alu

BSS Dimensioning Methods

in B10

Eugen Marza

December 2008

Agenda

1. Air Interface (Cell) Dimensioning

2. Abis Interface Dimensioning

3. BSC Dimensioning

4. Ater CS Dimensioning

5. Ater PS Dimensioning

6. GPU/GP Dimensioning

7. Gb Interface Dimensioning

8. Location Area Dimensioning

3 | Presentation Title | Month 2008 All Rights Reserved © Alcatel-Lucent 2008, XXXXX

BSS Dimensioning Methods in B10

Overview

SGSN

speech

data

A-ter mux

Gb

A

CS

CS+ PS

PS

CSA-bis

Air

TC

MT120

SMU TRCU TRCU

TRCU

MT120

SMU TRCU

TRCU

TRCU

TRX 2 M -EGC H link 1

PS traffic

TRX 3 M -EGC H link 2

M -EG CH link n

BTS

D ynam ic Abis

allocation GCH Extra

GCH Basic

GCH Basic

GCH Extra

GCH Bonus

T CH

T CH TRX 1 CS

traffic

TRX n

Assessment ofbasic and bonus Abis nibbles from

TRX and BTS configuration

Calculate the needed extra Abis TS for real traffic on Abis Itf and

the number of needed Abis links

Assessment ofCS and PS traffic

over AterMux

Calculate the total number of Ater

channels and the required number of

AterMux links Evaluate the

required number of Gb 64K TS

per GPU

Check the traffic capacity limits basedon BSC configuration

Calculate the needed radio TS for SDCCH,

TCH and PDCH, then nb of TRXs

Evaluate the required number

of GPU/GP boards per BSC

Assessment of traffic values for

SDCCH, TCH and PDCH channels

Check the load and conectivity on

DSP and GPU boards of MFS

MxBSC CCP board

CCP board

SSW board

TP board

LIU board

LIU board

MxMFS

GP board

DSP DSP DSP DSP

GP board

DSP DSP DSP DSP


Air Interface (Cell)

Dimensioning1



Air Interface (Cell) Dimensioning

Target

� Find the needed number of RTCH and TRX for one Cell

� Input (counters values):

– CS Traffic

– PS Traffic

– SDCCH Traffic

– CS Congestion

– PS Congestion

– SDCCH Congestion

– Customer requirements for blocking probability

� Output:

– Nb of SDCCH channels

– Nb of TCH

– Nb of TRX

– Real blocking




Method for SDCCH:

� Erlang B

� Needed counters for SDCCH:

� MC400 or GSDTRT (SDCCH_occy_total)

� MC04 or GSDNACGN (SDCCH_assign_cong)

� MC148 or GSDNACAN (SDCCH_assign_allocated)

Erlang B

Required SDCCH Traffic

•GoS:

•% SDCCH blocking

Nb of required SDCCH sub-channels

/ timeslots

•INPUT •OUTPUT•METHOD




Method for SDCCH:

3600400MC

traffic_SDCCH_Measured =

%MCMC

MCcong_SDCCH% 100

1480404 ×

+=

%) ,cong_SDCCH(%Mintraffic_SDCCH_Measured

traffic_SDCCH_quiredRe301−

=

( )0.5% ic;DCCH_traffRequired_SangBInverseErlssubchannel SDCCH quiredRe of Nb =

=8

ssubchannel SDCCH_required_NbTSs_SDCCH_required_Nb

For BCCH not-combined cell:

For BCCH combined cell:

−=8

4ssubchannel SDCCH_required_NbTSs_SDCCH_required_Nb




Method for TCH and PDCH:

� Kaufmann-Roberts.

� Needed counters for TCH:

� MC380a, MC380b, MC703, MC812.

� Needed counters for PDCH:

� P451a, P451b,

� P38e, P39f,

� P14, P27,

� P62x (x=a-c),

� P438c, P507,

� P91x (x=a-f),

� P505.

PS_DL service

CS_FR service

CS_HR service

PS_UL service

Required Traffic

•getMax

Nb RTS needed for CS and PS traffic

Kaufmann-Roberts

Algorithm




Method for TCH and PDCH:

� Kaufmann-Roberts.


� MC380a or GTCTRFT (RTCH_full_occy_total)

� MC380b or GTCTRHT (RTCH_half_occy_total)

� MC703 or GTCNACAN (RTCH_assign_allocated)

� MC812 or GTCNACGN (RTCH_assign_cong)




Method for TCH

703812 MCMCMC812

Request_nRTCH_AssigCong_nRTCH_Assig

ngCS_Real_Co+

==

Real_Cong)_CS %,min(Cong_CS 30=

Cong_CSbMCaMC

aMCCong_FR ×

+=

380380380

Cong_CSbMCaMC

bMCCong_HR ×

+=

380380380

)Cong_FR(aMC

Cong_FRTraffic_Successful_FR

Traffic_FR_quiredRe cell

−×=

−=

13600380

1

)Cong_HR(bMC

Cong_HRTraffic_Successful_HR

Traffic_HR_quiredRe cell

−×=

−=

13600380

1




Method for TCH

� The Required traffic for FR and HR is used together with Required traffic for PS as input for Kaufmann-Roberts algorithm.

� The blocking probability used for CS services is 2%.

Note:

Required CS Bandwidth is:

� 1 TS for FR

� 0.5 TS for HR




Method for PDCH

� Needed counters for PDCH:

� P451a or GARPDCTUBUT (GPRS_PDCH_used_UL_TBF_overall_time)

� P451b or GARPDCTDBUT (GPRS_PDCH_used_DL_TBF_overall_time)

� P38e or GARPDCUDBUT (GPRS_PDCH_DL_traffic_time)

� P38f or GARPDCUUBUT (GPRS_PDCH_UL_traffic_time)

� P14 or GQRDTECGN (GPRS_DL_TBF_estab_fail_radio_cong)

� P27 or GQRUTECGN (GPRS_UL_TBF_estab_fail_radio_cong)

� P62a+P62b+P62c- P438c+ P507 or GTRUTERQN (GPRS_UL_TBF_request)

� P91a + P91b + P91c + P91d + P91e + P91f + P505 or GTRDTERQN

(GPRS_DL_TBF_request)




Method for PDCH

3600451bP

traffic_PS_DL_Measured =

3600451aP

traffic_PS_UL_Measured =

%PfPePdPcPbPaP

Pcong_radio_TBF_DL% 100

50591919191919114 ×

++++++=

%PcPcPbPaP

Pcong_radio_TBF_UL% 100

50743862626227 ×

+−++=

%) ,cong_radio_TBF(%Mintraffic_PS_Measured

traffic_PS_quiredRe301−

=

Final value for Required PS traffic is Max between required DL and UL PS traffic.




Method for PDCH

� Based on TBF usage:

� For calculation 98% quantile and 0.01s delay are used.

Note:

Required PS Bandwidth (minimum number of TS per a request on each direction) is coming from:

� Average Nb of DL TBF per PDCH = P451b/P38e

� Average Nb of UL TBF per PDCH = P451a/P38f

If indicators are available, the required bandwidth is given by:

� GARPDCTDPIN = GPRS_DL_TBF_Pilled_avg

� GARPDCTUPIN = GPRS_UL_TBF_Pilled_avg




Final aggregation:

� Total nb of RTCH =

= 1 TS for BCCH + 1 TS for CCCH (if case) +

+ Nb of Required SDCCH TSs +

+ Nb of Required TSs for FR, HR and PS,

coming from Kaufmann-Roberts algorithm.

� Total nb of TRX = Roundup [(Total nb of RTCH)/8]




Method for PS throughput


� DL PS Traffic

� UL PS Traffic

� Output:

� DL PS Throughput

� UL PS Throughput





� Needed counters for PDCH DL throughput:

� P38e or GARPDCUDBUT (GPRS_PDCH_DL_traffic_time)

� P20a or GQRPDDR1N (GPRS_DL_RLC_block_PDTCH_CS1_retransmissing_ack)

� P20b or GQRPDDR2N (GPRS_DL_RLC_block_PDTCH_CS2_retransmissing_ack)

� P20c or GQRPDDR3N (GPRS_DL_RLC_block_PDTCH_CS3_retransmissing_ack)

� P20d or GQRPDDR4N (GPRS_DL_RLC_block_PDTCH_CS4_retransmissing_ack)

� P20f+P20g+P20h+P20i+P20j+P20k+P20l+P20m+P20n or GQRPDDRMN

(GPRS_DL_RLC_bytes_PDTCH_MCSx_retransmissing_ack from MCS1 to MSC9)(old P20e)

� P55x (x=a-d) or GTRPDDC1N to GTRPDDC4N (GPRS_DL_useful_RLC_blocks_CS1_ack to

GPRS_DL_useful_RLC_blocks_CS4_ack)

� P55x (x=e-m) or GTRPDDM1N to GTRPDDM9N (GPRS_DL_useful_RLC_blocks_MCS1_ack to GPRS_DL_useful_RLC_blocks_MCS9_ack)





� Needed counters for PDCH UL throughput:

� P38f or GARPDCUUBUT (GPRS_PDCH_UL_traffic_time)

� P21a or GQRPDUR1N (GPRS_UL_RLC_block_PDTCH_CS1_retransmissing_ack)

� P21b or GQRPDUR2N (GPRS_UL_RLC_block_PDTCH_CS2_retransmissing_ack)

� P21c or GQRPDUR3N (GPRS_UL_RLC_block_PDTCH_CS3_retransmissing_ack)

� P21d or GQRPDUR4N (GPRS_UL_RLC_block_PDTCH_CS4_retransmissing_ack)

� P21f+P21g+P21h+P21i+P21j+P21k+P21l+P21m+P21n or GQRPDURMN

(GPRS_UL_RLC_bytes_PDTCH_MCSx_retransmissing_ack from MCS1 to MSC9)(old P21e)

� P57x (x=a-d) or GTRPDUC1N to GTRPDUC4N (GPRS_UL_useful_RLC_blocks_CS1_ack to

GPRS_DL_useful_RLC_blocks_CS4_ack)

� P57x (x=e-m) or GTRPDUM1N to GTRPDUM9N (GPRS_UL_useful_RLC_blocks_MCS1_ack to GPRS_DL_useful_RLC_blocks_MCS9_ack)





� DL and UL throughput:

==n_Time_DLTransmisio

Data_DL]kbps[d DL_PS

==UL_Time_nTransmisio

UL_Data]kbps[d UL_PS

eP

PSize_Block_RLCPSize_Block_RLCPn

fxx

m

axxx

d

axxx

381000

2055208

×

+×+××=

∑∑∑===

fP

PSize_Block_RLCPSize_Block_RLCPn

fxx

m

axxx

d

axxx

381000

2157218

×

+×+××=

∑∑∑===


Abis Interface

Dimensioning2



Abis Interface Dimensioning

Target

� Find the required number of ExtraAbis TS

� Check RSL congestion

� Methods are applied at BTS level

� Based on Abis allocation priorities

MAX_PDCH_High_Load Zone From MAX_PDCH_High_Load to MAX_PDCH

Basic nibbles of cell

Extra + Bonus nibbles of BTS

•Priority N°1

•Priority N°2

•Priority N°3




Method for ExtraAbis TS

� ErlangC


– PS Traffic

– Extra-Bonus Traffic

– Available Extra-Bonus nibbles

– PS Congestion (Abis)

– Customer requirements for QoS (delay and quantile)

– Customer requirements for number of basic and bonus nibbles

� Output:

– Nb of extra Abis nibbles

– Nb of ExtraAbisTS




Extra and Bonus Nibbles Method

� (Method 1)

Erlang C

Required extra & bonus Abis nibble Traffic

GoS: % Quantile of x delay sec

Nb of required extra & bonus Abis Nibbles

•INPUT OUTPUT•METHOD

Nb of required extra Abis Nibbles

Nb of bonus Abis Nibbles

−





� Needed counters:

� P466 or GABGCHUSEBT (GPRS_transmission_GCH_use_bonus_and_extra_time),

� P105i or GQRDTECBN (GPRS_DL_TBF_estab_fail_abis_cong),



� P105j or GQRUTECBN (GPRS_UL_TBF_estab_fail_abis_cong),


� Note:

� The counters retrieved at cell level must be aggregated per BTS.





3600466P

traffic_Abis_bonus&extra_Measured =

%PfPePdPcPbPaP

iPcong_Abis_TBF_DL% 100

505919191919191105 ×

++++++=

%PcPcPbPaP

jPcong_Abis_TBF_UL% 100

507438626262105 ×

+−++=

)cong_Abis_TBF_UL% ,cong_Abis_TBF_DL(%Maxcong_Abis_TBF% =

%) ,cong_Abis_TBF(%Mintraffic_Abis_bonus&extra_Measured

traffic_Abis_bonus&extra_quiredRe301−

=





=nibbles bonus&extra quiredRe of Nb

( )delay quantile; fic;bonus_traf&xtraRequired_eangCInverseErl=

where quantile = 99% and delay = 0.01s





Number of required Extra Abis nibbles =

= Number of required extra & bonus Abis nibbles – Nb of bonus Abis nibbles,

Note: Nb of bonus nibbles corresponds to Nb of BCCH and static SDCCH timeslots.

and

Number of required Extra Abis TS =

= Roundup[(Number of required extra Abis nibbles)/4].

Note: 1 Abis TS contains 4 Abis nibble

This method is recommended in case of BTSs with 2 or more cells.




GCH Method

� (Method 2)

Erlang C

Required Data Traffic on Abis

GoS: % Quantile of x delay sec

Nb of required Abis Nibbles


Nb of required extra Abis Nibbles

Nb of basic & bonus Abis Nibbles

−




GCH Method

Needed counters for Data traffic:

� P100c or GAAGCHUST (GPRS_transmission_GCH_busy_time)

� Needed counters for Abis congestion:

� P105i or GQRDTECBN (GPRS_DL_TBF_estab_fail_abis_cong),



� P105j or GQRUTECBN (GPRS_UL_TBF_estab_fail_abis_cong),


� Note:

� The counters retrieved at cell level must be aggregated per BTS.




GCH Method

� Abis congestion:

%PfPePdPcPbPaP

iPcong_Abis_TBF_DL% 100

505919191919191105 ×

++++++=

%PcPcPbPaP

jPcong_Abis_TBF_UL% 100

507438626262105 ×

+−++=

)cong_Abis_TBF_UL% ,cong_Abis_TBF_DL(%Maxcong_Abis_TBF% =




GCH Method

� Measured traffic:

� Required traffic:

� Required Abis nibbles for PS:


3600100cP

traffic_GCH_Measured =

%) ,cong_Abis_TBF(%Mintraffic_GCH_Measured

traffic_GCH_quiredRe301−

=

=nibbles Abis quiredRe of Nb

( )delay quantile; ;CH_trafficRequired_GangCInverseErl=




GCH Method

Number of required Extra Abis nibbles =

= Number of required Abis nibbles – Nb of basic and bonus Abis nibbles,

Note: Nb of basic nibbles per cell = MAX_PDCH.

Nb of bonus nibbles corresponds to Nb of BCCH and static SDCCH timeslots.

and

Number of required Extra Abis TS =

= Roundup[(Number of required Extra Abis nibbles)/4].

Note: 1 Abis TS contains 4 Abis nibble

This method is recommended in case of BTSs with only 1 cell.




Abis Dimensioning

� Finally, at BTS level for Abis dimensioning

Total Number of Abis TS =

= 2*Total nb of TRX +

+ Nb of TS for RSL and OML (depending on MCB type)

+ Nb of required Extra Abis TS,

and

Number of required Abis Links =

= Roundup[(Total Number of Abis Ts)/31].




Method for RSL

� LAPD efficiency (in DL):

� Needed counters

– Conter Type: 7

– Measured Object: LAPD

� Conter L1.1 (NB_LAPD_INFO_FRAME_SENT)

– Number of Information frames transmitted on the LapD link, excluding the re-transmissions.

� Conter L1.15 (NB_LAPD_INFO_FRAME_RESENT)

– Number of Information frames re-transmitted on the LapD link.

� Formula:

LAPD efficiency [%] = L1.1/( L1.1+L1.15)*100




Method for RSL congestion

� LAPD congestion detection:

� Conter L1.18 (TIME_LAPD_CONG)

– Conter Type: 7

– Measured Object: LAPD

– Time in seconds during which the LapD link is congested in transmission in the BSC.

� In case LAPD congestion is present, the MCB load must be reduced:

� If the multiplexing rule is applied “per BTS” by changing at BTS level the signaling

load from “normal” to “high”;

� If the load is already “high” by changing the multiplexing rule from “per BTS” to “per

Sector” with the same load options “normal” or “high.

� Note: These changes may impact the Abis TS usage.


BSC

Dimensioning3



BSC Dimensioning

Target

� Find the total CS traffic

� Find the related CS signaling traffic

� Decide what solution is required for signaling traffic: LSL or HSL

� Check the HDLC occupancy to decide what type of TP GSM board is required:

TP GSM V1 or TP GSM STM1 (V3)

� Find the required number of AterMux CS links

� Find the total PS traffic

� Find the required number of AterMux PS links

� Find the required number of GPU/GP boards



BSC Dimensioning

Method for BSC Dimensioning

� ErlangB and ErlangC


– CS Traffic

– SS7 Traffic

– PS Traffic

– AterMux PS congestion

– Customer requirements for CS and SS7 blocking and QoS for PS

� Output:

– Nb of TCH, CS dedicated links and real blocking

– Nb of SS7 connections, links and real blocking

– Nb of GCH

– Nb of GPU boards per BSC

– Nb of PS links per BSC and PS real quantile



BSC Dimensioning

Method for CS Traffic


� MC380a or GTCTRFT (RTCH_full_occy_total)

� MC380b or GTCTRHT (RTCH_half_occy_total)

� Needed counters for SCCP:

� MC01+MC02 or GSDNASUN (SDCCH_assign_success),

� MC10 or GSDHOSUN (SDCCH_HO_success)

� MC390 or GSDAHCAN (SDCCH_allocated),

� MC400 or GSDTRT (SDCCH_occy_total),

� MC380a+MC380b or GTCTRT (RTCH_occy_total)

� or GQSTRSCE (SCCP_Erlang_BH)



BSC Dimensioning


� Max CS Traffic (during BH)

� The required value of TCH traffic must be below the BSC Erlang capacity

(depending on BSC configuration), else the BSC capacity must be extended if

possible by adding one CCP board.

3600380380 bMCaMC

traffic_TCH_Measured+=

inargm%traffic_TCH_measuredtraffic_TCH_quiredRe 15+=



BSC Dimensioning


� Max SCCP Traffic (during BH)

� Measured SCCP Traffic = SCCP traffic in Erlang during Busy Hour =

= ((MC400/MC390)*(MC01+MC02+MC10) + (MC380a+MC380b))/3600

� If the required number of SS7 TSs is below or equal to 16, the LSL solution

may be used.

� If the required number of SS7 TSs is above 16, the HSL solution is mandatory.

inargm%traffic_SCCP_measuredtraffic_SCCP_quiredRe 15+=

( )c;0.1%CCP_traffiRequired_SangBInverseErlsconnection SCCP quiredRe of Nb =

=103

7channels_SCCP_required_No

TSs_SS_required_No



BSC Dimensioning

Method for HDLC occupancy

� Due to limited number of HDLC channels inside TP GSM board, it is important

to check the number of HDLC channels in use.

1090910staticMux{signallingLoadBts dummy}G62A12_3{ amecID 1, moiRdn 17}

65056noMux{signallingLoadBts dummy}G62B091{ amecID 1, moiRdn 11}

41101112statisticMux64{signallingLoadBts normal}G62B122{ amecID 1, moiRdn 134}

14045statisticMux64{signallingLoadBts dummy}G62B271{ amecID 1, moiRdn 100}

23034statisticMux64{signallingLoadBts high}G62B083{ amecID 1, moiRdn 10}

60667statisticMux64{signallingLoadBts high}G62B011{ amecID 1, moiRdn 1}

Total #

HDLC

Total #

TRX FR

Total #

TRX DR

Total #

TRE

Total #

LAPDMuxRuleMuxRateUserLabel

AlcatelBtsSiteManager

InstanceIdentifier

from AlcatelBtsSiteManager.csv from AlcatelBts_Sector.csv

Apply MCB rule



BSC Dimensioning

Method for HDLC occupancy

� This check is important especially when the BSC must be extended by adding

new cells.

� If the total required number of HDLC channels is below 441, the TP GSM V1

board has enough capacity to be used.

� If the required number of HDLC channels is above 441, the multiplexing rule

must be changed from “noMux” to “statisticMux64”.

� If the resulted number of HDLC channels is still above 441, the TP GSM V1

board must be replaced by TP GSM STM1 (V3) board.



BSC Dimensioning

Method for PS Traffic

� Needed counters for GCH Traffic:

� P100c or GAAGCHUST (GPRS_transmission_GCH_busy_time),

� P383a or GQAGALCTT (GPRS_GPU_Ater_cong_time),

� P384 or GQRGPUCDT (GPRS_GPU_DSP_cong_time),

� Needed counters for GSL:

� P41 or GTALAPDLN (GPRS_LAPD_DL_traffic_sent_to_BSC),

� P42 or GTALAPULN (GPRS_LAPD_UL_traffic_received_from_BSC).



BSC Dimensioning


� Max GCH Traffic

� Number of required GCH per BSC

3600100cP


%aP

cong_Ater_GCH% 1003600383 ×= %

Pcong_GPU_GCH% 100

3600384 ×=

)cong_GPU_GCH,%cong_Ater_GCH(%Maxcong_GCH% =

%) ;cong_GCH(% Mintraffic_GCH_Measured


=

( )delayquantile;;CH_trafficRequired_G angCInverseErlGCH quiredRe of Nb =




BSC Dimensioning


� Number of GPU/GP boards per BSC

� GPU Capacity is of max 480 GCH.

� GP Capacity is of max 1560 GCH.

� N_ATER_TS_MARGIN_GPU resources must not be taken into account. So, the max

number of GCH per GPU/GP is:

� 480 – N_ATER_TS_MARGIN_GPU*4 (for legacy MFS)

� 1560 – N_ATER_TS_MARGIN_GPU*4 (for Mx MFS)

=Capacity GCH board GPU/GP

GCH Required of Nbboard GPU/GP quiredRe of Nb



BSC Dimensioning


� Number of GSL links per BSC

288004241 )P,P(Max

traffic_GSL_Measured =

inargm%traffic_GSL_Measuredtraffic_GSL_quiredRe 30+=

( )delayquantile;;SL_trafficRequired_G angCInverseErlGSL quiredRe of Nb =




BSC Dimensioning


� Number of GPU boards per BSC

� At least 2 GSLs are recommended to be defined per GPU due to security reason.

� Up to 4 GSLs can be defined per GPU.

� Number of GP boards per BSC

� At least 2 GSLs are recommended to be defined per GP due to security reason.

� Up to 8 GSLs can be defined per GP.

=8

GSL Required of Nbboard GPU/GP quiredRe of Nb

=4

GSL Required of Nbboard GPU/GP quiredRe of Nb



BSC Dimensioning


� Number of GPU boards per BSC

� The final number of required GPU/GP boards per BSC is the maximum value

between the number of boards needed for signaling traffic (GSL) and for user

traffic (GCH).


Ater CS

Dimensioning4



Ater CS Dimensioning

Target

� Find the required number of AterMux CS links

� Method: ErlangB


– CS Traffic

– SS7 Traffic

– Customer requirements for CS and SS7 blocking and QoS for PS

� Output:

– Nb of SS7 connections, links and real blocking

– Nb of TCH, CS dedicated links and real blocking




Method

� Find the max number of Ater CS links between TCH requirements and

signaling requirements (SCCP)

Erlang B

GoS: % TCH blocking

•Nb of required SS7 per BSC


Signalling Traffic

User Traffic

Required SDCCH Traffic

Required TCH Traffic

GoS: % SS7 blocking

Erlang B

•Nb of required

TCH per BSC

•Nb of required

AterMUX-CS links per BSC

•Nb of required


Choose “Max”value

•Final nb of required





CS Traffic

� Method for TCH

� The number of required AterMux CS links can be obtained by dividing the number of

AterMux CS channels obtained from the dimensioning process by the AterMux CS link

capacity.

� The total capacity of “n” AterMUX CS links is:

111TCH(link#1) + 111TCH(link#2) + 116TCH(link#3) + 116TCH(link#4) +

116TCH(link#5) + 116TCH(link#6) + 115TCH(link#7) + 115TCH (link#8) + 116TCH(link

#9) + 116TCH(link #10) + 116TCH(link #11)+ … + 116TCH(link #N),

where N =< MaxNbAterMuxCS.

3600380380 bMCaMC

traffic_TCH_Measured+=

inargm%traffic_TCH_measuredtraffic_TCH_quiredRe 15+=

( );0.1%CH_trafficRequired_TangBInverseErlchannels TCH quiredRe of Nb =




CS Signaling Traffic

� Method for SCCP

� Measured SCCP Traffic = SCCP traffic in Erlang during Busy Hour =

= ((MC400/MC390)*(MC01+MC02+MC10) + (MC380a+MC380b))/3600

� The result is obtained for 40% load at SS7 link level.

� The final number of required AterMux CS links is the maximum value between the

number of links needed for signaling traffic (SS7) and for user traffic (TCH).

inargm%traffic_SCCP_measuredtraffic_SCCP_quiredRe 15+=

( )c;0.1%CCP_traffiRequired_SangBInverseErlsconnection SCCP quiredRe of Nb =

=103

7channels_SCCP_required_No

links_SS_required_No





� Method for SS7 based on volume of data transferred

� Counters for N7 at link level (Type 9):

� N3.1 (NB_N7_SIF_SIO_SENT)

– Number of octets of Signalling Information (SIF) and Service Information Octets (SIO) transmitted on the N7 SL.

� N3.3 (NB_N7_MSU_SENT)

– Number of Message Signalling Units (MSU) transmitted on the N7 SL.

� N3.4 (NB_N7_SIF_SIO_REC)

– Number of octets of Signalling Information Field (SIF) and Service Information Octets (SIO) received on the N7 SL.

� N3.5 (NB_N7_MSU_REC)

– Number of Message Signalling Units (MSU) received on the N7 SL.

� N3.10 (NB_N7_MSU_DISC_DUE_CONG)

– Number Message Signalling Units (MSU) discarded due to a message buffer overflow caused by an extended period of Signalling Link congestion.






� Traffic evaluation in UL

– Counter values must be aggregated for the link set

2880000033613

7.N*.N

traffic_SS_Measured+=

%) ;cong_SS(% Mintraffic_SS_Measured

traffic_SS_quiredRe3071

77

−=

%.N.N

.Ncong_SS% 100

10333103

7 ×+

=

( );0.1%S7_trafficRequired_S angBInverseErlTS SS7 quiredRe of Nb =






� Traffic evaluation in DL

– Counter values must be aggregated for the link set

� The final number of SS7 TSs (links) is the max value between the results for

UL and DL.

� If this number is greater than 16, HSL usage is mandatory.

2880000053643

7.N*.N

traffic_SS_Measured+=

inargm%traffic_SS_Measuredtraffic_SS_quiredRe 1577 +=

( );0.1%S7_trafficRequired_S angBInverseErlTS SS7 quiredRe of Nb =






� N7 link efficiency based on couters (in UL):

� N3.3 (NB_N7_MSU_SENT)

� N3.10 (NB_N7_MSU_DISC_DUE_CONG)

� Formula:

N7 efficiency [%] = N3.3/( N3.3+N3.10)*100

� N7 link congestion detection:

� N1.6 (NB_N7_LINK_FAIL_CONG)

– Number of N7 SL failures due to congestion during an extended period of time.





� Method for SS7 link load based on volume of data transferred

� LSL case

� %N7 Utilization in UL = (N3.1 + (6 * N3.3)) / (3600*8,000)

� %N7 Utilization in DL = (N3.4 + (6 * N3.5)) / (3600*8,000)

� Explanation:

– MSU contains 6 bytes (fix part) + SIF&SIO (variable part).

– SIF is between 2 and 34 bytes.

– SIO is 1 byte.

� Note:

– 1 hour of usage of 1 E1 Time Slot (for N7) = 1hour * 64Kbps =

= 3600s * 8000 bytes/s = 28,800 Kbytes/h

� Warning:

– The load on one N7 link shall not exceed 40% (recommended).






� HSL case

� In B10, if HSL is actived, N7 can have 2 different frame formats:

– Normal frame format

– Extended frame format

� Parameter: MTP_Sequence_Number_Format

(MtpSequenceNumberFormat in ACIE AlcatelManagedElementComplex.csv)

Range / default value: (0=Normal, 1=Extended) / 0

Note:

� In case of Normal frame format


� In case of Extended frame format







� HSL case with Normal frame format

� %N7 Utilization in UL = (N3.1 + (6 * N3.3)) / (3600*8,000*31)

� %N7 Utilization in DL = (N3.4 + (6 * N3.5)) / (3600*8,000*31)

� Explanation:

– 32 TSs of 64Kbps are available for one HSL link.

� Note:


= 3600s * 8000 bytes/s = 28,800 Kbytes/h

– For 32 TS per HSL link we get

3600s * 8000 bytes/s * 31TS = 892,800 Kbytes/h

� Warning:







� HSL case with Extended frame format

� %N7 Utilization in UL = (N3.1 + (9 * N3.3)) / (3600*8,000*31)

� %N7 Utilization in DL = (N3.4 + (9 * N3.5)) / (3600*8,000*31)

� Explanation:

– 32 TSs of 64Kbps are available for one HSL link.

� Note:


= 3600s * 8000 bytes/s = 28,800 Kbytes/h

– For 32 TS per HSL link we get

3600s * 8000 bytes/s * 31TS = 892,800 Kbytes/h

� Warning:



Ater PS

Dimensioning5



Ater PS Dimensioning

Target

� Find the required number of AterMux PS links

� Method: ErlangC


– PS Traffic

– Number of Available GCH

– Number of Max Busy GCH

– AterMux PS congestion

– Customer requirements for PS QoS

� Output:

– Nb of GCH

– Nb of GSL links per BSC and PS real quantile

– Nb of PS links per BSC and PS real quantile




Method

� Find the max number of Ater PS links between GCH requirements and

signaling requirements (GSL)

QoS: quantile delay


User Traffic

Required GCH Traffic Erlang C

Nb of required

GCH per BSC

Nb of required PS links per BSC

QoS: quantile delay

Signaling Traffic

Required GSL Traffic Erlang C

Nb of required

GSL per BSC

Nb of required PS links per BSC


Final nb of required

AterMUX-PS links per BSC




Method for Ater PS

� Needed counters for GCH:




� Needed counters for GSL:






Method for GCH

� The number of required GCH

3600100cP


%aP

cong_Ater_GCH% 1003600383 ×=

%P

cong_GPU_GCH% 1003600

384 ×=

)cong_GPU_GCH,%cong_Ater_GCH(%Maxcong_GCH% =



=






Method for GCH

� The number of required AterMux PS TSs for user traffic

� The number of required AterMux PS links for user traffic

=4

GCH_required_NbTSs_AterPS_required_Nb

=28

TSs_AterPS_required_Nolinks_AterPS_required_Nb




Method for GSL

� GSL load checking

� It is recommended to increase the number of GSL per GPU if GSL load is greater than

80%.

