GPRS Intro

7/27/2019 GPRS Intro

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Leliwa Training Centre

General Packet Radio Service (GPRS)

Enhanced Data rates for GSM Evolution (EDGE)

Jakub Bluszcz

Leliwa Training Centre, Leliwa Telecom Sp. z o.o

ul. Garncarska 3/7, 31-115 Krakw, Poland, e-mail: [email protected]

[email protected]. +48 12 424 0220www.leliwa.com

&


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Traditional GSM data services:- data call 9.6 kbits/s (14.4 kbits/s)

- SMS

HSCSD High Speed Circuit Switched Data:(more than 1 Time Slot TSper subscriber !!!! high bit rate)

- data call 4 TS x 9.6 (14.4) kbits/s!!!! 38.4 (57.6) kbits/s

GPRS General Packet Radio Service:(more than 1 Time Slot TSper subscriber !!!! high bit rate)(more than 1 subscriber per Time Slot TS !!!! high efficiency)

- packet transfer 4 TS x 21.4 kbits/s !!!! 85.6 kbits/s

UMTS Universal Mobile Telecomminication System:(new WCDMA based air interface)

2 Mbits/s

EDGE Enhanced Data

Rates for GSM Evolution

28.8, 32, 43 kbit/s

2 x 32 !!!! 64 kbits/s

(8 x 43 !!!! 350 kbits/s)

4 x 59.2 !!!! 236,8 kbits/s

(8 x 59.2 !!!! 473.6 kbits/s)

GSM, GPRS and UMTS data services

tel. +48 12 424 0220Figure 1www.leliwa.com



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GSM/GPRS Network Architecture

AUC

IP

Backbone

IP

Backbone

Packet

Data Net

PacketData Net

HLREIR

Gf

Gb

BSS

SGSN GGSN

Other

PLMN

Other

PLMN

Gs

Gr

Gp

Gc

Gd

GnGi

Gn

Um

SMS

G-, IW-MSC

VLR

tel. +48 12 424 0220Figure 3awww.leliwa.com


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GSM/GPRS Network Architecture (description)AUC Authentication Centre

BSS Base Station System

EIR Equipment Identity RegisterGGSN Gateway GPRS Support Node

GMSC Gateway Mobile Services Switching Centre

HLR Home Location RegisterMSC Mobile Services Switching Centre

SGSN Serving GPRS Support Node

SMS Short Message ServiceSMS-GMSC SMS Gateway MSC

SMS-IWMSC SMS Interworking MSC

VLR Visitor Location Register

tel. +48 12 424 0220Figure 3bwww.leliwa.com


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SGSN and GGSN functionsSGSN Serving GPRS Support Node

packet transfer to / from SGSN service area, security (authentication, ciphering and IMEI check),

mobility management.

GGSN Gateway GPRS Support Node

interface towards external data networks,

data format, signalling protocols and address information

iiitranslation.



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VLR and SGSN Service Area

LA 1

LA 2LA 3

RA 1

RA 2

RA 3RA 4

RA 5

LA Location Area RA Routing Area

RA 1

RA 2

RA 3RA 4

RA 5

VLR Service Area SGSN Service Area



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Changes to Base Station System

PCU Packet Control Unit

BTS Base Transceiver Station

connectivity toward the SGSN (Gb interface) and towardsiiithe BTS (A-bis interface),

management of cells in terms of addressing of each single

iiicell for the use by the SGSN

management of GPRS radio channels, and entire

iiicommunication toward an MS, including acknowledgements,

iiibuffering and retransmissions

support of Packet Data Channels



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Changes to GSM Circuit Switch Domain

HLR Home Location Register

Stores GPRS subscription information: IMSI International Mobile Subscriber Identity

SGSN number - SS7 number of of SGSN currently serving the MS

SGSN address IP address of of SGSN currently serving the MS for every subscribed APN:

PDP type e.g. X.25, PPP, IP PDP address

Access Point NameAPN

QoS subscribed



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IMSI

International Mobile Subscriber Identity

MCC MNC MSIN

National MSI

International MSI

MCC Mobile Country CodeMNC Mobile Network Code

MSIN Mobile Subscriber Identity Number

3 digits 2-3 digits



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APN Access Point Name

GSM/GPRS network

MCC=260 MNC=01

GSM/GPRS network

MCC=310 MNC=630

Internet

(public)

Internet

(public)

Leliwa

(private)

Leliwa

(private)

Internet

(public)

Internet

(public)

IBM

(private)

IBM(private)

PL

USA

APN=.mnc.mcc.gprs

APN network identifier APN operator identifier

PL

PL

leliwa.mnc001.mcc260.gprs



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GPRS Backbone Network

(IP private)

GPRS Backbone network

SGSN

external netIP private or public

IP address

GGSN

IP IP

IPGTP

GTP - GPRS Tunnelling Protocol



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Network Evolution


GSM GPRS UMTS

CSS

BSS

PSS

UTRAN

EDGE

(GERAN)

CSS Circuit Switching System

PSS Packet Switching System

R99

BSS Base Station System UTRAN UMTS Terrestrial Radio Access Network

GERAN GSM EDGE Radio Access Network

EDGE Enhanced Data Rates for GSM Evolution

C


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GPRS Network Interfaces

AUC

IP

Backbone

IP

Backbone

Packet

Data Net

Packet

Data Net

HLREIR

Gf

Gb

BSS

SGSN GGSN

Other

PLMN

Other

PLMN

Gs

Gr

Gp

Gc

Gd

Gn GiGn

Um

SMS

G-, IW-MSC

VLR

IPSS7

FR


L li T i i C t


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SS7 Protocol Stack

TUPCAP/INAP BSSAP

TCAP

MAP

MTP

SCCP

ISUP


L li T i i C t


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SS7 Protocol Stack (description)

BSSAP Base Station System Application Part

CAMEL Customised Application of Mobile Enhanced LogicCAP CAMEL Application Part

INAP Intelligent Network Application Part

ISUP ISDN User PartMAP Mobile Application Part

MTP Message Transfer Part

SCCP Signalling Connection Control Part

TCAP Transaction Capabilities Application Part

TUP Telephony User Part


Leli a Training Centre


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SS7 Interfaces

Onetwork initiated PDP context

activation

MTP, SCCP,

TCAP, MAP

GGSN HLRGc

Oequipment checkMTP, SCCP,TCAP, MAPSGSN EIRGf

Opaging for CS services,

combined GSM/GPRS

procedures

MTP, SCCP,

BSSAP+

SGSN MSCGs

OSMS transferMTP, SCCP,

TCAP, MAP

SGSN SMS-GMSC

SGSN SMS-IWMSC

Gd

Mlocation updating, subscriberprofile management

MTP, SCCP,TCAP, MAP

SGSN HLRGr

implfunctionprotocol

stack

connectsI/F




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GPRS Transmission Protocol Stack

App.

GGSNSGSNBSSMS

Physical

NS

FR

BSSGP

LLC

SNDCP

N

E

T

IP

UDP/TCP

GTP

--Gn------Gb---PhysicalGSM RF---Um--GSM RF

N

E

T

NS

FR

RLCMACRLCMAC

IPBSSGP

UDP/TCPLLC

GTPSNDCP

IP (PDP)IP (PDP)




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GPRS Protocol Stack (description)App Application

BSSGP Base Station System GPRS Protocol

GSM RF GSM Radio Frequency

GTP GPRS Tunnelling Protocol

IP Internet Protocol

LLC Logical Link Control

MAC Medium Access Control

NS Network Service

PDP Packet Data Protocol

RLC Radio Link Control

SNDCP Sub-Network Dependent Convergence Protocol

TCP Transmission Control Protocol

UDP User Datagram Protocol




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GPRS Mobile Station

GPRS PacketData

NetworkTE MT

MS

MT - Mobile Terminal

TE - Terminal Equipment

MS - Mobile Station




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GPRS Attach and PDP Context Activation

GPRS Attach

PDP Context Activation

GPRSPacket

Data

Network




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GPRS Attach

!

AUC

IP

Backbone

IP

Backbone

HLR

EIR"

# $ % ! &

'

( )

MSC/VLR

SGSN

SGSN




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GPRS Attach (description)

" MS sends a message Attach request to SGSN.

# If MS is not known to SGSN, it asks the old SGSN for IMSI and triplets.

$ If MS is not known to the old SGSN, it sends an error message to the new

iiiiiSGSN and the new SGSN asks MS for IMSI.

% & SGSN authenticates MS.

' SGSN may request handset identity, IMEI, to check it in EIR.

) HLR is updated with SGSNs SS7 address. HLR provides subscription

iiioinformation.

" Optionally MSC/VLR is updated with MS location.

& SGSN sends Attach Accept message to MS




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PDP Context Activation

IP BackboneIP Backbone

DNS

Packet

Data Net

Packet

Data Net

$

'# ' %

DHCP

(SGSN GGSN




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PDP Context Activation (description)

" MS sends a PDP context activation request to SGSN.

# SGSN performs subscription check.

$ SGSN contacts DNS server to obtain IP address of GGSN

iiiioconnected to the APN selected by the user.% SGSN creates GTP tunnel to GGSN.

& The server in the external network sends the IP-address to GGSN.

' GGSN sends the IP-address back to MS.




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g

SMS Mobile Terminating

HLR

$

'

#

%!

(

SM-SCSMS-

GMSCSGSN




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g

SMS Mobile Terminating (description)

" SM-SC forwards SM to SMS-GMSC.

# SMS-GMSC interrogates HLR for routing information.

$ SMS-GMSC forwards the SM to SGSN.

%

SGSN delivers the SM to MS.& SGSN indicates successful delivery of the SM back

iiiiito SMS-GMSC.

' SMS-GMSC informs SM-SC about successful delivery ofthe SM.




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g

SMS Mobile Originating

$'

#

%!

SM-SCSMS-

IWMSCSGSN

)

(




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SMS Mobile Originating (description)

" MS transfers the SM to SGSN.

# SGSN verifies in subscription data whether MS can originate SM.

$ SM is forwarded to SMS-IWMSC.

% SM is forwarded to SM-SC.

& Successful delivery of the SM is indicated to SMS-IWMSC.

' Successful delivery of the SM is indicated to SGSN.

) Successful delivery of the SM is indicated to MS.




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Radio and physical channels

Uplink DownlinkP-GSM

890 915 960935 f [MHz]

1 radio channel (carrier)full duplex

200 kHz200 kHz

TDMA frame

107654321076543210

Time Slot

Basic Physical Channel




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Packet Data Channel

For GPRS usage, a certain group of Basic Physical Channels

(BPCs) in the cell is reserved. Such channels reserved for

GPRS are called Packet Data Channels (PDCHs)

Carrier 0

76543210TS!

Carrier 1

Carrier 2

GSM

GPRS

GSM/

GPRS




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GPRS vs GSM Logical Channels

PDTCH- TCH

- FACCH

PTCCH- SACCH

PACCH- SDCCH

DCCH:

- PAGCH- AGCH

- PRACH- RACH- PPCH- PCH

PCCCH:CCCH:

PBCCH- BCCH

- SCH

- FCCH

BCH:

GPRSGSM

} {

optional GPRS

logical channels

mandatory GPRS

logical channels




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GPRS vs GSM Logical Channels (description)

AGCH Access Grand Channel

BCCH Broadcast Control Channel

BCH Broadcast Channel

CCCH Common Control Channel

DCCH Dedicated Control Channels

FACCH Fast Associated Control Ch.

FCCH Frequency Correction Channel

PACCH Packet Associated Control Ch.

PAGCH Packet Access Grant ChannelPBCCH Packet Broadcast Channel

PCCCH Packet Common Control Ch.

PCH Paging Channel

PDTCH Packet Data Traffic Channel

PPCH Packet Paging Channel

PRACH Packet Random Access Channel

PTCCH Packet Timing Advance Control Ch.

RACH Random Access Channel

SACCH Slow Associated Control Channel

SCH Synchronisation Channel

SDCCH Stand alone Dedicated Control Ch.

TCH Traffic Channel




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Multiframe structure for GSM and GPRS


PT PTCCH, I Idle, B0 B11 other GPRS logical channels

GSM (example)

51-frame multiframe

52-frame multiframe

GPRS

F FCCH, B BCCH, C CCH (PCH+AGCH), I - Idle



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Temporary Blok Flow

Temporary Blok Flow (TBF) transmission of data block

iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiibetween MS and the network

MS can be involved in:

uplink TBF

downlink TBF both uplink and downlink TBF

Temporary Flow Identity (TFI) distinguishes between datablocks belonging to different TBFs (users) sharing the same

channel.




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TBF and usage of TFI

76543210TS ->

MS 1TFI = 1

MS 2

TFI = 2

MS 3

TFI = 3

MS 4

TFI = 1

GSM CS

BPC

GPRS PS

PDCH




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Uplink State Flag

The header of each downlink data block contains an Uplink

State Flag (USF), which notifies MSs with uplink TBF assigned

and sharing the same channel, which one of them is allowed tosend the next block on uplink.




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Usage of USF

76543210TS ->

MS4MS2MS2MS1UL TDMA

GSM CS BPC GPRS PS PDCH

432USF

654TS1

6

111USF

754TS

532USF

765TS

2USF

7TS

76543210TS ->

USF=2USF=4USF=3USF=1DL TDMA

MS 1MS 2

MS 3

MS 4




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GPRS Coding Schemes

data blockradio block

456 bits

21,4401CS-4

15,6293CS-3

13,4241CS-2

9,05160CS-1

Bit rate

(kbits/s)

Length of data block

(bits)Coding

channel

coder




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GPRS MS Mobility Management States

Idle

Ready

Stand-by

GPRS Attach GPRS Detach

Ready timer expires

Force to Stand-by

PDU transmission

Received paging




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Routing Area Update

!

HLR

SGSN

SGSN

# %

'(

GGSN

RA

RA

$




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Routing Area Update (description)

# MS sends Routing Area Update Request message to SGSN which includes MS

iioiidentity and previous RA identity. PCU adds to this message the new RA identity.

' The new SGSN contacts the old SGSN. The old SGSN will transfer authentication

oiiiparameters and information about activated PDP contexts for the subscriber.

$ New GTP tunnels for all activated PDP contexts are established between new SGSN

iiiiiand GGSN and the old tunnels connecting the old SGSN with GGSN are released.

( The location data are updated in HLR. From this time, subscriber record in HLRiiiiicontains IP and SS7 addresses to the new SGSN. In return, the HLR sends subscriber

iiiiidata (IMSI, GPRS subscription data) to the new SGSN.

% New SGSN sends to MS acknowledgement that the procedure was successfully

iiiiiperformed.!The HLR instructs the old SGSN to remove the subscriber record from its database.

Steps', $, ( and! are omitted when the new RA belongs to the same SGSN as the

old one.




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Cell Update

SGSNBSC

'

(

GGSN

C0$

C1 #

%




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DL & UL Transmission (Cell Update)


SGSNBSS

'

$

((

%



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Cell Update (description)

# MS decides to change the cell. It stops listening to the signal in the old cell and

iioimakes an access to the new cell.

' MS sends a first LLC frame of any type (possibly containing user packet) to SGSN.

iiiiiLCC frame contains MS identity and PCU adds to each LLC frame the identity ofiiiiithe cell from which the frame was received, so SGSN receives all needed data for

iiiiicell update (MS and cell identity).

$ The SGSN updates MS location and discovers that there was already an ongoing

iiiiidownlink packet transfer. The SGSN sends a Flush message to the PCUiiiiiresponsible for the old cell. The Flush message contains addresses to both old and

iiiiinew cell and MS identity.

( In case the PCU is also responsible for the new cell, all buffered frames, belonging to

iiiiithat MS, that have not been acknowledged or not sent downlink are moved to a

iiiiiqueue towards the new cell. The PCU assigns a downlink TBF to the MS and the

iiiiiretransmission of the old frames is started.

% The transmission of user packets in both directions can be continued.

tel. +48 12 424 0220Figure 33cwww.leliwa.com



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Network Operation Modes

MSC

BSS

SGSN

NOM ICS & PS paging over GPRS channels

CS paging in RA or cell

coordinated RA/LA update

NOM II & IIICS paging over GSM channels in LA

PS paging over GPRS channels in RA or cell

NOM II GSM & GPRS paging on PCHNOM III GSM paging in PCH

GPRS paging in PPCH

MSC

BSS

SGSN




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DL TBF established in Stand-by State

GPRS

(Packet) Paging Request (P)PCH

(Packet) Channel Request(P)RACH

(Packet) Downlink Assignment(P)AGCH

PACCH

PACCH

#

'

$

(PDTCH



DL TBF bli h d i S d b S (d )


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DL TBF established in Stand-by State (des.)

