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1. PRO XL Radio Network Design and Optimisation
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EFR Implementation
Executive Summary
EFR feature is one of feature that have been released in system release R6.1. The purpose of EFR is to give
enhanced speech quality whitin same bandwidth that is used for Full Rate Traffic channel. Beside improve
speech quality, EFR also improve retainability of radio connection againts to rxqual.
Technical Description
The Enhanced Full Rate feature is based on a new speech codec and changes to the signalling protocols.
These are implemented in accordance with the ETSI GSM Phase 2+ standards for GSM900/GSM1800 and in
accordance to the ANSI standard for GSM1900.
EFR is supported by RBS 2000 and for GSM900/GSM1800 also by RBS 200 (SPP, SPU+ and SPU+/SPE).
TRA R4, TRA R5 or newer versions, with software for the new speech encoding/decoding algorithms is
required. Changes to the signalling on the BSS interfaces to cater for new speech codecs has also been
implemented. The feature "Dynamic Allocation of Transcoder Resources" is a prerequisite for EFR. The
transcoder resource supporting the relevant speech codec, for example EFR, will be selected on a per call
basis depending on the MS capabilities.
Support for EFR is also required in the mobile stations.
The MS already supported by EFR ( MS Phase 2) will automatically use EFR when it performs Call setup
(Making a call). MSC/VLR selects an initial speech coder according to the first choice of the list (EFR set to
first priority) to ensure the MS always get EFR as long as it available at BSC.
The outcome of the algorithm is a Speech Quality Index that is measured in the MNRU scale dBQ which is
an absolute scale for measuring speech quality. The output values are from -20 to +30 and the higher value
the better speech quality.The algorithm in the base station calculates a value between -20 to +30 dBQ. The
top value is dependent on the speech codec that is used since the different codecs have different basic speech
quality (EFR has top value 30, fullrate 20 and halfrate 17 dBQ).
Impovement EFR implementation based on MOS value and Performance Comparison :
Subjective speech quality
GSM
FR
GSM
HR
GSM
EFR
Clean conditions (MOS) 3.71 3.85 4.43
Vehicle noise (DMOS) 3.83 3.45 4.25
Street noise (DMOS) 3.92 3.56 4.35
Source: TR 06.85 v5.0.0 (1998-07), "Subjective tests on the interoperability of the HR/FR/EFR speech codecs; single,
tandem and tandem free operation

2. PRO XL Radio Network Design and Optimisation
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Marketting Issues
Further investigation to check how far the speech quality improvement that perceived by customer with
taking sample of measurement from customer or identify MOS value as perceived by customer.
Result of Measurement
Benchmarking Result between MS EFR and FR on XL network on Friday 22, Augsut 2003
GSM
Handset Rx Qual Sub >= 3 SQI > 20
FR GSM 95.29243937 89.32316
EFR GSM 93.62192623 97.24317
Significant improvement on SQI level with EFR feature eventhough on bad rxqual.
Benchmarking Result between ProXL, Telkomsel and Satelindo on Thursdar –Friday 14-15, August 2003
Network
Measurement of
Density RxQualSub <
4
Measurement of
Density RxLevel Sub
> -69 dBm
Measurement of Density
RxLevel Sub> -80 dBm
SQI
Level>20
SQI
Level
>16
HO
Succ
Satelindo 80.62% 41.84% 81.04% 90.09% 93.60% 97.28%
Telkomsel 89.46% 37.46% 72.73% 86.15% 94.65% 98.94%
ProXL 92.06% 45.12% 80.17% 86.23% 94.13% 99.02%
Satelindo is best rated on SQI ( provide best Voice Quality) eventhough worst on rxqual, Excelcomindo is
best rated in Rxqual that show better frequency plan and network design. But better rxqual is not guarantee
good voice quality that perceived by customer.
Conclusion
Based on drive test result measurement that performed after activated EFR at BJKT 5 with capacity 10%
EFR.
• Some call setup failure occured on EFR Handset due to EFR congestion that showed need higher
EFR capacity and most of customer already used handset EFR.
• Improve Speech Quality Index with top value until 30
• Radio connection more retain againts to rxqual.
• SQI is a more sophisticated measure which is dedicated to reflecting the quality of the speech (as
opposed to radio environment conditions). This means that when optimizing the speech quality in
your network, SQI is the best criterion to use, because not too good to represent for all GSM system
such as frequency hopping.
• Standard measurement equipment such as TEMS record FER, this can be used to judge audio quality
and correlates better than BER which is normally used. Ericsson recently included SQI which is
based on BER, FER and includes handover delays.
• If the FER is too high, the audio codec will mute until the FER decreases
• If the FER is too high, the audio codec will mute until the FER decreases Enhanced Audio codecs
also have background noise suppression algorithms andsometimes adaptive gain.
• Further investigation wheter improve dropcall performance is still required.

