BSS Parameter Planning Nokia.PDF

NOKIA BSSPAR © CL Eng 6-Sep-02 / CTP Module 5 page: 1

BSS Parameter PlanningBSS Parameter Planning

Base Station Subsystem ParametersBase Station Subsystem ParametersBase Station Subsystem ParametersBase Station Subsystem ParametersBSSPARBSSPARBSSPARBSSPAR

Base Station Subsystem ParametersBase Station Subsystem ParametersBase Station Subsystem ParametersBase Station Subsystem ParametersBSSPARBSSPARBSSPARBSSPAR


Module 4 ObjectivesModule 4 Objectives• Channels Configurations and Dimensioning• Location Area Design• Cell Radio Design• BSS Parameter Design and Planning• MS Mobility Management


End of ModuleEnd of Module• You should be able to:

•Understand the GSM channel configuration•Dimension for channel configuration and set the related

BSS parameters•Dimension for signaling channel for Location Area•Design and set the BSS parameters•Apply various strategies in MS mobility management


ContentsContents

!Channel Configuration!Location Area Design!Cell Radio Design!BSC Parameters!BTS Parameters!Handover Control Parameters!Power Control Parameters!TRX parameters!Adjacency Parameters!MS Mobility Management


Content OutlinesContent Outlines• Day 1

• Channels Configurations•SDCCH Dimensioning•Common Control Channel Dimensioning• Location Area Design and Related Channels Dimensioning•Exercise•Summary



•BSS Parameters Structure•BSC Parameters• Idle Mode Operation:

• BTS parameters: cell selection and reselection•Exercise•Summary



•Dedicated Mode Operation:• Handover Control Parameters• Power Control Parameters

•Dedicated Mode Operation:• Handover Control Parameters• Handover Design• Handover Strategies

•Exercise•Summary



•Dedicated Mode Operation:• Power Control Parameters• Power Control Design• Power Control and Handover Control

• Exercise•Summary



•TRX Parameters•Adjacency Parameters•Mobility Management•Exercise•Assignment Briefing•Summary



• Channels Configurations•SDCCH Dimensioning•Common Control Channel Dimensioning• Location Area Design and Related Channels Dimensioning•Exercise•Summary


Channel ConfigurationChannel Configuration

"Channel Configuration!Location Area Design!Cell Radio Design!BSC Parameters!BTS Parameters!Handover Control Parameters!Power Control Parameters!TRX parameters!Adjacency Parameters!MS Mobility Management












Channel ConfigurationChannel Configuration----CCH, downlinkCCH, downlink


Channel ConfigurationChannel Configuration----CCH, uplinkCCH, uplink


Channel ConfigurationChannel Configuration----TCHTCH


Channel CombinationChannel Combination

� The following combinations of logical channel types are allowed for the radio timeslots and specified by GSM (Rec. 05.02):

� a) TCH/F + FACCH/F + SACCH/TF � b) TCH/H + FACCH/H + SACCH/TH� c) SDCCH/8 + SACCH/C8� d) FCCH + SCH + BCCH + CCCH (TS 0)� e) FCCH + SCH + BCCH + CCCH + SDCCH/4 + SACCH/C4 (TS 0)� f) BCCH + CCCH� g) SDCCH/8 + SACCH/8 + CBCH� h) FCCH + SCH + BCCH + CCCH + SDCCH/4 + SACCH/C4 + CBCH (TS 0)

� A "+" indicates that the channels are used simultaneously.


Channel ConfigurationChannel Configuration----CombinedCombined

T T T T T T T T T T T T A T T T T T T T T T T T T0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

full rate TCH multiframe

©C.L.Eng

T = TCH, A = SACCH

downlink, uplink

F S F S F S F S F S I0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

R R R R R R R R R R R R R R R R R R R R R R R R R R R0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

R=RACH + SDCCH/41 SACCH frame = 2 x 235.38 msec

©C.L.Eng

F = FCCH, S = SCH

SDCCH3 SACCH0

uplink

CCCH

TS0: BCCH + CCCH/3 + SDCCH/4

SDCCH3 SACCH2 SACCH3 SDCCH2

CCCH SDCCH0 SDCCH1 SDCCH2 SACCH1

SDCCH0 SDCCH1

CCCHdownlinkCombined BCCH/CCCH/SDCCH/4 Multiframe

BCCH


Channel ConfigurationChannel Configuration----SeparatedSeparated



©C.L.Eng

T = TCH, A = SACCH

downlink, uplink

F S F S F S F S F S0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

TS0: BCCH + CCCH/9

F = FCCH, S = SCH

R = RACH

SDCCH SDCCH SACCH

SDCCH/8 Multiframe TS1: SDCCH/8downlink

uplink

©C.L.Eng

SDCCH SDCCH SDCCHSDCCH SDCCHSACCH SACCH SACCH SDCCH

SACCH SACCH SACCH SACCH

CCCH CCCH

SDCCH SDCCH SDCCH SDCCH SDCCH SDCCH SDCCH SDCCH

CCCH CCCH CCCH CCCHCCCH

BCCH/CCCH Multiframe

uplink

downlinkBCCH CCCH CCCH


Channel ConfigurationChannel Configuration----HybridHybrid



©C.L.Eng

T = TCH, A = SACCH

downlink, uplink

F S F S F S F S F S I0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50


0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50SACCH

R=RACH + SDCCH/4


SDCCH SDCCH SDCCH SDCCH

SDCCH SDCCH SDCCH SDCCH

SACCH SACCH

uplinkSACCH SACCH SACCH SDCCH SDCCH SDCCH SDCCH


SDCCH0 SDCCH1 SDCCH2

SDCCH SDCCH SDCCH SDCCH SACCH SACCH

BCCH + CCCH/3 + SDCCH/4, F = FCCH, S = SCH

uplinkSDCCH3 SACCH2 SACCH3

SDCCH2 SDCCH3 SACCH0 SACCH1

Hybriddownlink

BCCH CCCH CCCH CCCH SDCCH0 SDCCH1

©C.L.Eng


SDCCH DimensioningSDCCH Dimensioning

• SDCCH used for:• Call setup signalling•Short message service (SMS)• Location update (LU)• IMSI attached/detached


SDCCH DimensioningSDCCH Dimensioningnumber of call attempts (MOC+MTC) per subscriber per hour 1.1 percentage of MOC 60% percentage of ‘engaged’ in the case of an MOC 19.8% duration of TCH occupation in the engaged case 3 sec no answer from a person called by MOC 14.4% mean TCH occupation for this case 30 sec percentage of successful MOC 65.8% mean time for ringing (MOC) 15 sec percentage of MTC 40.0% no paging response 32.5% duration of TCH occupation in this case 0 sec no answer from a mobile subscriber 13.5% means TCH occupation for this case 30 sec successful MTC 54.0% mean time for ringing (MTC) 5 sec mean call duration (MOC/MTC) 115 sec mean TCH occupation call attempt 83 sec TCH load per subscriber 0.026 Erl time for MOC/MTC setup signaling on SDCCH (authentications, ...) 3 sec time for a location update 5 sec number of location update per subscriber per hour 2.2 resulting SDDCCH load per subscriber (no TCH queuing applied) 0.004 Erl



• TCH load per subscriber = [ # of call attempts per sub per hour*%MOC

+ # of call attempts per sub per call*%MTC*(1-%no response)*(1-% no answer)*%MTC success] * mean call duration /

3600= [ 1.1 * 60% + 1.1 * 40% * (1-32.5%) * (1-13.5%) * 54%] * 115/3600= 0.026 Erlang

• SDCCH load per subscriber = [number of call attempts*setup signalling

+ #LU per sub per hour*duration for loc update] / 3600= [1.1 * 3 + 2.2 * 5] / 3600= 0.004 Erlang



• A cell with 2 TRXs• Combined SDCCH• 1 comb. CCCH/SDCCH →4 SDCCH• 15 TCH

• Offered TCH load at 2% blocking• 9.01 Erlangs#9.01/0.026=346 subscribers

• Offered SDCCH load at 1% blocking• 4 SDCCH blocks for combined configuration• Thus from Erlang B table, lookup 4 channels at 1% blocking• 0.87 Erlangs#0.87/0.004=217 subs

• SDCCH limited: 217 subscribers



• Non-combined SDCCH• 1 SDCCH/8 →8 SDCCH• 14 TCH

• Offered TCH load at 2% blocking• 8.20 Erlangs#8.20/0.026=315 subscribers

• Offered SDCCH load at 1% blocking• 8 SDCCH blocks for non-combined configuration• Thus from Erlang B table, lookup 8 channels at 1% blocking• 3.13 Erlangs#3.13/0.004=782 subs• TCH limited: 315 subscribers

• This configuration is preferred as it is TCH limited


Common Control Channel LoadCommon Control Channel LoadCHANNELS

TRAFFICCHANNELS

FULLRATE

HALFRATE

COMMONCONTROLCHANNELS

DOWNLINK UPLINK FAST

DOWNLINK&UPLINK

TCH/F TCH/H BCCH FCCH SCH PCH AGCH RACH SACCH SDCCH FACCH

SIGNALLINGCHANNELS

BROADCASTCONTROLCHANNELS

DEDICATEDCONTROLCHANNELS

DOWNLINK SLOW


Common Control Channel LoadCommon Control Channel Load



• CCCH CapacityCalculation (non-combined):

uplink– 51*3600/(51*0.004615) = 780000 RACH slots per hourdownlink – 36*3600/(51*0.004615) = 137658 CCH blocks per hour

F S F S F S F S F S0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

TS0: BCCH + CCCH/9

F = FCCH, S = SCH

R = RACH

SDCCH SDCCH SACCH


uplink

©C.L.Eng

SDCCH SDCCH SDCCHSDCCH SDCCHSACCH SACCH SACCH SDCCH

SACCH SACCH SACCH SACCH

CCCH CCCH

SDCCH SDCCH SDCCH SDCCH SDCCH SDCCH SDCCH SDCCH

CCCH CCCH CCCH CCCHCCCH

BCCH/CCCH Multiframe

uplink

downlinkBCCH CCCH CCCH



• CCCH CapacityCalculation (combined):

uplink– 27*3600/(51*0.004615) = 413000 RACH slots per hourdownlink – 12*3600/(51*0.004615) = 45886 CCH blocks per hour

F S F S F S F S F S I0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50


R=RACH + SDCCH/41 SACCH frame = 2 x 235.38 msec

©C.L.Eng

F = FCCH, S = SCH

SDCCH3 SACCH0

uplink

CCCH


SDCCH3 SACCH2 SACCH3 SDCCH2

CCCH SDCCH0 SDCCH1 SDCCH2 SACCH1

SDCCH0 SDCCH1

CCCHdownlinkCombined BCCH/CCCH/SDCCH/4 Multiframe

BCCH



• CCCH Capacity• 1 RACH slot: a channel message for 1 subscriber• 1 CCCH block (4 slots): 1 paging message for 1..4 subscribers* or

1 access grant message for 1..2 subscribers

* Depends on IMSI(2) or TMSI(4) paging



• RACH• Used by MS to request a dedicated channel (SDCCH)• The causes for the channel request can be:

• A paging response in MTC• An emergency call• A MOC• LU or• IMSI attach/detach

• Parameters related to RACH• maxNumberOfRetransmission (1, 2, 4 or 7)• numberOfSlotsSpreadTrans (3 ... 12, 14, 16, 20, 25, 32, 50)



• Continues…• The combination of maxNumberOfRetransmission and

numberOfSlotsSpreadTrans values determine the time period between sending of two channels requests.