� The final number of required AterMux PS links is the maximum value between

the number of links needed for signaling traffic (GSL) and for user traffic (GCH).

288004241 )P,P(Max




GSL required of Nbtraffic_GSL_Measured

GSL_traffic_Measured =1

%)Erlangs.(Capacity_GSL

GSL_traffic_Measuredload_GSL 100

7801 ×

==


GPU/GP

Dimensioning6



GPU/GP Dimensioning

Target

� Find the load and the required number of AterMux PS links per GPU/GP board

� Method: ErlangC


– PS Traffic

– MS context average

– MS context max

– DSP congestion

– GSL traffic

– Average & Max CPU load

– BSS failures rate

� Output:

– Max DL GCH Capacity

– Max UL GCH Capacity

– Max DL PDCH Capacity

– Max UL PDCH Capacity

– GSL load

– MCS usage



GPU/GP Dimensioning

GPU/GP load

� Check if GPU/GP board is not overloaded

QoS: quantile delay

INPUTOUTPUT

METHOD

User Traffic

Required GCH Traffic Erlang C Needed

GCH

GCH capacity of GPU

÷ +

MS_context_handling (= 0/1)

+Power_Limitation (= 0/1)

Number of GPU boards



GPU/GP Dimensioning

GPU/GP load

� GPU/GP board limitation control

Power Limitation Memory Limitation Power Limitation Memory Limitation

Dimensioning indicators

P76a P77a

=> P402 (thr )

P392aP392b

P201 (thr_1 )P202 (thr_2 )

P384

QoS indicators

(TBF establ)

P105e P105f

UL TBF estab BSS Failure

P203P204

P105cP105d

GPU limitation

PMU PTUPPC/CPU DSP

MFS parameters:Thr = PMU_CPU_Overload (Default=95%)

Thr_1 = DSP_Load_Thr_1 (Default=85%)

Thr_2 = DSP_Load_Thr_2 (Default=95%)

CPU Cong BSS Fail DSP Load DSP Cong



GPU/GP Dimensioning

GPU/GP load

� User traffic load (GCH)





� P201 or GTRGPULDLT (GPRS_DSP_CPU_load_time),

� P202 or GTRGPULDOLT (GPRS_DSP_CPU_overload_time),

� GQRDTELDR (GPRS_DL_TBF_estab_fail_dsp_load_rate)

– or P203 / (P91a + P91b + P91c + P91d + P91e + P91f + P505)

� GQRUTELDR (GPRS_UL_TBF_estab_fail_dsp_load_rate)

– or P204 / (P62a + P62b + P62c - P438c + P507)



GPU/GP Dimensioning

GPU/GP load

� Signaling load


� P392a or GTRGPUMCA (GPRS_MS_idle_context_avg),

� P392b or GTRGPUM (GPRS_MS_idle_context_max),

� P76a or GTRGPUPBA (GPRS_PMU_CPU_power_budget_avg),

� P77a or GTRGPUPBM (GPRS_PMU_CPU_power_budget_max),

� P402 or GTRGPUOT (GPRS_PMU_overload_time),

� GQRDTECCR (GPRS_DL_TBF_estab_fail_cpu_cong_rate)

– or P105e / (P91a + P91b + P91c + P91d + P91e + P91f + P505)

� GQRUTECCR (GPRS_UL_TBF_estab_fail_cpu_cong_rate),

– or P105f / (P62a + P62b + P62c - P438c + P507)



GPU/GP Dimensioning

GPU/GP load

� Required number of GPU/GP boards based on user traffic

3600100cP


%aP

cong_Ater_GCH% 1003600383 ×= %

Pcong_DSP_GCH% 100

3600384 ×=



=


%x)P,P(Max

load_DSP% 1003600

202201= %xP

overload_CPU% 1003600

402=

)overload_CPU,%load_DSP,%cong_DSP,%cong_Ater(%Maxcong_GCH% =




GPU/GP Dimensioning

GPU/GP load

� Required number of GPU/GP boards based on user traffic

where the GPU board capacity is 480 GCH and the GP board capacity is 1560 GCH.

� The result must be compared with the existing number of GPU/GP boards per BSC.

� If the required number of GPU/GP boards is less than the existing one, there is no

need for change.

� If the required number of GPU/GP boards is greater than the existing one, then the

number of GPU/GP boards per BSC must be increased by one unit.

� For a BSC in multi GPU configuration, the method (GCH traffic) may be applied per

each GPU/GP board separately to check the load on each board.

=Capacity GCH board GPU/GP

GCH Required of Nbboard GPU/GP quiredRe of Nb



GPU/GP Dimensioning

GPU/GP load

� Required number of GPU/GP boards

� GPU power limitation from PTU (DSP/CPU)

If

MAX(P201;P202)/3600 > 0.1% for at least 12% of the observation period

and

dsp_load_fail_rate = MAX(GQRDTELDR; GQRUTELDR) > 1%

then PTU_Power_Limitation = 1

else PTU_Power_Limitation = 0



GPU/GP Dimensioning

GPU/GP load


� GPU power limitation from PMU (CPU)

If

P402/3600 > 0.1% or P76a > 70% for at least 12% of the observation period

and

cpu_cong_fail_rate = MAX (GQRUTECCR; GQRDTECCR) > 1%

then PMU_Power_Limitation = 1

else PMU_Power_Limitation = 0



GPU/GP Dimensioning

GPU/GP load


� GPU memory limitation from PMU (CPU)

If P392b = 1000 and P392a > 900 for at least 12% of the observation period

for Legacy MFS

or

if P392b = 4000 and P392a > 3600 for at least 12% of the observation period

for MxMFS

then MS_context_handling = 1

else MS_context_handling = 0



GPU/GP Dimensioning

GPU/GP load

� Final result

The number of required GPU/GP boards =

= Number of required GPU/GP board (from user traffic) +

+ MAX(PTU_Power_Limitation; PMU_Power_Limitation; MS_context_handling)

Note:

If the required number of GPU/GP boards is greater than the existing one, it

is recommanded to add a single board at one time and redo the load

assessment after it.



GPU/GP Dimensioning

Number of AterMux PS links per GPU/GP board

� Check the number of links from GCH and GSL requirements

QoS: quantile delay


User Traffic

Required GCH Traffic Erlang C

Nb of required

GCH per BSC

Nb of required

GPU boards per BSC

Nb of required PS links per GPU board

QoS: quantile delay

Signaling Traffic


Nb of required

GSL per BSC

Nb of required PS links per GPU board


Final nb of required

AterMUX-PS links per GPU

÷



GPU/GP Dimensioning


� Based on total GCH load and final number of required GPU/GP bords, the

number of Ater PS links per board is:

=board GP/GPU_required_Nb

/)GCH_required_Nb(GP/GPU_per_links_AterPS_required_Nb

112



GPU/GP Dimensioning


� Method based on total number of GSL links and final number of required

GPU/GP bords

•OUTPUT

Nb of required GSL links per GPU

INPUT METHOD

QoS: quantile delay

Signaling Traffic


Nb of required

GSL per BSC

Nb of required

GPU boards per BSC

÷



GPU/GP Dimensioning


� Assessment based on GSL bandwidth




� Required number of GSL links per BSC:

288004241 )P,P(Max







GPU/GP Dimensioning


� Assessment based on GSL bandwidth

� Checking the GSL load:

� GSL link load is:

� Compare GSL_load with GSL_link_band_capacity

where GSL_link_band_Capacity = 0.78 Erlang

(corresponding to max rate of 50 Kbps in a 64 Kbps Time slot).

� GSL load on a given GPU/GP should not exceed 0.78 Erlang.

It is recommended to increase the number of GSL per GPU/GP if GSL load is greater

than 0.78 Erlang.

links GSL required of Nbtraffic_GSL_Measured

load_GSL =



GPU/GP Dimensioning


� Assessment based on the number of GSL messages per second

� Number of GSL messages/s per GPU is calculated as a function of PS traffic (UL and

DL TBF establish requests) and of the number of cells mapped to the GPU/GP.

� GSL_link_Max_capacity per GPU is defined as:

K_GSL * (1000ms/GSL_round_trip_delay) * Nb of GSL links per GPU/GP, where

– K_GSL is the maximum number of outstanding I frames on a GSL link

(Min = 1, Max = 32, Default = 7)

– For terrestrial links: GSL_round_trip_delay < 500ms

(default value = 60ms)

– For satellite links: GSL_round_trip_delay > 500ms

(default value = 500ms)

BSC

GPU

K_GSL

GSL messages buffer

GSL_round_trip_delay

A message is kept in the buffer during GSL_round_trip_delay



GPU/GP Dimensioning



� How to estimate the number of GSL messages per second:

� Msg on GSL due to RAE4 mechanism 0.3 Msg/s x Nb_cell

� Msg on GSL due to PS traffic

Msg on GSL due to PS/CS paging: Nb_PS_paging/s+ Nb_CS_paging/s

Msg on GSL due to PS data traffic (TBF requests):

TBF (UL & DL) corresponding to RA update 1.7 x Nb_TBF_Sig_req/s

TBF (UL & DL) corresponding to PS data (3 cases)

Low GSL usage (eg. Ping 5 s) 2.5

Medium GSL usage 3.5 x Nb_TBF_Data_req/s

High GSL usage (worst case) 5

The Sum of all rates above gives the Total Nb of Msg/s.



GPU/GP Dimensioning



� The GSL usage condition can be defined through the following table:

The values provided in the table above are relibale if T_GCH_INACTIVITY = 3s and

T_GCH_INACTIVITY_LAST = 20s (default setting).

Otherwise (I.e. T_GCH_INACTIVITY = 2s and T_GCH_INACTIVITY_LAST = 6s) GSL load will be

greater due to the consequent increase of deallocation/allocation messages.

3.52.5Low

53.5HighAvailable

GCH

LowHigh

PS traffic

(TBF req)Nb of Msg on GSL

per TBF_data_req

If #TBF req /s < 20 TBF/s

If Ater congestion observed



GPU/GP Dimensioning



� Nb_cell: number of cell (at BSC level or managed by the GPU, depending if the

method is applied at BSC or GPU level)

� Nb_PS_paging: number of processed PS paging requests/s is measured by

P391a/3600

� Nb_CS_paging: number of processed CS paging requests/s is measured by P391b/3600

� Nb_UL_TBF_req: the total number of UL TBF requests/s

(P62a+P62b+P62c-P438c+P507)/3600

� Nb_DL_TBF_req: the total number of DL TBF requests/s

(P91a+P91b+P91c+P91d+P91e+P91f+P505)/3600

� Nb_UL_TBF_req_noGSL: number of UL TBF requests/s which will not generate any

message on the GSL is counted by P62b.



GPU/GP Dimensioning



� Nb_TBF_Sig_req: the number of TBF (UL and DL)/s which correspond to signalling

traffic. The part of DL TBF signalling requests is estimated with %_DL_TBF_Sig_req =

P160 / Nb_DL_TBF_succ.

where P160 = NB_DL_TBF_1_succ (Number of DL TBF establishment requests

requesting 1 slot which are satisfied) and

Nb_DL_TBF_succ = P90a+P90b+P90c+P90d+P90e+P90f+P506. So,

Nb_TBF_Sig_req = %_DL_TBF_Sig_req x (Nb_UL_TBF_req - Nb_UL_TBF_req_noGSL +

Nb_DL_TBF_req)

� Nb_TBF_Data_req: the number of TBF (UL and DL)/s which correspond to data

traffic.

Nb_TBF_Data_req = Nb_UL_TBF_req + Nb_DL_TBF_req - Nb_UL_TBF_req_noGSL -

Nb_TBF_Sig_req



GPU/GP Dimensioning



� GSL load (in terms of treated messages)

� GSL load in terms of treated messages per second on a given GPU/GP should not

exceed 75%

� It is recommended to increase the number of GSL per GPU/GP if GSL load is greater

than 75%.

%Capacity_Max_Link_GSL

sec_per_messages_GSL_Nbload_GSL 100×=



GPU/GP Dimensioning


� Based on total GSL load and final number of required GPU/GP bords, the

number of GSL links per board is:

� If the result is greater than 4 (8), we must increase the number of GPU (GP)

boards with 1, and redo the calculations.

� The final number of required AterMux PS links per GPU/GP boards is the

maximum value between the number of links needed for signaling traffic

(GSL) and for user traffic (GCH).

=board GPU/GP quiredRe of NbBSC per GSL Required of Nb

GPU/GP per GSL quiredRe of Nb


Gb Interface

Dimensioning7



Gb Interface Dimensioning

Gb over Frame Relay

Target

� Find the required number of Gb TS


� PVC downlink Traffic

� PVC uplink Traffic

� PVC downlink average throughput

� PVC uplink average throughput

� Customer requirements for QoS (delay and quantile)

� Output:

� Nb of Gb TS




Gb over Frame Relay

� Method: ErlangC


� P45 or GTGPVCDLN (GPRS_PVC_DL_traffic_from_SGSN),

� P46 or GTGPVCULN (GPRS_PVC_UL_traffic_to_SGSN).

•Erlang C

Required Gb Traffic

QoS: % Quantile of x delay sec

Nb of required Gb Timeslot per

link





Gb over Frame Relay

� The required Gb traffic is:

� The required number of Gb TS is:

� The maximum number of Gb links from one GPU/GP board to the SGSN is 8.

� Maximum 31 Gb TS (TS no. 1 to 31) can be configured per one Gb link.

288004645 )P,Pmax(

traffic_Gb_Measured =

inargm%traffic_Gb_Measuredtraffic_Gb_quiredRe 15+=

)delay;quantile;traffic_Gb_quired(Re ErlangClink_per_TS_Gb_No =





Gb over Frame Relay

� The Gb over FR configuration

� Parameters:

� Tc (Measurement interval) = 1s

� CBS (Committed Burst Size)

� CIR (Committed Information Rate)

CIR = (CBS*8)/Tc

� NIR (Normal Information Rate)

NIR ≥ CIR

� EBS (Excess Burst Size)

� EIR (Excess Information Rate)

EIR = CIR+EBS*8/Tc

� AC (Access Rate Bearer Channel)

AC ≥ CIR(1+EBS/CBS)

� NbGbTS = AC/64kbps

Tc

EBS

CBS

Bit rate

time

EIR

CIRNIR

ACCESS_RATE_BC




Gb over Frame Relay


� Rules if no direct access is used between MFS and SGSN:

CIR ≤ NIR ≤ CIR x (1 + EBS/CBS) ≤ ACCESS_RATE_BC

� Example:

number16NbGbTS

kbps≥ 1008AC

kbps1008EIR

kbyte2EBS

kbps≥ 992NIR

kbps992CIR

kbyte124CBS

s1Tc

unitvalueParameter




Gb over Frame Relay


� Rules if direct access is used between MFS and SGSN:

CIR = 0 <=> CBS = 0 => EBS > 0 (mandatory)

NIR = 0 (recommanded)

EBS = ACCESS_RATE_BC (expressed in kbit/s)/8, if CIR = 0 (recommanded)

� Example:

For CBS = 0; CIR = 0 and NIR = 0:

number20NbGbTS

kbps1280EIR

kbps≥ 1280AC

kbyte160EBS

s1Tc

unitvalueParameter




Gb over IP

� Using Gigabit Ethernet link to the aggregation Router, the max load is:

� For MxMFS: 1560 GCHperGP * 16 Kbps = 24.96 Mbps

Assuming all this traffic coming from SGSN for one MxMFS with 21 GP boards we get:

21 boards*24.96 Mbps = 524.16 Mbps �� Half of the GigaEthernet link capacity

� For Legacy MFS: 480 GCHperGPU * 16 Kbps = 7.68 Mbps

Assuming all this traffic coming from SGSN for one MFS DS10 with 30 GPU boards we

get:

30 boards*7.68 Mbps = 230.4 Mbps �� Quarter of the GigaEthernet link capacity

Congestion is not expected at the level of the link to the aggregation router.Any Congestion seen afterwards is dependent on bandwidth management of the core IP network.




Gb over IP

Target

� Find the DL and UL traffic during BH


– Ip Endpoint downlink data volume

– Ip Endpoint uplink data volume

� Output:

– DL and UL data rate

� Counters in the MFS

� New counters per IP Endpoint are defined in case of GboIP:

– P34a (TIME_SGSN_IP_ENDPOINT_NOT_AVAIL_GBIP),

– P45a (NB_KBYTES_RECEIVED_FROM_SGSN_GBIP),

– P46a (NB_KBYTES_SENT_TO_SGSN_GBIP).




Gb over IP

� Data rate calculation in DL (SGSN to MFS) and in UL (MFS to SGSN)

� Data rate DL/UL, at IP Endpoint level or aggregated at GP or MFS level:

� DL Data rate [Kbps] = 1.233*(P45a*8 )/(3600-P34a)

� UL Data rate [Kbps] = 1.233*(P46a*8)/(3600-P34a)

� Explanation:

� Assuming LLC PDU and BSSGP payload are 300 bytes, NS, UDP, IP and Fast Ethernet

overhead are 70 bytes (i.e. 4+28+38),

� SNS layer (where Kbytes counts is done) overhead ratio at this layer is 0.23% (i.e.

70/300).




Gb over IP

� GboIP traffic estimation based on actual GboFR traffic

� Estimated Traffic:

� Estimated DL IP Data rate [Kbps] = (370/306)*(P45*8)/(3600-P34)

� Estimated UL IP Data rate [Kbps] = (370/306)*(P46*8)/(3600-P34)

� Explanation:

� Assuming LLC PDU and BSSGP payload are 300 bytes, NS, UDP, IP and Fast Ethernet

overhead are 70 bytes (i.e. 4+28+38), NS and FR overhead are 6 bytes (i.e. 4+2).

� Packet size increase ratio = Total IP packet (i.e. 370) / Total FR packet (i.e. 306)


Location Area

Dimensioning8



Location Area Dimensioning

Location Area definition

� Set of cells which are paged each time one Terminating Call is initiated

� Specified with a unique Location Area Code (LAC)

� Position of each MS in a specific Location Area stored in HLR / VLR

� MS tells mobile network (using SDCCH resources)

� when it moves from one LAC to another (Location Update)

� periodically its current LAC position (Periodical LU)

Location Area size

� Trade off between

� Signalling load in cells located at LAC border

– SDCCH resources in each cell has to be sized accordingly

� Number of simultaneous pagings in each cell of the LAC

– All MS in LAC and in MT call are paged simultaneously




CCCH Sharing

� Air interface

� Pagings sent in DL on CCCH

� Sharing between PCH & AGCH within one CCCH M-51 frame (235 mS duration)

–CCCH_CONF

– Combined mode 3 blocks

– Non combined mode 9 blocks

–Nb of AGCH blocks = BS_AG_BLKS_RES

� Nb of PCH blocks = Nb of total CCCH blocks - BS_AG_BLKS_RES

6 CCCH blocks are available for the PCHReserved for AGCH

CCCH 8CCCH 7CCCH 6CCCH 5CCCH 4 CCCH 3CCCH 2CCCH 1CCCH 0

Example of AGCH and PCH organisation when BS_AG_BLKS_RES = 3 (Non combined mode)




PCH content

� Air interface

� Nb of pagings per CCCH block, depends on

– Paging request type

– Subscriber’s behavior (mobile often on/off)

� Paging efficiency

– between 1.5 – 3

– 2.5 pagings / PCH block considered usually in dimensioning

TYPE 1 TYPE 2 TYPE 3 - IMSI - (P)TMSI - IMSI,IMSI - IMSI, (P)TMSI - (P)TMSI, (P)TMSI

- (P)TMSI, (P)TMSI, (P)TMSI - (P)TMSI, (P)TMSI,IMSI

- (P)TMSI, (P)TMSI, (P)TMSI, (P)TMSI




PCH content

BTS

BSCCellMS

GPU

MFS

TCMSC

SGSN

AbisAterMUX-PS

AterMUX-CS

Gb

APaging request message

(type 1, 2 or 3)

Paging commandMessage

(RSL)

Paging commandor

Immediate assign command message

(RSL)

PCH blockson CCCH

CS Paging(SS7)

(GSL)PS/CS Paging

orChannel assignment downlink message

Paging request or

Packet downlink assignment

message

Gs




PCH capacity

� Non-Combined cell

� BS_AG_BLKS_RES = 4 (AGCH blocks) 9 - 4 = 5 PCH blocks (default configuration)

� 5 PCH blocks/Multiframe * (3600s / 235 ms) =

76 594 PCH blocks/ hour

� 2.5 paging / Block x 76 594 Blocks =

191 485 paging/hour at 100% load

� If 60 % engineering limit applied: 114 891 paging/hour

31.91 paging/s




PCH capacity

� Combined cell

� BS_AG_BLKS_RES = 1 3 - 1 = 2 PCH blocks

� 2 PCH blocks/Multiframe x (3600s / 235 ms) =

30 638 PCH blocks/ hour

� 2.5 paging / Block x 30 638 Blocks =


� If 60 % engineering limit applied: 45 957 paging/hour

12.76 paging/s




AGCH content

BTS

BSCCellMS

GPUMFS

AbisAterMUX-PS

Access grant message

(IA, IAE or IAR)


(RSL)


(RSL)

AGCH blockson CCCH

Immediate assignment orImmediate assignment reject message

Access grant message

(PUA, PDA or IAR)

(GSL)Channel assignment uplink (EGPRS Uplink assign.),Channel assignment downlink(Downlink assign.)orChannel assignment uplink message (Assign. reject)

Note: IA= Immediate Assign; IAE=Immediate Assign Extended; IAR= Immediate Assign Reject;

PUA= Packet Uplink Assignment; PDA= Packet Downlink Assignment.