3. PRO XL Radio Network Design and Optimisation
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Speech Quality Index (SQI)
SQI is an objective, transmission-based integrity measure for performance evaluations, presented in dBQ.
Based on radio link parameters, it is independent of transmitter signal and can provide better performance
than PSQM (a speech-based method) and much better performance than RxQual, when used for network
tuning. By optimizing the radio network towards SQI, a better network with higher average speech quality
will be achieved. In short, SQI can be defined as a speech quality measure with these characteristics:
• Of Integrity;
• Objective;
• Absolute;
• Non-intrusive;
• Radio-Link based;
• One-way/Listening only;
• Continuous Real-time score;
• Benchmark capable1
.
Traditionally, speech quality in GSM networks is measured by means of the RxQual parameter (which is also
available in TEMS Investigation). RxQual, however, suffers from a number of drawbacks which make it an
unreliable indicator of speech quality. SQI is a more sophisticated measure which is dedicated to reflecting
the quality of the Speech (as opposed to radio environment conditions). This means that when optimizing the
speech quality in your network, SQI is the best criterion to use.
SQI has been designed to take into consideration all the phenomena discussed in the preceding section. This
ensures that it will produce an unbiased prediction of the speech quality, independently of channel conditions
and other circumstances. Somewhat roughly, the computation of. SQI involves
• the bit error rate (BER)
• the frame erasure rate (FER)
• data on handover events
• statistics on the distributions of each of these parameters.
For this report, SQI has been divided into Good (scores ≥ 22.0), Fair (16.0 > scores ≥ 22.0) and Bad (scores
< 16.0) . SQI Scores range from –20 dBQ to 30 dBQ. The percentages of the total number of SQI scores
that have been categorized as Good, Fair or Bad are summarized for each carrier as follows:
SQI Occurrence Summary
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
90.0%
100.0%
FRMS
GSM
EFRMS
GSM
SQI >= 22 22 > SQI >= 16 SQI < 16
1
Karlsson, Heikkila et al.: Radio Link Parameter Based Speech Quality Index – SQI, IEEE Workshop on Speech
Coding, 1999.

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The Probability and Cumulative Density Function Charts for the tested carriers are shown below.
SQI (All Carriers)
Probability Density Function (PDF)
0
500
1000
1500
2000
2500
3000
3500
4000
30.00
to
28.00
26.00
to
24.00
22.00
to
20.00
18.00
to
16.00
14.00
to
12.00
10.00
to
8.00
6.00
to
4.00
2.00
to
0.00
-2.00
to -
4.00
-6.00
to -
8.00
-10.00
to -
12.00
-14.00
to -
16.00
-18.00
to -
20.00
SQI R ange
EFR MS
GSM
FR MS
GSM
SQI (All Carriers)
Cumulative Distribution Function (CDF)
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
90.0%
100.0%
30.00
to
28.00
26.00
to
24.00
22.00
to
20.00
18.00
to
16.00
14.00
to
12.00
10.00
to
8.00
6.00
to
4.00
2.00
to
0.00
-2.00
to -
4.00
-6.00
to -
8.00
-10.00
to -
12.00
-14.00
to -
16.00
-18.00
to -
20.00
SQI R ange
EFR MS
GSM
FR MS
GSM

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The SQI scores are summarized in the following table.
Range
FR MS
GSM
EFR MS
GSM
30.00 to 28.00 0 3530
28.00 to 26.00 0 81
26.00 to 24.00 0 59
24.00 to 22.00 0 37
22.00 to 20.00 3748 32
20.00 to 18.00 146 13
18.00 to 16.00 47 12
16.00 to 14.00 77 11
14.00 to 12.00 46 13
12.00 to 10.00 20 18
10.00 to 8.00 22 12
8.00 to 6.00 24 5
6.00 to 4.00 32 6
4.00 to 2.00 19 5
2.00 to 0.00 4 4
0.00 to -2.00 1 0
-2.00 to -4.00 3 2
-4.00 to -6.00 2 0
-6.00 to -8.00 1 1
-8.00 to -10.00 2 2
-10.00 to -12.00 1 2
-12.00 to -14.00 1 0
-14.00 to -16.00 0 0
-16.00 to -18.00 0 0
-18.00 to -20.00 0 0
Total 4196 3845
Rx Qual Sub Distribution MS1 EFR GSM

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Rx Qual Sub Distribution MS2 FR GSM
Rx Qual Sub Distribution MS1 EFR GSM and MS2 FR GSM
The Probability and Cumulative Density Function Charts for the tested carriers are
shown below
0
10
20
30
40
50
60
70
80
90
100
0 1 2 3 4 5 6 7
Rx Qual Sub Range
Percentage
FR EFR

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Measurement Chart that show RxQual vs Radio linkTimeout before drop call even on EFR Handset and FLP
:
Measurement Chart that show RxQual vs Radio linkTimeout before drop call even with FR Handset: