transfer (new resources)

UL and DL Data transfer (old resources)

RLC data block

RLC data block

Packet timeslot reconfigure, polling

Packet control ack

the MS switches to the new resources (max. 40 ms)

MS MFS

RLC data block

RLC data block

PACCHDL of DL TBF

PDTCHUL

PDTCHDL

PACCHUL of DL TBF

B8

� During the re-allocation procedure, the set of PDCHs allocated to the UL or/and the DL TBF are modified; the following resourcescan be modified as well:

� the timing advance slot and index of the UL or/and the DL TBFs� the PACCH slot of the UL or/and DL TBFs� the USFs allocated to the UL TBF� UL or/and DL TFI

� It should be noted that, during the radio resource re-allocation procedure:� the TBF mode can not be modified� the EGPRS window size cannot be decreased. However the EGPRS window size in DL (resp. UL) must be increasedin case the number of time slots allocated to the MS in DL (resp. UL) increases.

�Timers� MS_TIME_TO_SWITCH_TO_NEW_PDCH: time that a Mobile Station is expected to need for switching to theassigned PDCHs after acknowledging a (re)assignment message (PACKET DOWNLINK ASSIGNMENT, PACKETUPLINK ASSIGNMENT or PACKET TIMESLOT RECONFIGURE).

� MS_TIME_TO_SWITCH_TO_NEW_PDCH = 40 ms (default value) and is not settable at OMC-R.� The 3GPP standard mandates the MS to switch to the new resources in 40 msec but some MSs can takelonger.

� Consider a MS is having 2 TBFs on-going in both directions UL and DL but which is candidate for re-allocation in UL only (T1 orT3 or T4):

� then the counter of re-allocation request in the DL direction is also incremented� At the end of the UL re-allocation procedure the counter of DL re-allocation success in incremented whether the UL re-allocation has been successful or not because the counter of re-allocation request in the DL direction has been previouslyincremented

� Same consideration can be done when a MS is having 2 TBs on-going in both directions UL and DL but which is candidate for re-allocation in DL only (T1 or T3 or T4)� MFS starts timer T_ACK_WAIT after sending Packet Timeslot Reconfigure message to wait for MS acknowledgement (PacketControl Ack message).

� If Packet Control Ack is not received the MS resent the Packet Timeslot Reconfigure message.� If after the MAX_RETRANS_DL re-attempts the MS did not acknowledge the resource re-allocation then both DL andUL are released.

� New counters in B8: P403d, P404d, P405d, P406d.� Modified in B8: P403a, P404a, P405a, P406a, P403c, P404c, P405c, P406c take into account TBF established in EGPRS mode.


1.101

3.2 Data Transfer ProgressTBF Re-allocation of the only TBF on-going (DL or UL)


RRBP delay

DL:P403aUL:P404a

T1

DL:P405aUL:P406a

DL:P403cUL:P404c

T3

DL:P405cUL:P406c

DL:P403dUL:P404d

T4

DL:P405dUL:P406d

DL/UL Data transfer (new resources)

DL/UL Data transfer (old resources)

RLC data block

RLC data block

Packet downlink/uplink Assignment, polling

Packet control ack


MS MFS

RLC data block

RLC data block

PACCHDL of DL TBF / PACCHDL of UL TBF

PDTCHUL

PDTCHDL

PACCHUL of DL TBF / PACCHUL of UL TBF

B8

� MFS starts timer T_ACK_WAIT after sending Packet Downlink/Uplink Assignment message to wait for MS acknowledgement(Packet Control Ack message).

� If Packet Control Ack is not received the MS resent the Packet Downlink/Uplink Assignment message.� If after the MAX_RETRANS_DL re-attempts the MS did not acknowledge the resource re-allocation then the on-goingDL/UL is released

� New counters in B8: P403d, P404d, P405d, P406d.� Modified in B8: P403a, P404a, P405a, P406a, P403c, P404c, P405c, P406c take into account TBF established in EGPRS mode.


1.102

3.2 Data Transfer ProgressTBF Re-allocation of on-going UL TBF on DL TBF Establishment


RRBP delay

P404bT2

P406b


UL Data transfer (old resources)

RLC data block


Packet control ack


MS MFS

RLC data block

RLC data block

PACCHDL of UL TBF

PDTCHUL

PACCHUL of UL TBF

LLC PDU

PDTCHUL

PDTCHDL

� MFS starts timer T_ACK_WAIT after sending Packet Timeslot Reconfigure message to wait for MS acknowledgement (PacketControl Ack message).



1.103

3.2 Data Transfer ProgressTBF Re-allocation of on-going DL TBF on UL TBF Establishment


RRBP delay

P403bT2

P405b


DL Data transfer (old resources)

RLC data block


Packet control ack


MS MFS

RLC data block

RLC data block

PACCHDL of DL TBF

PDTCHDL

PACCHUL of DL TBF

PDTCHUL

PDTCHDL

Packet DL Ack/Nack with Channel requestPACCHUL of DL TBF

� MFS starts timer T_ACK_WAIT after sending Packet Timeslot Reconfigure message to wait for MS acknowledgement (PacketControl Ack message).



1.104

3.2 Data Transfer ProgressTBF Resource Re-allocation, Failures

TBF resource re-allocation FAILURE

no new PDCHallocation can

be foundRadio pb BSS pb External TBF

release request

Suspend Cell reselection

B8

�


1.105

3.2 Data Transfer ProgressTBF Resources Re-allocation, Failures, no new PDCH Allocation

� T1 case

� counter =

� if no new PDCH allocation can be found then the TBFmarked for soft preemption will be released atT_PDCH_PREEMPTION expiry

� T2/T3/T4 cases

� counter =

� if no new PDCH allocation can be found then the on-goingTBF continue with its current PDCH allocation

P424a

P424b/P424c/P424d

B8

� T3 re-allocation conditions have been modified in B8� T3 trigger conditions are unchanged for TBF established in GPRS mode� one more condition is added for TBF established in EGRPS mode

� if the EDGE TBF is not established on the highest class TRX (it has been allocated the maximum number ofPDCHs according to its multislot class but which is on a TRX that does not offer the optimal throughput)

� T4 re-allocation condition is new in 8� a GPRS MS becomes candidate for a T4 re-allocation as soon as its UL GPRS TBF shares at least one PDCH with a DL EGPRS

TBF, on a 8-PSK capable TRX� The MS remains candidate for a T4 re-allocation, after an UL TBF release, if a DL TBF is still on-going.� The candidate time slot allocation does not require to offer the same number of PDCHs as the one currently served to the

MS� The candidate time slot allocation cannot contain a PDCH in the “EGPRS” state in the UL direction.

� New counters in B8: P424d.� Modified in B8: P424a, P424b, P424c take into account TBF established in EGPRS mode.


1.106

3.2 Data Transfer ProgressTBF Resources Re-allocation, Failures, Radio

DL:P407aUL:P408a

T1

DL:P407cUL:P408c

T3

DL:P407dUL:P408d

T4

UL and/or DL Data transfer (old resources)

RLC data block

RLC data block

Packet timeslot reconfigure, polling or,Packet downlink assignment or,Packet uplink assignment

Packet control ack

MS MFS

PDTCCHUL

PDTCHDL

PACCHUL of DL TBF

T_ACK_WAITexpiry

DL:P407bUL:P408a

T2

B8

� All these counters are incremented when the last MAX_DL_RETRANS re-allocation re-attempt has failed (Packet Control Ackmessage not received from the MS)

� Re-allocation failures due to radio can be due to a problem on the DL path� In case of trigger T2 the re-allocation failure of the TF will also lead to an establishment failure due to radio of the TBF to be

established in the concurrent direction.

� New counters in B8: P407d, P408d.� Modified in B8: P407a, P408a, P407b, P408b, P407c, P408c take into account TBF established in EGPRS mode.


1.107

3.2 Data Transfer ProgressTBF Resources Re-allocation, Failures, External Request, BSS

DL:P425aUL:P426a

T1

DL:P425cUL:P426c

T3

DL:P425dUL:P426d

T4UL and/or DL Data transfer (old resources)

RLC data block

RLC data block

Packet timeslot reconfigure, polling or,Packet downlink assignment or,Packet uplink assignment

MS suspend

MS MFS

PDTCCHUL

PDTCHDL

GSL

T_ACK_WAIT

DL:P425bUL:P426b

T2

BSC SGSN

Flush-LLOROR

� External request

� Problem at BSS level


B8

� All these counters are incremented when the last MAX_DL_RETRANS re-allocation re-attempt has failed (Packet Control Ackmessage not received from the MS)

� Re-allocation failures due to radio can be due to a problem on the DL path� In case of trigger T2 the re-allocation failure of the TF will also lead to an establishment failure due to radio of the TBF to be

established in the concurrent direction.

� New counters in B8: P425d, P426d.� Modified in B8: P425a, P426a, P425b, P426b, P425c, P426c take into account TBF established in EGPRS mode.


1.108

3.2 Data Transfer ProgressQoS Indicators

� DL and UL TBF progress:

TBF establishment

TBF statistics: duration, number, throughput

time

TBF release

Delayed DL TBF: active/delayed phase,transfer resumption

TBF resources re-allocation

Triggers T1. T2. T3.T4

Number of candidate TBFs

Number of successes and success rate

Failures: congestion, radio, BSS,external request

B8


1.109

� DL and UL TBF progress: TBF statistics

TBF statisticsDownlink Uplink

Average GPRS TBF durationin ack mode

(P52a / 10) / (P90a + P90b +P90c + P90d + P90e + P90f)

Average TBF duration (P29a / 10) / (P30a + P30b + P30c)

Average GPRS TBF durationin nack mode

(P52b / 10) / (P90a + P90b +P90c + P90d + P90e + P90f)

Average TBF duration (P29b / 10) / (P30a + P30b + P30c)

Average EGPRS TBFduration in ack mode

(P52c / 10) / (P90a + P90b +P90c + P90d + P90e + P90f)

Average TBF duration (P29c / 10) / (P30a + P30b + P30c)

Average EGPRS TBFduration in nack mode

(P52d / 10) / (P90a + P90b +P90c + P90d + P90e + P90f)

Average TBF duration (P29d / 10) / (P30a + P30b + P30c)

Maximum number of TBFsimultaneously established

p35 Maximum number of TBFsimultaneously established

p39

Average number of TBFsimultaneously established

p36 / 10 Average number of TBFsimultaneously established

p40 / 10

Average useful throughputin kbit/s at RLC level perGPRS TBF

(P55a * N1 + P55b * N2 + P55c* N3 + P55d * N4) / ((P52a/10) *1000)

Average useful throughput inkbit/s at RLC level per GPRSTBF

(P57a * N1 + P57b * N2 + P55c *N3 + P55d * N4) / ((P29a/10) *1000)

Average useful throughputin kbit/s at RLC level perEGPRS TBF

(P55e*176 + P55f*224 +P55g*296 + P55h*352 +P55i*448 + P55j*592 +(P55k*896 + P55l*1088 +P55m*1184)/2) /((P52c/10)*1000)

Average useful throughput inkbit/s at RLC level perEGPRS TBF

(P57e*176+ P57f*224 + P57g*296+ P57h*352) / ((P29c/10)*1000)

