Nortel v15 edge_training2

1 Nortel Confidential Information

EDGE RF Seminar 2Agenda:>Nortel specific implementations>EDGE Hardware >EDGE software enhancements >EDGE backhaul >EDGE TS sharing>EDGE performance>EDGE optimization concerns


TCUBSCe3*

BTS

MSC

HLR/AUC

PSTN

SCP

A

GPRS

SGSN

GGSN

IntranetInternet

PCUSN*

Backbone

GbEdge Radio

V15.0 SW Upgrade

Nortel EDGE SolutionsEDGE Leverages GSM/GPRS Capital Investment

*Additional BSC & PCUSN might be need to support the higher data usage.

NSS 15, 16 or 17 & GPRS 5.0

DS512Fiber

Nortel Confidential Information

Nortel EDGE Hardware SolutionsBased on Existing Architecture

> S8000 and S12000• eDRX and ePA with GMSK/8PSK power parity (30/30

Watts)• HePA option available that is EDGE capable (60/45 Watts)

> BSCe3 & TCUe3• DS512 fiber addition (for high switching capacity BSC –

4096 DS0)> PCUSN

• Increase to 24 Agprs interfaces per BSC> Increased Abis & Agprs Backhaul

• Might impact BSC Capacity due to increase T1 connectivity per site

• Might impact PCUSN due to Increase Agprs connectivity per site

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eDRX: GMSK & 8-PSK ModulationeDRX needed for the new RF modulation scheme

> 8PSK has same spectrumas GMSK but does nothave constant envelope

GMSK Time

Envelope (amplitude)

8PSK(0,0,1)

(1,0,1)

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

(0,1,1)

(1,1,1)

(1,1,0)

(1,0,0)

Time


22.5° offset


ePA: 8-PSK modulation PA impactePA needed to handle new amplification requirements

> Linear modulation needs ‘linear’ PA• PA efficiency is decreased• GMSK/8PSK average power delta

Pin

Pout

8PSK PAR :3.2 dB

1dB

Back-offin

1 dB

Peak8PSK

Average8PSK

GMSK

One burst


8-PSK- TX Power Reduction

GMSK

8PSK

Time


Time


Peak to Average of ≅ 3,2 dB

Pin

Pout

Back Off= 4 dB

Compression point

•Nortel e-PA is designed to deliver 30W average 8-PSK power and 30W GMSK (in this last case average=peak)

>Active RF components designed for ~60W peak power>Impact on higher peak power on 8-PSK as MS measures mean power

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Other’s ePA Power Limitation…Reduced throughput

Urban cell at 1800 MHzC/I = 12 dB at cell edge

with Incremental Redundancyaverage 8-PSK = 15 W

0

10

20

30

40

50

0,0000,1000,2000,3000,4000,500distance from the cell center (km)

Dow

n-Li

nk th

roug

hput

/ TS

kbit/

s

raw LLCnet LLCcell average

8-PSKMCS-9

8-PSKMCS-8

8-PSKMCS-7

8-PSKMCS-6

GMSKMCS-3

cell average = 27 kbit/s

cell radius = 583 m

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Nortel’s ePA Power Advantage…20% Bigger EDGE Throughput

Urban cell at 1800 MHzC/I = 12 dB at cell edge

with Incremental Redundancyaverage 8-PSK = 30 W

0

10

20

30

40

50

0,0000,1000,2000,3000,4000,500distance from the cell center (km)

Dow

n-Li

nk th

roug

hput

/ TS

kbit/

s

raw LLCnet LLCcell average

cell radius = 583 m

8-PSKMCS-9

8-PSKMCS-8

8-PSKMCS-7

8-PSKMCS-6

cell average = 33 kbit/s

+ 20 % compared with 8-PSK at 15 W

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> Performance Enhancements• 8-PSK modulation and 7 new Modulation & Coding

Schemes• Link Quality Measurements and Link Adaptation• Retransmission & Incremental Redundancy (ARQ type

II for DL)• ARQ Window Management and Compress Bitmap• Asynchronous PCU/BTS interface• EDGE/GPRS RLC Polling Improvements

> Backhaul Optimization• Dynamic Abis / Agprs

> Bandwidth Optimization• GPRS/EDGE Multiplexing• TS Sharing w/ Voice Pre-emption

Nortel EDGE Software SolutionsIntroducing Advanced Features


> Each coding scheme belong to a family which is based on the the same unit of payload size in order to allow retransmission of RLC block with more robust coding.

Family Name

Modulation Coding Schemes

User Payload (octets)

A MCS-3, MCS-6, MCS-9

37, 2x37, 4x37

A with padding

MCS-3, MCS-6, MCS-8

34+padding, 2x(34+padding), 4*34

B MCS2, MCS-5, MCS-7

28, 2x28, 4x28

C MCS-1 and MCS-4 22 and 2x22

37 octets 37 octets 37 octets37 octets

MCS-3

MCS-6

Family A

MCS-9

28 octets 28 octets 28 octets28 octets

MCS-2

MCS-5

MCS-7

Family B

22 octets22 octets

MCS-1

MCS-4

Family C

Nortel EDGE Software SolutionsNew Coding schemes for EDGE

Family Coding Scheme

EGPRS RLC data unit

size - octets

Number of Basic data unit

Number of Radio

Block

Number of RLC

data Block

Required jokers

Data rate in kb/s

C MCS-1 22 1 1 1 or 1/2* 0 8.8 B MCS-2 28 1 1 1 or 1/2* 0 11.2 A MCS-3 37 1 1 1 or 1/2* 1 14.8 C MCS-4 44 2 1 1 1 17.6 B MCS-5 56 2 1 1 1 22.4 A MCS-6 74 2 1 1 2 29.6 B MCS-7 2x56 = 112 4 1 2 3 44.8 A MCS-8 2x68 = 136 4 1 2 4 54.4 A MCS-9 2x74 = 148 4 1 2 4 59.2