AGCH capacity


� BS_AG_BLKS_RES = 4

� 4 AGCH blocks/Multiframe x (3600s / 235 ms) =

61 272 AGCH blocks/ hour

� 1 Immediate Assign message / Block x 61 272 Blocks =


� If 60 % engineering limit applied: 36 763 IA message/hour

10.21 IA message/s

� AGCH efficiency: between 1 – 2 (2 if Immediate Assign Extended)

1 Immediate Assign message / AGCH block used usually in dimensioning




AGCH capacity

� Combined cell

� BS_AG_BLKS_RES = 1

� 1 AGCH block/Multiframe x (3600s / 235 ms) =

15 318 AGCH blocks/ hour

� 1 Immediate Assign message / Block x 15 318 Blocks =


� If 60 % engineering limit applied: 9 180 IA message/hour

2.55 IA message/s




AGCH and PCH capacity


PCH blocks

AGCH blocks

Paging Request/s (PCH blocks/s)

Access Grant msgs/s (AGCH blocks/s)

Paging msgs/s at 60% limit

ImmAs msgs/s at 60% limit

PCH msgs/h at 60% limit

ImmAs msgs/h at 60% limit

Total # msgs sent/h at 60% limit

6 3 25.53 12.75 38.29 7.65 137851 27540 165391

5* 4 21.27 17.02 31.91 10.21 114893 36763 151656

4** 5 17.02 21.27 25.53 12.76 91908 45936 137844

Notes: * Alcatel recommended default configuration.

** Recommended for 16 TRX cells with CS only.




B9 limitations

� Abis interface limitation

� max paging load of 33 paging commands per second = 118 800 paging/hour

� G2 BSC limitation


� MxBSC limitation





Location Area dimensioning in B9

� G2 BSC:

� MxBSC:

2 Location Areas with an average of 132 cells per LA


G2 BSC

(max 264 cells)

AAbis

70 paging/s33 paging/s

LA

•LA

Mx BSC

(max 264 cells)

AAbis


LA

•LA

•LA




B10 limitations

� Abis interface limitation

� max paging load of 33 paging commands/second 118 800 paging/hour

� max paging load of 66 paging commands/second 237 600 paging/hour with mCCCH

� G2 BSC limitation

� max paging load of 70 paging commands/second = 252 000 paging/hour

� MxBSC limitation

� max paging load of 120 paging commands/second= 432 000 paging/h

(expected in B10)




B10 limitations

� CCCH capacity in B10 with mCCCH

� (rounded figures)

Nb CCCH TS BS_AG_BLKS_RES

PCH blocks AGCH blocks Max paging/s at 60% load

Max assign/s at 60% load

1 3 6 3 38 7 1 4 5 4 32 10 1 5 4 5 25 12 2 3 12 6 76 15 2 4 10 8 63 20 2 5 8 10 51 25 2 6 6 12 38 31





� G2 BSC without mCCCH:

1 Location Area with up to 264 cells per LA

� G2 BSC with mCCCH:

G2 BSC

(max 264 cells)

AAbis


LA

•LA2 Location Areas with an average of 132 cells per LA

G2 BSC

(max 264 cells)

AAbis


LA





� MxBSC without mCCCH:



Mx BSC

(max 500 cells)

AAbis

120 paging/s2 CCCH 66 paging/s

LA

LA

Mx BSC

(max 500 cells)

AAbis

120 paging/s1 CCCH 33 paging/s

LA

LA

LA

LA

� MxBSC with mCCCH:





� There is no relationship between the BSC paging mechanism and CCCH

configuration.

� The BSC has just the task of broadcasting paging messages per LAC.

� If paging coming from MSC has a high rate, the BSC will send on Abis paging

commands at high speed, ignoring the fact that some cells are not able to

send it.

� As a consequence, some paging commands shall be discarded by cells with

less radio capacity compared with BSC capacity for sending paging on Abis.





� The Paging load must be assessed during busy hour.

� If the paging rate on Abis doesn’t exceed 33 paging/s, cells with 1 CCCH TS

may be used without loses.

� If the paging rate is higher (up to 66 paging/s), all the cells in LAC should be

configured with 2 CCCH TS, to avoid paging messages to be discarded.

� If the paging rate per LAC is higher than 66 paging/s, the LAC should be split.




Dimensioning Target

� Verify if the Location Area size is OK

� Method:

� Check the BSC and Abis limits

� Check the related parameters

� Check the load on CCCH (PCH, AGCH, RACH)

� Input (counter values):

� Paging rate, Nb of paging messages discarded, PS Paging rate, AGCH load, Nb of IA

messages discarded

� Output

� Location area load




Method for Location area:

� Needed telecom parameters:

� BS_AG_BLKS_RES

� CCCH_CONF

� Needed counters for PCH and AGCH:

� MC8a = NB_CELL_PAGING_CMD

� MC8b = NB_CELL_IMM_ASS_CMD

� MC8d = NB_CELL_IMM_ASS_REJ

� P49 = NB_IMM_ASS_AGCH

� MC27 = CCCH_TS_Cell_available





� New counters for CCCH in B10:

� MC925a = NB_AGCH_USEFUL_BLOCKS_SENT

� MC925b = NB_PCH_USEFUL_BLOCKS_SENT

� MC925c = NB_BUSY_RACH_SLOTS

� MC925d = NB_CHANNEL_RQ_RADIO

� MC925e = NB_ASSIGN_CMD_RECEIVED_ABIS

� MC925f = NB_ASSIGN_CMD_DISCARDED

� MC925g = NB_PAGING_CMD_RECEIVED_ABIS

� MC925h = NB_PAGING_CMD_DISCARDED

� MC930 = NB_ABIS_PAGING_MESSAGE_RECEIVED





� B9 Method

Total MC8a > 252000(Total for all LA in the BSC)

Re-Design LA, and/orReduce nb of LA per BSC

All Cells in a LA are non-combined

MC8a > 57,446 MC8a >114,891

Yes

No

No

No

NoYes Yes

Yes

OK OK Re-Design LAChange to non-combined Re-Design LA

Check BSC Limitation

Check Um Limitation

This value represents G2 BSC limit.

For MX BSC the limit is 342 000.

This value represents 60% of PCH channel capacity.





� B10 Method

Total MC8a > 252000(Total for all LA in the BSC)

Re-Design LA, and/orReduce nb of LA per BSC

All Cells in a LA are non-combined

MC8a > 57,446 MC8a >114,891

Yes

No

No

No

NoYes Yes

Yes

OK OK Re-Design LAChange to non-combined Re-Design LA

Check BSC Limitation

Check Um Limitation

This value represents G2 BSC limit.

For MX BSC the limit is 432 000.

This value represents 60% of PCH channel capacity.

This value must be double in case of 2 CCCH TS.




Method for Location area (and Routing Area):

� Abis approach

� If (CS+PS) Paging load is less than 60% of PCH channel capacity:

� The LA size is OK (no overload)

� It is possible to keep RA size = LA size

LA RA

Note: • Total PCH channel capacity is 191 485 paging/hour for 1 CCCH TS and 382 970 paging/hour for 2 CCCH TSs (for BS_AG_BLKS_RES = 4).

• (CS+PS) Paging load = MC8a• 60% represents engineering limit





� Abis approach

� If (CS+PS) Paging load is greater than 60% of PCH channel capacity and if

PS Paging load/(CS+PS) Paging load is greater than 20% then:

� Is necessary to have RA size < LA size, so LA must be splitted in two or more RAs.

Note: (CS+PS) Paging load = MC8aPS Paging load = P53a

LA

RA1RA2

RA





� Abis approach

� If (CS+PS) Paging load is still greater than 60% of PCH channel capacity after

PS Paging load/(CS+PS) Paging load has been changed to be under 20%, then:

� Is necessary to splitt the initial LA in two or more LAs.

LA LA1

LA2





CCCH frame tuning at cell level

� Checking during busy hour

� Check BS_AG_BLKS_RES value

� Check AGCH load (MC925e/AGCH capacity) and congestion (MC925f/ MC925e)

� Check PCH load (MC925g/PCH capacity) and congestion (MC925h/ MC925g)

� Tuning

� If PCH load is below 60% and no congestion but AGCH load is above 60% and with

congestion => BS_AG_BLKS_RES may be increased by 1.

� If PCH load is above 60% and with congestion but AGCH load is below 60% and without

congestion => BS_AG_BLKS_RES may be decreased by 1.


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