• This period is measured in RACH slots and is the sum of a deterministic part S and a random part tr. (refer to GSM 04.08)

• RACH can be configured in combined and non-combined case• Combined: all 27 timeslot0 out of 51 timeslots• Non-combined: all timeslot0,2,4,6



• values for 50000 RACH activities per hour



• The minimum blocking is achieved by the following setting of parameters: maxNumberOfRetransmission = 7, numberOfSlotsSpreadTrans = 50

• The configuration of CCCH is mainly determined by the capacity needed by the downlink channels, the RACH configuration is uncritical



• PCH• PCH may be used as AGCH but not vice-versa• MOC requires AGCH and MTC requires PCH• Typical network will have MOC higher than MTC• Strategy: to dimension the AGCH to a smaller value and let the

system organise the use of channels• Parameter related to PCH:

• noOfMultiframesBetweenPaging (2 ... 9)• It indicates the number of TDMA multiframes between

transmission of paging message to the same paging sub-group• It impacts on the MS battery life and MTC setup time• Higher value will save battery life but longer call setup time

and vice versa• Recommended value is 5



• AGCH• Parameter related to AGCH:

• NumberOfBlocksForAccessGrant (0 ... 7)• It defines the number of blocks reserved for access grant

messages from the CCCH during the 51 TDMA frame (a multiframe)

• Recommended value is 1 for combined and 2 for non-combined configuration

• Note that if the AGCH is insufficient, PCH can be used as AGCH



• Example:



• Example: continue…

• [5] For MOC, response to paging in MTC, LU and IMSI attached/detached, thus 4 RACH activities per sub per hour



• Example: continue…• Analysis:

• DL CCCH (PCH and AGCH) is the limiting factor• The usage for PCH and AGCH is almost equal



• Paging Capacity• Paging demand is a function of:

• Number of MTC• Number of subscribers in the LAC• Paging repetition



• Paging Capacity• PCH can be configured as combined or non-combined:

• Combined: both BCCH and SDCCH occupy the TS0• 12 out of 51 slots per multiframe form 3 PCH/AGCH, each

block consists of 4 slots



• Paging Capacity• PCH can be configured as combined or non-combined:

• Non-combined: BCCH occupies TS0 and SDCCH occupies TS1• 36 out of 51 slots per multiframe form 9 PCH/AGCH, each

block consists of 4 slots

• Split of blocks between PCH and AGCH: the available blocks in 51multiframe is splitted between PCH and AGCH and it is set by parameter NumberOfBlocksForAccessGrant



• Paging Capacity• IMSI/TMSI paging:

• IMSI: 2 mobiles can be paged with each page message occupying 4 slots

• TMSI: 4 mobiles can be paged with each page message occupying 4 slots

• Paging capacity calculation:• PCH per second



• Paging Capacity

• What does the table mean?• CCCH can be used for both AGCH and PCH• Example for combined configuration, 3 CCCH blocks are available• If u reserve 0 blocks for AGCH, all 3 CCCH blocks will be used for

PCH• If u reserve 2 blocks for AGCH, only 1 CCCH blocks will be used for

PCH



• Paging Capacity• For combined BCCH:

• Making sense out of the table:• Number of MS that can be paged in a second:

• Depends on IMSI or TMSI paging and• Number of blocks reserved for AG



• Paging Capacity• For combined BCCH:• Example: if u reserved 1 block for AG, then u have 2 blocks for PCH• If u decide TMSI paging, I.e. 4 MS can be paged with 1 block of PCH• Thus; (number of PCH blocks*number of pages per block)/(51*one

TDMA frame period);• =(2*4) / (51*0.004615) = 34• 34 MS can be paged in a second (using TMSI paging)



• Paging Capacity• For combined BCCH:

Access Grant vs Pages per second

0

10

20

30

40

50

60

0 1 2

Number of AG Blocks

NU

mbe

r of P

ages

per

se

cond 2 mobiles per page

3 mobiles per page4 mobiles per page



• Paging Capacity• For non-combined BCCH:

• Making sense out of the table:• 3 blocks reserved for AG, remaining 6 blocks used for PCH• Number of MS can be paged in a second (TMSI paging)• = (6*3)/(51*0.004615) = 76 MS/second



• Paging Capacity• For non-combined BCCH:


Location Area DesignLocation Area Design

!Channel Configuration"Location Area Design!Cell Radio Design!BSC Parameters!BTS Parameters!Handover Control Parameters!Power Control Parameters!TRX parameters!Adjacency Parameters!MS Mobility Management



• Location Area Size• What is Location Area?

• A location area is an area in which MSs may roam without updating the location registers

• A location area consists of one or more cells

• What information you need?• Traffic model

• What is next?• Calculate SDCCH traffic• Determine paging capacity• Calculate LA size (in term of number of cells)



• Location Area Size--SDCCH traffic calculationTCH blocking 2.0%number of TRXs per cell 4total TSL 32

TCH 30sig-ch 2

cell traffic 21.9traffic per subscriber 0.025cell subscribers 876

call setupSD reserve time for call setup 7 secSDCCH traffic 0.001944 Erlcell SDCCH traffic 1.703333 Erl


Location Area DesignLocation Area Designlocation updateSD reserve time for LU 7 secLU period per sub 120 minutescell SDCCH traffic 0.851667 Erl

smssms/sub 1SD reserve time for SMS 4sms traffic per sub 0.001 Erlcell SDCCH traffic 0.973333 Erl

IMSI attach/detachIMSI de-attach/sub 1SD reserve time for IMSI de-attach 2IMSI traffic per sub 0.00056cell SDCCH traffic 0.48667

total SDCCH traffic 4.01500 ErlSDCCH blocking 1.0%TOTAL SDCCH required 10SDCCH configuration to be used non-comb



• Location Area Size--Paging Capacitypaging capacity:combined or non-combined non-combAG blocks (combined-[0..2]) or (non-combined-[0..7]) 3PCH blocks 6pages per block [2..4] 2total pages per second 51total pages per hour 183600total PCH-block per hour 91800total AG block per hour 45886



• Location Area Size--Paging and AG traffic demand

number of subscribers within the cell SUBS 876number of cells on the location area LA_size 227mobile terminating calls per subscriber per hour (with and without paging response) MTC_ph 0.46mean number of repetitions of a paging message (no paging response to first paging) REPET 2mobile terminating calls per subscriber per hour with paging response to first paging) MTC_PR_ph 0.3mobile originating calls per subscriber per hour MOC_ph 0.64location updates per subscriber per hour LU_ph 2.2IMSI attach/detach per subscriber per hour IMSI_ph 1SMS per subscriber per hour SMS_ph 1total paging-block per hour capacity 91800

CCCH demandtotal paging message per hour 91472access grant messages per hour 4503random messages per hour 4503

number of subs per AGCH message [1..2] subs per agch 1number of pages per block IMSI=2, TMSI=4 [2..4] subs per page 2



•BSS Parameters Structure•BSC Parameters• Idle Mode Operation:

• BTS parameters: cell selection and reselection•Exercise•Summary


BSC ParametersBSC Parameters

!Channel Configuration!Location Area Design!Cell Radio Design"BSC Parameters!BTS Parameters!Handover Control Parameters!Power Control Parameters!TRX parameters!Adjacency Parameters!MS Mobility Management


Nokia BSS Parameters StructureNokia BSS Parameters Structure

BTS

BCF

HOC

POC

TRX

RTSL

BA

MA

ADJC

FHS

BSC


Nokia BSS Parameters StructureNokia BSS Parameters Structure$ Base Station Controller (BSC)

The BSC object contains BSC-specific radio network data.

$ BCCH Allocation Frequency List (BA)The BA object contains data for building the BCCH allocation. <option>

$ Mobile Allocation Frequency List (MA)The MA object contains data for building the mobile allocation for RF hopping.

$ Base Control Function (BCF)The BCF object contains data that is specific for the O&M functions of the BTS.

$ Base Transceiver Station (BTS)The BTS object contains BTS-specific radio network data.

$ Handover Control (HOC)The handover control object contains parameters which control the handover

procedure.


Nokia BSS Parameters StructureNokia BSS Parameters Structure$ Power Control (POC)

The power control object contains parameters which control the power control procedure.

$ Adjacent Cell (ADJC)The adjacent cell object contains a description of the adjacent cell of the BTS.

$ Transceiver (TRX)The TRX object contains TRX-specific data.

$ Radio Time Slot (RTSL)The radio time slot object contains parameters for the physical radio time slot.

$ Frequency Hopping System (FHS)The frequency hopping system object contains hopping parameters for the BTS.



BSC

Directed Retry

FACCH

MS SpeedDetection

Handover

Cell Definition forMultilayer

MSC HOAdvancedMultilayer

Dynamic Hotspot



• Cell Definition for Multilayer NetworkBSC PARAMETERS BSC PARAMETERS BSC PARAMETERSEXPLANATION Q3 NAME UNITthis parameter indicates the size of a macrocell by means the maximum transmission power of the MS in a gsm cell. If parameter is set to the value 5dBm, the share between macrocells and microcell is not in use

gsmMacrocellThreshold GMAC dBm

this parameter indicates the size of a microcell by means the maximum transmission power of the MS in a gsm cell. If parameter is set to the value 43dBm, the share between macrocells and microcell is not in use

gsmMicrocellThreshold GMIC dBm

this parameter indicates the size of a macrocell by means the maximum transmission power of the MS in a dcs cell. If parameter is set to the value 0dBm, the share between macrocells and microcell is not in use

dcsMacrocellThreshold DMAC dBm

this parameter indicates the size of a microcell by means the maximum transmission power of the MS in a dcs cell. If parameter is set to the value 36/33dBm, the share between macrocells and microcell is not in use

dcsMicrocellThreshold DMIC dBm



• Cell Definition for Multilayer Network• How to set?%MsTxPwrMaxCell(n) >= gsmMacrocellThreshold– adjacent cell type is

macrocell%MsTxPwrMaxCell(n) <= gsmMicrocellThreshold– adjacent cell type is

microcell

• BSC Parameters:%gsmMicrocellThreshold = 33 dBm%gsmMacrocellThreshold = 35 dBm

• Cell Parameter:%msTxPwrMax(n) = 33 dBm



• Cell Definition for Multilayer Network• What these values mean?

(MsTxPwrMax(n) = 33dBm) <= (gsmMicrocellThreshold = 33dBm)• the adjacent cell type is microcell



• MSC HO

BSC PARAMETERS BSC PARAMETERS BSC PARAMETERSEXPLANATION Q3 NAME UNITdisable internal ho. With this parameter you define whether all handovers are controlled by the MSC or not.

disableIntHo DINHO

Number of preferred cells for MSC HO. With this parameter you define the maximumnumber of preferred cell identifiers that theBSC sends to the MSC in the HANDOVER_REQUIRED message. Define the number of target cells for inter-BSC HO.

genHandoverRequestMessage NPC



• MSC HO• How to set disableIntHo?• Set to YES – not all HO is controlled by MSC

"Only inter-BSC HO requires MSC"Intra-BSC HO will not require MSC"To reduce MSC load

• Set to NO - all HO is controlled by MSC



• MSC HO• How to set genHandoverRequestMessage?• Typical values is 3

"3 preferred cells are included in the HANDOVER REQUIRED message

"The message is sent from BSC to MSC"Only for inter-BSC HO scenario



• Directed RetryBSC PARAMETERS BSC PARAMETERS BSC PARAMETERSEXPLANATION Q3 NAME UNITDisable external directed retry. The parameter indicates that only internal directed retry handovers are allowed. Others are terminated. Y Disable external directed retry handoversN Enable external directed retry handovers

disableExtDr DEXDR



• Directed Retry• How to set disableExtDr?• Set to YES – external directed retry HO will not be allowed

• Set to NO – external directed retry HO will be allowed when it is necessary"Inter-BSC directed retry HO will take place for cells at the BSC

boundary



• Handover type:

BSC PARAMETERS BSC PARAMETERS BSC PARAMETERSEXPLANATION Q3 NAME UNITHo Preference order Interference DL/UL hoPreferenceOrderInterfDL HDL

hoPreferenceOrderInterfUL HULthis par indicates the execution after the timing advance has exceeded the threshold

msDistanceBehaviour DISB sec.

