GPRS+doc

1 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials

Company Confidential

(E)GPRS Network Infrastructure

GPRS IPBackboneNetwork

DNS

CG

GGSN

Internet

Corporate 1Intranet

LIG

Corporate 2Intranet

SS7Network

PSTNMSCBSCBTS

MS

EIR

HLR/AuC

SMS-GMSC

SGSN

SGSN

SGSN

MODEMPOOL FOR DIALUP

Nokia IP650 sec GW

Router

Router

RouterSTM-1

STM-1

SGSN

GGSN

Router

Router

Nokia Security GW

LAN SWITCH

MODEMPOOL FOR DIALUP

Nokia Security GW

Nokia Security GW

Nokia IP650 sec GW

Nokia IP650 sec GW

Nokia Security GW



BSC

Metro

Hub

SGSN

GGSN

ELECTRICAL ET

GB LINKGB LINK



NSEI 1 NSEI 2

NSEI 3

NSEI 4

NSEI PLANNING



Network Element and Configuration Audit - Summary

BSC GGSN

IP/MPLS/IPoATM-

Application Servers

(co-located

2GSGSN

BTS

HLR/AC/EIR

TCSM

TC

MSC/VLR

Abis GbBSC BSC

GGSNGGSN-backbone

Application Servers

2GSGSN

2GSGSN

BTS

HLR/AC/EIR

HLR/AC/EIR

TCSM

TC

MSC/VLR

GnGi

Gs

RF interface

• Coverage

•C/I

• Capacity

• Traffic volume

• Mobility

MS/Client parameters

• GPRS/EDGE capability and release

•Multislot support

Abis interface

• EDAP size / dimensioning

• # of E1/T1s

• GPRS/EDGE traffic

Gb interface

• Bearer size

• IP v.s. FR

• Dimensioning

BTS

• GPRS territory

• BTS HW considerations (TRX & BB-card)

• BTS SW (EPCR)

BSS

• PCU variant & dimensioning

• PCU strategy in mixed configuration

• BSS SW and features

SGSN

• Unit capacity (PAPU etc.)

• BSS Gb Flow control

RF

Server

• load

• settings (Linux/Win)

HLR

• QoS profile

• GPRS settings



INPUT GIVEN FOR THE GPRS PLANNING

• No. of time slot required for the GPRS territory : CDED=1 and CDEF=1

• No. of BTS per EDAP i.e the No. of sectors prevalent : 3

• No. of time slot used for EDAP on Abis (64 Kbps) : 3 Time slot

• % of upgrade is the Teritory upgrade for the future perspective : 10 %

• No. Of sites planned per BSC : 100

• Access rate (CIR) is the speed required at the GB interface : 256 Kbps



OUTPUT REQUIRED

• No. of sites per NSEI required

• No. of NSEI required in BSC

• No. of PCU or No. Of BCSU required

• No. Of Gb Link required

• No. of E1 required from the BSC to Metro Hub



How to calculate what

• No. of EGPRS resources used in 1 sector * No. of sectors : 2 x 3

• No. of time slot/sector * no of time slot used for EDAP :- 2 * 3 = 6

• So total time slots per site 6 + 6 = 12

• 1 NSEI support 256 time slot with upgrade % as 10 so total no of time slots which can be equipped is 256 - 10% of 256 = 230.4 ~ 230

• So no. of sites per NSEI is 230/12 = 19.16 ~ 19

• So no NSEI required / BSC : 100 / 19 = 5.2 +1 (for future use) ~ 6

• 2 NSEI supports 1 BCSU so no. of PCU required : 6/2 = 3

• No. of NSEI required is equivalent to the no. of Gb link = 3

• On 1 E1 we can get 31x64 = 1984 , so access rate can be given by 1 E1 = 1984/ access rate (256) = 1984 / 256 ~ 7



Coding scheme Data rate

MCS-1 8.8 kbit/s

MCS-2 11.2 kbit/s

MCS-3 14.8 kbit/s

MCS-4 17.6 kbit/s

MCS-5 22.4 kbit/s

MCS-6 29.6 kbit/s

MCS-7 44.8 kbit/s

MCS-8 54.4 kbit/s

MCS-9 59.2 kbit/s

Abis PCM allocation (fixed + pool)

Transmission requirement for EGPRS coding schemes in Abis interface



EDGE modulations



GPRS & EGPRS coding schemes

• GPRS has four coding schemes,CS-1...4. All use GMSK.

• EDGE has nine modulation and coding schemes, MCS-1...9.

• MCS-1...4 use GMSK,MCS-5...9 use 8-PSK modulation

• Operator can set the MCS to start with

• E.g. always start with MCS-9

MCS-7

MCS-1

22

MCS-2

28

MCS-3

37

MCS-4

44

MCS-5

56

MCS-6

74

5656

MCS-8

6868

MCS-9

74 74

redundancy fromchannel coding

RLC data block,number of octets

RLC/MAC block(radio block)

CS-1

20

CS-2

30

CS-3

36

CS-4

50



EDGE link performance

• GPRS with re-transmission with same coding scheme

• Retransmissions with EDGE can be sent with the new scheme

•Bit Error Probability (BEP) is a new MS quality measurement introduced

• In general, a higher coding scheme has higher coding rate, and consequently higher peak throughput, but it also tolerates less noise or interference.

• New parameters

• Max BLER for Ack and Non-Ack modes

• Can be used to tune to use more higher MCS’s

• Mean BEP offset for GMSK and 8-PSK

• Set threshold for MCS change

• The figure shows throughput vs. C/I of EGPRS coding schemes in TU50iFH, without incremental redundancy.

0

10

20

30

40

50

60

0 5 10 15 20 25 30

MCS-1MCS-2MCS-3MCS-4MCS-5MCS-6MCS-7MCS-8MCS-9

Ideal Link AdaptationIn RLC layer (kbit/TSL)

C/I



GPRS: territory (S9-10)

AVG. AVAILABLE TCH in CS territoryava_15 (S9)ave_avail_TCH_sum/ ave_avail_TCH_den

AVG. AVAILABLE GPRS CHANNELS in PS territoryava_16 (S9)ave_GPRS_channels_sum/ave_GPRS_channels_den

AVG. AVAILABLE DEDICATED GPRS CHANNELSava_17 (S9) ave_GPRS_channels_sum/ave_GPRS_channels_den

PEAK DEDICATED GPRS CHANNELS/c2066(S9)peak_permanent_gprs_ch

PEAK GPRS CHANNELS/c2063(S9) peak_gprs_channels

Used capacity for GPRS

The following are the operator configurable parameters for territorymanagement:

GPRSenabled (BTS-level)

GPRSenabledTRX (TRX-level)

DedicatedGPRScapacity (BTS-level)

DefaultGPRScapacity (BTS-level)

PreferBCCHfreqGPRS (BTS-level)

TerritoryUpdateGuardTimeGPRS (BSC-level)

GENA

GTRXCDED

CDEFBFG

GTUGT

ADDIT.GPRS CH USEDach_1

UNAVAILABLE TCHc2040

AVG. BUSY TCH = CS traffictrf_12bave_busy_tch/ res_av_denom14

AVG. TSL used for UL GPRS trf_78b

AVG. TSL used for DL GPRS trf_79b

Free capacity

Allocated resources

Usedresources

CDEDCDEF

Used capacity for speech

Availability ava_1d

The main principle is that GPRS (PS) uses the capacity that remains from the CS traffic.

Given as % over dual TCH tsls ofGPRS enabled TRXs. Includes dedicated time slots. Rounded downwards.

• Circuit Switched traffic has priority

• In each cell Circuit Switched & Packet Switched territories are defined

• Territories consist of consecutive timeslots

TRX 1

TRX 2

CCCH TS TS TS TS TS TS TS

TS TS TS TS TS TS TSTS

DedicatedGPRS

Capacity

CircuitSwitchedTerritory

PacketSwitchedTerritory

Territory border movesDy n a m ic a l ly based onCircuit Switched traffic load

Circuit Switched capacity not affected

by introducing GPRS

DefaultGPRS

Capacity

AdditionalGPRS

Capacity



RTSL

RequestsTRX 1

0 1 2 3 4 5 6 7

- - CS-2 MCS-1 MCS-9 MCS-7 MCS-1 MCS-7

Grants- - CS-2 MCS-1 MCS-9 MCS-7 MCS-1 MCS-7

PC

M T

SL

PCM subTSL

1 2 3 4

8

11109

5

2

5

-

5

-

-

-7 7 7 -4 4 4 4

• There are enough EDAP resources to handle adequately all the TBFs and MCS requests. (e.g PS Active EGPRS ch < EDAP resources)

DL Data Scheduling Example – “No need to share case”



DL Data Scheduling Example (sharing case)

Grants

RTSLRequestsTRX 1

0 1 2 3 4 5 6 7

- - CS-2 MCS-5 MCS-9 MCS-8 MCS-1 MCS-7

- - CS-2 MCS-5 MCS-7 MCS-7 MCS-1 MCS-6PCU-TRX 0

5

2

35

7

5

744 4 -P

CM

TS

L

PCM subTSL

1 2 3 4

1112

10

-

• Because EDAP is a shared resource between a higher number of EGPRS TSL it is possible to encounter the situation where there are not enough EDAP resources to handle “adequately” all the TBFs (e.g PS Active EGPRS ch > EDAP resources)



EDAP utilization

TRX 2

TRX 1

TS TS TS TS TS TS

TS TS T TS TSTS TS TSSPBCCHBCCH

TSTS

TS

TS

Dedicated EGPRS TSL

Default territory EGPRS TSL

•6 EGPRS RTSLs (Dedicated + Default territory)• 50 % utilization assumed (3 Data Erlangs traffic)• On average 3 RTSLs used

• RTSLs use MCS7 (44.8 kbit/s) with average C/I=13dB and throughput 30kbit/s• Effective data rate factor excluding retransmissions over the air-interface is 30/44.8 ~ 0.7

• Slave group utilization is 0.7*0.5= 0.35



PLAN A PLAN B



SNO PLAN A PLAN B

1Both Non BCCH and

BCCH Trx can access the EDGE Facility

Only BCCH TRX can access the EDGE facility

2

If the BCCH TRX goes faulty then also the EDGE users can access the N/W

since the 2nd TRX has been defined on the

EDAP Pool

If BCCH TRX goes faulty then The EDGE Service can not be accessed

since the 2nd TRX has not been defined on the EDAP POOL

3

Using this plan we can change the BFG priority

depending on the Interference in the N/W

We can not change the BFG unstill and unless the EDAP pool need to be

redesigned

4

In case of extending the time slot of EDGE in Non BCCH TRX also can be done if congestions is observed in the Site

We can not extend the Non BCCH TRX time slot during the congestion since that TRX is not mapped on the

EDAP Pool

5

While expanding the N/W from the 222 to 332

configuration we need to Modify the EDAP pool

Need not to modify the EDAP pool since only BCCH TRX is being

mapped



Conclusion

• The No. of sites per NSEI depend on the EDAP pool size and no. of time slot used for the GPRS territory

• Beside if we need to extend the resourced at ABIS end we need to defince the EDAP pool

• If we require the Speed at GB we need to go to higher CIR

Date post:	26-Nov-2014
Category:	Documents
Upload:	jitender-kumar-kumar
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