3.2 Data Transfer ProgressQoS Indicators, TBF Statistics

KPI

KPI

B8

� Max Nb of TBF simultaneously established is meaningful per hour or per day basis� Average Nb of TBF simultaneously established is less reliable due to the difference between gauge polling period and

Average TBF duration

� New counters in B8: P52a, P52b, P52c, P52d, P55c, P55d, P55e, P55f, P55g, P55h, P55i, P55j, P55k, P55l, P55m,P29a, P29b, P29c, P29d, P57c, P57d, P57e, P57f, P57g, P57h


1.110

3.2 Data Transfer ProgressQoS Indicators, Delayed DL TBF

� DL and UL TBF progress: Delayed DL TBFDelayed DL TBF

Cumulated time of active DL GPRS TBFconnections

P52a + P52b

Cumulated time of active DL EGPRS TBFconnections

P52c + P52d

Percentage of time during which the DL TBFconnections are in the “active” state

(P52a+P52b+P52c+P52d) / P16 * 100

Percentage of time during which the DL GPRSTBF connections are in the “active” state

(P52a + P52b) / P16 *100

Percentage of time during which the DLEGPRS TBF connections are in the “active”state

(P52c + P52d) / P16 * 100

Number of DL TBF transfer resumptions indelayed release state

P422

Rate of DL TBF transfer resumptions perestablished DL TBF

P422 / (P90a + P90b + P90c + P90d + P90e + P90f)

Number of DL RLC blocks containing onlydummy LLC UI Command PDU on PDTCH

P421

Number of DL RLC blocks sent on PDTCH P350aRate of RLC blocks containing only dummyLLC UI commands on DL PDTCH

P421 / P350a

B8

� New counters in B8: P52a, P52b, P52c, P52d, P350a


1.111

Detailed throughputs on Downlink

012345678

14/08

/2003

16/08

/2003

18/08

/2003

20/08

/2003

22/08

/2003

24/08

/2003

26/08

/2003

28/08

/2003

30/08

/2003

01/09

/2003

03/09

/2003

05/09

/2003

07/09

/2003

09/09

/2003

11/09

/2003

13/09

/2003

kbit/s per TBF

kbit/s perPDCHkbit/s per cell

Detailed throughputs on uplink

0

2

4

6

8

10

12

14/08

/2003

16/08

/2003

18/08

/2003

20/08

/2003

22/08

/2003

24/08

/2003

26/08

/2003

28/08

/2003

30/08

/2003

01/09

/2003

03/09

/2003

05/09

/2003

07/09

/2003

09/09

/2003

11/09

/2003

13/09

/2003

kbit/s per TBF

kbit/s perPDCHkbit/s per cell

3.2 Data Transfer ProgressQoS Indicators, TBF Throughput, Graph 1/2

� These throughputs are under-estimated due to the precision of the cumulated TBF duration (0.1 seconds), higher than theduration of one RLC block (4*240/52 = 18.5 ms). This error margin increases with the area of consolidation and the type oftraffic (user/signaling). This indicator should be better interpreted at the cell Busy Hour rather than the averaged value perday in order to avoid the influence of signaling.

� These indicators will be more reliable when the Average TBF duration is high because the error margin will have lessimpact.


1.112

DL TBF state

05000

100001500020000250003000035000400004500050000

14/08

/2003

16/08

/2003

18/08

/2003

20/08

/2003

22/08

/2003

24/08

/2003

26/08

/2003

28/08

/2003

30/08

/2003

01/09

/2003

03/09

/2003

05/09

/2003

07/09

/2003

09/09

/2003

11/09

/2003

13/09

/2003

01020304050607080 Delay-

>ActiveSuccess

% Efficiency

% Active

� On RNO graphs:� % Efficiency = Rate of DL TBF resumptions per DL TBF

establishment� % Active = Percentage of time during which the DL TBF

connections are in the active state

3.2 Data Transfer ProgressQoS Indicators, TBF Throughput, Graph 2/2

� Typical values of Efficiency rate and Active rate:� Efficiency rate = 40%, 60%� Active rate = 15%, 20%


1.113

� TBF resource re-allocation for each trigger

time

Preparation of the resource re-allocation

Failures cause: no PDCH can be found

Execution of theresource re-allocation

Failures causes

Nb of TBF candidate resource re-allocations

Drop causeRadio problems

Preparation efficiency rate

External requests

BSS problems Drop cause

Execution efficiency rate

Nb of TBF resource re-allocation successes

Ratio of triggers

Success rate

3.2 Data Transfer ProgressQoS Indicators, TBF Resources Re-allocationB8

� External requests: FLUSH_LL received from SGSN, Suspend from MS� Split between Preparation and Execution phases is driven by the fact that the problems to be interpreted during re-

allocation are relating to the Trigger type� TBF Re-allocation is like an Intra cell HO in GPRS


1.114

� DL and UL TBF progress: Resources re-allocation T1

TBF resources re-allocation : trigger T1Downlink Uplink

Nb of TBF candidate for resource realloc P403a Nb of TBF candidate for resource realloc P404aResource realloc ratio due to trigger T1 P403a / (P403a + P403b +

P403c + P403d)Resource realloc ratio due to trigger T1 P404a / (P404a + P404b +

P404c + P404d)Nb of resource realloc successes P405a Nb of resource realloc successes P406aResource realloc success rate P405a / P403a Resource realloc success rate P406a / P404aNb of resource realloc exec fail due toradio problems

P407a Nb of resource realloc exec fail due toradio problems

P408a

Resource realloc exec fail rate due to radioproblems

P407a / P403a Resource realloc exec fail rate due to radioproblems

P408a / P404a

Nb of resource realloc preparation failuresbecause no PDCH could be found

P423a Nb of resource realloc preparation failuresbecause no PDCH could be found

P424a

Resource realloc preparation fail rate dueto lack of radio resources

P423a / P403a Resource realloc preparation fail rate dueto lack of radio resources

P424a / P404a

Resource realloc prep efficiency rate (P403a - P423a) / P403a Resource realloc prep efficiency rate (P404a - P424a) / P404aNb of resource realloc failures due externalrequest (suspension request or Flushmessage) during exec of the reallocprocedure

P425a Nb of resource realloc failures due externalrequest (suspension request or Flushmessage) during exec of the reallocprocedure

P426a

Nb of resource realloc failures due to BSSpb during exec of the realloc procedure

P403a - P423a - P425a -P407a - P405a


P404a - P424a - P426a -P408a - P406a

Exec fail rate due to BSS pb (P403a - P423a - P425a -P407a - P405a) / P403a

Exec fail rate due to BSS pb (P404a - P424a - P426a -P408a - P406a) / P404a

Resource realloc exec efficiency rate P405a / (P403a - P423a) Resource realloc exec efficiency rate P406a / (P404a - P424a)

3.2 Data Transfer ProgressQoS Indicators, TBF Resources Re-allocation, Trigger T1

� New counters in B8: P403d


1.115



Nb of TBF candidate for resource realloc P403b Nb of TBF candidate for resource realloc P404bResource realloc ratio due to trigger T1 P403b/ (P403a + P403b +

P403c + P403d)Resource realloc ratio due to trigger T1 P404b / (P404a + P404b +

P404c + P404d)Nb of resource realloc successes P405b Nb of resource realloc successes P406bResource realloc success rate P405b / P403b Resource realloc success rate P406b / P404bNb of resource realloc exec fail due toradio problems

P407b Nb of resource realloc exec fail due toradio problems

P408b


P407b / P403b Resource realloc exec fail rate due to radioproblems

P408b / P404b


P423b Nb of resource realloc preparation failuresbecause no PDCH could be found

P424b


P423b / P403b Resource realloc preparation fail rate dueto lack of radio resources

P424b / P404b

Resource realloc prep efficiency rate (P403b - P423b) / P403b Resource realloc prep efficiency rate (P404b - P424b) / P404bNb of resource realloc failures due externalrequest (suspension request or Flushmessage) during exec of the reallocprocedure

P425b Nb of resource realloc failures due externalrequest (suspension request or Flushmessage) during exec of the reallocprocedure

P426b


P403b - P423b - P425b -P407b - P405b


P404b - P424b - P426b -P408b - P406b

Exec fail rate due to BSS pb (P403b - P423b - P425b -P407b - P405b) / P403b

Exec fail rate due to BSS pb (P404b - P424b - P426b -P408b - P406b) / P404b

Resource realloc exec efficiency rate P405b / (P403b - P423b) Resource realloc exec efficiency rate P406b / (P404b - P424b)




1.116



Nb of TBF candidate for resource realloc P403c Nb of TBF candidate for resource realloc P404cResource realloc ratio due to trigger T1 P403c / (P403a + P403b +

P403c + P403d)Resource realloc ratio due to trigger T1 P404c / (P404a + P404b +

P404c + P404d)Nb of resource realloc successes P405c Nb of resource realloc successes P406cResource realloc success rate P405c / P403c Resource realloc success rate P406c / P404cNb of resource realloc exec fail due toradio problems

P407c Nb of resource realloc exec fail due toradio problems

P408c


P407c / P403c Resource realloc exec fail rate due to radioproblems

P408c / P404c


P423c Nb of resource realloc preparation failuresbecause no PDCH could be found

P424c


P423c / P403c Resource realloc preparation fail rate dueto lack of radio resources

P424c / P404c

Resource realloc prep efficiency rate (P403c - P423c) / P403c Resource realloc prep efficiency rate (P404c - P424c) / P404cNb of resource realloc failures due externalrequest (suspension request or Flushmessage) during exec of the reallocprocedure

P425c Nb of resource realloc failures due externalrequest (suspension request or Flushmessage) during exec of the reallocprocedure

P426c


P403c - P423c - P425c -P407c - P405c


P404c - P424c - P426c -P408c - P406c

Exec fail rate due to BSS pb (P403c - P423c - P425c -P407c - P405c) / P403c

Exec fail rate due to BSS pb (P404c - P424c - P426c -P408c - P406c) / P404c

Resource realloc exec efficiency rate P405c / (P403c - P423c) Resource realloc exec efficiency rate P406c / (P404c - P424c)




1.117



Nb of TBF candidate for resource realloc P403d Nb of TBF candidate for resource realloc P404dResource realloc ratio due to trigger T4 P403d / (P403a + P403b +

P403c + P403d)Resource realloc ratio due to trigger T4 P404d / (P404a + P404b +

P404c + P404d)Nb of resource realloc successes P405d Nb of resource realloc successes P406dResource realloc success rate P405d / P403d Resource realloc success rate P406d / P404dNb of resource realloc exec fail due toradio problems

P407d Nb of resource realloc exec fail due toradio problems

P408d


P407d / P403d Resource realloc exec fail rate due to radioproblems

P408d / P404d


P423d Nb of resource realloc preparation failuresbecause no PDCH could be found

P424d


P423d / P403d Resource realloc preparation fail rate dueto lack of radio resources

P424d / P404d

Resource realloc prep efficiency rate (P403d - P423d) / P403d Resource realloc prep efficiency rate (P404d - P424d) / P404dNb of resource realloc failures due externalrequest (suspension request or Flushmessage) during exec of the reallocprocedure

P425d Nb of resource realloc failures due externalrequest (suspension request or Flushmessage) during exec of the reallocprocedure