* When MCS6, MCS5 and MCS4 is respectively re-segmented in MCS3, MCS2 and MCS1

Nortel did not implement MCS-1 & MCS-4 (both from family C), since there is no real gain.MCS-2,MCS-3,MCS-5,MCS-6,MCS-7,MCS-8,MCS-9 from families A & B are implemented.

GMSK

8-PSK

x

x









> Throughput highly depends on radio quality (distance from cell center and interferences).

Link Adaptationadapts the MCS based on those variable radio conditions. 0 5 10 15 20 25 30 35

0

10

20

30

40

50

60

MCS2MCS3MCS5MCS6MCS7MCS8MCS9

Throughput=f(C/I) URBAN IFH

C/I

Thro

ughp

ut (k

b/s)

Nortel EDGE Software SolutionsEffective Link Adaptation (LA)


Nortel EDGE Software SolutionsLink Adaptation Mechanism - Downlink

• MeasurementMS measures the signal quality of

each received block.

• ReportMS reports the signal measurement

to PCU.

• AdaptationPCU selects the accurate MCS

based on MS measurements.



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Es/p for polling


DL TBF Establishment (MCS2)

Data block (MCS2)

MS PCU

Data block (MCS2)

Data block (MCS2; RRBP; ES/P)

Data block (MCS7)

EDGE PDAN (LQM)

2

3

4

5

1

Sliding Window:Mean_Bep & Cv_Bep per modulation computed on each received block and averaged with BEP_Period past blocks

DL TBF established withInitialMCS_DL=MCS2

The PCU polls the MS (ES/P bit), requesting acknowledgment bitmap & LQM.

DL MCS selection

=> MCS7

The PCU acknowledges the polling request, including LQM.

Nortel EDGE Software SolutionsDL LQM at the MS and LA PCU

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UL TBF Establishment (MCS2)

Data block (MCS2)

MS PCU

Data block (MCS2)

Data block (MCS2)

Data block (MCS7)

EDGE PUAN (MCS7)

2

3

1Sliding Window:Mean_Bep & Cv_Bep•Per TFI•Computed on each received block and averaged with UL_BEP_Period past blocks•Sent in TRAU header

UL TBF established withInitialMCS_UL=MCS2

UL MCS selection

=> MCS7

Nortel EDGE Software SolutionsUL LQM at the BTS and LA at the PCU

Data block (MCS2)

Data block (MCS2)

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DL: BEP Period UL: UL BEP Period


> Data Transmission start with InitialMCS-(UL or DL)

> MCS2 is the default MCS if LA is not activated

> Link Quality Measurement (LQM) reports Mean Bit Error Probability (Mean-BEP from 0…31) and Coefficient of Variance of Bit Error Probability (CV-BEP from 0…7)

> DL BEP filtering period is specified in BEP_Period field on SI13

> LQM reporting is not automatic like SAACH reporting but is polled by PCU

> DL LQM reporting uses CS1

> UL LQM reporting uses TRAU frame header per block filtered according to 5.08

Nortel EDGE Software SolutionsEffective LA with Efficient LQM Mechanism

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Polling

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• The couple {MEAN_BEP;CV_BEP} is used as indices in the 8-PSK (or GMSK) table to derive the LA-DL-CommandedMCS. These tables are tunable through a set of parameters DL_MCSyUpperThreshold.

• If only GMSK is allowed, a separate table is used with tunable parameters DL_GMSK_MCSxUpperThreshold

• Parameter exist for 8PSK table. GMSK table is base on 8PSK table by adding 3 Mean_BEP values to 8PSK threshold

• Similar tables and parameters exist for UL as well

CV_BEP 0 1 2 3 4 5 6 7MEAN_BEP

0 2 2 2 2 2 2 2 21 2 2 2 2 2 2 2 22 2 2 2 2 2 2 2 23 2 2 2 2 2 2 2 54 5 5 5 5 5 5 5 55 5 5 5 5 5 5 5 56 5 5 5 5 5 5 5 57 5 5 5 5 5 5 5 58 5 5 5 5 5 5 5 59 6 6 6 6 6 6 6 6

10 6 6 6 6 6 6 6 611 6 6 6 6 6 6 6 612 6 6 6 6 6 6 6 613 6 6 6 6 6 6 6 614 6 6 6 6 6 6 6 615 6 6 6 6 6 6 6 616 6 6 6 6 6 6 6 617 7 7 7 7 7 7 7 718 7 7 7 7 7 7 7 719 7 7 7 7 7 7 7 720 7 7 7 7 7 7 7 721 7 7 7 7 7 7 7 722 7 7 7 7 7 7 8 823 8 8 8 8 8 8 8 824 8 8 8 8 8 8 8 925 9 9 9 9 9 9 9 926 9 9 9 9 9 9 9 927 9 9 9 9 9 9 9 928 9 9 9 9 9 9 9 929 9 9 9 9 9 9 9 930 9 9 9 9 9 9 9 931 9 9 9 9 9 9 9 9

