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GPRS NETWORK

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					(E)GPRS Network Infrastructure
MS BSC MSC PSTN SS7 Network SGSN SGSN Nokia Security GW
Router

BTS

SMS-GMSC HLR/AuC

Nokia Security GW
Router
STM-1

EIR

CG DNS

Nokia IP650 sec GW
Router
LAN SWITC H

LIG GGSN

GPRS IP Backbone Network

GGSN
Router
STM-1

Nokia IP650 sec GW Corporate 1 Intranet

Router

Nokia IP650 sec GW

MODEM POOL FOR DIALUP

Nokia Security GW Nokia Security GW
MODEM POOL FOR DIALUP

Internet

Corporate 2 Intranet

SGSN Company Confidential
1 © 2005 Nokia

SGSN

V1-Filename.ppt / yyyy-mm-dd / Initials

ELECTRICAL ET

Metro BSC Hub

GB LINK

GB LINK

SGSN

GGSN
Company Confidential
2 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials

NSEI PLANNING
NSEI 1
NSEI 2

NSEI 3

NSEI 4

Company Confidential
3 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials

Network Element and Configuration Audit - Summary
BTS • GPRS territory BSS • PCU variant & dimensioning • PCU strategy in mixed configuration • BSS SW and features TC HLR/ AC/ EIR MSC/VLR SGSN • Unit capacity (PAPU etc.) • BSS Gb Flow control Gs IP/MPLS/IPoATM backbone RF BTS BSC Abis Gb 2G SGSN Gn Gi Application Applicatio Servers n Servers (colocated Server • load • settings (Linux/Win) HLR • QoS profile • GPRS settings

• BTS HW considerations (TRX & BB-card)
• BTS SW (EPCR) MS/Client parameters • GPRS/EDGE capability and release

TCSM

GGSN

•Multislot support

RF interface • Coverage •C/I • Capacity • Traffic volume • Mobility

Gb interface
Abis interface • EDAP size / dimensioning • # of E1/T1s • GPRS/EDGE traffic • Bearer size • IP v.s. FR • Dimensioning

Company Confidential
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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

Company Confidential
5 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials

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

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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

Company Confidential
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Transmission requirement for EGPRS coding schemes in Abis interface
Coding scheme MCS-1 Data rate 8.8 kbit/s

Abis PCM allocation (fixed + pool)

MCS-2
MCS-3 MCS-4 MCS-5 MCS-6 MCS-7 MCS-8 MCS-9 Company Confidential
8 © 2005 Nokia

11.2 kbit/s
14.8 kbit/s 17.6 kbit/s 22.4 kbit/s 29.6 kbit/s 44.8 kbit/s 54.4 kbit/s 59.2 kbit/s

V1-Filename.ppt / yyyy-mm-dd / Initials

EDGE modulations

Scheme

Modulatio n 8PSK

Maximum rate [kb/s]

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

59.2 54.4 44.8 29.6 / 27.2 22.4 17.6 14.8 / 13.6 11.2 8.8

GMSK

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GPRS & EGPRS coding schemes
MCS-1

• 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

22 MCS-2 28 MCS-3 37 MCS-4 44 MCS-5 56

RLC/MAC block (radio block)

• Operator can set the MCS to start with
• E.g. always start with MCS-9

redundancy from channel coding RLC data block, number of octets

CS-1 20 CS-2 30 CS-3 36 CS-4 50

MCS-6 74 MCS-7 56 MCS-8 68 MCS-9 74 74 68 56

Company Confidential
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EDGE link performance
In RLC layer (kbit/TSL)
• • • • 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.

Ideal Link Adaptation

60

50

40

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

30

20

10

0 0
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5

10

15

20

25

30

C/I

GPRS: territory (S9-10)
TRX 1 TRX 2
CCCH TS TS TS TS TS TS TS

Circuit Switched Territory Packet Switched Territory

The following are the operator configurable parameters for territory management:  GPRSenabled (BTS-level) GENA  GPRSenabledTRX (TRX-level)  DefaultGPRScapacity (BTS-level)  PreferBCCHfreqGPRS (BTS-level)  DedicatedGPRScapacity (BTS-level)

TS

TS

TS

TS

TS

TS

TS

TS

The main principle is that GPRS (PS) uses the capacity that remains from the CS traffic. Given as % over dual TCH tsls of GPRS enabled TRXs. Includes dedicated time slots. Rounded downwards.

Additional GPRS Capacity

Default GPRS Capacity

Dedicated GPRS Capacity

GTRX CDED CDEF BFG GTUGT

Circ ui
Territory border moves Dy n a m i c a l l y based on Circuit Switched traffic load

t Sw itche by in not affecd capac ity trod ucin ted g GP RS

 TerritoryUpdateGuardTimeGPRS (BSC-level)

• Circuit Switched traffic has priority • In each cell Circuit Switched & Packet Switched territories are defined • Territories consist of consecutive timeslots
CDEF CDED Used capacity for GPRS
PEAK GPRS CHANNELS /c2063(S9) peak_gprs_channels AVG. AVAILABLE DEDICATED GPRS CHANNELS ava_17 (S9) ave_GPRS_channels_sum/ave_GPRS_channels_den PEAK DEDICATED GPRS CHANNELS /c2066(S9) peak_permanent_gprs_ch

Used capacity for speech

UNAVAILABLE TCH c2040

AVG. AVAILABLE TCH in CS territory ava_15 (S9) ave_avail_TCH_sum/ ave_avail_TCH_den

AVG. AVAILABLE GPRS CHANNELS in PS territory ava_16 (S9) ave_GPRS_channels_sum/ave_GPRS_channels_den ADDIT.GPRS CH USED ach_1

Allocated resources Availability ava_1d

AVG. BUSY TCH = CS traffic trf_12b ave_busy_tch/ res_av_denom14

Free capacity

AVG. TSL used for UL GPRS trf_78b AVG. TSL used for DL GPRS trf_79b

Company Confidential
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Used resources

DL Data Scheduling Example – “No need to share case”
• There are enough EDAP resources to handle adequately all the TBFs and MCS requests. (e.g PS Active EGPRS ch < EDAP resources)
TRX 1
RTSL 0 1 CS-2 2 MCS-1 MCS-9 MCS-7 MCS-1 MCS-7 3 4 5 6 7

Requests

PCM subTSL 1 2 3 4 PCM TSL 8 9 10 11 5 4 7 2 5 4 7 5 4 7 4 -

-

-

CS-2

MCS-1 MCS-9 MCS-7 MCS-1 MCS-7

Grants

Company Confidential
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DL Data Scheduling Example (sharing case)
• 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)
TRX 1
RTSL 0 1 CS-2 MCS-5 MCS-9 MCS-8 MCS-1 MCS-7 2 3 4 5 6 7

Requests

PCM TSL

PCM subTSL 1 2 3 10 11 12 5 4 2 5 4 7 5 4 7

4
3 -

PCU-TRX 0

-

-

CS-2 MCS-5 MCS-7 MCS-7 MCS-1 MCS-6

Grants

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

TRX 1 TRX 2

TS TS BCCH PBCCH TS

TS

TS

TS

TS

TS

TS

Dedicated EGPRS TSL Default territory EGPRS TSL

TS

TS

TS

TS

TS

TS

TS

TS

TS

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
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Company Confidential
15 © 2005 Nokia

PLAN A
Company Confidential
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PLAN B

SNO

PLAN A

PLAN B

1

Both Non BCCH and BCCH Trx can access the EDGE Facility 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 Using this plan we can change the BFG priority depending on the Interference in the N/W In case of extending the time slot of EDGE in Non BCCH TRX also can be done if congestions is observed in the Site

Only BCCH TRX can access the EDGE facility

2

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

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

4

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

Company Confidential
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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

Company Confidential
18 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials


				
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