P426d


P403d - P423d - P425d -P407d - P405d


P404d - P424d - P426d -P408d - P406d

Exec fail rate due to BSS pb (P403d - P423d - P425d -P407d - P405d) / P403d

Exec fail rate due to BSS pb (P404d - P424d - P426d -P408d - P406d) / P404d

Resource realloc exec efficiency rate P405d / (P403d - P423d) Resource realloc exec efficiency rate P406d / (P404d - P424d)

3.2 Data Transfer ProgressQoS Indicators, TBF Resources Re-allocation, Trigger T4B8

� New counters in B8: P403d, P405d, P407d, P408d, P432d, P425d


1.11

� Distribution of triggers and total success rate:

DL ressource realloc

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

01/09/2003 02/09/2003 03/09/2003 04/09/2003 05/09/2003 06/09/2003 07/09/200300.511.522.533.544.55

T3 RequestT2 RequestT1 Request% Success

3.2 Data Transfer ProgressQoS Indicators, TBF Resources Re-allocation, Graph 1/2


1.11

DL ressource realloc T1

0

5

10

15

20

25

01/09/2003 02/09/2003 03/09/2003 04/09/2003 05/09/2003 06/09/2003 07/09/200380828486889092949698100102

External stopFail radioFail BSSPrep failSuccess% Success


0

10000

20000

30000

40000

50000

60000

70000

01/09/2003 02/09/2003 03/09/2003 04/09/2003 05/09/2003 06/09/2003 07/09/20030

0.2

0.4

0.6

0.8

1

1.2

1.4

External stopRadio failBSS failPrep failSuccess% Success


0100002000030000400005000060000700008000090000

100000

01/09/2003 02/09/2003 03/09/2003 04/09/2003 05/09/2003 06/09/2003 07/09/20030

1

2

3

4

5

6

7

8

External stopRadio failBSS failPrep failSuccess% Success

3.2 Data Transfer ProgressQoS Indicators, TBF Rresources Re-allocation, Graph 2/2




3.3 Data Transfer Release

B8


1.121

3.3 Data Transfer ReleaseTBF Release

TBF release

Normal release Acceptablerelease

Abnormalrelease

Cellreselection

PDCH fastpreemption

Suspend

Radio Gb

others

BSSRe-allocation

executionfailure

B8

Modified B8

�


1.122

3.3 Data Transfer ReleaseNormal TBF Release

Normal TBF release

UL TBF release DL TBF release

Without Delayed Final PUAN

With Delayed Final PUAN

Without Delayed Without Delayed DL TBF releaseDL TBF release

With Delayed DL TBF release

Without Extension With Extension

B8

new B8modified B8

�


1.123

� In case no DL TBF is established, it is better to delay the UL TBFrelease to be able to establish quickly a subsequent DL TBF on thePACCHDL of the delayed UL TBF rather than on CCCH or PCCCH

Active UL Data transfer

Packet uplink ack/nack (FAI=1) all blocks acknowledged

P22

one but last useful RLC data block (CV=1)

MS MFS

PDTCHUL

SGSN

last useful RLC data block (CV=0)

PACCHDL

Packet control ack

last LLC PDU

P22

Packet uplink ack/nack (FAI=1), polling

3.3 Data Transfer ReleaseUL TBF, Normal Release, without Delayed Final PUAN

�


1.124

Active UL Data transfer

T_DELAYED_FINAL_PUANexpiry

last block not acknowledgedPacket uplink ack/nack (FAI=0)

P22

Packet uplink ack/nack (FAI=1), pollingPACCHDL last block acknowledged

Packet control ack

3.3 Data Transfer ReleaseUL TBF, Normal Release, with Delayed Final PUAN

one but last useful RLC data block (CV=1)

MS MFS

PDTCHUL

SGSN

last useful RLC data block (CV=0)

PACCHDL

last LLC PDU

� Timer T_DELAYED_FINAL_PUAN corresponds to the duration during which the UL is maintain “alive” in order to be able toestablish a DL TBF on PACCH

� T_DELAYED_FINAL_PUAN = 0.4 s (default value) but is settable at OMC-R� it should be long enough to let the server send its response to the uplink PDUs received from the MS, while remainingshort enough in order not to jeopardise the sending of further uplink PDUs by the MS� Setting T_DELAYED_FINAL_PUAN = 0 s leads to disable this feature


1.125

not last acknowledgementPacket downlink ack/nack (FAI=0)

P9

3.3 Data Transfer ReleaseDL TBF,Normal Release,Delayed DL TBF Release no Extension

one but last useful RLC data block (FBI=0)MS MFS

PDTCHDL

last useful RLC data block (FBI=0), polling

PACCHUL

T_DELAYED_DL_TBF_REL

T_DELAYED_DL_TBF_POL_INITIALlast block not mentioned

Packet downlink ack/nack (FAI=0)

Dummy UI command (FBI=0), pollingT_DELAYED_DL_TBF_POL


Dummy UI command (FBI=0), polling




T_DELAYED_DL_TBF_RELexpirylast block mentioned

last acknowledgement

Active DL data transfer

Delayed DL data transfer

DL TBF released

B8

Modified B8

� As soon as all the useful blocks have been transferred the Delayed DL TBF release procedure is triggered in order to allow:� to send a coming LLC PDU frame using the same radio resources without being obliged to re-establish the DL TBFagain (T3192 running or not)� the MS to establish an UL TBF on PACCH rather than on CCCH or PCCCH

The DL TBF goes from Active state to Delayed state.

�As the MS will trigger a local DL TBF release if it does not receive DL RLC data blocks (T3190 is running) the MFS is schedulingDummy UI command blocks in DL according to the following timers:





� A global timer t_delayed_dl_tbf_rel monitors the whole Delayed DL TB release procedure. At t_delayed_dl_tbf_rel expiry the DLTBF stays in Delayed phase before being actually released. This timer corresponds to the time duration of a typical response time ofa network server as seen from this MFS

� t_delayed_dl_tbf_rel = T_NETWORK_RESPONSE_TIME = 700 ms (default value). It is settable at OMC-R.modified in B8


1.126

3.3 Data Transfer ReleaseDL TBF,Normal Release,Delayed DL TBF Release with Extension

MS MFS

T_DELAYED_DL_TBF_REL is stopped

Packet downlink ack/nack (FAI=0)with Channel request

Dummy UI command (FBI=0), pollingT_DELAYED_DL_TBF_POL

Packet uplink ack/nack (FAI=1), polling




T_DELAYED_DL_TBF_RELis restarted

last block mentioned

last acknowledgement

Delayed DLTBF releaseis on-going

T_ACK_WAIT

Packet UL assignment

USF Scheduling

UL RLC data block




Delayed DLTBF releaseis extended

Packet control ack



UL TBFestablishment

UL TBFis released

Delayed DLTBF releaseis resumed

from beginning

B8

New B8

� If an UL TBF is established during a Delayed DL TBF release phase then:� the countdown of this Delayed DL TBF release phase is stopped (timer t_delayed_dl_tbf_rel)� but the Dummy UI command blocks are sent in DL in order that the MS does not release the DL TBF.

The Delayed DL TBF release phase is said to be extended.

� Two cases of UL TBF should be considered:� “question-answer” traffic: corresponds to WAP services or WEB browsing where the UL command induced by the userare small and usually lead to a transfer of only one LLC PDU:

� UL polling period induced by Dummy UI command scheduling is kept to T_DELAYED_DL_TBF_ POL�T_DELAYED_DL_TBF_POL_INITIAL = 100 ms (default value). It is not settable at OMC-R.

� Other cases: corresponds to applications like UL FTP file transfer where a lot of LLC PDUs have to be transferredduring the same TBF:

� UL polling period induced by Dummy UI command sending is increased to T_DELAYED_DL_TBF_ UL inorder to decrease the UL load due to the Delayed DL TBF release phase in favor of the UL FTP throughput

�T_DELAYED_DL_TBF_POL_UL = 2 s (default value). It is not settable at OMC-R.

� As soon as the UL TBF is released the Delayed DL TBF:� Countdown of Delayed DL TBF release procedure is resumed from beginning (t_delayed_dl_tbf_rel restarted)� Scheduling period of Dummy UI command blocks is set back to T_DELAYED_DL_TBF_ POL

� At the end of a Delayed DL TBF procedure the DL TBF is released and the counter P9 is incremented whether the DelayedDL TBF phase has been extended or not.


1.127


3.3 Data Transfer ReleaseTBF Normal Release, Exercise

� Exercise: Using the trace 1, find theduration between two consecutiveDummy UI command blocks during theDelayed DL TBF release procedure


1.128

3.3 Data Transfer ReleaseTBF Acceptable Release

Acceptable release

Cellreselection

PDCH fastpreemptionSuspend

PDCH carryingPACCH of the TBFis to be released

MS is establishing aCS connectionwhile in PTM

MS is reselecting aneighbor cell while

in PTM

B8

modified B8

�


1.129

3.3 Data Transfer Release TBF Acceptable Release, Fast preemption

MS MFS

DL transfer

useful RLC data block, polling

Packet DL Ack/Nack

useful RLC data block

P146


Packet TBF release

PDTCHDL

PACCHUL


PACCHDL

Traffic load ➚➚➚➚

��The PDCH carrying

the PACCH of the TBFis released

P147

DL UL

� Data transfer resumption is not a real TBF establishment since the TBF previously established with the MS and in Delayed phaseis re-activated.

� As application data transfer is burstly in a GPRS network (download of a web page made of a lot of components (text, pictures) itis very important to provide the way to resume a DL transfer of LLC PDU using the same radio resources already established ratherthan re-establish again the DL TBF with the MS.

� Timers





� t_delayed_dl_tbf_rel is the maximum time during which the DL TBF stays in Delayed phase before being actuallyreleased. It corresponds to the time duration of a typical response time of a network server as seen from this MFS

� t_delayed_dl_tbf_rel = T_NETWORK_RESPONSE_TIME = 700 ms (default value). It is settable at OMC-R.


1.130

3.3 Data Transfer Release TBF Acceptable Release, MS Suspend

MS MFS

DL transfer


Packet DL Ack/Nack


MSC/VLR

P98a


PDTCHDL

PACCHUL


P98b

DL UL

SGSNBSC

The MS enters the CS dedicated mode

Suspend MS Suspend Suspend PDU

� If the MFS does not receive the MS SUSPEND message in case of MS data transfer suspension due to CS connection then theMFS will identify the TBF released as due to radio failure and will increment the related counters rather than P98a and/or P98b.


1.131

UL transfer establishment in the new cell

UL transferMS sends an LLC PDU to warn the SGSN about its new cell location

3.3 Data Transfer Release TBF Acceptable Release, Cell Reselection

MS MFSserving cell

DL transfer


Packet DL Ack/Nack


P396a


PDTCHDL

PACCHUL


P396b

SGSN

expiryPacket measurement report

PACCHUL

MFStarget cell

Better cell

�� MFS trigger

cell reselection Packet cell change order, polling

PACCHDLnew cell (BCCH,BSIC) Packet control ack

The MSswitches tothe new cell

T3158

T3158

Radio resourcesare released locally

LLC PDU(TLLI,new BVCI)

FLUSH-LL(TLLI,old BVCI)

FLUSH-LL ACK(TLLI)

T_ACK_WAIT

DL UL

T_WAIT_FLUSH

B8

� If FLUSH-LL message is not received before T_WAIT_FLUSH expiry then the TBF release is considered as abnormal andP396a/P396b is not incremented.