LA 8PSK DL

Nortel EDGE Software SolutionsLink Adaptation Tables Usage

The value implies MCS and the position corresponds to the value of MeanBEP and CVBEP

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> LA Effectiveness• pcuEdgeLADnTargetedTransmittedMCSX – Number of EDGE Radio

Data Blocks that are commanded and sent in MCSX by the PCU• pcuEdgeMcsXRequestRetransDataBlockDn – Number of EDGE

Radio Data Blocks that were commanded and sent in MCSX by the PCU and nacked by the MS

• pcuEdgeLAUpTargetedTransmittedMCSY• pcuEdgeMcsYRequestRetransDataBlockUp

> Radio Quality• pcuEdgeUpCumMeanBep – Cumulative value of BEP received on a

TDMA• pcuEdgeUpNbsMeanBep – Number of MEAN_BEP values received• pcuEdgeDnCum8pskMeanBep• pcuEdgeDnNbs8pskMeanBep• pcuEdgeDnCumGmskMeanBep• pcuEdgeDnNbsGmskMeanBep

Nortel EDGE Software SolutionsCounters to Monitor and Optimize LA









> Each coding scheme belong to a family which is based on the minimum payload size

> Edge gives the possibility to retransmit a block in a different MCS belonging to the same family, according to the success or failure of previous transmission

Nortel EDGE Software SolutionsImproving Retransmissions with Lower MCS

Family Name Modulation Coding Schemes User Payload (octets)

A MCS-3, MCS-6, MCS-9 37, 2x37, 4x37

A with padding MCS-3, MCS-6, MCS-8 34+padding, 2x(34+padding), 4*34

B MCS2, MCS-5, MCS-7 28, 2x28, 4x28

C MCS-1 and MCS-4 22 and 2x22

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> What is IR : • IR is the possibility to retransmit a data block• Using a different puncturing schemes at each retransmission• And by combining the soft bits of each retransmission with the

original to decode the RLC/MAC block

Nortel EDGE Software SolutionsImproving Retransmissions w/ Incremental Redundancy

IR improves throughput in degraded RF environment.

Throughput vs. C/I



Nortel EDGE Software SolutionsIncremental Redundancy Mechanism

• StoreA block partially received is stored

at the receiver level.

First Block

Errors, decoding KO

Repetition• RepeatThe block is repeated.

Combined blockNo Errors, decoding OK

• DecodeThe chance to decode the block is

highly increased.

First Block

+ Combining Function• CombineThe repeated block is combined

with the stored block












Nortel EDGE Software SolutionsReduce Stalling Conditions with Larger ARQ Windows

> ARQ Window determines how many MAC blocks can be transmitted before the first block in the window gets acknowledged

> If the ARQ window limit is reached before the first block in thewindows gets acknowledged, a stalling condition is reached• No new blocks are transmitted• Only retransmission of the first unacknowledged block• Result in loss of throughputs

> In GPRS, a circular buffer of 128 blocks with an ARQ window of 64 blocks was defined• More prone to stalling condition when

• Higher CS are used with• Multi-slot assignments

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Nortel EDGE Software SolutionsReduced Stalling Conditions with Larger ARQ Windows

> EDGE introduces variable ARQ windows up to 1024 blocks based on multi-slot assigment• Greatly reduce Stalling

conditions• Allows for higher MCS

usage• Improve overall

throughputs

> Nortel set WS to Maximum for each allocation

> WS of 64 is used as default if no MSC information is available

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II for DL)• ARQ Window Management and Compress Bitmap• EDGE/GPRS RLC Polling Improvements• Asynchronous PCU/BTS interface





Market Driver

Performance

Feature

In order to improve reactivity for UL TBF establishment (during DL pre-establishment, preventive retransmission and Keep alive periods) the polling frequency becomes configurable through a parameter defined by the operator according to the user call profile :

RLCPolling = 0 : polling every 240 ms, i.e. every 12 blocksRLCPolling = 1 : polling every 120 ms, i.e. every 6 blocksRLCPolling = 2 : polling every 60ms, i.e. every 3 blocks

The number of blocks used for polling is intentionally limited to 50% (hard-coded) of the overall TS bandwidth if at least one TBF is established on this TS.

Benefits

Improve the performances for GPRS applications like HTTP, SMTP, …, requiring few UL TBF establishments.

Example of Gain: 10% for an i-mode page download

Performances improvementRLC Polling Frequency Improvement

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II for DL)• ARQ Window Management and Compress Bitmap• EDGE/GPRS RLC Polling Improvements• Asynchronous PCU/BTS interface





• A frame can be shipped on the interface whenever it is built, no synchronous frame boundary :

When the transmitter has nothing to send, it fills the line withan IDLE patternwhenever a frame is ready to be sent , it can send it immediately with no time constraint, encapsulating it with a START and a STOP patternA gain of 80ms in RTD

Nortel EDGE Software Solutions RTD Improvement w/ Asynchronous PCU-BTS interface


Nortel EDGE Software SolutionsRTD Approaching 600ms in V15.0

FeatureRelease

[email protected]

RLC PollingAsyn. Int.