uplink interference level calculations, difference between UL signal level and DL witrhin a BSC coverage ares

rxLevBalance RXBAL dB



• Handover type:• How to set hoPreferenceOrderInterfDL?• Set to inter – intercell HO is preferred when HO is due to DL

interference• Set to intra - intracell HO is preferred when HO is due to DL

interference



• Handover type:• How to set hoPreferenceOrderInterfUL?• Set to inter – intercell HO is preferred when HO is due to UL

interference• Set to intra - intracell HO is preferred when HO is due to UL

interference



• Handover type:• How to set msDistanceBehaviour?• Action taken after timing advance has exceeded the threshold• Value = 255 – no channel release, only HO attempts• Value = 0 – release channel immediately, no HO attempts• Value = 10

"HO attempt within 10 seconds after the timing advance has been exceeded

"Channel will be released if HO does not succeed during the 10 seconds window period



• Handover type:• How to set rxLevBalance?• This parameter is used for the purpose of uplink interference level

calculation• Typical value = 6 dB



• MS Speed DetectionBSC PARAMETERS BSC PARAMETERS BSC PARAMETERSEXPLANATION Q3 NAME UNITupper limit of ms speed class1. With this parameter you define the upper limitof MS speed for the first class in MS speedmeasurement. One parameter step equalsthe speed of 2 km/h.

msSpeedC11 MSSCF

upper limit of ms speed class2. With this parameter you define the upper limitof MS speed for the second class in MSspeed measurement. One parameter stepequals the speed of 2 km/h.

msSpeedC12 MSSCS



• MS Speed Detection• How to set msSpeedC11?• This parameter for MS speed related HO• If you decide maximum MS speed for slow moving traffic is 20 km/h• The value should be set to 10• Any MS speed exceeds the 20 km/h threshold will be considered fast

moving traffic



• Advanced Multilayer HandlingBSC PARAMETERS BSC PARAMETERS BSC PARAMETERSEXPLANATION Q3 NAME UNITBSC TRHO, upper threshold for BTS load. upperthreshold for the load of the base station. Theparameter is used to trigger BSC-controlledtraffic reason handovers.

amhUpperLoadThreshold AUT %

IUO &/or Dual Band/micro, lower thresh. for BTS load. define the lowerthreshold for the load of the base station. Theparameter is used to trigger advancedmultilayer handling functionality with IUO and/or Dual Band/ microcell features.

amhLowerLoadThreshold ALT %

BSC TRHO, max traffic load of an adj cell amhMaxLoadOfTargetCell %BSC TRHO, guard time for going back to original cell. define the guard timeafter a BSC-controlled or an MSC-controlledTRHO, during which a handover back to theoriginal cell is not allowed.

amhTrhoGuardTime TGT sec.



• Advanced Multilayer Handling• How to set amhUpperLoadThreshold?• This parameter defines the maximum cell traffic load• When the the cell traffic load exceeds the threshold, intra-BSC traffic

reason HO will occur• Example: amhUpperLoadThreshold = 70%

"If the cell traffic load is 75%, Traffic Reason HO will be initiated



• Advanced Multilayer Handling• How to set amhLowerLoadThreshold?• This parameter defines the minimum cell traffic load• If the traffic load of the serving cell does not exceed the

amhLowerLoadThreshold, the IUO handover or the Direct Access to super-reuse TRX are not allowed



• Advanced Multilayer Handling• How to set amhMaxLoadOfTargetCell?• This parameter defines the maximum adjacent cell traffic load• If the adjacent cell traffic load is below this threshold, the cell can be

the target for Traffic Reason HO• Example: amhMaxLoadOfTargetCell = 80%

"If the adjacent cell traffic load is 60%, this cell can be the target cell for Traffic Reason HO



• Advanced Multilayer Handling• How to set amhTrhoGuardTime?• This parameter defines the guard time before Handover back to

original cell is allowed• If set to 10 seconds

"BSC-controlled or MSC-controlled Traffic Reason HO occurs"During this 10 seconds period, HO back to the original cell is NOT

allowed"Handover back to original cell can only be allowed after the 10

seconds period expires



• Dynamic HotspotBSC PARAMETERS BSC PARAMETERS BSC PARAMETERSEXPLANATION Q3 NAME UNITThe quality limit in the threshold table are the thresh. Values for the adj cell signal qual.

badQualLimit %

The limits have the following dependence: goodQualLimit %GQL<=SQL2<=SQL1<=BQL sigQualLimit1 %TCP1<=TCP2<=TCP3 sigQualLimit2 %defined by the operator tchProbability1 %defined by the operator tchProbability2 %defined by the operator tchProbability3 %



• Dynamic Hotspot• What these parameters mean?• badQualLimit:

%define the limit for bad signal quality in term of proportion of bad samples in all samples in signal quality measurement.

• goodQualLimit: %define the limit for good signal quality. %The value of the parameter has to be equal to or smaller than the

value of the signal quality limit 2 (SQL2) parameter.



• Dynamic Hotspot• What these parameters mean?• sigQualLimit1:

%define the lower limit for adequate signal quality in adjacent cells.%The value of the parameter has to be equal to or smaller than the

value of the bad quality limit (BQL) parameter.

• sigQualLimit2:%define the upper limit for adequate signal quality in adjacent cells. %The value of the parameter has to be equal to or smaller than the

value of the signal quality limit 1 (SQL1) parameter.

• GQL<=SQL2<=SQL1<=BQL



• Dynamic Hotspot• What these parameters mean?• tchProbability1: define the probability of TCH allocation when signal

quality in the adjacent cell, xsignal quality limit 1 (SQL1) <= x < bad quality limit (BQL) .

• tchProbability2: define the probability of TCH allocation when signal quality in the adjacent cell, ysignal quality limit 2 (SQL2) <= y < signal quality limit 1 (SQL1) >= TCH probability 1 (TCP1) parameter.

• tchProbability3: define the probability of TCH allocation when signal quality in the adjacent cell, zgood quality limit (GQL) <= z < signal quality limit 2 (SQL2). >= TCH probability 2 (TCP2) parameter.



• Dynamic Hotspot• Operator defined probability table• The probability is set by operator

100%<goodQualLimit

tchProbability380%<sigQualLimit2>=goodQualLimit

tchProbability272%<sigQualLimit1>= sigQualLimit2

tchProbability151%<badQualLimit>=sigQualLimit1

0%>=badQualLimit

ProbabilitySignal Quality



• Dynamic Hotspot• Example: fixed reference is set at 50%

Cell A

Cell B

100%goodQualLimit

20%sigQualLimit2

30%sigQualLimit1

90%badQualLimit

valueSignal Quality

Measurement result

15%Cell B50%Cell A

Signal QualityAdjacent cell



• Dynamic Hotspot• The probability to allocate TCH in cell A is 51%• The probability to allocate TCH in cell B is 80%• The average probability is 51%*80% = 40% < fixed reference = 50%• Reject resource request

100%<goodQualLimit

Cell B80%<sigQualLimit2>=goodQualLimit

72%<sigQualLimit1>= sigQualLimit2

Cell A51%<badQualLimit>=sigQualLimit1

0%>=badQualLimitAdjacent cellProbabilitySignal Quality


BTS ParametersBTS Parameters

!Channel Configuration!Location Area Design!Cell Radio Design!BSC Parameters"BTS Parameters!Handover Control Parameters!Power Control Parameters!TRX parameters!Adjacency Parameters!MS Mobility Management


BTS ParametersBTS Parameters

BTSAGCH and PCH

Loc Update

Cell/SystemAccess

Cell Selection &Reselection

FACCH CallSetup

BCCH TRXAllocation

Dropped CallControl

Averaging

Queueing

DR & IDR

InterferenceProcessing

C2 Reselection

FrequencyHopping

Dual Band

Dynamic Hotspot

Extended CellRadius


IDLE MODEIDLE MODE----Cell SelectionCell Selection

• Radio constraints:• The MS uses a "path loss criterion" parameter C1 to determine

whether a cell is suitable to camp on [GSM 03.22] • C1 depends on 4 parameters:

• 1. Received signal level (suitably averaged)• 2. The parameter rxLevAccessMin, which is broadcast on the

BCCH, and is related to the minimum signal that the operator wants the network to receive when being initially accessed by an MS

• 3. The parameter msTxPwrMaxCCH, which is also broadcast on the BCCH, and is the maximum power that an MS may use when initially accessing the network

• 4. The maximum power of the MS.



• path loss criterion parameter C1 used for cell selection and reselection is defined by:

• C1 = (A - Max(B,0))

where• A = Received Level Average - rxLevAccessMin• B = msTxPwrMaxCCH – P

• except for the class 3 (4 watts) DCS 1 800 MS where:• B = msTxPwrMaxCCH + POWER OFFSET - P



• rxLevAccessMin = Minimum received level at the MS required for access to the system.

• msTxPwrMaxCCH = Maximum TX power level an MS may use when accessing the system until otherwise commanded.

• POWER OFFSET = The power offset to be used in conjunction with the MS TXPWR MAX CCH parameter by the class 3 DCS 1 800 MS.

• P = Maximum RF output power of the MS.


ye s

C ell S e lectio n A lgorithm

(no B C C H Info)

m easure a ll ca rrie rs

so rt b y rece ived leve l

carrie rs in list

tr ia l carrier: best le ve l in list

B C C H

decode B C C H

suitab le ce ll

no rm al p riority

S electio n of anacceptable ce ll

no

ye s

no

no

ye s

no

no ye s

ye s

low p riority ce ll found

C am p on low priority ce ll

su itab le low p riority ce ll found

try o n ly carriers o fB C C H allocatio n

try o n ly norm a l prio rity ce lls

rem ove tr ia l carrie r from list

nocell in se lected

P LM N

C am p on norm a lpriority ce ll

ye s




• Example:

C1(cell_A) = AV_RXLEV - rxLevAccessMin - Max(0, msTxPwrMaxCCH – max output power of MS)

C1(cell_A) = -80dBm – (-100dBm) – max(0, 36dBm – 33dBm)C1(cell_A) = 17 > 0

C1(cell_B) = -82dBm – (-105dBm) – max(0, 33dBm – 33dBm)C1(cell_B) = 23 > C1(cell_A)

Thus MS camps on cell_B

-105-100RxLevAccessMin (dBm)

1Watt GSM MS3336msTxPwrMaxCCH (dBm)

-82-80Av_RxLev (dBm)cell_Bcell_A


Idle ModeIdle Mode----Cell ReCell Re--selectionselection

• Why C2?• Cell Prioritisation%As a means of encouraging MSs to select some suitable

cells in preference to others

• Example:"In dualband network--to give different priorities for

different band"In multilayer--to give priority to microcell for slow

moving traffic"Any other special case where specific cell required

higher priority than the rest



• How the MS knows?• cellReselectOffset, penaltyTime, temporaryOffset are

cell reselection parameters• These parameters are broadcast on the cell BCCH when

cellReselectparamInd is set to yes

• Cell Reselection Strategy:%Positive offset--encourage MSs to select that cell%Negative offset--discourage MSs to select that cell for the

duration penaltyTime period



• MS will calculate the C1 and C2 for the serving cell, every 5 s• MS will calculate the C1 and C2 for the neighbour cells, every 5 s

• Cell re-selection is needed if:• Path Loss criterion C1 < 0 for cell camped on, for more than 5 sec• There is DL signaling failure• The cell camped on has been barred• The is a better cell in terms of C2 criterion


IDLE MODEIDLE MODE----Cell ReCell Re--selection with C2..selection with C2..IDLE MODEIDLE MODE----Cell ReCell Re--selection with C2..selection with C2..