� The chart above corresponds to a NC2 reselection. The same P396a/P396b counter is incremented in case of a TBF release dueto NC0 reselection provided that the FLUSH-LL message is received before a TBF drop is detected.

� Modified in B8: P396a, P396b take into account cell reselection in NC2 mode.


1.132

3.3 Data Transfer ReleaseTBF Abnormal Release

Abnormal release

Radio Gb othersBSS

Re-allocationexecution

failure

Real radioproblem

Cellreselection

problem

Stagnatingtransmission

window

Blockingsituation

�


1.133

� Real radio problem:

� Radio link failure:

� N3105 exceeds the limit for a DL TBF� N3103 or N3101 exceeds the limit for a UL TBF

� Too low efficiency of RLC blocks transmission

� Re-allocation execution failure:

� Cell reselection:

3.3 Data Transfer ReleaseTBF, Abnormal Release, Radio

P302bDL P302cUL

DL

P407a+P407b+P407c+P407d

P408a+P408b+P408c+P408d

UL

P396aDL P396bUL

B8

� radio link failure can be due to real radio problem like coverage, interference but also to undetected BSS problems like badhardware components, Abis microwave link transmission

� after a radio link failure a RADIO STATUS message is sent to the SGSN on Gb interface with a cause:� “radio contact lost with the MS”: when the radio block transfer has been interrupted� “radio link quality insufficient to continue the communication”: when the radio blocks transfer was of too lowefficiency

�New counters in B8: P407d, P408d.�Modified in B8: P407a, P408a, P407b, P408b, P407c, P408c take into account TBF established in EGPRS mode. P396a, P396btake into account cell reselection in NC2 mode.


1.134

� Gb:

� BSS: no specific counter

� Other abnormal release cases:

� Blocking situation(MS error, too high UL traffic)

� Stagnating transmission window(MS error, radio problem)

3.3 Data Transfer ReleaseTBF, Abnormal Release, Gb, BSS, Others

P303a P303b

DL UL

P11 P24

DL UL

P385a P385b

� radio link failure can be due to real radio problem like coverage, interference but also to undetected BSS problems like badhardware components, Abis microwave link transmission


1.135


3.3 Data Transfer ReleaseExercise

� Exercise 1: Using the trace 11, findwhich kind of TBF release is observed

� Exercise 2: Using the trace 13, findwhich kind of TBF release is observed


1.136

� DL and UL TBF release:

TBF establishment

time

TBF end Normal release rate

Acceptable release rate

Drop causes

PDCH fast preemption

Suspend procedure

Flush messageRadio

Radio fail during resource realloc exec

BSS

Gb

Other problems: blocking situation +N_stagnating window

Cell reselection

3.3 Data Transfer ReleaseQoS IndicatorsB8


1.137

� DL and UL TBF release: Drop rate

3.3 Data Transfer ReleaseQoS Indicators, KPI

Normal release rate P9 / (P90a + P90b + P90c + P90d + P90e + P90f)

Normal release rateP22 / (P30a + P30b + P30c)

Acceptable release rate

(P146 + P98a + P396a - ((P434b + P434d) - (P396a))) / (P90a + P90b + P90c + P90d + P90e + P90f)

Acceptable release rate (P147 + P98b + P396b - ((P434a

+ P434c) - (P396b))) / (P30a + P30b + P30c)

Drop rate (P90a + P90b + P90c + P90d + P90e + P90f - P9 - P146 - P98a + P396a - ((P434b + P434d) - (P396a))) / (P90a + P90b + P90c + P90d + P90e + P90f)

Drop rate

(P30a + P30b + P30c - P22 - P147 - P98b + P396b - ((P434a + P434c) - (P396b))) / (P30a + P30b + P30c)

Release rate due to PDCH fast pre-emption

P146 / (P90a + P90b + P90c + P90d + P90e + P90f)

Release rate due to PDCH fast pre-emption P147 / (P30a + P30b + P30c)

Release rate due to suspend procedure

P98a / (P90a + P90b + P90c + P90d + P90e + P90f)

Release rate due to suspend procedure P98b / (P30a + P30b + P30c)

Release rate due to Flush message

P396a / (P90a + P90b + P90c + P90d + P90e + P90f)

Release rate due to Flush message P396b / (P30a + P30b + P30c)

TBF releases and dropsDownlink Uplink

KPI

KPI

KPI

B8

� New counters in B8: P434a, P434b, P434c, P434d


1.138

� DL and UL TBF release: TBF drops

TBF drop causesDL TBF UL TBF

Radio problem : realradio pb + reselections

P302b / (P90a + P90b + P90c +P90d + P90e + P90f)

Radio problem : realradio pb + reselections

P302c / (P30a + P30b + P30c)

Real radio drop rate (P302b-( - (P434b + P434d -P396a)) / (P90a + P90b + P90c +P90d + P90e + P90f)

Real radio drop rate (P302c - (P434a + P434c -P396b)) / (P30a + P30b + P30c)

Radio failure duringradio resource reallocexecution

(P407a + P407b + P407c +P407d) / (P90a + P90b + P90c +P90d + P90e + P90f)

Radio failure duringradio resource reallocexecution

(P408a + P408b + P408c +P408d) / (P30a + P30b + P30c)

Gb problem P11 / (P90a + P90b + P90c +P90d + P90e + P90f )

Gb problem P24 / ( P30a + P30b + P30c)

N_StagnatingWindow P385a / (P90a + P90b + P90c +P90d + P90e + P90f)

N_StagnatingWindow P385b / (P30a + P30b + P30c)

Blocking situation P303a / (P90a + P90b + P90c +P90d + P90e + P90f)

Blocking situation P303b / (P30a + P30b + P30c)

BSS problem (P90a + P90b + P90c + P90d +P90e + P90f - P146 - P98a -P396a - P9 - P302b - P11 - P385a- P303a - P407a - P407b - P407c) / (P90a + P90b + P90c + P90d +P90e + P90f)

BSS problem (P30a + P30b + P30c - P22 -P147 - P98b - P396b - P24 -P385b - P303b - P408a - P408b -P408c - P302c) / ( P30a + P30b +P30c)

3.3 Data Transfer ReleaseQoS Indicators, TBF Abnormal ReleaseB8

� On a DL TBF:� Radio problem: N3105 exceeds the limit (6) or too low TX efficiency (<10%) .� Blocking situation: no reception of the PDAN with Final indicator = 1 at the end of the Downlink TBF during

T_TBF_BCK_REL = 3 seconds (MS error) OR transmission window of MFS is stalled during T_TBF_BCK_REL= 3 seconds (radio problem) No polling of MS since UL traffic too high

� Stagnating window: RLC counter N_StagnatingWindowDL is incremented when the Same oldest RLC datablock in the transmit window is not acknowledged by the received bitmap of the last Packet Downlink Ack/Nackmessage.DL TBF is released because the RLC counter N_Stagnating WindowDL exceeds the system parameterN_STAGNATING_ WINDOW_DL_LIMIT =8 (MS error)

� On an UL TBF:� radio problem: N3101 or N3103 exceeds the limits (48 and 1) or too low TX efficiency (<10%).� Blocking situation: Reception of N_UL_Dummy_Limit = 15 dummy UL RLC blocks (MS error or radio problem)

OR no reception of the Packet Control Ack at the end of the Uplink TBF during T_TBF_BCK_REL = 3 seconds(MS error)

� Stagnating window: RLC counter N_StagnatingWindowUL is incremented provided that the receive window isstalled whenever an UL RLC data block whose BSN is different from the receive window state variable V(Q) andis received a round trip delay after the previous sending of a Packet Uplink Ack/Nack message.UL TBF is released because the RLC counter N_StagnatingWindowUL exceeds the system parameterN_STAGNATING_WINDOW_UL_LIMIT = 8 (MS error or radio problem).

� New counters in B8: P434a, P434b, P434c, P434d


1.139

Downlink Data Transfer

050

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20

40

60

80

100

120

BSS pb

Gb drop

BlockingdropStagnat drop

Radio pb

% AccRelease% NormRelease

Uplink Data Transfer

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BSS pb

Gb drop

Blocking pb

Stagnat pb

Radio pb

% AccRelease% NormRelease

3.3 Data Transfer ReleaseQoS Indicators, TBF Drops, Graph

� The cause of drop during DL data transfer is mainly radio problems� The cause of drop during UL data transfer is radio problems + blocking problems (MS error suspected because seen

on every network).


1.140

� Thresholds:

� When the Delayed DL TBF release is not activated andCS2 is not used at the beginning of the TBF:� the UL/DL TBF normal release rate is seen as good

above 98%

� When the Delayed DL TBF release is activated or CS2 isused at the beginning of the TBF (without optimization ofthe coding scheme adaptation):�The threshold of the DL TBF normal release rate

should be lower

3.3 Data Transfer ReleaseQoS Indicators, TBF Drops, Graph

� The QoS thresholds values assumes that MS mobility (reselection) is neglictible� Typical values for DL TBF normal release rate:

� When Delayed DL TBF release is activated: 95%� When Delayed DL TBF release is activated and CS2 is activated at the beginning of TBF: 90%

� The longer the TBF duration the higher the probability to drop� there is a high probability to be in CS2 during the Delayed phase

� Typical values for UL TBF normal release rate:� When CS2 is activated at the beginning of TBF: 98.3%, 98.9%

� an UL TBF is often short� the Coding Scheme is always CS1 during the MS contention resolution (based on TLLI) for security

� RLS procedures are active during the delayed phase




3.4 MS Sessions / Transfers

B8

� This chapter is also valid for B7 release.


1.142

3.4 MS Sessions / TransfersDefinitions

� Transfer

� Bi-directional exchange of RLC data blocks between the MS andthe BSS

� The bias of a transfer is the main direction of the transfer in termsof throughput

� Session

� Uninterrupted sequence of data transfers between the MSand the BSS

�Begin: a UL or DL TBF is established for an MS in PIM�On-going: at least one TBF is established�End: the last on-going UL or DL TBF is released

B8

� A session never ends when a DL TBF is released but at the expiry of T3192 timer in case there is no UL TBF on-going in themeantime.

� The Alcatel BSS regularly determines the bias of the on-going transfer at MS if the Bias Determination feature is enabled.�The number of octets transferred in both directions is counted and averaged for that purpose.

�If disabled the bias remains the one chosen at the establishment of the TBF.�By default a transfer is deemed downlink biased (at first establishment), except in case the MS context is created uponreceipt of an UL two phase access, in which case the bias is set to uplink.