# Packet paging request (PPCH) or Paging request (PCH) containing MS identity is

iiiiisent to MS within all cells belonging to RA.'When MS decodes its own identity in (Packet) Paging request it sends Packet

iiiiichannel request (PRACH) or Channel request (RACH) message asking for

iiiiiassignment of radio resources for downlink TBF.

$ The network assignees the downlink TBF in Packet Downlink Assignment messageiiiiisent on PAGCH or AGCH. This message contains description of uplink radio

iiiiiresources that will be used by PDTCH: (frequency, TS numbers, Temporary Flow

iiiiiIdentity).

( The network sends packets to MS on PDTCH. MS acknowledges the receipt ofiiiiidata blocks on PACCH.



DL TBF t bi h d i R d t t


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DL TBF estabished in Ready state

(Packet) Downlink Assignment(P)AGCH

PACCH

PACCH

#

'

GPRS

PDTCH



DL TBF t bi h d i R d t t (d ti )


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DL TBF estabished in Ready state (descrption)

# The network assigns the downlink TBF in Packet Downlink

iiioAssignment message sent on (P)AGCH.

' The network sends packets to MS on PDTCH. MS acknowledges iio

reception of data blocks on PACCH.



DL TBF t bli h d i P k t T f d


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DL TBF established in Packet Transfer mode

GPRS

Packet Downlink Assignment

PDTCH

PACCH

PACCH

#

'

PDTCH$

PACCH

PACCH



DL TBF t bli h d i P k t T f d


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DL TBF established in Packet Transfer mode

# MS transfers the packets to the network on PDTCH. Network sends

acknowledgements for the received data blocks to MS iioion

PACCH.

' MS receives the Packet Downlink Assignment on PACCH.

$ Packets and acknowledgements are sent in both directions.



Establishment of plink TBF


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Establishment of uplink TBF

The uplink TBF establishment is more complicated than the downlink

TBF establishment because the network has no idea about the amount of

data the MS wants to send to the network. There are two types of uplinkTBF establishment:

one-step, when MS does not specify precisely the amount of data it

wants to send to the network; and the network can assign uplink radioresources only on one PDCH for the limited amount of data.

two-steps, when MS specifies precisely the amount of data to be sent,

together with: priority, mean and peak throughput; and the network can

assign radio resources on a number of PDCHs for limited or unlimited

amount of data trying to meet MS needs.



UL TBF one step setup


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UL TBF one-step setup

GPRS

(Packet) Channel Request(P)RACH

Packet Uplink Assignment(P)AGCH

PACCH

#

'

$PDTCH



UL TBF one step setup (description)


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UL TBF one-step setup (description)

# MS sends (Packet) Channel Request on (P)RACH. Inside the

iioimessage MS indicates that it initiates one-step uplink TBFiiiiiestablishment procedure.

' The network sends Packet Uplink Assignment message on (P)AGCH

iiiiicontaining the description of uplink radio resources (PDTCH): ARFCNiiiii(or ARFCN, HSN and MAIO in case of a hopping channel), TS, TFI,

iiiiiUSF and coding scheme (CS).

$ MS transfers the packets to the network on the assigned PDTCH. The

iiiiinetwork acknowledges the data blocks on PACCH.



UL TBF two steps setup


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UL TBF two-steps setup

GPRS

(Packet) Channel Request

(P)RACH


PACCH

#

'

$ Packet Resource Request (P)RACH


(

% PDTCH



UL TBF two steps setup (description)


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UL TBF two-steps setup (description)

# MS sends (Packet) Channel Request on (P)RACH. Inside the message

iioiMS indicates that it initiates the two-step uplink TBF establishment

iioiprocedure.

' The network sends Packet Uplink Assignment message on (P)AGCH

ioiiallowing MS to transfer a single data block on a certain PDCH.

$ MS sends a single data block containing the Packet Resource Request

oiiimessage, which specifies the MS demand for uplink radio resources.( The network allocates uplink radio resources for MS according to MS

oiiineeds and its multislot class. The Packet Uplink Assignment message,

oiiiamong other parameters, contains: frequency, TS numbers and

oiiicorresponding values of USF, TFI, Coding Scheme.

% MS transfers packets to the network on the specified PDTCH(s). The

oiiinetwork acknowledges the receipt of data blocks on PACCH(s).