C1 + cellReselectOffset for penaltyTime = 640• C2=

C1 – cellReselectOffset –temporaryOffset*H(penaltyTime – T) for penaltyTime < 640

1 when T <= penaltyTime• H(x) =

0 when T > penaltyTime


IDLE MODEIDLE MODE----Cell ReCell Re--selection with C2..selection with C2..

• For penaltyTime = 640 seconds,• C2 = C1 – cellReselectOffset

• For penaltyTime < 640 seconds,• C2 = C1 + cellReselectOffset – temporaryOffset for T <=

penaltyTime

• C2 = C1 + cellReselectOffset for T > penaltyTime


Time, TpenaltyTime

C1cellReselectOffset

cellReselectOffset

C2

C2

temporaryOffset

dB

C2 when penaltyTime = 640C2 when penaltyTime < 640


T <= penaltyTimeT <= penaltyTime T > penaltyTimeT > penaltyTime


© C.L.Eng


C2 = C1 - cellReselectOffset ! for penaltyTime = 640 and arbitrary T

C2 = C1 + cellReselectOffset - temporaryOffset " for T < penaltyTime < 640

C2 = C1 + cellReselectOffset # else


cellReselectOffset

temporaryOffset

penaltyTime

Cell included in the list of 6 strongest

T! " #

C1

C2

cellReselectOffset

C2 for penaltyTime = 640

© C.L.Eng



Cell SelectionCell Selection----Case StudyCase Study

• Case Study:• A dualband network, 1800 layer is preferred during call setup• Why?

"To relieve blocking in 900 layer"To absorb traffic from 900 layer

• Strategy?"Use C2 parameters

• How?"Minimising massive BSS parameters change in the existing 900 layer"Traffic is increase in a control manner"Only 1800 layer required BSS parameter change


Cell SelectionCell Selection----Case Study..Case Study..

• Case Study:• How to set?

"Cell Reselection Parameters activated in 1800 layer"900 layer remain unchanged--operation as normal

• What value?

"reselectOffset is initial set at low value during initial stage and further optimised in later stage

cellReselectParamInd PI Y / N - YcellReselectOffset REO 0 ... 126 dB - 8penaltyTime PET 20 ... 640 sec 10 20temporaryOffset TEO 0 ... 70 dB - 10cellBarQualify QUA Y / N - N



• Case Study:• The Rationale?

"cellReselectParamInd--YES" No C2 parameters will be broadcast on cell BCCH if this

parameter is not turned on"cellReselectOffset = 8 dB

" The 1800 layer having a C2 of 8 dB higher than C1 of 900 after the penaltyTime expires

"PenaltyTime = 20 seconds" Assume 1800 cell radius 400 meters" Fast moving traffic speed 80 km/h" A MS takes approximately 20 seconds to cross a cell 1800 cell" Because the initial coverage for 1800 is not contiguous, the

fast moving traffic is not allowed to move to 1800 layer




"PenaltyTime = 20 seconds" During the penaltyTime period, the fast moving MS will set up

call on 900 layer" Slow moving traffic will set up call on 1800 layer

"temporaryOffset = 10 dB" This value should be set higher than cellReselectOffset value" In order to have a negative offset (with reference to 1800 C1

value) during the penaltyTime period




"cellBarQualify = NO" Cell selection priority is normal status" If set to YES, cellBarred parameter can be overwrite and cell

selection priority will become low

cellBarQualify cellBarred Cell selection priority Status for cell reselection

N N normal normal N Y barred barred Y N low normal Y Y low normal



• Case Study:• The Scenario:

"GSM900: rxLevAvg = -75dBm; rxLevAccessMin = -97dBm"DCS1800: rxLevAvg = -80dBm; rxLevAccessMin = -95dBm

"For serving GSM900 cell," C2 = C1 = rxLev – rxLevAccessMin – max ([msTxPowerMaxCCH

– max RF output of MS], 0)" C1 = -75dBm – (-97dBm) – max([33 – 33], 0)" C1 = 22 dB




"For non-serving DCS1800 cell," C1 = rxLev – rxLevAccessMin – max ([msTxPowerMaxCCH – max

RF output of MS], 0)" C1 = -80dBm – (-95dBm) – max([30 – 30], 0)" C1 = 15 dB

"During the penalty time period of 20 seconds; before the penaltytime expires

C2 = C1 + cellReselectOffset – temporaryOffset= 15 + 8 –10= 13dB < C2 for GSM900 cell (= 22dB)

"MS stays in GSM900 layer during this period




"After the penalty time period of 20 seconds expiresC2 = C1 + cellReselectOffset

= 15 + 8= 23dB > C2 for GSM900 cell (= 22dB)

"MS reselects DCS1800 layer after penalty time expires


8dB10 dB

20 sec

Cell included in the list of 6 strongest

T! " #

C11800

C21800

8dB

C1=C2900

penaltyTime = 640

© C.L.Eng



BCCH, C2

BCCH, C2

time

dcs1800

gsm900

cell attractiveness

dcs1800

gsm900



Non-serving cell dcs1800

Serving cell gsm900 RxLevAvg=-75dBm,RxLevAccesMin=-97dBmC1= -75- (-97)=22dB=C2

RxLevAvg=-80dBm,RxLevAccesMin=-95dBmC1= -80- (-95)=15dBFor 0 to 20 sec;C2=15+8-10x1 =13dB < C2=22dB

For 20 to infinityC2=15+8-10x0 =23dB > C2=22dB

MS reselects dcs1800 after penalty time expires

MS reselects dcs1800 after penalty time expires

© C.L.Eng



IDLE MODEIDLE MODE----Cell ReselectionCell Reselection HysteresisHysteresis

• Cell Reselection Hysteresis• MS is moving in a border area between location areas• MS might repeatedly change between cell of different location areas• Each change of location area requires a location update• LU causes

%Causes heavy signalling load%Increases risk of paging message being lost

• To prevent this, cell reselect hysteresis is used• How this parameter works?

"A cell in a different location area is only selected if it is “better” than all the cell in the current LA by at least the value of cellReselectHysteresis

"In term of path loss criterion



• Cell Reselection Hysteresis• What value to set?• Typical value is 6~8 dB• Example:

• A static class 4 MS camping on cell 1 in idle mode.• The MS monitor the BCCH of cell 1 and cell 2 and measures the

following levelsrxLevAvg = -80dBm in cell 1 rxLevAvg = -86dBm from neighbour cell 2• The following parameters are set:



• Cell Reselection Hysteresis• The following parameters are set:

• Does the MS perform cell reselect?• If cell 1 and cell 2 belong to the same LA• If the cell 1 and cell 2 belong to different LAs

msTxPwrMaxCCH = 33dBmrxLevAccessMin = -104dBm

Cell 2

msTxPwrMaxCCH = 36dBmrxLevAccessMin = -100dBmcellReselectHysteresis = 6dB

Cell 1



• Cell Reselection Hysteresis• What are the conditions?• For the same LA:

"C1 (cell 2) > C1 (cell 1)• For the different LA:

"C1 (cell 2) > C1 (cell 1) + cellReselectHysteresis• C1 (cell 1) = rxLevAvg – rxLevAccessMin – max ([msTxPowerMaxCCH –

max RF output of MS], 0)C1 (cell 1) = -80dBm – (-100dBm) – max([36 – 33], 0)C1 (cell 1) = 17 dB

• C1 (cell 2) = rxLevAvg – rxLevAccessMin – max ([msTxPowerMaxCCH –max RF output of MS], 0)

C1 (cell 2) = -84dBm – (-104dBm) – max([33 – 33], 0)C1 (cell 2) = 20 dB



• Cell Reselection Hysteresis• C1 (cell 2) = 20 dB > C1 (cell 1) = 17 dB

• For the same LA:"C1 (cell 2) > C1 (cell 1)"cell reselection

• For the different LA:"C1 (cell 2) < C1 (cell 1) + cellReselectHysteresis"No cell reselection


IDLE MODEIDLE MODE----Cell Reselection Cell Reselection HysteresisHysteresis

C2= 0

C2cell1 cell2

MS direction

x y z

X: cell2 radius for cell reselection

cellReselectHysteresis

Cell reselection:Y: no location area changeZ: change of location area© C.L.Eng



•Dedicated Mode Operation:• Handover Control Parameters• Power Control Parameters

•Dedicated Mode Operation:• Handover Control Parameters• Handover Design• Handover Strategies

•Exercise•Summary


Dedicated ModeDedicated Mode

• Handover• Power control


Handover ParameterHandover Parameter

!Channel Configuration!Location Area Design!Cell Radio Design!BSC Parameters!BTS Parameters"Handover Control Parameters!Power Control Parameters!TRX parameters!Adjacency Parameters!MS Mobility Management


Handover ParameterHandover Parameter

HOC

AveragingWindows &Weighting

Thresholds

Fast moving MSin Macrocell

Enhanced RapidField Drop

AveragingAdjacent Cells

HO MeasurementAveraging

method

MinimumIntervals

HO types allowed

Extended CellRadius

IUO

C/I Based HOCandidateEvaluation

AdvancedMultilayer


Handover DesignHandover Design

• Handover definition:• A mechanism that transfers an ongoing call from one cell to another

as a user moves through a coverage area of a GSM system

• Trends:• Smaller cells to meet the demands for increased capacity # number

of cell boundary crossing increase

• Impact:• Network Resource: switching load• Delay # Quality of Service



• Network resource:• Minimising number of HO # minimising switching load

• QoS:• Minimising delay # minimises co-channel interference

• Challenge#optimium HO parameters settings using the existing HO algorithm so that the perceived QoS does not degrade



• General HO Design Guidelines• HO design involves setting of:

"HO parameters"GenHandoverRequestMessage in BSC parameter"MsTxPwrMax in BTS parameter"PcLowerThresholdLevDL/UL in power control parameter"hoMargin in adjacency parameter

• HO objectives:"maintenance of connection in case of cell change (movement)"channel change in case of severe disturbance (interference)"design of cell borders and radio network structure



• HO is divided into several sub-processes



• HO is divided into several sub-processes…continue



• HO sub-processes flow

serving cell measurement adjacent cell measurement

measurement pre-processing& btsMeasAverage& hoAveragingLev/Qual UL/DL window size& weighting& msDistanceAveragingParam window size

measurement pre-processing& btsMeasAverage& hoAveragingLev/Qual UL/DL window size& weighting& msDistanceAveragingParam window size

adjacent cell book keeping& averagingWindowSizeAdjCell& numberOfZeroResults& allAdjacentCellsAveraged

HO decision& hoThresholdsLev/Qual/Interference UL/DL& msDistanceHoThresholdParam



• HO sub-processes flow…continue

target cell list generation& rxLevMinCell (n)

target cell evaluation& hoMarginPBGT/Lev/Qual& hoPreferenceOrderInterfUL/DL& btsLoadThreshold& hoPriorityLeve& hoLoadFactor

channel selection

HO execution& maxNumberOfRepetitions



• Handover performance metrics used to evaluate HO performance:1. Call blocking probability -the probability that a new call attempt is

blocked2.Handover blocking probability - the probability that a handover

attempt is blocked3.Handover probability - the probability that, while communicating

with a particular cell, an ongoing call requires a handover before the call terminates. This metric translates into the average number of handovers per call

4.Call dropping probability - the probability that a call terminates due to a handover failure. This metric can be derived directly from the handover blocking probability and the handover probability



• Handover performance metrics used to evaluate HO performance:5.Probability of an unnecessary handover - the probability that a

handover is stimulated by a particular handover algorithm when the existing radio link is still adequate

6.Rate of handover - the number of handovers per unit time. Combined with the average call duration, it is possible to determine the average number of handovers per call, and thus the handover probability.