V15.0

PBCCH/NACCV16

0

500

1 000

1 500

2 000

2 500average theoreticalCell Reselection duration

min UL TBF establishment

Round Trip Delay

ms

V12.4d One-Phase

V15.0 GPRSV15.2 EDGE

with NACC

with PBCCH

avg UL TBF establishment

V15.0 RTDGPRS 700ms 1st ping, 600-700ms subs. pingEDGE 860ms 1st ping, 600-700ms subs. Ping

15.2 RTDEDGE 700ms 1st ping, 600-700ms subs. ping


EDGE : A Performance RealityFTP Applicative End-to-End Throughput

0.42%212.37210.61501024MCS-9

0.22%197.37195.17501024MCS-8

0.26%163.19162.39501024MCS-7

0.10%108.79108.58501024MCS-6

0.11%82.2382.19501024MCS-5

0.10%54.6454.5750672MCS-3

0.31%41.5341.4350672MCS-2

MS 4+1

StandardDeviation

Maximum(kbps)

Average(kbps)

Number ofiterations

File size(kByte)DL MCS

High applicative performance and low varianceFTP at more than 210 kbps on 4 radio TS

Measurement

Results









Nortel EDGE Software SolutionsBackhaul Update for EDGE Throughput

> Higher coding schemes for increased user data throughput drives higher backhaul requirements.

Required Bandwidth (kbps)

8,8

11,2

14,8

17,6

22,4

29,6

44,8

54,4

59,2

0,0 16,0 32,0 48,0 64,0 80,0Required Bandwidth (kbps)

MCS1

MCS3

MCS5

MCS7

MCS9

EDGE Data To Backhaul Requirements

PayloadControl fieldAdditional CRCSTART & STOP patternRLC/MAC Hdr + FBI/EAbis overhead

Required Backhaul Bandwidth (kbps)

MAIN Joker1 Joker4Joker3Joker2MAIN Joker1 Joker4Joker3Joker2

• Backhaul increased in 64kbps (DS0) increments for Abis. (Even though on a tdma, the increments are in 16kbps (¼ DS0) per user.)

• Backhaul increased in 16kbps (¼ DS0) increments for Agprs.


> Today, each radio channel is linked to one 16 kbps Abis channel,

> Manage the supplementary bandwidth induces by :• MCS1 to MCS9 Edge radio channels.

Nortel EDGE Software SolutionsBackhaul Efficiency with Dynamic Abis

TRX

64 kbps

Abis16161616

16161616

59.2

MCS9

54.4

MCS8

17.6

MCS4

22.4

MCS5

29.6

MCS6

44.814.811.28.8

MCS7MCS3MCS2MCS1


> Main TS : 16k TS used for voice, data circuit and GPRS/EDGE dedicated to one radio TS,

> Joker TS : each TDMA is associated to a set of 64K TS• OMC-R parameter numberOfJokerDS0 – Max is 4 in V15.0• each 64k TS is divided in 16 k TS• these 16k TS used only for EDGE,• dynamically shared between all radio TS of the TDMA every 20ms

> Each radio frame is managed w/ :• the main TS,• n joker TS, according to

the PDU size.• each joker frame indicates

the associated main TS at each occurrence

radio frameAbis

main

joker

joker

Nortel EDGE Software SolutionsBackhaul Efficiency with Dynamic Abis – 1st Step

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Nortel EDGE Software SolutionsHigh Dynamic Agprs Gain When Starting Out

> Purpose• To optimize Agprs usage, considering

heterogeneous traffic distribution between cells> Benefits

– Minimize the number of Agprs PCM increasing PCUSN connectivity capacity: CAPEX saving

> Mechanism:• On a Agprs PCM basis, the PCU computes every

second the Agprs load of each cell and triggers reconfiguration procedures in order to exchange 1 or more Agprs TS from the less to the most loaded cell

Cell ALow loaded

Cell BHigh loaded

AgprsPCM

t

Cell A Cell B

t + 1

Cell CMedium loaded

Cell C

AgprsE1/T1

PCUPCU

BSCBSC

Cell A: Less loaded cell

Cell B: Most loaded cell

t









> Lower cost of ownership and network impacts• Less radio to provision by sharing radio versus dedicated radio• Sharing of backhaul resources increasing equipment

connectivity• No need for additional spectrum for EDGE deployment initially

> Reduce operational cost• Less re-engineering required as EDGE MS penetration

increases since resources are dynamically shared between EDGE and GPRS

• Less backhaul lease costs

Nortel EDGE Software SolutionsMultiplexing EDGE and GPRS MS on the same TS

BCCHVoice Voice Voice Voice

VoiceGPRSEDGE

GSM TDMA Radio

VoiceGPRSEDGE

VoiceGPRSEDGE

VoiceGPRSEDGE


> Fixed TCH for GSM• For a GSM only usage

> Dynamic TCH/PDCH Pool• Channels not used by GSM are made available to EDGE and GPRS• When requested by GSM, preempted on GPRS then on EDGE• Pre-emption can be rejected with GPRSpreemption Parameter

> Minimum TS number of GPRS/EDGE• A minimum number of TS is allocated for EDGE and GPRS Traffic

> Multiple TDMA for GPRS

TS: 10 2 3 4 5 6 7

PDCHMin. TCH Only

PDCHwith circuitpre-emption

Standard GPRS/EDGE bandwidth

Min GPRS/EDGE bandwidth (if high circuit traffic)

Nortel EDGE Software SolutionsGPRS/EDGE TS Sharing w/ GSM Principle

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> The same GPRS algorithm is used for EDGE TDMA selection> The algorithm is modified in order to take into account :

• TDMA with or without EDGE capabilities.• MS with or without EDGE capabilities.• Better throughput offered on EDGE TDMA.

> The main modifications for the EDGE TDMA selection is :• Introduction of a new parameter for EDGE TDMA : EDGEFavor. It is

used to increase the weight of an EDGE capable TDMA to push EDGE MS on those TDMA.

• For a MS allocated in EDGE, it is “forced” on the same EDGE TDMAup to the end of the TBF. This behavior is related to the standard constraints that a TBF cannot be dynamically changed from EDGE to GPRS and vice-versa.

> The main modifications for the GPRS TDMA selection is :• Introduction of a new parameter for GPRS TDMA : EDGEMixity. It is

used to reduce the weight of an EDGE capable TDMA to push GPRS Only MS away from the EDGE Capable TDMA.

Nortel EDGE Software SolutionsEDGE TDMA & TS Allocation Principles

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Nortel EDGE Software SolutionsEDGE TDMA & TS Allocation – EDGEFavor

EDGE Capable TDMA. GPRS only TDMA.

New EDGE MS with 4+1 capabilities

EDGEFavor = 1 :•EDGE throughput is equivalent to GPRS•MS is allocated in GPRS with 4 TS

EDGEFavor = 3 :•EDGE throughput is triple from GPRS•MS is allocated in EDGE with 3 TS

EDGE Capable TS

GPRS only Capable TS

Non-GPRS TS

To favor an EDGE MS on EDGE capable TDMA


Nortel EDGE Software Solutions EDGE TDMA & TS Allocation – EDGEMixity

EDGE Capable TDMA. GPRS only TDMA.

New GPRS MS with 4+1 capabilities

EDGEMix = 0.5 :•GPRS De-favored by a half factor in EDGE TDMA•MS is allocated in GPRS with 3 TS on the GPRS Only TDMA

EDGEMix = 1 :•GPRS MS are not de-favored in EDGE TDMA.•MS is allocated in GPRS with 4 TS on the EDGE TDMA

EDGE Capable TS

GPRS only Capable TS

Non-GPRS TS

To disfavor a GPRS MS on EDGE capable TDMA


> The parameter EDGEMix is available to control the level of multiplexing between GPRS & EDGE MS on the EDGE TDMA.

> If throughput is better according to PDCH occupancy and QoS, the EDGE & GPRS MS can be multiplexed on the same TS.

> A GPRS UL TBF & a EDGE DL TBF allocated on the same TS.• The PDCH is shared according to QoS.• The EDGE MCS is selected according to Link Adaptation or

Backhaul constraints when the UL block is not allocated to the GPRS MS.

• The EDGE MCS is downgraded to GMSK when the UL block is allocated to the GPRS MS. This allows the GPRS MS (GMSK only) to decode the USF in the DL direction.

Nortel EDGE Software SolutionsEDGE MCS Selection GPRS UL Multiplexing

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Nortel EDGE Software SolutionsDL MCS Selection: 4 steps

Backhaul: Final MCS chosen according Abis/Agprs constraints

Link Adaptation: Chooses the optimal Modulation & Coding Scheme based on radio measurements (LQM) received from MS

RLC: Chooses optimal MCS based on retransmission rules in a given family

Dynamic Allocation: Chooses optimal Modulation (GMSK or 8-PSK), based on presence of GPRS MS on the same resources on the UL direction

NB: This decision process is repeated every time a data block has to be sent on the DL direction on a TS.

1

2

3

4

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Nortel EDGE Software SolutionsUL Commanded MCS : 2 steps

Link Adaptation: Chooses the optimal Modulation & Coding Scheme based on radio measurements in the PCU

Backhaul: Final MCS commanded according to availability of jokers on Agprs to serve all MS in the TDMA

• Max number of jokers required from max commanded MCS per TS

• Max commanded MCS per TS changes every time• New allocation• New release• LA due to changing radio environment• PUAN message to the MS triggering backhaul

optimization

1

2

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Existing V14.3 FeatureCCCH management at the BTS level

> Without this feature, all GPRS Channel Request are managed by the PCU

> with this feature, some GPRS radio blocks are managed by the BTS, which can allocate single radio block, in case of GPRS Channel Request

PCU BSC BTS MSChannel Request

Immediate Assignment

PCU BSC BTS MSChannel Request

Immediate Assignment

Packet Resource Request

Packet Resource Request

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Nortel GPRS Performance Enhancement One phase / two phases access

> Two phases access :• the MS sends a “two phases access” Channel Request,• at reception of a two phases access, the BSS allocates one

uplink block, • the MS uses this block, in order to require more blocks.• 1st phase allocation is handle by BTS with CCCH@BTS

activated

> One phase :• The MS sends a “one phase access” Channel Request• BTS forward Channel Request to PCUSN• At reception of a one phase access at the PCUSN, the BSS

allocates one resource for UL transfer until completed• A saving of 270ms on TBF establishment

One phase Access is only available for GPRS MS in this release. It will be available for EDGE MS in the following releases.

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EDGE RF Optimization concerns


E-GPRS Optimization Approach> E-GPRS end user quality of service is impacted by the

cumulative effect of various parameters. The picture below shows the contributing factors to the end user throughput.

End user throughput

BLER at Air I/F:Retransmission

rate

Radio Environment& parameters• C/I, Eb/No• Link Adaptation• RF features

Delay of celltransition

Mobility• RA update• Cell update• C1 & C2

Available bandwidth per user

Dimensioning parameter

• Nbr of active users/cell

• Nbr of E-GPRS TS/Cell

• Call Profile,MS capability

• Joker DS0’s• Abis / Agprs / Gb dim.

End to End Performance,

Core ntwrk delays

Core network performance

• IP delays• Session Performance• Nodes performance

Establishment Times for TBF

BTS / PCUSNE-GPRS ParamsAudit• Rec. values


Optimization / Access Parameter Audit> Access parameter audit would be the first point of starting the E-

GPRS optimization.• In most cases, these timers and counter max values thresholds should

be set at the recommended values, which are determined after testing and provided in the parameter guides.

• However certain peculiar situations and applications may require a study to determine more optimal values.

> BTS / PCUSN RLC / MAC & TBF params• Need to ensure the various timers and counter max thresholds pertaining

to the RLC / MAC layer and TBF establishments are set according to the recommendations.

> PCUSN BSSGP / NS / FR params• Need to ensure the various timers, counter max thresholds & parameters

pertaining to the BSSGP layer (BSS GPRS protocol: BVC’s and flow-control), NS layer (Network service : NSVC’s) and FR layer (Frame Relay) are set according to the recommendations.

HAIDERMA

Highlight

HAIDERMA

Highlight


Optimization / Radio Environment

> Coverage / Frequency plan• Adequate RF coverage & coverage overlap.

• Improvement in C/I through a good frequency plan. This, in turn,reduces the BLER and increases the throughput

• In the beginning, E-GPRS TS’s are preferred in the BCCH TDMA

> Coding scheme / Link Adaptation• For given radio conditions, there is a trade-off for selecting the

appropriate coding scheme

• The relationship of maximum BLER for each MCS with the C/I values can be found with the use of simulation graphs

• The throughput for each MCS can then be estimated based on the BLER values giving a relationship between C/I and throughput

HAIDERMA

Highlight


GPRS/EDGE Engineering RF Design

•Minimise impacts on the actual network & see what can be carried by this network

•Specify a minimum designed throughput

C/I Eb/NoOptimum coding scheme

Minimum Designed Throughput

Service areas

Optimum coding schemeMinimum Designed Throughput

C/I Eb/No

2 design approaches:


E-GPRS and speech share the same hopping frequency plan channels

E-GPRS and speech share the same hopping frequency plan channels

> E-GPRS introduction in GSM network and spectrum optimization

Design / Frequency Plan Evolution

E-GPRS and speech use different hopping

frequency plan channels

E-GPRS on non-hopping TRXs

E-GPRS on BCCH TRXs

High EGPRSLoad

Low EGPRSLoad

Tight Spectrum Wide Spectrum


860 688 516 344 172 0 172 344 516 688 860860

688

516

344

172

0

172

344

516

688

860

55

55

55

55

50

50

50

50

45

45

45

45

45

40

40

40

40

40

40

35

35

35

35

35

3530

30

30

30

30

3030

30

25

25

25

25

2020

2020

Cumulative Averaged Throughput

AT

1

10

100

-10 0 10 20 30

C/(I+N) (dB)

BLER

(%)

MCS1MCS2MCS3MCS4MCS5MCS6MCS7MCS8MCS9

BLER = f (C/(I+N))TU 50, 1900 MHz, without Frequency Hopping, without IR

cell range

Offered throughput

0

Excellent QoS Poor QoS

Max

> Throughput varies with : BLER

> BLER vary with : C/I and Eb/No

⇒ For each (C/I, Eb/No), offered throughput can be predicted

RF Environment: GPRS/EDGE Throughput


> Throughput highly depends on radio quality (distance from cell center and interferences).

Link Adaptation adapts the MCS based on the variable radio conditions.

0 5 10 15 20 25 30 350

10

20

30

40

50

60

MCS2MCS3MCS5MCS6MCS7MCS8MCS9

Throughput=f(C/I) URBAN IFH

C/I

Thro

ughp

ut (k

b/s)

RF Environment: Link Adaptation & Throughput

EffectiveThroughput =

MaxThroughput*

(1-BLER)*TS_allocated

•EDGE application user throughput vs. BLER

Need to choose the MCS with the best “effective”payload for a given C/I

HAIDERMA

Highlight


Optimization / Mobility Parameters

> Cell update• No handover mechanism in E-GPRS• During a E-GPRS transfer, a change from one cell to another requires

the TBF to be released from the old cell and a new establishment on the new cell

• This results in extra signaling and a break in data flow• The cell selection procedure is similar to GSM idle cell

re-selection with the exception that, in the GMM ready state, the cell reselect hysteresis value is used in all cell selections instead of LAC boundary ones only. (C1 and C2 values could be modified)

• C2 criteria can be used to control unnecessary reselections especially in high mobility areas

> RA update• RA optimization will may be required to provide a trade-off

between RA updates and paging load

HAIDERMA

Highlight

HAIDERMA

Highlight

HAIDERMA

Highlight

HAIDERMA

Highlight


Optimization / Air-Interface Dimensioning

> CCCH signaling load• Every release of TBF due to cell boundary change or RLC/MAC

drop will require a new establishment on CCCH• Increased activity on AGCH

• May need to dimension additional CCCH due to congestion

• CCCH on BTS feature

• Paging may not be increased significantly (since no page in ready state and mostly MS initiated transfers)

• But DRX parameters still used for by GPRS MS during standby/Ready state

• NoOfMultiFramesBetweenPaging has impact on DL TBF establishment as MS will only listen to CCCH and thus AGCH of its own paging group for any immediate assignment message

• Use of non-DRX timer

HAIDERMA

Highlight


Optimization / Air-Interface Dimensioning

> Radio dimensioning is done on a per cell basis • E-GPRS radio interface dimensioning consists of evaluating the number of time

slots required to deal with the amount of data carried during the network busy hour

• Voice pre-emption will reduce the bandwidth and thus data throughputs.

Estimate EGPRS TS/cellEstimate EGPRS TS/cell

E-GPRS product performance in terms of BLER

Real user throughput of 1 GPRS timeslot

Average throughput required in a cell

E-GPRS Timeslot requirement in a cell


EDGE Bandwidth Considerations

BSC

BTS

VLRVLRVLRLPP PSTNTCU

DTCDTCDTC

DMS-MSC

Abis Dynamic Agprs

A

Ater

SGSN

Gb

>Gb over IP

> PCUSN 36 T1/ 32 E1PCUSN 54T1/E1

>Optical BSC3000

> High Cap/DensityAll-freq support

> Optimized Abis

Air Interface TSJoker DS0s and Abis BSC Switching capabilityJPMT and AgprsGb links


Optimization / Back-Haul Dimensioning

> Back Haul Dimensioning• Higher Coding scheme usage in EDGE requires more

resources on the backhaul.

• Abis resources need to be correctly allocated in order to guarantee the higher throughputs of EDGE.

• Use of Dynamic Abis / Joker DS0’s

• Agprs resources need to be correctly dimensioned as well. • Use of Dynamic Agprs

• Gb interface should have enough bandwidth so that it doesn’t become a bottleneck at peak usage hours.

• Additional DS0’s are a must in order to achieve throughputs beyond what is offered by MCS-2.


Optimization / Core Network Audits

> A big percentage of issues could be related to the Core Network performance as well.• SGSN / GGSN / Gb / Gn / Gi performance

• Public Data Network delays

• Issues on the TCP/IP layers pertaining to the user device & remote server

• Other Application layer problems transparent to the EGPRS network

> May need to put protocol analyzers at multiple interfaces for trouble-shooting purposes

• Any problem on any of the nodes may be perceived as bad throughput on the air interface by the end users.


Backup SlidesNew V15 EDGE counters


V15 / EDGE Counters summary

95 countersTOTAL

5 countersNMO1

3 countersOne Phase Access

7 countersGPRS monitoring improvement

9 countersEDGE Traffic profile and throughput

4 countersLack of EDGE Radio Resource

3 countersEDGE Abis

13 countersGPRS/EDGE Agprs

42 countersEDGE Link Adaptation Tables Fine tuning

9 countersEDGE Radio Quality


EDGE monitoring: EDGE Radio Quality

> To characterize the UL/DL radio quality for EDGE: • UL MEAN_BEP • DL GMSK MEAN_BEP• DL 8-PSK MEAN_BEP

> 9 countersTDMAAVG15104/0pcuEdgeUpAvgMeanBep

TDMAAVG15103/0pcuEdgeDnAvgGmskMeanBep

TDMAAVG15102/0pcuEdgeDnAvg8PskMeanBep

TDMANBS15104/0pcuEdgeUpNbsMeanBep

TDMACUM15104/0pcuEdgeUpCumMeanBep

TDMANBS15103/0pcuEdgeDnNbsGmskMeanBep

TDMACUM15103/0pcuEdgeDnCumGmskMeanBep

TDMANBS15102/0pcuEdgeDnNbs8PskMeanBep

TDMACUM15102/0pcuEdgeDnCum8PskMeanBep


EDGE monitoring: EDGE Link Adaptation Tables Fine tuning

> To characterize• the UL/DL radio BLER per

MCS • The UL/DL effective

throughput per MCS • The UL/DL MCS

downgraded due to non-Radio limitations (backhaul or GPRS/EDGE multiplexing)

> 42 counters

TDMACUM15162/0pcuEdgeUpTransmittedMcsX

X=2,3,5 tp 9

TDMACUM1513X/0pcuEdgeDnTransmittedMcsX

X=2,3,5 tp 9

TDMACUM1518X/0pcuEdgeLAUpTargetedTransmittedMcs2

X=2,3,5 tp 9

TDMACUM1517X/0pcuEdgeMcs2RequestRetransDataBlockUp

X=2,3,5 tp 9

TDMACUM1515X/0pcuEdgeLADnTargetedTransmittedMcs2

X=2,3,5 tp 9

TDMACUM1514X/0pcuEdgeMcsXRequestRetransDataBlockDn

X=2,3,5 tp 9

• pcuEdgeMcsXRequestRetransDataBlockDn\Up= All Dn\Up blocks sent in MCSX and nacked