UL TBF in Packet Transfer mode


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UL TBF in Packet Transfer mode

GPRS

PACCH

PACCH

PACCH

Packet Resource Request

Packet Uplink Assignment

PDTCH

PDTCH



UL & DL TBF independency


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UL & DL TBF independency

GPRS



PLMN DNS & Inter-GPRS Backbone Network


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PLMN DNS & Inter-GPRS Backbone Network

HPLMNMNC=7 MCC=123

HPLMNMNC=7 MCC=123

leliwaleliwa

HLR

HSGSN HGGSN

IGBNIGBN

Gp

VPLMNMNC=4 MCC=260

VPLMNMNC=4 MCC=260

internetinternetVSGSN VGGSN

Gr Gp

DNS

DNS

DNS

mnc004.mcc260.gprs

mnc007.mcc123.gprs

.gprs

internetinternet



PDP Context to Visited GGSN


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PDP Context to Visited GGSN

HPLMNHPLMNleliwaleliwa

HLR

HSGSN HGGSN

IGBNIGBN

VPLMNVPLMN

internetinternetVSGSN VGGSN

Gr

APN: internet



PDP Context to Home GGSN


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PDP Context to Home GGSN

HPLMN

HPLMNleliwaleliwa

HLR

HSGSN HGGSN

IGBNIGBN

Gp

VPLMNVPLMN internetinternetVSGSN VGGSN

Gr Gp

internetinternet

APN: leliwa



QoS service precedence classes


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QoS service precedence classes

Service commitments shall bemaintained after the high and normal

priority commitments have been fulfilled

Low precedence3

Service commitments shall bemaintained ahead of low precedence

level

Normalprecedence

2

Service commitments shall bemaintained ahead of all other

precedence levels

Highprecedence

1

InterpretationPrecedence

Name

Class



QoS reliability classes


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QoS reliability classes

Not error sensitive, error correction capability and/or

very good error tolerance capability

3

Error sensitive, limited error correction capability,good error tolerance capability

2

Error sensitive, no error correction capability, limited

error tolerance capability

1

Application CharacteristicsClass



GPRS Charging Architecture


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GPRS Charging Architecture

IP

Backbone

IP

Backbone

PacketData Net

PacketData Net

Billing System

CGF

SGSN GGSN

GaGa Ga



GMSK and EDGE


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GMSK and EDGE

I

Q

+

-0

1

GMSK

I

Q

(0,1,1)

(1,1,0)(1,0,1)

(0,0,0)

(0,0,1) (1,1,1)

(1,0,0)

(0,1,0)

EDGE (8PSK)



ECSD Enhanced Circuit Switched Data


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CS a ced C cu S c ed a a

Three new Traffic Channel types:

E-TCH/F28.8 28.8 kbits/s E-TCH/F32.0 32.0 kbits/s

E-TCH/F43.2 43.2 kbits/s

Multislot configurations (HSCSD):

2 x E-TCH/F28.8 !!!! 57.6 kbits/s

2 x E-TCH/F32.0 !!!! 64.0 kbits/s



E-GPRS Coding Schemes


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g

59.2 kbits/sEDGEMCS-9

54.4 kbits/sEDGEMCS-844.8 kbits/sEDGEMCS-7



17.6 kbits/sGMSKMCS-4




max bit rate per TSmodulationcoding scheme



GSM/GPRS/UMTS Network Architecture


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AUC

SMSG-, IW- .

VLR

MSC

IPBackbone

IPBackbone

PacketData NetPacketData Net

HLREIR

Gf

Gb

BSS

SGSN GGSN

OtherPLMN

OtherPLMN

Gs

Gr

Gp

Gc

Gd

GnGi

Gn

UTRAN Iu




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Leliwa Telecoma support connected with the highest level of competence!

Our competence encompasses support in:

Each of Leliwa consultant have a deep knowledge in several fields of

mobile telecommunications GSM, GPRS, UMTS.

www.leliwa.comtel. +48 12 424 [email protected]

General and advanced courses in GSM, GPRS, UMTS and IP

Customized trainings

ConsultingSupport in Cell Planning, In-building Cell Planning, RF Optimisation

Over 100 various Ericsson licensed courses

Over 50 various Leliwa licensed courses

Documents

GPRS Intro