Practical case studies(E)GPRS Advanced
(E)GPRS Advanced – Case Studies
Bad EDGE Performance
Low EDGE throughput
* © Nokia Siemens Networks Presentation / Author / Date
High EDGE UL TBF Establishment Failure
During EDGE optimization project one BSC – BSC01 – was having high EDGE UL TBF failure rate (10-20 %)
Next slide shows daily statistics over BSC
Problem was constant before BSS parameter change (27.10) – no other changes were made at the same day.
Question: What parameter was changed?
* © Nokia Siemens Networks Presentation / Author / Date
BSC01 – TBF Failure Rate
High TBF Establishment Failure - Answer
In project MCA was set to 6
27.10 MCA was changed to 3
Network had coverage limitations
Changing MCA to 3 changed initial MCS modulation type from 8-PSK to GMSK
More robust coding scheme helped in initial connection against coverage and interference
* © Nokia Siemens Networks Presentation / Author / Date
Bad EDGE Performance
Operator was complaining bad EDGE performance in general in specific area based on customer complaints
Following performance problems were found
Low GPRS attach ratio
Problem had emerged during last few months for specific area
What could be behind all problems?
* © Nokia Siemens Networks Presentation / Author / Date
Bad EDGE Performance
BSS parameters were audited and everything were set as defaults – no problems found
Radio interface
Maximum hard blocking in cells for data around 5% (tbf_16)
Abis interface
EDAP usage was seen high for some busy DAPs
Bad performance was observed from drive tests where RLC download were having breaks although there were no cell reselections
Note – High EDAP usage cannot cause any end-user blocking
* © Nokia Siemens Networks Presentation / Author / Date
Bad EDGE Performance
* © Nokia Siemens Networks Presentation / Author / Date
Bad EDGE Performance
High Gb utilization was limiting traffic and causing bad performance
90% Gb link load = Gb link used 90% of time with CIR 128 kbit/s
Data through Gb link during one hour = 0.9*128Kbit/s*3600s - 400 Mbit
In the worst case high Gb link utilization was causing real user blocking
Solution
Increase radio interface capacity
Unstable and Low EDGE Throughput
During EDGE trial throughput problems were seen in laboratory environment
Laboratory environment
Tested application was FTP, file size 2 Mb
4 RTSL MS – average throughput 120 - 160 kbit/s
Several downloads
* © Nokia Siemens Networks Presentation / Author / Date
Unstable and Low EDGE Throughput - Configuration Data
* © Nokia Siemens Networks Presentation / Author / Date
Unstable and Low EDGE Throughput - Configuration Data
* © Nokia Siemens Networks Presentation / Author / Date
Low EDGE Throughput Measurement – FTP Throughput Example
* © Nokia Siemens Networks Presentation / Author / Date
Low EDGE Throughput Measurement
Answer – PRFILE parameter problems
Polling intervals were not frequent enough
* © Nokia Siemens Networks Presentation / Author / Date
Exercise
Please list all factors which can affect to EDGE throughput and which do not relate to BSS/packet core network
Network capacity (all elements and interfaces) and all network parameters are assumed to be optimal
No congestion
Answer to Exercise
Simultaneous other programs
Used method for throughput verification
RLC, LLC or application throughput
Program used for measurement - MSDOS or throughput application– how throughput will be calculated?
Mobile terminal
Tested file size should be large enough (>2 MB)
HLR parameters (CS core)
0029
0028
0027
0026
0025
0024
0023
0022
0021
0020
Num.
B
B
B/s
B/s
B
B
B/s
B/s
B
% (/10)
Unit
Default Flow Control Parameters
0029
0028
0027
0026
0025
0024
0023
0022
0021
0020
Num.
B
B
B/s
B/s
B
B
B/s
B/s
B
% (/10)
Unit
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
Date
10.13
10.14
10.15
10.16
10.17
10.18
10.19
10.2
10.21
10.22
10.23
10.24
10.25
10.26
10.27
10.28
10.29
10.3
10.31
11.01
11.02
11.03
11.04
11.05
11.06
11.07
11.08
11.09
11.1
11.11
11.12
11.13
11.14
GPRS_UL_TBF_EST_FAILURE
GPRS_DL_TBF_EST_FAILURE
EDGE_UL_TBF_EST_FAILURE
EDGE_DL_TBF_EST_FAILURE
UL_TBF_LOST
DL_TBF_LOST
UL_TBF_EST_FAILURE
DL_TBF_EST_FAILURE
E P B
F T R C D -CHANNEL BUSY
ADM OP R ET - BCCH/CBCH/ R E S O&M LINK HR FR
===================== === ====== ==== == ==== =========== = = = ===== == === ===
N 7
EDGE TRX-002 L BL-USR 848 0 36 2
COMMAND EXECUTED
TRANSCEIVER DATA
ADM.STATE OP.STATE
GTRX Y
FREQ 844 TSC 0 FRT 0 (REGULAR) LEV N (NOT USED)
BFREQ - BTSC - BFRT - BLEV -
DAL N (NOT USED) DAP 1 LEVD N (NOT USED)
BDAL -
RTSL PCM-TSL SUB_TSL TYPE I.LEV ADM.STATE OP.STATE CH.STATUS
------------------------------------------------------------------------------
1 36- 1 1 TCHF 0 UNLOCKED WO GP
2 36- 1 2 TCHF 0 UNLOCKED WO GP
3 36- 1 3 TCHF 0 UNLOCKED WO GP
4 36- 2 0 TCHF 0 UNLOCKED WO GP
5 36- 2 1 TCHF 0 UNLOCKED WO GP
6 36- 2 2 TCHF 0 UNLOCKED WO GP
7 36- 2 3 TCHF 0 UNL OCKED WO GP
LOADING PROGRAM VERSION 7.5 -0
BSC BSCNAME 2005-04-07 14:13:32
Parameter Parameter class/id (Before)(After)