• pcuEdgeLADn\UpTargetedTransmittedMcsX= All Dn\Up blocks LA-commanded in MCSX and sent in MCSX

• pcuEdgeDn\UpTransmittedMcsX= All Dn\Up blocks sent in MCSX


GPRS/EDGE monitoring: Agprs

> To characterize• The number of Agprs

Jocker TS allocated to the cell by the BSC

• The UL/DL AGPRS PCM resource occupancy

• The cell load and the number of allocated AgprsTS for the dynamic Agprs

> 13 counters

CELLNBS15076/0pcuDyAgprsLoadCriterionNbs

CELLCUM15076/0pcuDyAgprsLoadCriterionCum

CELLNBS15075/1pcuDyAgprsNbTimeslotsNbs

CELLCUM15075/1pcuDyAgprsNbTimeslotsCum

CELLCUM15128/0pcuEdgeAgprsJokerNbofBlocksUp

CELLCUM15127/0pcuEdgeAgprsMainNbofBlocksUp

CELLCUM15119/0pcuEdgeAgprsJokerNbofBlocksDn

CELLMAX15118/0pcuEdgeDynAgprsJokerMaxNbTimeslot

CELLMIN15118/0pcuEdgeDynAgprsJokerMinNbTimeslot

CELLAVG15118/0pcuEdgeDynAgprsJokerAvgNbTimeslot

CELLNBS15118/0pcuEdgeDynAgprsJokerNbsNbTimeslot

CELLCUM15118/0pcuEdgeDynAgprsJokerCumNbTimeslot

CELLCUM15110/0pcuEdgeAgprsMainNbofBlocksDn


EDGE monitoring: Abis

> To detect a lack of EDGE Abis PCM jockerTS

> 3 countersTDMAAVG15129/0pcuEdgeLackAbisJokerTSAvg

TDMANBS15129/0pcuEdgeLackAbisJokerTSNbs

TDMACUM15129/0pcuEdgeLackAbisJokerTSCum


EDGE monitoring: Lack of EDGE Radio Resource

> To detect a lack of EDGE resource configured in the cell

> 4 counters CELLAVG15111/0pcuEdgeDowngradedTbfAvg

CELLNBS15111/0pcuEdgeDowngradedTbfNbs

CELLCUM15122/0pcuEdgeTbfEstReq

CELLCUM15111/0pcuEdgeDowngradedTbf


EDGE monitoring: Traffic profile and throughput

> To characterize• The UL/DL EDGE

effective RLC/MAC throughput in the cell without BLER impact

• The EDGE to GPRS data traffic ratio

• The UL/DL EDGE to GPRS data transfer duration ratio

• The average UL/DL TBF duration

> 9 counters

CELLAVG15113/0pcuEdgeDnAvgUsefulDataPerCell

CELLNBS15113/0pcuEdgeDnNbsUsefulDataPerCell

CELLAVG15112/0pcuEdgeUpAvgUsefulDataPerCell

CELLNBS15112/0pcuEdgeUpNbsUsefulDataPerCell

CELLCUM15124/0pcuEdgeDnUsefulDataDurationPerCell

CELLCUM15123/0pcuEdgeUpUsefulDataDurationPerCell

CELLCUM15113/0pcuEdgeDnCumUsefulDataPerCell

CELLCUM15112/0pcuEdgeUpCumUsefulDataPerCell

TDMACUM15101/0pcuEdgeDataBlocksReceivedUp


GPRS monitoring improvement

> To characterize• The UL/DL GPRS

effective RLC/MAC throughput in the cell without BLER impact

• The number of GPRS UL pipes greater than 22 kbps

• The number of DL TBF pre-established with LLC frames transmitted

> 7 counters

CELLCUM15195/0pcuDnPreEstWithLLCFrameTransmitted

CELLCUM15194/0pcuUpPipeGreater22kbps

CELLAVG15193/0pcuUpThroughputAvg

CELLNBS15193/0pcuUpThroughputNbs

CELLCUM15193/0pcuUpThroughputCum

CELLNBS15007/1pcuDlThroughputNbs

CELLCUM15007/1pcuDlThroughputCum


NMO1

> To characterize • the NMO1 gain by

allowing the transmission of CS-paging messages towards GPRS/EDGE MS in Packet Transfer Mode

• To get the ratio between PS-paging messages and CS-paging messages on Gb I/f.

> 5 counters

PCMCUM15073/1csPaging

PCMCUM15073/0psPaging

LAPDCUM15023/1PsPagingOnCcch

LAPDCUM15024/0CsPagingOnPacch

LAPDCUM15023/0CsPagingOnCcch


One Phase Access

> To characterize• The part of the GPRS and

EDGE One-Phase access RACH load compared to the total RACH load (GSM included).

• The allocation failure ratio during the One-Phase access half-duplex UL TBF establishment.

• The contention failure ratio of a One-Phase access half-duplex UL TBF establishment.

> 3 counters

CCCHCUM15192/0pcuContentionFailureOnePhase

CCCHCUM15191/0pcuUpTbfImmediateAssignmentOnePhase

CCCHCUM15190/0pcuChannelRequestOnePhase


Technology

Nortel v15 edge_training2