7.Duration of interruption - the length of time during a handover for which the mobile terminal is in communication with neither base station. This metric is heavily dependent on the particular network topology and the scope of the handover

8.Delay -the distance thc mobile moves from the point at which the handover should occur to the point at which it does



BTS 1BTS 1 BTS 2BTS 2

T1

T2

T3

A B C D

h

© C.L.Eng



• Relative signal strength: • HO triggered at point A• Unnecessary HO when the serving cell signal is still adequate

• Relative signal strength with threshold:• If threshold set at T1, same as relative signal strength trigger point A• If threshold set at T2, HO is delayed, occurs at point B• If threshold set at T3, delay too long# may result in dropped call and

suffers co-channel interference



• Relative signal strength with margin:• Triggered only when the target cell signal strength is stronger than the

serving cell by a margin h, point C• Prevent “ping-pong” effect #repeated HO between two cells due to rapid

fluctuations in received signal from both cells• Unnecessary HO may occur if the serving cell is sufficiently strong

• Relative signal strength with margin and threshold• Triggered when the serving cell signal drop below threshold and the target

cell signal is stronger by a margin• Occurs at point C if the threshold is set at T1 and T2• Occurs at point D if threshold is set at T3



• HO initiation criteria based on 4 variables:1. Averaging window size2.Measurement value weighting3.Threshold level4.Margin



enableIntraHoInterfUL EIC Y enableIntraHoInterfDL EIH Y enablePwrBudgetHandover EPB Y enableUmbrellaHandover EUM N enableMSDistanceProcess EMS N enableSDCCHHandover ESD Y

• Parameters to enable different type of HO:



• HO Priority:



• HO Priority:• RR-radio resource:

%target cells are ranked according to radio link properties and%priority levels

• Imperative: %target cells are ranked according to radio link properties%priority levels are not used


Handover Detection AlgorithmHandover Detection Algorithm

• 1 AV_RXLEV_NCELL(n) > rxLevMinCell(n) + Max (0, A)A = msTxPwrMax(n) – P P = MS Classmark

• 1’ AV_RXLEV_NCELL(n) > hoLevelUmbrella(n)

• 2 PBGT > hoMarginPBGT(n)PBGT = (msTxPwrMax – AV_RXLEV_DL_HO – (btsTxPwrMax -BTS_TXPWR)) – (msTxPwrMax(n) – AV_RXLEV_NCELL(n))

• 2’ AV_RXLEV_NCELL(n) > AV_RXLEV_DL_HO + (btsTxPwrMax –BTS_TXPWR) + hoMarginLev/Qual(n)


Handover Causes and DecisionsHandover Causes and Decisions

• Causes and Decisions


Handover Causes and DecisionsHandover Causes and Decisions

• Causes and Decisions…continue


Handover RegionsHandover Regions• Thresholds Settings:

-110dBm

HO due to level

7

-47dBmhoThresholdsLevDL/UL

hoThresholdsQualDL/UL

HO due to interference

HO due to quality

RXLEV

RXQUAL

0

hoThresholdsInterferenceDL/UL

© C.L.Eng


Handover RegionsHandover Regions• Handover Level Thresholds

© C.L.Eng

MS/BTS sensitivity

hoThresholdsLevDL/UL (outgoing)

rxLevMinCell (incoming)

hoThresholdsInterferenceDL/UL (outgoing)


HO Required- cause- reduced target cell list

HandoverDetection

BTS

yes

yes

no

yes

try next cell

selectchannel

Handover Failure

HO Cond Ind- cause- target cell list

BSC

next cellavailable

next cell external

no

channel available

no

MSC

yesChannel Activation

© C.L.Eng

Handover FlowHandover Flow


HandoverHandover--ScenarioScenario

• HO Thresholds:• Set to meet the optimum HO performance

• 2 Scenarios to be considered:%Noise Limited%Interference Limited

• MS behaves differently in the above 2 scenarios


HandoverHandover--ScenarioScenario

• HO Thresholds Parameters and valuesQ3 NAME RANGE UNIT REC. ToBeUsedhoThresholdsLevDL LDR -110 ... -47 - -87px LDP 1 ... 32 - 3nx LDN 1 ... 32 - 4hoThresholdsLevUL LUR -110 ... -47 - -95px LUP 1 ... 32 - 3nx LUN 1 ... 32 - 4hoThresholdsQualDL QDR 0 ... 7 - 5px QDP 1 ... 32 - 3nx QDN 1 ... 32 - 4hoThresholdsQualUL QUR 0 ... 7 - 5px QUP 1 ... 32 - 3nx QUN 1 ... 32 - 4hoThresholdsInterferenceDL IDR -110 ... -47 - -78px IDP 1 ... 32 - 1nx IDN 1 ... 32 - 1hoThresholdsInterferenceUL IUR -110 ... -47 - -85px IUP 1 ... 32 - 1nx IUN 1 ... 32 - 1msDistanceHoThresholdParam MSR 0 ... 63 - 63px MSP 1 ... 32 - 1nx MSN 1 ... 32 - 1


HandoverHandover--Noise Limited ScenarioNoise Limited Scenario

• Noise Limited Scenario• Large cell with low traffic load, specially in rural area• rxLev at cell border is just a few dB higher than receiver reference

sensitivity• Main Handover criteria is level criteria

• Receiver Reference Sensitivity according to GSM 05.05



• Noise Limited Scenario• Imperative to set the optimum values to avoid “forward-back” HO• General guideline:• rxLevMinCell – hoThresholdsLevDL = level hysteresis > 0 (+4dB..10dB)

rxLevMinCell > hoThresholdsLevDL + level hysteresis and• hoThresholdsLev > MS sensitivity + 3 dB• only DL is mentioned for illustration; in actual parameters planning, both

UL/DL



• Noise Limited Scenario

Level Handover

rxLevMinCell(cell2) = -90dBmhoMarginLev(n) = 3dBhoThresholdsLevDL = -90dBm

rxLevMinCell(cell1) = -90dBmhoMarginLev(n) = 3dBhoThresholdsLevDL = -91dBm

av_rxLev + hoMarginLev(n)= -95 + 3 = -92dBm < hoThresholdsLevDL = -91dBm

av_rxLev + hoMarginLev(n)= -95 + 3 = -92dBm < hoThresholdsLevDL = -91dBm

av_rxLev = -95dBm

rxLevMinCell(cell2) � hoThresholdsLeDL=-90 � (-91) = +1dB

cell1cell2

© C.L.Eng



• Noise Limited ScenarioLevel Handover

av_rxLev + hoMarginLev(n)= -92 + 3 = -89dBm > hoThresholdsLevDL = -90dBm


av_rxLev = -92dBmcell1

cell2

© C.L.Eng



• Noise Limited Scenario

Level Handover

rxLevMinCell(cell2) = -90dBmhoMarginLev(cell2) = 3dBhoThresholdsLevDL = -95dBm




av_rxLev = -96dBm

rxLevMinCell(cell2) � hoThresholdsLevDL= -90 � (-94) = +4dB

cell1cell2

© C.L.Eng



• Noise Limited ScenarioLevel Handover





av_rxLev = -96dBm

rxLevMinCell(cell2) - hoThresholdsLevDL = -92 � (-96) = 4dB

cell1cell2

© C.L.Eng


HandoverHandover--Interference Limited ScenarioInterference Limited Scenario

• Interference Limited Scenario• Small cell with high traffic load, especially in urban area• rxLev at cell border is significant higher than the receiver sensitivity• C/I is not much higher than the reference interference level• Main Handover criteria is power budget criteria

• Receiver Reference Interference Level according to GSM 05.05



• Interference Limited Scenario• Better cell criteria should be the main HO criteria• Power budget HO guarantee that the MS is served by the cell with

lowest path loss• Thus, higher chance for power control to reduce interference



• General guideline:• hoMarginPBGT (cell1# cell2) + hoMarginPBGT (cell2# cell1) = PBGT

hysteresis > 0 (+6dB..12dB)• Normally hoMarginPBGT is set symmetrically• Low hoMarginPBGT values# high “forward-backward” HO rate• High hoMarginPBGT values #low “forward-backward” HO rate

• Unsymmetrical hoMarginPBGT value is set to adapt cell service area to traffic load

• Increases one cell service area and at the same time reducing its corresponding neighbour cell service area



• Power budget hysteresis

cell1 cell2

a bx y

X: hoMarginPBGT(cell2 to cell1) = 6 dBY: hoMarginPBGT(cell2 to cell1) = 3 dB

A : hoMarginPBGT(cell1 to cell2) = 6 dBB : hoMarginPBGT(cell1 to cell2) = 9 dB

© C.L.Eng


cell2cell1

a b

Service area with hoMarginPBGT:a: 6 dBb: 9 dB

x y

© C.L.Eng

Service area with hoMarginPBGT:x: 6 dBy: 3 dB




• General guideline:• Symmetrical hoMarginPBGT = 6dB: point x and a• Unsymmetrical hoMarginPBGT (cell1# cell2) = 9dB and hoMarginPBGT

(cell2# cell1) = 3dB• PBGT hysteresis = 12dB• Point y and b• Cell2 service area reduced from point x to y• Cell1 service area increased from point a to b


cell1

cell1

cell2

PBG

T H

yste

resi

s = 1

2 dB

hoMarginPBGT = 6 dB

hoMarginPBGT = 6 dB

cell1

cell2

hoMarginPBGT = 9 dB

hoMarginPBGT = 3 dB

© C.L.Eng



HandoverHandover----other featuresother features

• Other HO type and features:


Umbrella HandoverUmbrella Handover

• The Objective:"To serve the target traffic more efficiently

• Umbrella HO has priority over power budget HO• The mapping table for gsmMacrocellThreshold and

gsmMicrocellThreshold



• What does the table mean?• Example:

%If you set the gsmMocrocellThreshold** smaller than the MS class maximum output power, the MS is only allowed to HO to macrocell

%At the same cell, its adjacency parameter msTxPwrMaxCell(n) should be set smaller than gsmMacrocellThreshold

Note ** gsmMacrocellThreshold is a BSC parameter, it need additional adjacency parameter to control per adjacency basis


Umbrella Handover AlgorithmUmbrella Handover Algorithm


Microcell Parameters:hoMarginLev(n) = 6dBhoThresholdsLevDL = -95dBmrxLevMinCell(n) = -86 dBm

Macrocell parameters:gsmMicrocellThreshold = 33 dBmgsmMacrocellThreshold = 35 dBmmsTxPwrMaxCell(n) = 33 dBmMS class 4 = 33dBmhoLevUmbrella(n) = -80 dBm

-95dBm

-80dBm

Umbrella HO Level HO

Umbrella HO Level HO

macrocellmicrocell

© C.L.Eng



Umbrella HandoverUmbrella Handover• When AV_RXLEV_NCELL(n) = -75dBm• A MS class 4 in dedicated mode is in macrocell

• 1’ AV_RXLEV_NCELL(n) > hoLevUmbrella(n)

• (MS class 4 = 33dBm) <= (gsmMicrocellThrsehold = 33dBm) and• (MsTxPwrMaxCell(n) = 33dBm) <= (gsmMicrocellThreshold = 33dBm)

• Umbrella HO to microcell occurs

• When MS is at microcell border, av_rxLev = -98dBm and av_rxLev_cell(n) = -82dBm

• 1. av_RxLevUL/DL < hoThresholdsLevUL/DL• 2. AV_RXLEV_NCELL(n) – av_RxLevDL – (btsTxPwrMax – BTS_TXPWR) >

hoMarginLev(n)


Umbrella HandoverUmbrella Handover• When MS is at microcell border, av_rxLev = -98dBm and AV_RXLEV_NCELL(n)

= -82dBm• 1. av_RxLevDL < hoThresholdsLevDL

-98 dBm < -95 dBm

• 2. AV_RXLEV_NCELL(n) – av_RxLevDL – (btsTxPwrMax – BTS_TXPWR) > hoMarginLev(n)

-82 – (-98) – (0 – 0) = 16 dB > 3 dB• HO due to level


Handover Handover –– due to fast/slow MS Speeddue to fast/slow MS Speed• 2 possibilities:

%MS speed in relation to cell size%Measured MS speed

• Both need AdjCellLayer(n) and hoLevelUmbrella(n) parameters **

Note ** see detail HO due to fast/slow moving MS algorithm


Handover Handover –– due to fast/slow MS Speed Algorithmdue to fast/slow MS Speed Algorithm


Macrocell parameters:hoLevUmbrella(n) = -80 dBmadjCellLayer(n) = LowerrxLevMinCell(n) = -86 dBmfastMovingThreshold = 50

-95dBm

-80dBm

Level HO

Umbrella HO due to slow moving MS Level HO

macrocellmicrocell

Umbrella HO due to Slow Moving MS

Microcell Parameters:hoMarginLev(n) = 6dBhoThresholdsLevDL = -95dBmrxLevMinCell(n) = -86 dBmadjCellLayer(n) = Upper

-86dBm

© C.L.Eng

Handover Handover –– due to fast/slow MS Speeddue to fast/slow MS Speed


Handover Handover –– due to fast/slow MS Speeddue to fast/slow MS Speed• MS speed in relation to cell size• Parameters are set per adjacency basis• From Macro to micro

• Counter for each adjacent microcell• +2 for each measurement >= rxLevMinCell(n)• –1 for each measurement < rxLevMinCell(n) or no measurement

• How to set fastMovingThreshold?


Handover Handover –– due to fast/slow MS Speeddue to fast/slow MS Speed• How to set fastMovingThreshold?

• if microcell radius is about 200 meters, taking 2.5 m/s as slow moving limit; thus

• total time to cross the microcell is 200/2.5 = 80 seconds• if averaingWindowSizeAdjCell is set to 6 SACCH, this equal to about 3

seconds for each measurement• it take 5 seconds to decode an adjacent cell BSIC, thus total

measurements is (5 + 3* measurements) = 80 seconds• thus total measurements are (80-5)/3 = 25 number of measurements• the fastMovingThreshold = 25*2 = 50 (because counter increases by 2

for each measurement)

36km/hour = 36000/3600 =10 m/s 10 m/s 18 km/h 5 m/s 9 km/h 2.5 m/s 4.5 km/h 1.25 m/s


Handover Handover –– due to fast/slow MS Speeddue to fast/slow MS Speed• How to set fastMovingThreshold? …continue• When the counter > fastMovingThreshold = 50; and • AV_RXLEV_NCELL(n) > hoLevUmbrella (n) = -80dBm• #Umbrella HO due to slow moving MS

• ? what is the speed limit if fastMovingThreshold = 24 for a cell radius of 205 meters ?

• 24 = 12 measurements; 12*3 + 5 = 41 seconds; 200 meters/ 41 = 4.8 m/s


Macrocell parameters:hoLevUmbrella(n) = -80 dBmadjCellLayer(n) = LowerrxLevMinCell(n) = -86 dBmlowerSpeedLimit = 10, px/nx=5/6upperSpeedLimit = 30, 5/6

Microcell Parameters:hoLevUmbrella(n) = -90 dBmadjCellLayer(n) = UpperrxLevMinCell(n) = -86 dBmlowerSpeedLimit = 10, 5/6upperSpeedLimit = 30, 5/6

microcell

Fast moving MSHO to upper layer adjacent cell

slow moving MSHO to lower layer adjacent cell

macrocell

© C.L.Eng




• Measured MS speed• Related parameters:

• Slow moving MS to lower layer adjacent cells (lowerSpeedLimit)• Fast moving MS to upper layer adjacent cells (upperSpeedLimit)• One unit value of lowerSpeedLimit upperSpeedLimit equal to 2km/h


Handover Handover –– MSMS--BS DistanceBS Distance

• To prevent MS from exceeding cell boundary• Related Parameters:

• msDistanceBehaviour$ 0 : Release immediately$ 1 - 60 : Release after certain time 1 - 60 s, try imperative handover

during that time$ 255 : No release, only imperative handover attempt


Handover Handover –– MSMS--BS DistanceBS Distance

• msDistanceHoThresholdParam$ 1 step size correlates to 550 meters$ this parameter value depends on the designed cell radius$ if the value is set to 2, the maximum cell radius for the MS is 2*550

= 1100meters before the imperative HO is attempted in the 30 seconds period set in the parameter msDistanceBehaviour; if HO execution fails; the call will be terminated

• enableMSDistanceProcess$Set to yes to activate this feature


Traffic Reason Handover..Traffic Reason Handover..

• TRHO effectively • reduces the service area of a congested cell and• Increases the service area of the under-utilised target cells• HO is triggered with amhTrhopPbgtMargin instead of hoMarginPBGT • General guideline:

• Target cell minimum access level should be set higher to avoid bad DL rxQual after HO

• amhTrhoPbgtMargin should be much lower than hoMarginPBGT



• TRHO Algorithm



• TRHO Parameters:• BSC Parameters:

• BTS Parameters:



• TRHO Parameters:…continue• Adjacency Parameters:

• amhTrhoPbgtMargin(n) should be set lower than hoMarginPBGT• trhoTargetLevel(n) should be set higher than rxLevMinCell(n) to ensure

only good adjacent cell is used


Congested cell parameters:amhUpperLoadThreshold = 80%amhMaxLoadOfTargetCell = 60%amhTrhoGuardTime = 20 sectrhoTargetLevel(n) = -85dBmrxLevMinCell(n) = -90 dBmamhTrhoPbgtMargin(n) = -6dBhoMarginPBGT(n) = 6dB

Under utilised cell Parameters:hoMarginPBGT(n) = 9dB

Under utilised cell: loading 40%Congested cell: loading 90%

-90dBm

-85dBm6dB

a b

a: Traffic reason HOb: PBGT HO

© C.L.Eng

Traffic Reason HandoverTraffic Reason Handover


Directed RetryDirected Retry

• Directed Retry :• A transition (handover) from a SDCCH in one cell to a TCH in another

cell during call setup due to unavailability of an empty TCH within the first cell

• To control traffic distribution between cells to avoid a call rejection• Can be used for both MOC and MTC• Setting guidelines:

• drThreshold should be higher than rxLevMinCell; else the improved target cell selection criteria will be ignored even drMethod = 1



• Directed Retry:• Related Parameters:



• Directed Retry Algorithm



• Directed Retry Example:

macrocell microcell

After 6 seconds, MS attempt to try access macrocell

Call setup in microcellencounters congestion

Call setup in macrocellencounters congestion

DR

DR



• the BSC cannot start the target cell evaluation within 2 seconds period from the start of directed retry procedure is triggered

• after 2 seconds, the BSC continues to evaluate the target cell until 6 seconds period expires and if no suitable target cells are available, directed retry will be aborted **

• ** MS need at least 5 seconds to decode the neighbouring BSIC. Thus minimum maxTimeLimitDirectedRetry should be 5 seconds

• cellType will be set based on the macro or micro cell in the network


Intelligent Directed RetryIntelligent Directed Retry

• Intelligent Directed Retry:• if IdrUse = Y, intelligent directed retry is used; • additional criteria are taken into account when evaluate the target

cells:• MS class• MS priority• Adjacent cell type

• MS class is based on the following:• classmark 1-4= GSM subscriber• classmark 5 = MCN subscriber


Intelligent Directed RetryIntelligent Directed Retry

• Intelligent Directed Retry Example:

macrocell microcellIDR

MCN MSClass 5

macrocell microcellIDR

GSM MSClass 1-4

IDR

Call setup in Call setup in microcellmicrocellencounters congestionencounters congestion

Call setup in Call setup in microcellmicrocellencounters congestionencounters congestion

Target cell list consists of microcells only

Target cell list consists of all neighbouring cells (micro or macro)


QueuingQueuing

• Queuing Related Parameters:

• If both queuePriorityUsed and msPriorityUsedInQueueing are used,queuePriorityUsed will be dominant factor

• TimeLimitCall should be shorter than (maxTimeLimitDirectedRetry + minTimeLimitDirectedRetry)


QueuingQueuing

• MaxQueueLength: The parameter specifies the number of call attempts and handover attempts that can wait for a TCH release in a BTS. The value is the percentage of TRXs times 8

• For a 4 TRXs cell, maxQueueLength = 50%, 50%*4*8 = 16 call attempts and HO attempts can wait for a TCH release in a cell

• queuingPriorityHandover should be set higher than queuingPriorityCall• queuingPriorityCall should be set higher than queuePriorityNonUrgentHo

• Non urgent HO: power budget HO, umbrella HO, slow moving MS HO and traffic reason HO

• Urgent HO: quality and level reason HO


11

0 2 4 86 10 2 4 86 10 2SACCH frame

0 1 2 43 5 6 7 98 10 seconds

' maxTimeLimitDirectedRetry

' timeLimitCall

minTimeLimitDirectedRetry

Queue and DR triggered

HO from SDCCH to TCH

' maxTimeLimitDirectedRetry

' timeLimitCall

minTimeLimitDirectedRetry

© C.L.Eng

Queuing and Directed RetryQueuing and Directed Retry


Queuing and Directed RetryQueuing and Directed Retry

• Reference to Figure in previous slide,• Timing Diagram for Queuing and Directed Retry

• the call setup will not be able to handover to directed retry if thetimeLimitCall is longer than maxTimeDirectedRetry and the call will be terminated when the timeLimitCall expires



•Dedicated Mode Operation:• Power Control Parameters• Power Control Design• Power Control and Handover Control

• Exercise•Summary


Power Control ParameterPower Control Parameter

!Channel Configuration!Location Area Design!Cell Radio Design!BSC Parameters!BTS Parameters!Handover Control Parameters"Power Control Parameters!TRX parameters!Adjacency Parameters!MS Mobility Management


Power ControlPower Control

POC

Step Sizes

UL Signal QualityBands

BTS PowerRange

AveragingWindows

BTS PowerControl

Interval

Thresholds



• Objective:• to adapt the transmit power of MS & BTS to reception conditions

MS1 Tx Power: 33 dBm

MS2 Tx Power: 27 dBm

TRX-TCH Tx Power: 36 dBmTRX-TCH Tx Power:

30 dBm



• Power control advantages:• reduction in MS average power consumption• reduction in overall network interference level

• Power control is applied separately:• for uplink and downlink• each logical channel

• Power control is not applied to:• downlink burst using the BCCH frequency


Power ControlPower ControlPC Decision

Process

RXQUAL_XX<pcUpperThresholdsQualXX

RXLEV_XX<pcLowerThresholdsLevXX

+POW_RED_STEP SIZE

Power decrease

no

yes

xRXQUAL_XX>

pcLowerThresholdsQualXX

Power increase

noyes

xRXQUAL_XX>

pcUpperThresholdsQualXX

Power decrease

noyes

no

RXQUAL_XX<pcLowerThresholdsQualXX

Power increase

noyes

no

no

x

x


Power Control Power Control ---- RegionsRegions

-110dBm

7

-47dBm

pcLowerThresholdsLev

pcLowerThresholdsQual

pcUpperThresholdsLev

pcUpperThresholdsQual

Power up(bad level)

Power up(bad quality)

Power down(good level)

Power down(good quality)

RXLEV

RXQUAL

powerRedStepsizepowerIncrStepsize

6dB margin



• Power control implementation

MS or BTS& radio link measurements

BSC& measurement averaging& HO thresholds comparison& HO target cell evaluation& HO decision & command& PC threshold comparison& PC command

MSC& external HO: decision &

command

Implementaion of POC and HOC©C.L.Eng



• Measurement preprocessing for power control:• for each call

• UL and DL received signal level• UL and DL received signal quality

• The measurements are made over each SACCH multiframe• 104 TDMA frames (480 ms) for a TCH• 102 TDMA frames (470,8 ms) for an SDCCH

• every SACCH multiframe, MS sends in the next SDCCH message block the DL measurement on dedicated channel via the Measurement report message to the serving TRX of the BTS

