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
2 Nortel Confidential Information
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
4 Nortel Confidential Information
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
Envelope (amplitude)
22.5° offset
5 Nortel Confidential Information
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
6 Nortel Confidential Information
8-PSK- TX Power Reduction
GMSK
8PSK
Time
Envelope (amplitude)
Time
Envelope (amplitude)
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
7 Nortel Confidential Information
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
8 Nortel Confidential Information
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
Nortel Confidential Information
> 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
10 Nortel Confidential Information
> 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
Nortel Confidential Information
> 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
12 Nortel Confidential Information
> 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)
13 Nortel Confidential Information
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.
14 Nortel Confidential Information
15 Nortel Confidential Information
16 Nortel Confidential Information
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
17 Nortel Confidential Information
18 Nortel Confidential Information
19 Nortel Confidential Information
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)
20 Nortel Confidential Information
> 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
21 Nortel Confidential Information
22 Nortel Confidential Information
• 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
23 Nortel Confidential Information
24 Nortel Confidential Information
25 Nortel Confidential Information
> 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
Nortel Confidential Information
> 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
27 Nortel Confidential Information
> 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
28 Nortel Confidential Information
> 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
29 Nortel Confidential Information
30 Nortel Confidential Information
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
31 Nortel Confidential Information
32 Nortel Confidential Information
33 Nortel Confidential Information
Nortel Confidential Information
> 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
35 Nortel Confidential Information
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
36 Nortel Confidential Information
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
37 Nortel Confidential Information
Nortel Confidential Information
> 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• EDGE/GPRS RLC Polling Improvements• Asynchronous PCU/BTS interface
> Backhaul Optimization• Dynamic Abis / Agprs
> Bandwidth Optimization• GPRS/EDGE Multiplexing• TS Sharing w/ Voice Pre-emption
Nortel EDGE Software SolutionsIntroducing Advanced Features
39 Nortel Confidential Information
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
Nortel Confidential Information
> 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• EDGE/GPRS RLC Polling Improvements• Asynchronous PCU/BTS interface
> Backhaul Optimization• Dynamic Abis / Agprs
> Bandwidth Optimization• GPRS/EDGE Multiplexing• TS Sharing w/ Voice Pre-emption
Nortel EDGE Software SolutionsIntroducing Advanced Features
41 Nortel Confidential Information
• 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
42 Nortel Confidential Information
Nortel EDGE Software SolutionsRTD Approaching 600ms in V15.0
FeatureRelease
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
43 Nortel Confidential Information
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 Confidential Information
> 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
45 Nortel Confidential Information
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.
46 Nortel Confidential Information
> 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
47 Nortel Confidential Information
> 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
48 Nortel Confidential Information
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
Nortel Confidential Information
> 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
50 Nortel Confidential Information
> 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
51 Nortel Confidential Information
> 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
52 Nortel Confidential Information
> 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
53 Nortel Confidential Information
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
54 Nortel Confidential Information
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
55 Nortel Confidential Information
> 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
56 Nortel Confidential Information
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.
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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
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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
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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.
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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
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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:
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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
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860 688 516 344 172 0 172 344 516 688 860860
688
516
344
172
0
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516
688
860
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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
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> 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
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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
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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
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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
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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
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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.
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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.
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Backup SlidesNew V15 EDGE counters
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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
76 Nortel Confidential Information
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
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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
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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
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EDGE monitoring: Abis
> To detect a lack of EDGE Abis PCM jockerTS
> 3 countersTDMAAVG15129/0pcuEdgeLackAbisJokerTSAvg
TDMANBS15129/0pcuEdgeLackAbisJokerTSNbs
TDMACUM15129/0pcuEdgeLackAbisJokerTSCum
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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
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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
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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
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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
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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
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