1.143

� Sessions and transfers:

Session

Transfer

Number of sessions

Average duration

Cumulated time an MS is engaged in DL/UL biased transfers

% of time DL/UL TBF are granted the max nb of PDCHs they supportand the corresponding MSs are engaged in DL/UL biased transfers

Average number of DL/UL TBF per session

3.4 MS Sessions / TransfersQoS IndicatorsB8


1.144

� MS Sessions:

GPRS sessionsNumber of GPRS sessions P413Average duration of a session ((P419 + P420) / 10) / P413

Downlink UplinkAverage number ofDL TBF establishedper session

(P90a +P90b + P90c +P90d + P90e + P90f) /P413

Average number ofUL TBF establishedper session

(P30a + P30b +P30c) /P413

3.4 MS Sessions / TransfersQoS indicators, MS SessionsB8


1.145

� MS Transfers:Bias of the ongoing transfers

Downlink UplinkCumulative time MSare engaged in DLbiased transfers

P419 / 10 Cumulative time MSare engaged in ULbiased transfers

P420 / 10

Donwlink biaised ratio P419 / (P419 + P420) Uplink biaised ratio P420 / (P419 + P420)Cumulative time MSare served by DL TBFand engaged in DLbiased transfers

P411/10 Cumulative time MSare served by UL TBFand engaged in ULbiased transfers

P412/10

Cumulative time DLTBF are granted themaximum number ofPDCH they support andthe corresponding MSare engaged in DLbiased transfers

P409/10 Cumulative time ULTBF are granted themaximum number ofPDCH they support andthe corresponding MSare engaged in ULbiased transfers

P410/10

% of time DL TBF aregranted the maximumnumber of PDCH theysupport and thecorresponding MS areengaged in DL biasedtransfers

P409 / P411 % of time UL TBF aregranted the maximumnumber of PDCH theysupport and thecorresponding MS areengaged in UL biasedtransfers

P410 / P412

3.4 MS Sessions / TransfersQoS Indicators, MS TransfersB8


1.146

DL session

0

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100000

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86889092949698100102

Time Opt alloc

DL Time bias

Time bias

%Time OptAlloc

UL session

0

1000

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5000

6000

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Time Opt alloc

UL Time bias

Time bias

%Time OptAlloc

3.4 MS Sessions / TransfersQoS Indicators, GraphB8

� Typical values of DL TBF optimal allocation time rate (without resource re-allocation):� Without congestion (GSM+GPRS): 93%, 94%, 95%, 96%� With congestion: 79.5%

� UL TBF optimal allocation time rate can be biased, due to the restriction on P29.� However, on small area, it can give typical values:

� Without congestion (GSM+GPRS): 68.5%, 76%, 92%, 98%� With congestion: 98%

➨ These typical values are highly depend on the penetration rate of class 9 or class 10 mobiles (mobiles able to use 2 TSon UL path).




3.5 Resource Usage

B8


1.148

� The BSS uses several resources to transfer data between theMS and the GPRS core network

� Air interface resources� Physical channels: MPCDH, SPDCH� Air interface channels:

� physical channels: MPDCH, SPDCH� logical channels:

� control channels– without MPDCH: BCCH, AGCH, PCH, RACH– with PDCH: PBCCH, PAGCH, PPCH, PRACH

� traffic channels: PDTCH� associated signaling channel: PACCH

3.5 Resource UsageBSS Resources, Air InterfaceB8


1.149

� The GPU resource (BSS internal resource)� The GPRS traffic of a group of cells is handled by the GPU

function mapped on a hardware component: the GPU board

3.5 Resource UsageBSS Resources, GPU

GP

U

8 PCM 8 PCM

Ater Gb

SGSN

BSC

in MFS equipment

B8

Each GPU handle the GPRS traffic of cellsbelonging to the same BSSThere is a maximum of GPU to monitor thetraffic of one BSSUp to 240 PDCH can be active at the same timeon the same GPUEach GPU can


1.150

� Ater interface resource� A GCH is the 16 Kbit/s physical channel carrying the GPRS

traffic between the BTS and the MFS� A group of 1 to 5 GCHs called EGCH is allocated per PDCH

according to the maximum CS or MCS number in use

3.5 Resource UsageBSS Resources, Ater Interface

G

P

UBSC

BTS

AbisAbis PCM PCM

Ater Ater PCMPCM

GCHGCH

PDCHPDCH

1 GCH per PDCHif

Max CS = CS2 or Max MCS = MCS2

B8

For EGPRS traffic an EGCH physical channel isallocated per PDCH which is a set of n GCHs, ndepending on the maximum CS or MCS that canbe used on the PDCH:

Scheme Modulation Raw data rate(in kbit/s)

Number ofGCH

CS-1 GMSK 8 1CS-2 GMSK 12 1CS-3 GMSK 14.4 2CS-4 GMSK 20 2

MCS-1 GMSK 8.8 1MCS-2 GMSK 11.2 1

14.8 2MCS-3 GMSK 13.6 2MCS-4 GMSK 17.6 2MCS-5 8-PSK 22.4 2

29.6 3MCS-6 8-PSK 27.2 3MCS-7 8-PSK 44.8 4MCS-8 8-PSK 54.4 4MCS-9 8-PSK 59.2 5


1.151

� Gb interface resource� A BVC is the logical identifier to which is linked the traffic of

a cell carried over the Gb interface� The traffic of all the BVCs controlled by the same GPU is

multiplexed and carried by the 64 Kbit/s PCM time slots onthe Gb interface

3.5 Resource UsageBSS Resources, Gb Interface

GPU

8 PCM

GbBVCI=2BVCI=2

BVCI=1BVCI=1

BVCI=3BVCI=3BSC1

BVCI=5BVCI=5

BVCI=6BVCI=6BVCI=4BVCI=4 BSC2

SGSN

B8


1.152

� GPRS radio resources: PDCH

PDCH usageAverage , max, min number of established PDCHs

Cumulated time PDCHs are : - allocated- allocated with EGPRS traffic- degraded

Smooth PDCH adaptation to cell load variationEN_DYN_PDCH_ADAPTATION = enable

MAX_PDCH_DYNvariable follow-up

PDCH dynamic establishment success rate

% time during which the cell is in high load situation

Soft preemption

3.5 Resource UsageQoS Indicators, PDCHB8

� A PDCH is established when it is allocated on a radio point of view and for which an Ater (GCH) resource has beenallocated

� Pre-allocated PDCH (MIN_PDCH) are :� not established if not used for TBF (no GCH allocated) when EN_FAST_GPRS_INITIAL_ACCESS = disabled� always established when EN_FAST_GPRS_INITIAL_ACCESS = enabled


1.153

Average number of established PDCH in the GPU P149g / 10Maximum number of established SPDCH in the cell P150bMinimum number of established SPDCH in the cell P150cCumulated time during which the PDCH are established for the cell P38 / 10Cumulated time during which the SPDCH is used for data traffic P38b / 10Cumulated time during which the SPDCH is used for EGPRS data traffic P38c / 10Cumulated time during which the SPDCH is used for GPRS data traffic (P38b - P38c) / 10PS "erlang" P38b / 10 / GPPS GPRS "erlang" (P38b - P38c) / 10 / GPPS EGPRS "erlang" P38c / 10 / GPCumulated time during which the SPDCH is degraded P38d / 10PDCH dynamic establishment success rate P19 / P54% of time the cell is in high load situation (P1 / 10) / GP% of time a PDCH DL congestion exists in DL (P13 / 10) / GP% of time a PDCH UL congestion exists in DL (P26 / 10) / GP

PDCH usage

� GPRS radio resources: PDCH usage

3.5 Resource UsageQoS Indicators, PDCH UsageB8

� The cell is in high load situation if MAX_PDCH_DYN is equal to MAX_PDCH - Number of MPDCH

� New counters in B8: P150b, P150c, P38, P38c, P38d

Soft pre-emptionNumber of PDCH released after having beenmarked by the soft pre-emption procedure

P417

Number of times the soft pre-emption procedureis called

P418

Average number of UL+DL TBF candidates to aT1 reallocation per PDCH released after havingbeen marked

(P403a + P404a) / P417


1.154

� GPRS radio resources PDCH: MAX_PDCH_DYN

MIN_PDCH

MAX_PDCH_HIGH_LOAD

MAX_PDCH_DYN

MAX_PDCH

number of timeslots in the cell

MAX_PDCH_DYN variable follow-upMAX_PDCH_DYN value integrated over time P414 / 10Average value of MAX_PDCH_DYN (P414 / 10) / GPMaximum value of MAX_PDCH_DYN P415Minimum value of MAX_PDCH_DYN P416MAX_PDCH_DYN maximum range P415 - P416MAX_PDCH_DYN reduction rate (PERIOD*(MAX_PDCH - P414/10)) /

(PERIOD*MAX_PDCH)

3.5 Resource UsageQoS Indicators, MAX_PDCH_DYN Follow-upB8


1.155

PDCH dynamic allocation load report

0123456789

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00.10.20.30.40.50.60.70.80.91

Alloc max

% BSC Highload

Dyn dealloc procedure

0

1

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5

6

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05101520253035

T1 Success

RR Softpreempt% Reduction

3.5 Resource UsageQoS Indicators, PDCH, GraphB8

� Typical reference values of BSC high load time rate is:� Without congestion (GSM+GPRS): 0.4%, 0.6%� With some congestion: 5.5%, 4.6%� With high level of congestion: 26%


1.156

� GPRS radio resources: MPDCH

MPDCH usage

MPDCH signaling traffic

MPDCH resource allocation is static � no indicators

PPCH

PRACH

PACCH

PAGCH

3.5 Resource UsageQoS Indicators, MPDCHB8


1.157

� GPRS radio resources: MPDCH signaling

MPDCH signalling trafficDedicated PPCH signalling load on all the existing MPDCH P61Number of PACKET PAGING REQUEST for PS paging sentto the MS on PPCH

P61a

Number of PACKET PAGING REQUEST for CS paging sentto the MS on PPCH

P61b

Number of Packet DL assignment messages on PPCH P61 - 0.5*P61a - 0.5*P61bOccupancy rate of PS paging messages on PPCH load 0.5 * P61a / P61

Occupancy rate of Packet DL assignment messages on PPCH (P61 - 0.5*P61a - 0.5*P61b) / P61

PRACH signalling load on all the existing MPDCH P399

PRACH signalling load due to NC2 feature P438d% PRACH load induced by NC2 feature (P438d / P399) * 100Dedicated PAGCH signalling load on all the existing MPDCH P400UL PACCH signalling load on all the existing MPDCH P401

3.5 Resource UsageQoS Indicators, MPDCH SignalingB8

� Factor of 0.5 comes from the fact that a PACKET PAGING REQUEST can contain 2 paging messages (like in GSMbetween Paging Commands and Paging Requests)



1.158

� GPRS radio resources: CCCH

CCCH load RACH

PCH: PS paging, CS paging, Immediate assignment

AGCH

3.5 Resource UsageQoS Indicators, CCCHB8


1.15

� GPRS radio resources: CCCH load

CCCH loadPaging usage rate due to GPRS P53a / MC8APCH use due to GPRS Immediat Assignment P53cRatio PS/CS paging through SGSN P53a / (P53a+P53b)RACH usage rate due to GPRS P62c / MC8CAGCH usage rate due to GPRS (P49 + P27) / (MC8B + P49 + P27)

3.5 Resource UsageQoS Indicators, CCCH LoadB8

� P53a = Number of (BSCGP) PAGING REQUEST for PS paging sent to the MS (through the BSC which manages thePCH resource). (used for instance for a MT picture transfer MMS service)

� P53b = Number of (BSCGP) PAGING REQUEST for CS paging sent to the MS (through the BSC which manages thePCH resource) -> Need of Gs interface.

� P53c =Number of (BSCGP) IMMEDIATE ASSIGNMENT sent to the MS (through the BSC which manages the PCHresource) for a DL TBF establisment when the MS is in DRX mode.