• serving TRX performs UL measurements on the dedicated channel


Power ControlPower Control• General POC Parameters:powerCtrlEnabled PENA Yes / No Y powerControlInterval INT 0 ... 31 sec 2 powerIncrStepsize INC 2,4 or 6 dB 4 powerRedStepsize RED 2 or 4 dB 2


Power Control Power Control ---- Step SizeStep Size


Power Control Power Control ---- Step SizeStep Size• Power step size or variable? BTS MS Power up due to quality variable variable Power down due to quality

step; rxLev > pcLowerThresholdsLevDL + 6dB

variable or step; rxLev > pcLowerThresholdsLevUL + 6dB

Power up due to level variable or step variable or step Power down due to level step variable or step


Power Control Power Control ---- RangeRange• POC Range Parameters:

rfMaxPowerReduction 0 pwrDecrLimitBand0 PD0 10 pwrDecrLimitBand1 PD1 8 pwrDecrLimitBand2 PD2 6 pwrDecrQualFactor PDF 1 bsTxPwrMin PMIN 10 bsTxPwrMax PMAX 0


Power Control Power Control ---- RangeRange• POC Range Parameters:• If optimumRxLevUL feature is activated; i.e. set to –85 dBm; • alternative power control algorithm for MS will be used

• pwrDecrLimitBand0• pwrDecrLimitBand1• pwrDecrLimitBand2• pwrdecrQualFactor

• PWR_DECR_STEP =

MIN( PwrDecrLimit, MAX( MAX (0, RXLEV_UL - OptimumRxLevUL),(PwrDecrFactor + MAX(0, Qa)) *PowRedStepSize ) )

• where Qa = PcUpperThresholdsQualUL - AV_RXQUAL_UL_PC


pwrDecrLimitBands for PcUpperThresoldQualUL=1

02468

1012

-110

-107

-104

-101 -98 -95 -92 -89 -86 -83 -80 -77 -74 -71 -68 -65 -62

av_rxLev

pwr_

decr

_ste

p

AV_RX_QUAL_UL_PC=0 pwrDecrLimitBand0 10dBAV_RX_QUAL_UL_PC=1 pwrDecrLimitBand1 8dBAV_RX_QUAL_UL_PC=2 pwrDecrLimitBand2 6dB

MS power reduces by 4 dB when rxLev < optimumRxLevUL (av_rxQual_UL quality = 0 ) 10dB when rxLev > optimumRxLevUL

© C.L.Eng

PC PC ---- Power Decrement Band SettingPower Decrement Band Setting


PC PC ---- Power Decrement Band Setting..Power Decrement Band Setting..• POC Range Parameters:• TRX parameter: optimumRxLevUL = -85 dBm• POC parameter:

• pcUpperThresholdQualUL = 1• pwrDecrLimitBand0 = 10 dB• pwrDecrLimitBand1 = 8 dB• pwrDecrLimitBand2 = 6 dB

• av_rxLev_UL = -80 dBm and av_rxQual_UL = 0• Power reduction is MS is 10 dB



pwrDecrLimitBands for PcUpperThresoldQualUL=1

02468

1012

-110

-107

-104

-101 -98

-95

-92

-89

-86

-83

-80

-77

-74

-71

-68

-65

-62

av_rxLev

pwr_

decr

_ste

p

AV_RX_QUAL_UL_PC=0 pwrDecrLimitBand0 10dBAV_RX_QUAL_UL_PC=1 pwrDecrLimitBand1 8dBAV_RX_QUAL_UL_PC=2 pwrDecrLimitBand2 6dB

MS power reduces by 2 dB when rxLev < optimumRxLevUL (av_rxQual_UL quality = 1 ) 8 dB when rxLev > optimumRxLevUL

© C.L.Eng

PC PC ---- Power Decrement Band Setting..Power Decrement Band Setting..


PC PC ---- Power Decrement Band Setting..Power Decrement Band Setting..• POC Range Parameters:• TRX parameter: optimumRxLevUL = -85 dBm• POC parameter:

• pcUpperThresholdQualUL = 1• pwrDecrLimitBand0 = 10 dB• pwrDecrLimitBand1 = 8 dB• pwrDecrLimitBand2 = 6 dB




Power Control Power Control ---- AveragingAveraging• Averaging

• Weighting is used when DTX is activated in the network

pcAveragingLevDL LDS 1 ... 32 SACCH 4 weighting LDW 1 ... 3 1 pcAveragingLevUL LUS 1 ... 32 SACCH 4 weighting LUW 1 ... 3 1 pcAveragingQualDL QDS 1 ... 32 SACCH 1 weighting QDW 1 ... 3 1 pcAveragingQualUL QUS 1 ... 32 SACCH 1 weighting QUW 1 ... 3 1

-75 -72 -70 -76 -71 -78 -74 -76UL level (dBm)

0 1 0 0 1 1 1 0DTX used

1 2 3 4 5 6 7 8pcAveragingLevUL, sample


Power Control Power Control ---- AveragingAveraging• Weighting:• Window size = 8, weighting = 2

• Av_RxLev_UL_PC = (-75x2 + -72x1 + -70x2 + -76x2 + -71x1 + -78x1 + -74x1 + -76x2)

(2 + 1 + 2 + 2 + 1 + 1 + 1 + 2)Av_RxLev_UL_PC = 74 dBm

Window size:Window size (POC) <= window size (HOC)


Power Control Power Control ---- AveragingAveraging• PC Priority:

• PC due to Lower quality thresholds (UL and DL)• PC due to Lower level thresholds (UL and DL)• PC due to Upper quality thresholds (UL and DL)• PC due to Upper level thresholds (UL and DL)


Power Control Power Control ---- ThresholdsThresholdspcLowerThresholdsLevDL LDR -110 ... -47 dBm -82 px LDP 1 ... 32 2 nx LDN 1 ... 32 3 pcLowerThresholdsLevUL LUR -110 ... -47 dBm -89 px LUP 1 ... 32 2 nx LUN 1 ... 32 3 pcLowerThresholdsQualDL LDR 0 ... 7 4 px LDP 1 ... 32 2 nx LDN 1 ... 32 3 pcLowerThresholdsQualUL LUR 0 ... 7 4 px LUP 1 ... 32 2 nx LUN 1 ... 32 3 pcUpperThresholdsLevDL UDR -110 ... -47 dBm -70 px UDP 1 ... 32 2 nx UDN 1 ... 32 3 pcUpperThresholdsLevUL UUR -110 ... -47 dBm -75 px UUP 1 ... 32 2 nx UUN 1 ... 32 3 pcUpperThresholdsQualDL UDR 0 ... 7 1 px UDP 1 ... 32 3 nx UDN 1 ... 32 4 pcUpperThresholdsQualUL UUR 0 ... 7 1 px UUP 1 ... 32 3 nx UUN 1 ... 32 4


Power Control Power Control ---- ThresholdsThresholds• POC thresholds values• Guideline:• thresholds setting is imperative to avoid undesirable ping pong effect

of power control• if the pcUpperThresholdsLev is set too low, power down due to level at

low rxlev will casue rxqual to deteriorate and subsequently power up occurs due to rxqual

• rxqual improvement will lead to power down due to level again and the loop recurs


Power Control Power Control ---- RegionsRegions


Power Control Power Control ---- ThresholdsThresholds• POC thresholds values--an example

-70 -75 -80 -85 -90 -95 -100

7

6

5

4

3

2

1

0

pcU

pper

Thre

shol

dsLe

vUL

2/3

pcU

pper

Thre

shol

dsLe

vDL

2/3

pcLo

wer

Thre

shol

dsLe

vDL

2/3

pcLo

wer

Thre

shol

dsLe

vUL

2/3

pcLowerThresholdsQualUL/DL 3/4

pcUpperThresholdsQualUL/DL 3/4

© C.L.Eng


Power Control Power Control ----MS PowerMS Power OptimisationOptimisation• MS Power Optimisation• 2 scenario:

"During call setup"During handover

• Use the optimized MS output power to reduce the uplink interference


Power ControlPower Control----MS Power MS Power OptimisationOptimisation• MS Power Optimisation• Without MS Power Optimisation, MS access the cell with maximum Tx

power as specified by msTxPwrMaxCCH• During Call Setup:• Related Parameters: per TRX

• Example:• MS_TXPWR_ OPT = MsTxPwrMax - MAX ( 0, (RXLEV_UL -

OptimumRxLevUL) )• When RXLEV_UL = -80dBm• MS-TXPWR_OPT = 33 – max(0, (-80 + 85) = 28dBm • compare to maximum power 33 dBm

optimumRxLevUL LEV -85 msTxPwrMax PMAX 33


Power ControlPower Control----MS Power MS Power OptimisationOptimisation• MS Power Optimisation• During Handover:• Related Parameters: per Adjacency

• Indicates the optimum UL RF signal level after Handover• Only for intra-BSC HO• When BSC calculates the optimized MS output power, it presumes that

the UL signal level is equal to downlink signal level measured by MS• If the DL is stronger than UL by 6 dB, msPwrOPtLevel should be set 6

dB than the desired UL signal level

msPwrOptLevel POPT -85


Power ControlPower Control----MS Power MS Power OptimisationOptimisation• MS Power Optimisation• During Handover:• If AV_RXLEV_NCELL(n) = -75dBm, and• Set msPwrOptLevel = -80dBm

• MS_TXPWR_ OPT(n) = msTxPwrMax(n) - MAX ( 0, (AV_RXLEV_NCELL(n) - msPwrOptLevel) )

• MS_TXPWR_ OPT(n) = 33 – max ( 0, (-75 + 80) = 28 dBm• Thus MS uses 28 dBm output power instead of 33 dBm


Power Control and Handover ControlPower Control and Handover Control• Rule of thumb:• POC should happen before HOC

• 2 ways to make this happens• Thresholds• Averaging windows size

• RxLev Thresholds for POC > RxLev Thresholds for HOC• RxQual Thresholds for POC >= RxQual Thresholds for HOC• Window size (POC) <= window size (HOC)


Power Control & HandoverPower Control & Handover• RxLev timing diagram:


Power Control and Handover ControlPower Control and Handover Control• Example:• RxLev Thresholds and window size:• For UL (refer to the figure in previous slide)• POC:• pcUpperThresholdsLevDL = -75 dBm, px = 2, nx = 3• pcLowerThresholdsLevDL = -89 dBm , px = 2, nx = 3

• HOC:• hoThresholdsLevDL = -95 dBm, px = 3, nx = 4

• What these setting mean?


Power Control and Handover ControlPower Control and Handover Control• Example:• What these setting mean?• MS will power down if the 2 out of 3 av_RxLev_UL measurement

samples is better than –75dBm • MS will power up if the 2 out of 3 av_RxLev_UL measurement samples

is worse than –89dBm• If after powering up, the av_RxLev_UL is still lower than –95dBm with

measurement sample 3 out of 4, HO will take place**

• **Note: this happen when the MS is at the cell border and is transmitting at the maximum power


Power Control & Handover..Power Control & Handover..• RxQual timing diagram:


Power Control & Handover..Power Control & Handover..

-70 -75 -80 -85 -90 -95 -100

7

6

5

4

3

2

1

0

pcU

pper

Thre

shol

dsLe

vUL

2/3

pcU

pper

Thre

shol

dsLe

vDL

2/3

hoTh

resh

olds

Inte

rfer

ence

DL

1/1

pcLo

wer

Thre

shol

dsLe

vDL

2/3

hoTh

resh

olds

Inte

rfer

ence

UL

1/1

hoTh

resh

olds

LevD

L3/

4

hoTh

resh

olds

LevU

L3/

4

pcLo

wer

Thre

shol

dsLe

vUL

2/3

hoThresholdsQualUL/DL 3/4



© C.L.Eng

• POC and HOC thresholds relationships


Power Control & Handover ULPower Control & Handover UL

-70 -75 -80 -85 -90 -95 -100

7

6

5

4

3

2

1

0

pcU

pper

Thre

shol

dsLe

vUL

2/3

hoTh

resh

olds

Inte

rfer

ence

UL

1/1

hoTh

resh

olds

LevU

L3/

4

pcLo

wer

Thre

shol

dsLe

vUL

2/3




!"#$%&'()*

© C.L.Eng


Power Control & Handover ULPower Control & Handover UL

-70 -75 -80 -85 -90 -95 -100

7

6

5

4

3

2

1

0

pcU

pper

Thre

shol

dsLe

vUL

2/3

hoTh

resh

olds

Inte

rfer

ence

UL

1/1

hoTh

resh

olds

LevU

L3/

4

pcLo

wer

Thre

shol

dsLe

vUL

2/3




!"#$%&'()*

!

"#

$

%

&

'

()

*

© C.L.Eng


Power Control & Handover DLPower Control & Handover DL

-70 -75 -80 -85 -90 -95 -100

7

6

5

4

3

2

1

0

pcU

pper

Thre

shol

dsLe

vDL

2/3

hoTh

resh

olds

Inte

rfer

ence

DL

1/1

pcLo

wer

Thre

shol

dsLe

vDL

2/3

hoTh

resh

olds

LevD

L3/

4




© C.L.Eng


Power Control & Handover DLPower Control & Handover DL

-70 -75 -80 -85 -90 -95 -100

7

6

5

4

3

2

1

0

pcU

pper

Thre

shol

dsLe

vDL

2/3

hoTh

resh

olds

Inte

rfer

ence

DL

1/1

pcLo

wer

Thre

shol

dsLe

vDL

2/3

hoTh

resh

olds

LevD

L3/

4




!

"#

$

%

&

'

(

)

*

© C.L.Eng



•TRX Parameters•Adjacency Parameters•Mobility Management•Exercise•Assignment Briefing•Summary


TRX ParameterTRX Parameter

!Channel Configuration!Location Area Design!Cell Radio Design!BSC Parameters!BTS Parameters!Handover Control Parameters!Power Control Parameters"TRX parameters!Adjacency Parameters!MS Mobility Management


TRX ParametersTRX Parameters

© C.L.Eng

TRX IUOE-TRX



© C.L.Eng

• TRX Parameters:

GROUP Q3 NAME RANGE UNITpreferredBCCHMark PREF N … PoptimumRxLevUL LEV -109 ... -47 / N dBmT1 - T6 0 (meas) / 1 (estim)W1 - W6 0 ... 10L1 - L6 -63 ... 63 dBdirectAccessLevel DAL -47 … -109 / N dBmtrxFrequencyType FRT 0 ... 16

E-TRX "optional" eTrxInd ETRX N / EFloating TRX floatingMode FLO F / N

IUO "optional"



© C.L.Eng

• TRX Parameters:• preferredBCCHMark:

• BCCH is automatically configure to its original state after the TRX fault has been eliminated

• Benefit of using TRX output power within a common cell• optimumRxLevUL:

• Used in conjunction with POC –MS power optimisation

• ETRX:• Extended TRX • A cell radius of an ordinary cell is 35 km. • Extended TRX can serve up to about 70 km• The implementation is based on one-BCCH (broadcast control channel)

and two-TRX (transceiver) solution. • The normal coverage area is served with different TRXs than the

extended coverage area.



© C.L.Eng

• ETRX:• Timing of the TRXs which serve the extended coverage area is

delayed so that they can serve the area beyond 35 km• Effectively 2 cell radius for a single cell

• floatingMode:• TRX can be dynamically switched to operate in any of the sectors

within a BTS• Automatically replaces a faulty BCCH TRX


Adjacency ParameterAdjacency Parameter

!Channel Configuration!Location Area Design!Cell Radio Design!BSC Parameters!BTS Parameters!Handover Control Parameters!Power Control Parameters!TRX parameters"Adjacency Parameters!MS Mobility Management


Adjacency ParametersAdjacency Parameters

© C.L.Eng

ADJC

Fast Moving MSin Macrocell

Rapid Field Drop

Directed Accessto Desired Layer

Dynamic Hotspot

C/I Target CellEvaluation Intelligent DR

Margins

Priority ofAdjacent Cell

ImprovedSolution for

Extended Cell

Cell AreaDefinition



© C.L.Eng

• Adjacency Parameters:• Used to control dedicated mode MS for HO purpose• These parameters play only the support role to HO or any other optional

featuresQ3 NAME RANGE UNIT featurecellType CTY GSM / MCN intelligent DRenableHoMarginLevQual MRGS Yes / No HOhoLevelUmbrella AUCL -110 ... -47 dBm umbrealla HOtrhoTargetLevel TRHO -109 ... -47/ N dBm traffic reason HOsyncronised SYN Yes / No HOmsPwrOptLev POPT -110 ... -47/ N dBm MS power optimisationfastMovingThreshold FMT 0 ... 255 fast moving HOadjCellLayer ACL N/SAME/

LOWER/UPPER

multilayer network

chainedAdjacentCell CHAIN Yes / No chained celldadlbTargetCell Yes / No dualband network

interferedCell 0 … 3 dynamic hotspot



© C.L.Eng

• Adjacency Parameters:Q3 NAME RANGE UNIT featurerxLevMinCell SL -110 ... -47 dBm HOmsTxPwrMaxCell *GSM* PMAX 5 ... 43 dBm HOhoTargetArea HOTA 0 ... 3 extended cellhoPriorityLevel PRI 0 ... 7 HOhoLoadFactor OF 0 ... 7 HOhoMarginPBGT PMRG -24 ... 63 dB HOhoMarginLev LMRG -24 ... 24 dB HOhoMarginQual QMRG -24 ... 24 dB HO

ciEstWeight 0 ... 10 C/I target evaluationlevelAdjustment -63 ... 63 dB C/I target evaluation



© C.L.Eng

• Adjacency Parameters:• hoTargetArea:

• indicates whether the adjacent cell is an extended range cell or a normal cell

• If the adjacent cell is an extended cell, it determines which TRX (extended or normal) of the adjacent cell from where the BSC will allocates a TCH during an intra-BSC HO attempt

• 0 = Normal cell• 1 = Extended range cell, a TCH is allocated from a normal TRX• 2 = Extended range cell, a TCH is allocated from an extended range

TRX.• 3 = Extended range cell, a TCH is allocated from a TRX whose type

(extended range or normal range) is the same as the type of the serving TRX.


DualDual--Band ParametersBand Parameters

• multibandCell%define whether adjacent cells with a BCCH allocated from a

different frequency band than the serving cell BCCH are taken into account in handovers and in idle mode cell selection or reselection

• earlySendingIndication%accept or forbid the early sending of the MS Classmark 3 message

in call setup phase to the network

• multiBandCellReporting%define the number of adjacent cells from the other frequency band

that the MS will report in the RX level report


MS Mobility ManagementMS Mobility Management

!Channel Configuration!Location Area Design!Cell Radio Design!BSC Parameters!BTS Parameters!Handover Control Parameters!Power Control Parameters!TRX parameters!Adjacency Parameters"MS Mobility Management


Mobility ManagementMobility Management

• Dual-band MS:• Idle mode• Dedicated mode

• Objectives:• To manage traffic more efficiently• To increase call setup success rate

• Strategies:• Accommodate both single and dualband MS in both dedicated and

idle mode with existing network configuration and traffic volume

• How to design?• Using existing BSS parameters• Dualband parameters


DCS 1800 cell

GSM 900 cell

DCS1800 MS

Dual Band MS

GSM 900 MS

rxAccessMin = -105dBmpenaltyTime = 640C2 = -20 dB

rxAccessMin = -105dBmC2 = C1

© C.L.Eng

Mobility Management Mobility Management –– Idle ModeIdle Mode



• Case study as follows:• Network access preference:

• GSM900 layer• DCS1800 layer

• Justification?• GSM900 is a contiguous coverage layer• DCS1800 is a capacity relief layer

• How to design?• Idle Mode:

• Make DCS1800 layer less attractive by setting negative offset to C2• Only singleband (1800) MS is allowed to access the DCS1800 layer• Dualband and singleband(900) access GSM900 layer


DCS 1800 cell

GSM 900 cell

Dual Band MS

GSM 900 cell

DCS 1800 cell

hoMarginPBGT = -20dBhoPriorityLevel = 4rxLevAccessMinCell = -90dBm

hoMarginPBGT = +6dBhoThresholdsQual = 4hoTresholdsLev = -92DL/-95ULhoPriorityLevel = 4



hoMarginLev/Qual = 3dBrxLevAccessMinCell = -105dBm unless stated otherwise© C.L.Eng

Mobility Management Mobility Management –– Dedicated ModeDedicated Mode



• Case study as follows:…continue• Dedicated Mode:

• Depending on the cell traffic and cell configuration• HO preference:

" G900 to D1800 (negative power budget margin)" D1800 to D1800 (normal power budget with higher priority)" G900 to G900 (normal power budget with lower priority)" D1800 to G900 (large positive power budget margin)



• Case study as follows:…continue• The good and the bad of this strategy• Advantage:

• Simple parameter modification (only C2 required change for idle mode MM)• DCS1800 traffic load can be managed based on cell-by-cell basis••

• Disadvantage:• GSM900 may suffer call setup blocking (both dualband and G900 MS access

network directly)• High HO rate••


DCS 1800 cell

GSM 900 cell

DCS1800 MS

Dual Band MS

GSM 900 MS

rxAccessMin = -100dBmpenaltyTime = 20C2 = +10 dB**

rxAccessMin = -105dBmC2 = C1

** varies based on cell-by-cell basis© C.L.Eng

Mobility Management Mobility Management –– Idle ModeIdle Mode


DCS 1800 cell

GSM 900 cell

Dual Band MS

GSM 900 cell

DCS 1800 cell

hoMarginPBGT = +6dBhoPriorityLevel = 4rxLevAccessMinCell = -90dBm




hoMarginLev/Qual = 3dBrxLevAccessMinCell = -105dBm unless stated otherwise© C.L.Eng

Mobility Management Mobility Management –– Dedicated ModeDedicated Mode


Non-serving cell dcs1800Serving cell gsm900

RxLevAvg=-75dBm,RxLevAccesMin=-97dBmC1= -75- (-97)=22dB=C2

RxLevAvg=-80dBm,RxLevAccesMin=-95dBmC1= -80- (-95)=15dBFor 0 to 20 sec;C2=15+8-10x1 =13dB < C2=22dBFor 20 sec to infinityC2=15+8-10x0 =23dB > C2=22dB

DualDual--Band Network OperationBand Network OperationIdle Mode for Dualband Mobile Management

MS reselect dcs1800 after penalty time expires

MS reselect dcs1800 after penalty time expires

© C.L.Eng



• Complex enough?• A dual-band multi-layer network design• Design criteria:

• GSM band layer consideration• Macro-micro layer consideration

• Idle mode preference:• GSM900->DCS900• Micro followed by macro for slow moving• Macro followed by micro for fast moving

• Dedicated mode preference:• DCS1800->GSM900



• A dual-band multi-layer network design…continue• Network topology consideration

• Neighbour relationships• Adjacency parameters set

Source 900 Macro 1800 Macro 900 Micro900 Macro rxLevMinCell900 Macro hoMarginPBGT900 Macro hoMarginLev900 Macro hoMarginQual900 Macro hoPriorityLevel1800 Macro rxLevMinCell1800 Macro hoMarginPBGT1800 Macro hoMarginLev1800 Macro hoMarginQual1800 Macro hoPriorityLevel900 Micro rxLevMinCell900 Micro hoMarginPBGT900 Micro hoMarginLev900 Micro hoMarginQual900 Micro hoPriorityLevel

TARGET

Documents

BSS Parameter Planning Nokia.PDF