� GSM Paging Command (one per Mobile) or GPRS (BSCGP) PAGING REQUEST are merged into PAGING REQUESTon radio layer.


1.16

GPRS/GSM AGCH breakdown

050000

100000150000200000250000300000350000400000450000

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00.511.522.533.544.5

PS AGCHTot AGCH% PS AGCH

GPRS/GSM RACH breakdown

050000

100000150000200000250000300000350000400000450000

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00.511.522.533.54

Tot RACH% PS RACH

GPRS/GSM PCH breakdown

02000000400000060000008000000

100000001200000014000000160000001800000020000000

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00.10.20.30.40.50.60.70.80.91

CS PAgingPS Imm. AsPS PAging%io PS Pag

CS AGCH

3.5 Resource UsageQoS Indicators, CCCH, GraphB8


1.161

� GPRS radio resources: GPU

GPU counters Overall traffic

MS capabilities breakdown

Processing limitation, GCH interface

3.5 Resource UsageQoS Indicators, GPUB8


1.162

GPU trafficNumber of LLC PDU transferred (UL+ DL) P104Number of UL+DL TBF establishment requestsper GPU

P107

Number of UL+DL TBF establishment successesper GPU

P106

(UL+DL) TBF success rate per GPU (P106 / P107) * 100Number of PS PAGING request per GPU P391aNumber of CS PAGING request per GPU P391b

MS capabilitiesNumber of MS contexts created for Releases1997 or 1998 mobile stations.

P450a

Number of MS contexts created for non-EGPRScapable Release 1999 onwards mobile stations

P450b

Number of MS contexts created for EGPRScapable Release 1999 onwards mobile stations.

P450c

Ratio of MS contexts created for Releases 1997or 1998 mobile stations.

P450a / ( P450a+P450b+P450c)

Ratio of MS contexts created for non-EGPRScapable Release 1999 onwards mobile stations

P450b / ( P450a+P450b+P450c)

Ratio of MS contexts created for EGPRS capableRelease 1999 onwards mobile stations.

P450c / ( P450a+P450b+P450c)

� GPRS radio resources: GPU usage

3.5 Resource UsageQoS Indicators, GPU UsageB8

� New counters in B8: P450a, P450b, P450c


1.163

� GPRS radio resources: GPU load

GPU loadDSP congestion duration (in seconds). P384Percentage of time during which the DSP is incongestion

P384 / GP

Cumulative time during which the GPU stays inthe PMU CPU overload state due to PMU CPUpower limitations.

P402

Percentage of time during which the GPU staysin the PMU CPU overload state due to PMUCPU power limitations.

P402 / GP

Average PMU CPU power budget of the GPU P76aMaximum PMU CPU power budget of the GPU P77a

3.5 Resource UsageQoS Indicators, GPU LoadB8

� New counters in B8: P402


1.164

� GPRS radio resources: GCH usage

GCH counters Cumulated time:- GCHs are busy in GPU- GCHs are available in GPU- no GCH available- GPU is in Ater congestion- GPU is in « high » Ater usage state

Maximum nb of busy GCH in GPU

3.5 Resource UsageQoS Indicators, GPU UsageB8


1.165

� GPRS radio resources: GCH load

Ater interface - GCHCumulative time (in seconds) during which aGCH (16k channel) is busy in the GPU

P100a

GCH “Erlang” P100a / GPMaximum number of busy GCH (16k channel) inthe GPU

P100b

Cumulative time (in seconds) during which aGCH resource (16k channel) is available in theGPU

P101

% of time GCH resources are busy in the GPU (P100a / P101) * 100Atermux congestion duration (in seconds) due toa lack of GCH transmission resources on theAtermux interface

P383a

% of time the GPU is in Ater congestion state P383a / GPTime (cumulated over a granularity period)during which the GPU remains in "high" Aterusage

P383b

% of time the GPU is in “high” Ater usage state P383b / GP

3.5 Resource UsageQoS Indicators, GCHB8

� New counters in B8: P100a, P100b, P101


1.166

3.5 Resource UsageQoS Indicators, BVC

� GPRS radio resources: BVC

BVC Number of DL LLC bytes

Number of UL LLC bytes

Received from the SGSN

Discarded due to congestion

Discarded due to a Suspend procedure

Received from the MS

Rerouted

Not rerouted

Well received from the SGSN

BVC availability

B8


1.167

3.5 Resource UsageQoS Indicators, BVC, Traffic, Availability

� GPRS radio resources: BVC traffic, BVC availability

Number of DL LLC bytes received from SGSN P43 Number of UL LLC bytes received from MS P44Number of DL LLC bytes received by MS in GPRS ACK mode P43a

Number of UL LLC bytes received from MS in GPRS ACK mode P44a

Number of DL LLC bytes received by MS in GPRS NACK mode P43b

Number of UL LLC bytes received from MS in GPRS NACK mode P44b

Number of DL LLC bytes received by MS in EGPRS ACK mode P43c

Number of UL LLC bytes received from MS in EGPRS ACK mode P44c

Number of DL LLC bytes received by MS in EGPRS NACK mode P43d

Number of UL LLC bytes received from MS in EGPRS NACK mode P44d

Number of DL LLC bytes discarded due to congestion P10

Number of UL LLC bytes discarded due to congestion at SNS level P23

Average DL useful throughput in kbit/s ((P43 - P10) * 8) / (GP * 1000) Average UL useful throughput in kbit/s ((P44 - P23) * 8) / (GP * 1000)DL LLC congestion rate P10 / P43Number of DL LLC bytes discarded due to suspend procedure P99% of DL LLC bytes discarded due to suspend procedure P99 / P43Downlink LLC bytes well rerouted P95DL LLC bytes not rerouted P96DL LLC bytes well received P43 - P10 - P96DL LLC bytes well received rate (P43 - P10 - P96) / P43

BVC (cell) traffic

BVC (cell) availabilityTime during which the BVC associated to a cell is unavailable for traffic P67

Downlink Uplink

B8

� LLC bytes discarded: relating to PDU LifeTime expiry or GPU buffer congestion (canbe linked to degraded DL FlowControl algorithm)


1.16

3.5 Resource UsageQoS Indicators, Graph

Details of downlink LLC traffic

0100000020000003000000400000050000006000000700000080000009000000

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98.498.698.89999.299.499.699.8100100.2 Blocked bytes

DiscardedbytesNot rerouted

ReroutedbytesReceivedbytes%Well receiv

Details of uplink LLC traffic

0500000

1000000150000020000002500000300000035000004000000

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UL sent bytes

B8




3.6 CS and MCS Adaptation

B8


1.170

3.6 CS and MCS AdaptationModulations and Data Rates

� Data rate per radio TS (RLC payload)Scheme Modulation Maximum rate

(kbps) GPRS

CS-4 GMSK 21.4 CS-3 GMSK 15.6 CS-2 GMSK 13.4 CS-1 GMSK 9.05

EGPRS MCS-9 8PSK 59.2 MCS-8 8PSK 54.4 MCS-7 8PSK 44.8 MCS-6 8PSK 29.6 / 27.2 * MCS-5 8PSK 22.4 MCS-4 GMSK 17.6 MCS-3 GMSK 14.8 / 13.6 * MCS-2 GMSK 11.2 MCS-1 GMSK 8.8

* case of padding

8PSK modulation toprovide

higher data rates

GMSK modulation to ensurea certain level of

performance in case of poorradio conditions

B8

�


1.171

3.6 CS and MCS AdaptationDL CS Adaptation

� GPRS CS adaptation in the DLAV_RXQUAL_LT

AV_SIR

CS1

CS2

CS3CS4

CS_QUAL_DL_1_2_X_Y+ CS_HST_DL_LT

CS_QUAL_DL_1_2_X_Y

CS_QUAL_DL_2_3_X_Y

C S_QUAL_DL_3_4_X_Y

0

7

0 15CS_SIR_DL_4_3_X_Y CS_SIR_DL_3_4_X_Y+ CS_SIR_HST_DL

CS1 or CS2 (hysteresis)


CS3 orCS4

(hysteresis)

CS_QUAL_DL_2_3_X_Y + CS_HST_DL_LT

B8

� The change from CS3 to CS4 is not only based on AV_RXQUAL_LT for the two following reasons:� RXQUAL range only goes down to 0.2%. However, the change of the coding scheme from CS3 to CS4 will probablyhave to be done for even lower values. Indeed, when the coding scheme is CS4, in static (AWGN), a BLER of 0.1 (typicalvalue of the BLER threshold to change from CS3 to CS4) is obtained for a raw BER of 1-(1-0.1)1/456 = 2.10-4. This rawBER would be larger in multipath channels but is likely to remain below 0.2%. This means that CS_QUAL_DL_3_4 shouldbe closed to 0 and that a condition based on RXQUAL is not sufficient to change the coding scheme from CS3 to CS4.� If the changes from CS3 to CS4 and from CS4 to CS3 are based on different metrics, Ping-Pong effect can occur.Indeed, it can happen that the conditions to change from CS3 to CS4 and CS4 to CS3 are simultaneously true in somesituations.


1.172

3.6 CS and MCS AdaptationUL CS Adaptation

� GPRS CS adaptation in the ULAV_RXQUAL_LT

AV_SIR

CS1

CS2

CS_QUAL_UL_1_2_X_Y + CS_HST_UL_LT

CS_QUAL_UL_1_2_X_Y

CS_QUAL_UL_2_3_X_Y

0

7

0 15



CS3

CS4

CS3 or CS4 (hysteresis) CS_QUAL_UL_3_4_X_Y



B8

� In uplink, the RXQUAL is available in CS4 and the SIR measurements are not reported by the BTS to the MFS so far.Therefore, it is possible to also use RXQUAL measurements to change the coding scheme from CS3 to CS4 or from CS4 toCS3, contrary to the downlink algorithm, where the SIR was used.


1.173

3.6 CS and MCS AdaptationDL MCS Adaptation

� EGPRS MCS adaptation in the DL� In RLC ack mode, the MFS applies a given MCS taking into account:

� the current MCS� MCS1 to MCS4 in GMSK� MCS5 to MCS9 In 8-PSK

� the average Power Decrease: APD set = [0, 1, 3, 4, 5, 6, 8, 10]� the automatic ReQuest for repetition

� ARQ type I� ARQ type II (Incremental Redundancy)

� In RLC nack mode, the MFS applies a given MCS taking into account:� the current MCS

� MCS1 to MCS4 in GMSK� MCS5 to MCS9 in 8-PSK

� the average Power Decrease: APD set = [0, 1, 3, 4, 5, 6, 8, 10]

B8

� Extract of a table when APD=0dB, Type 1 ARQ, 8PSK table: if MCScurrent belongs to {5,6,7,8,9}

0 1 2 3 4 5 6 70 5 5 5 5 1 1 1 11 5 5 5 5 1 1 2 22 5 5 5 5 1 2 2 23 5 5 5 5 2 2 2 34 5 5 5 5 5 2 3 35 5 5 5 5 5 3 3 36 5 5 6 5 5 5 3 37 5 5 6 5 5 5 3 38 5 5 6 6 5 5 5 49 5 6 6 6 5 5 5 510 5 6 6 6 6 5 5 511 6 6 6 6 6 6 5 512 6 6 6 6 6 6 5 513 6 6 6 6 6 6 5 514 7 6 6 6 6 6 6 615 7 6 6 6 6 6 6 616 7 7 6 7 6 6 6 617 7 7 7 7 7 6 6 618 7 7 7 7 7 7 7 719 7 7 7 7 7 7 7 720 7 7 7 7 7 7 7 721 7 7 7 7 7 7 7 722 7 8 8 8 8 8 8 823 8 8 8 8 8 8 8 824 8 8 8 8 8 8 8 8

CV_BEP

MEA

N_B

EP


1.174

3.6 CS and MCS AdaptationUL MCS Adaptation 1/2

� EGPRS MCS adaptation in the UL� The MFS applies a given MCS taking into account:

� the current MCS� MCS1 to MCS4 in GMSK

� the average Power Decrease: APD set= [0, 1, 3, 4, 5, 6, 8, 10]

B8

� In Uplink the same tables as in downlink apply.

� In RLC acknowledged mode� Since Incremental Redundancy is not supported in uplink, only tables related to downlink link adaptation withoutIncremental Redundancy must be considered.� Since 8PSK is not supported in the uplink, only tables related to MCS1 to MCS4 must be used.

� In RLC unacknowledged mode� Since 8PSK is not supported in the uplink, only tables related to MCS1 to MCS4 must be used.

� When the optimal MCS which is indicated by the table is higher than MCS4, the resulting MCS must be MCS4, otherwisethe result of the table must apply.


1.175

3.6 CS and MCS AdaptationUL MCS Adaptation 2/2

� EGPRS MCS adaptation in the UL� The MFS applies a given MCS taking into account:

� the current MCS� MCS1 to MCS4 in GMSK

� the average Power Decrease: APD set= [0, 1, 3, 4, 5, 6, 8, 10]

B8

� In Uplink the same tables as in downlink apply.

� In RLC acknowledged mode� Since Incremental Redundancy is not supported in uplink tables related to downlink link adaptation withoutIncremental Redundancy must be considered.� Since 8PSK is not supported in the uplink, only tables related to MCS1 to MCS4 must be used.

� In RLC unacknowledged mode� Since 8PSK is not supported in the uplink, only tables related to MCS1 to MCS4 must be used.

� When the optimal MCS which is indicated by the table is higher than MCS4, the resulting MCS must be MCS4, otherwisethe result of the table must apply.


1.176

� CS and MCS adaptation

PDTCHRLC blocks

PACCHRLC blocks

Number of useful, retransmitted, lost blocks for GPRS CS1,2,3,4

Retransmission rate, lost rate

Throughput per cell, per PDCH, per TBF

PDTCH occupancy

Useful CSx and MCSx distribution

PACCH occupancy

GPRS Coding Schemeincrease and decrease

3.6 CS and MCS AdaptationQoS IndicatorsB8


1.177

RLC statisticsDownlink Uplink

Number of useful PDTCHRLC blocks acknowledged bythe MS in GPRS ack mode

CS1 : P55aCS2 : P55bCS3 : P55cCS4 : P55e

Number of useful PDTCHRLC blocks acknowledged bythe MS in GPRS ack mode

CS1 : P57aCS2 : P57bCS3 : P57cCS4 : P57e

Number of retransmittedPDTCH RLC blocks inGPRS ack mode

CS1 : P20aCS2 : P20bCS3 : P20cCS4 : P20d

Number of retransmittedPDTCH RLC blocks inGPRS ack mode

CS1 : P21aCS2 : P21bCS3 : P21cCS4 : P21d

Number of lost PDTCH RLCbytes in GPRSnack mode

CS1+CS2+CS3+CS4 : P72c Number of lost PDTCH RLCbytes in GPRSnack mode

CS1+CS2+CS3+CS4 : P72d

PDTCH RLC blockretransmission rate in GPRSack mode

(P20a + P20b + P20c +P20d) / (P55a + P55b +P55c + P55d + P20a + P20b+ P20c + P20d)

PDTCH RLC blockretransmission rate inGPRS ack mode

(P21a + P21b + P21c +P21d) / (P57a + P57b +P57c + P57d + P21a + P21b+ P21c + P21d)

PDTCH RLC block CSx /(CS1+CS2+CS3+CS4) ratio

P55x /(P55a+P55b+P55c+P55d)

PDTCH RLC block CSx /(CS1+CS2+CS3+CS4) ratio

(P57x) /(P57a+P57b+P57c+P57d)

In RLC ack mode, rate ofRLC retransmitted databytes sent on PDTCH andencoded in CS-x

(P20a*160+P20b*240+P20c*288+P20d*400)/(P20a*160+P20b*240+P20c*288+P20d*400+P55a*160+P55b*240+P55c*288+P55d*400)

In RLC ack mode, rate ofRLC retransmitted databytes sent on PDTCH andencoded in CS-x

(P21a*160+P21b*240+P21c*288+P21d*400)/(P21a*160+P21b*240+P21c*288+P21d*400+P57a*160+P57b*240+P57c*288+P57d*400)

Average TX_EFFICIENCY P335 Average TX_EFFICIENCY P336

� CS and MCS adaptation: RLC statistics in GPRS mode

KPIKPI

3.6 CS and MCS AdaptationQoS Indicators, RLC Statistics, GPRS Mode

KPI

B8

� AverageTX_EFFICIENCY is equal to:� Where:

• NB_SENT is the number of transmitted RLC data blocks,

• NB_RECEIVED is the number of correctly received RLC data blocks (i.e. blocks such that apositive acknowledgment is reported),

• ρi is the equal to the number of information bits in the i-th correctly received RLC data blockdivided by the number of bits per RLC data block with GMSK modulation (456 in GPRS). Thisratio only depends on the coding scheme used for the i-th correctly received RLC data blockand is between 0 and 1 in GPRS. The values of the number of information bits per RLC datablock for each coding scheme are defined in [3], in Table 3 for GPRS.

CS1 CS2 CS3 CS4ρ 0.40 0.59 0.68 0.94

• ni is the number of RLC data blocks in the i-th radio block. Therefore, this number is alwaysequal to 1 for GPRS,

� It is computed every TX_EFFICIENCY_PERIOD (=50) RLC data blocks

� It is compared to TX_EFFICIENCY_(N)ACK_THR (=10%) to trigger radio drop.

� New counters in B8: P55c, P55d, P57c, P57d, P20c, P20d, P21c, P21d


1.178

RLC statisticsDownlink Uplink

Number of useful RLCblocks sent in RLCacknowledged mode onPDTCH encoded in MCS-1/2/…/9.

MCS1 : P55eMCS2 : P55f…………MCS9 : P55m

Number of useful RLCblocks sent in RLCacknowledged mode onPDTCH encoded inMCS-1/2/3/4.

MCS1 : P57eMCS2 : P57fMCS3 : P57gMCS4 : P57h

MCSx, retransmitted databytes

P20e MCSx, retransmitted databytes

P21e

MCS-x lost bytes P72d MCS-x lost bytes P73dIn RLC ack mode, rateof RLC retransmitteddata bytes sent onPDTCH and encoded inMCS-x

P20e/(P20e+(P55e*176+P55f*224+P55g*296+P55h*352+P55i*448+P55j*592+(P55k*896+P55l*1088+P55m*1184)/2)/ 8))

In RLC ack mode, rateof RLC retransmitteddata bytes sent onPDTCH and encoded inMCS-x

(p21e) / ((p21e)+( ((P57e)*176+(P57f)*224+(P57g)*296+(P57h)*352) / 8))

3.6 CS and MCS AdaptationQoS Indicators, RLC Statistics, EGPRS Mode

� CS and MCS adaptation: RLC statistics in EGPRS mode

KPI

B8

� New counters in B8: P55e, P55f, P55g, P55h, P55i, P55j, P55k, P55l, P55m, P57e, P57f, P57g, P57h, P20e, P21e, P72d,P73d


1.179

Coding scheme adaptationDownlink Uplink

Number of CSadaptions from a givencoding scheme to a lessrobust coding scheme.Does not apply toEGPRS TBFs

P351a Number of CSadaptions from a givencoding scheme to a lessrobust coding scheme.Does not apply toEGPRS TBFs

P352a

Number of CSadaptions from a givencoding scheme to amore robust codingscheme. Does not applyto EGPRS TBFs

P351b Number of CSadaptions from a givencoding scheme to amore robust codingscheme. Does not applyto EGPRS TBFs

P352b

Average number of CSincrease per TBF

P351a / (P90a + P90b +P90c + P90d + P90e +P90f)

Average number of CSincrease per TBF

P352a / (P30a + P30b +P30c)

Average number of CSadaptions decrease perTBF

P351b/ (P90a + P90b +P90c + P90d + P90e +P90f)

Average number of CSadaptions decrease perTBF

P352b / (P30a + P30b +P30c)

3.6 CS and MCS AdaptationQoS Indicators, CS Adaptation

� CS and MCS adaptation: CS adaptation

B8

� New counters in B8: P351a, P351b, P352a, P352b


1.180

Downlink Traffic Load

050000

100000150000200000250000300000350000400000

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010203040506070

Blocks CS2Blocks CS1%io CS2

RLC Efficiency on downlink

050000

100000150000200000250000300000350000400000

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0.5

1

1.5

2

2.5

CS2 useful

CS1 useful

% CS2retrans% CS1retrans

3.6 CS and MCS AdaptationQoS Indicators, DL, GraphB8

� Typical values of CS2/(CS1+CS2) ratio on DL path are:� When CS2 is not at beginning of TBF:

40%, 45%, 47%� When CS2 is at beginning of TBF:

97%, 98%to be correlated to the Average useful RLC throughput per TBF on page 171

� Typical values of global retransmission rate on DL path are:� When CS2 is not at beginning of TBF:

0.7%, 0.8%, 0.9%� When CS2 is at beginning of TBF:

1.1%, 1.2%

� Optimise CS adaptation to optimise user data throughput (best useful RLC throughput and while avoiding TBF drop)

� All blocks are considered in graph 1 whereas only useful blocks are considered in graph 2


1.181

Uplink Traffic Load

0

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Blocks CS2Blocks CS1%io CS2

RLC Efficiency on uplink

0

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1

1.5

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2.5

CS2 useful

CS1 useful

% CS2retrans% CS1retrans

3.6 CS and MCS AdaptationQoS Indicators, UL, GraphB8

� Typical values of CS2/(CS1+CS2) ratio on UL path are:� When CS2 is not at beginning of TBF:

6%, 12%, 16%� When CS2 is at beginning of TBF:

48%, 77% (less high than for DL since for UL TBF CS1 is always used during the TLLI Contention Resolution)� Typical values of global retransmission rate on UL path are:

� When CS2 is not at beginning of TBF:0.1%, 0.2%, 0.4%,

� When CS2 is at beginning of TBF:0.2%, 0.6%




3.7 Cell Reselection

B8


1.183

3.7 Cell Reselection NC0, Success

MS MFSserving cell

DL transfer


Packet DL Ack/Nack



PDTCHDL

PACCHUL


SGSNMFStarget cell

The MS decidesfor cell reselection



FLUSH-LL ACK(TLLI)

P436

NC0reselection

success


UL transferThe MS sends an LLC PDU to warn the SGSN about its new cell location

P434d

DL TBFrelease

P434c

UL TBFrelease

B8

� P434c (resp.P434d) is the number of UL (resp. DL) TBFs which have been released due to a NC0 reselection. These TBFs canhave been previously counted as abnormally released or acceptably released due to reselection depending on the occurrence timeof the FLUSH-LL message.

� New counters inB8: P434c, P434d, P436.


1.184


UL transferMS sends an LLC PDU to warn the SGSN about its new cell location

3.7 Cell Reselection NC2, Request / Success

MS MFSserving cell

DL transfer

SGSN

Packet measurement reportPACCHUL

MFStarget cell

NC2 cell reselectionrequest for cause:

too bad uplink quality

too bad downlink quality

too low downlink level

better neighbor cellPacket cell change order, polling

PACCHDLnew cell (BCCH,BSIC) Packet control ack

The MSswitches tothe new cell

T3158expiry

T3158




FLUSH-LL ACK(TLLI)

T_ACK_WAIT

T_WAIT_FLUSH

P433d

P433c

P433a

P433b

NC2 cell reselectionsuccess for cause:

too bad uplink quality

too bad downlink quality

too low downlink level

better neighbor cell

P433d

P433c

P433a

P433b

P434b

DL TBFrelease

P434a

UL TBFrelease

B8

� If FLUSH-LL message is not received before T_WAIT_FLUSH expiry then the TBF release is considered as abnormal andP396a/P396b is not incremented.

� The chart above corresponds to a NC2 reselection. The same P396a/P396b counter is incremented in case of a TBF release dueto NC0 reselection provided that the FLUSH-LL message is received before a TBF drop is detected.

� New counters inB8: P433a, P433b, P433c, P433d, P434a, P434b.


1.185

UL transfer establishment in the new cellis impossible

3.7 Cell Reselection NC2, Failure

MS MFSserving cell

DL transfer

SGSN

Packet measurement reportPACCHUL

MFStarget cell

NC2 cell reselectionrequest

Packet cell change order, pollingPACCHDLnew cell (BCCH,BSIC)

Packet control ackThe MS

switches tothe new cell

T3158expiry

T3158


T_ACK_WAIT

T_WAIT_FLUSH

P437b

Targetcell notrejected

P437a

Targetcell

rejected

Packet channel request

Packet uplink assignment

USF scheduling

Packet cell change failure

PRACH

PAGCH

PDTCH

PACCH

B8

� When receiving the PACKET CELL CHANGE FAILURE message the MFS will increment either P437a or P437b according to thecause value reported by the MS in the message.

�P437a is incremented if the cause reported is one of the following:

� "Frequency not implemented”

� "No response on target cell”

� "Immediate Assign Reject or Packet Access Reject on target cell”

�P437b is incremented if the cause reported is one of the following:

� "On going CS connection”

� "MS in GMM Standby state”

�"Forced to the Standby state”

� New counters inB8: P437a, P437b.


1.186


3.7 Cell ReselectionExercise

� Exercise 1: What kind of cell reselectionprocedure you can observe in Trace13and Trace14?

� Exercise 2: For each case of cellreselection, find old and new cellidentities


1.187

� NC0 reselection

3.7 Cell Reselection QoS Indicators

� NC2 reselection

NC2 reselection start

Number of requestsNumber of successes, Nb of DL/UL TBF releases

Success rate

Failure causes

time

TBF establishment end

Target cell rejected

Target cell not rejected

reselection time Outgoing

Incoming

Max

Avg

Min

Number of successes, Nb of DL/UL TBF releases

B8


1.18

� Cell reselection: ALL = NC0+NC2

3.7 Cell ReselectionQoS Indicators, all, NC0

Number of successful cell re-selection P397

Number of successful NC0 cell re-selection P436

NC0+NC2 re-selection

NC0 re-selection

B8

� New counters in B8: P436� Modified in B8: P397 to take into account cell reselection in NC2 mode.


1.189

Number of NC2 cell re-selection request cause PT1 (too low downlink level)

P433a

Number of NC2 cell re-selection request cause PT2 (better neighbour cell)

P433b

Number of NC2 cell re-selection request cause PT3 (too bad downlink quality)

P433c

Number of NC2 cell re-selection request cause PT4 (too bad uplink quality)

P433d

Ratio of NC2 re-selection cause Emergency (P433a+P433c+P433d) / (P433a+P433b+P433c+P433d) * 100

Ratio of NC2 re-selection cause Better Condition

(P433b) / (P433a+P433b+P433c+P433d) * 100

Number of NC2 cell re-selection success cause PT1 (too low downlink level)

P435a

Number of NC2 cell re-selection success cause PT2 (better neighbour cell)

P435b

Number of NC2 cell re-selection success cause PT3 (too bad downlink quality)

P435c

Number of NC2 cell re-selection success cause PT4 (too bad uplink quality)

P435d

Number of NC2 cell re-selection requests

P433a+P433b+P433c+P433d

Number of NC2 cell re-selection successes P435a+P435b+P435c+P435dNC2 cell re-selection success rate (P435a+P435b+P435c+P435d) /

(P433a+P433b+P433c+P433d)

NC2 re-selection

� Cell reselection: NC2

3.7 Cell ReselectionQoS Indicators, all, NC2 1/2

KPI

KPI

B8

� New counters in B8: P433a, P433b, P433c, P433d, P435a, P435b, P435c, P435d


1.190

� Cell reselection: NC2

3.7 Cell ReselectionQoS Indicators, all, NC2 2/2

Number of NC2 cell re-selection failure when target cell is rejected

P437a

Number of NC2 cell re-selection failure when target cell is not rejected

P437b

Rate of NC2 cell re-selection failure reported by the MS

(P437a+P437b) / (P433a+P433b+P433c+P433d)

Average outgoing NC2 cell re-selection duration

P431a

Maximum outgoing NC2 cell re-selection duration

P431b

Minimum outgoing NC2 cell re-selection duration

P431c

Average incoming NC2 cell re-selection duration

P432a

Maximum incoming NC2 cell re-selection duration

P432b

Minimum incoming NC2 cell re-selection duration

P432c

NC2 re-selection

B8

� New counters in B8: P431a, P431b, P431c, P432a, P432b, P432c, P433a, P433b, P433c, P433d, P437a, P437b



4 Detection of the Main BSS GPRS QoS Problems

B8

� Most information of this chapter are available for B7 release.


1.192

4 Detection of the Main BSS GPRS QoS ProblemsSession Presentation

� Objective: to be able to detect the main GPRS QoS problems ofthe Alcatel BSS

� Program:� 4.1 General Principles� 4.2 Main BSS GPRS QoS Problems

B8




4.1 General Principles

B8


1.194

4.1 General Principles KPI, Warning Indicator

� A lot of QoS indicators are computed from BSS GPRS counters

� QoS indicators that will be followed-up by management arecalled KPI: Key Performance Indicator

� Among all BSS GPRS QoS indicators some are used to detectQoS problems: they are called WARNING indicators

� usually all KPIs� other major indicators as from radio optimizer view

B8

�


1.195

4.1 General PrinciplesQoS Threshold, Sampling Indicator

� A WARNING indicator is often attached a QoS threshold value todecide if the indicator value is bad or not

� In case a WARNING indicator value is considered as bad thenanother indicator called the SAMPLING indicator and attached tothe WARNING indicator must be checked

� A SAMPLING indicator is attached a sample threshold value todecide if the WARNING indicator value is relevant or not

B8

�


1.196

4.1 General PrinciplesQoS Problem Detection

List of BSS QoS indicators

I1. I2. I3. I4. I5, I6, I7, I8, etc

Are someWarning indicator

values bad?

end Check the relatedSampling indicator value

Is the Warningindicator value

relevant?

Analyze QoSproblem

no

no

yes

yes

B8

�


1.197


4.1 General PrinciplesQoS Problem Detection, Exercise

� Exercise: Using analogy with BSSGSM QoS indicators find the Samplingindicator attached to each of thefollowing GPRS Warning indicators:

� TBF establishment success rate� TBF drop rate� Cell reselection success rate

B8




4.2 Main BSS GPRS QoS problems

B8


1.199

4.2 Main BSS GPRS QoS Problems Exercise 1: List Them


� Exercise 1: List the main BSS QoSproblems seen as a QoS degradation bythe end user

� BSS GPRS QoS problems are relatingto Data transfer problems between theMS and the GPRS Core network,which are due to the BSS

B8

�


1.200

4.2 Main BSS GPRS QoS Problems Exercise 2: Find Warning and Sampling Indicators


� Exercise 2: Find the Warning andSampling indicators which will be used todetect each of these problems:

� Data transfer not established� Data transfer degraded� Data transfer interrupted� Data transfer dropped

B8

�


1.201

4.2 Main BSS GPRS QoS Problems Exercise 3: UL Data Transfer Establishment Degradation


� Exercise 3: Find the Warning indicatordegraded by difficulties to establish a ULTBF resulting in a TBF establishment afterMS repetitions of channel request

� Can this problem be identified throughQoS indicators?

� If not, what must be done to find thecause of the UL data transferestablishment degradation?

B8

�


1.202

4.2 Main BSS GPRS QoS Problems Exercise 4: DL Data Transfer Establishment Degradation


� Exercise 4: Find the Warning indicatordegraded by difficulties to establish a DLTBF resulting in a TBF establishment afterMFS repetitions of channel assignment

� Can this problem be identified throughQoS indicators?

� If not, what must be done to find thecause of the DL data transferestablishment degradation?

B8

�



5 Analysis of the Main BSS GPRS QoS Problems

B8

� Most information of this chapter are available for B7 release.


1.204

� Objective: to be able to analyse the main GPRS QoS problemsof the Alcatel BSS

� Program:� 5.1 Find the Causes of a BSS GPRS QoS Problem� 5.2 What kind of QoS Problem is recorded in the Trace?

5 Analysis of the Main BSS GPRS QoS ProblemsSession PresentationB8



5 Analysis of main BSS GPRS QoS problems

5.1 Find the causes of a BSS GPRS QoS problem

B8


1.206

5.1 Find the Causes of a BSS GPRS QoS ProblemExercise 1: Find the Probable Causes


� Exercise 1a: Find the probable causesof a data transfer establishment failure

� Exercise 1b: Find the probable causesof a data transfer degradation

� Exercise 1c: Find the probable causesof a data transfer interruption

� Exercise 1d: Find the probable causesof a data transfer drop

B8

�


1.207

5.1 Find the Causes of a BSS GPRS QoS ProblemExercise 2: Find the Related QoS Indicators


� Exercise 2a: Find the QoS indicators tobe use to characterize the probablecauses of a data transfer establishmentfailure

� Exercise 2b: Find the QoS indicators tobe use to characterize the probablecauses of a data transfer degradation

� Exercise 2c: Find the QoS indicators tobe use to characterize the probablecauses of a data transfer interruption

� Exercise 2d: Find the QoS indicators tobe use to characterize the probablecauses of a data transfer drop

B8

�



5 Analysis of the Main BSS GPRS QoS Problems

5.2 What kind of QoS Problem is recorded in theTrace?

B8


1.209


5.2 What kind of QoS Problem is recorded in the Trace?Exercise

� What kind of BSS GPRS QoS problemyou can observed in the trace 15?

Documents

Introduction to GPRS E-GPRS Quality of Service Monitoring - BSS Release B8 (2)