Post on 12-Oct-2015
5/21/2018 PCU Info Session v1
1/26Company Confidential1 2005 Nokia PCU dimensioning / Raquel Sanchez
PCU dimensioning
BSS10.5/BSS11(PCU1)
Raquel Sanchez,
NET/Services/OSPP France
5/21/2018 PCU Info Session v1
2/26Company Confidential2 2005 Nokia PCU dimensioning / Raquel Sanchez
Agenda
I. Introduction to the problem
II. Practical PCU dimensioning guidelines for BSS10.5and BSS11
III. Results of new dimensioning
IV. Conclusions
Annex1: PCU Technical Detailscause of the problemMixed EDGE and GPRS configurations in S10.5
and S11 releases
Annex2: Simple dimensioning example
5/21/2018 PCU Info Session v1
3/26Company Confidential3 2005 Nokia PCU dimensioning / Raquel Sanchez
DL FTP maximum performance degradationPCU capacity
BSS10.5-PCU1
NET/Services/OSPP France
5/21/2018 PCU Info Session v1
4/26Company Confidential4 2005 Nokia PCU dimensioning / Raquel Sanchez
Introduction : Performance Degradation
DL FTP Application Throughput - Per Point Analysis
181.50
200.56
142.56
194.35201.92
174.24171.54
200.56
113.36
194.10201.60
168.00
0.00
50.00
100.00
150.00
200.00
250.00
Average Maximum Minimum
kbps
Point 1 Point 2 Point 3 Point 4
There are some cells in the EDGE Golden Cluster where maximum performance was not
achieved
Perfect radio conditions (not interferences, RxLevel > -70dBm, RxQual = 0)
Not other users in the area (country side area)CDED= 4 TSLs, EDAP= 8 TLSs, Gb= 8 TSLs
Committed performance > 195 kbps(average)
Achieved performance 185.37 kbps (average)
DL FTP Application Throughput - Summary
185.37
201.92
113.36
0.00
50.00
100.00
150.00
200.00
250.00
Average Maximum Minimum
k
bps
Best
conditions
There were clearly twopoints performing worse:Point 1 and Point 3.
5/21/2018 PCU Info Session v1
5/26Company Confidential5 2005 Nokia PCU dimensioning / Raquel Sanchez
Analysis of the observed performance degradation
DL FT P Perf.Cond. 20-06-2005
Average DL M CS distribution
based on BSS counters - EosFlex
0.00
10.00
20.00
30.00
40.00
50.00
60.0070.00
80.00
90.00
100.00
MCS_1 MCS_2 MCS_3 MCS_4 MCS_5 MCS_6 MCS_7 MCS_8 MCS_9
%
Point 4 Point 2 Point 1 Point 3
DL FTP Perf.Cond. 20-06-2005
PCU statistics
Network Doctor report 280
0
20000
40000
6000080000
100000
120000
140000
160000
180000
200000
Point 2 Point 4 Point 1 Point 3
Nr.
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
TBF with inad eq EDAP DL TBF wi tho ut ED AP D L Usag e(% ) D L Pe ak
MCS distribution shows that in the points with worse
performance MCS is downgraded. There is 31-36% MCS-
7.
Downgrading of MCS causes lower throughput for
end-users.
ND280 shows that in the points with worse performancethe connections are served with inadequate resources due
to lack of resources in EDAP/PCU.
EDAP usage is never 100%, is more like that
there is lack of resources in the PCU (DSPs).
End user performance
5/21/2018 PCU Info Session v1
6/26
Company Confidential6 2005 Nokia PCU dimensioning / Raquel Sanchez
Conclusions (I)
Based on statistics analysis, PCU traces and detailed study of PCU functionality:
The PCU is being the limiting factor in some cells of EDGE Golden Cluster to get maximum
performance.
SFR has a very specific configuration that may need extra considerations in EDGE
dimensioning:
Mixed GPRS and EDGE cellsEDGE is only activated in some spots.
Width default territory in the radiominimum 4 TSLs default territory in all the cells -> Thisconsumes PCU internal resources even when there is not traffic.
Maximum performance requirements (195kbps application throughput).
These mixed configurations require more restrictive PCU dimensioning to avoid PCU
being the limiting factor of the user performance in BSS10.5 and S11.
5/21/2018 PCU Info Session v1
7/26
Company Confidential7 2005 Nokia PCU dimensioning / Raquel Sanchez
Conclusion (II): Dimensioning strategies
In BSS10.5 and S11 PCU dimensioning can be done following two different strategies:
Maximizing the performance of EDGE in mixed EDGE and GPRS configurations
new PCU dimensioning rule for BSS10.5 & BSS11 FOCUS of this presentat ion!
Maximum connectivity
In mixed EDGE and GPRS scenarios this strategy allows good performance but does not guarantee
maximum throughput.
This was the original followed strategy
New PCU dimensioning has to be put in place for maximum performance!
customerwithagreedpercentagenutilizatioPCUtheisUwhere
*64*31,
*128,
*64,
*64,
*16,
*256max
Ukbps
hputBHGbThroug
U
TRXs
U
SEGs
U
BTSobjs
U
EDAPs
U
AbischsroundupNrPCUs
5/21/2018 PCU Info Session v1
8/26
Company Confidential8 2005 Nokia PCU dimensioning / Raquel Sanchez
Practical PCU dimensioning guidelines for S10.5and S11
NET/Services/OSPP France
5/21/2018 PCU Info Session v1
9/26
Company Confidential9 2005 Nokia PCU dimensioning / Raquel Sanchez
PCU functionality cause of the capacity limitation Example:
One MS Class 10 in perfect conditions (MCS-9) requires 4 EDGE master channels and 16 slave
channels. One DSP is able to handle 20 channels. If one DSP controls all the master channels of this
connection, it has to controls all the slave channels. Therefore the whole capacity of the DSP is required. If this DSP control more master channels (e.g. GPRS master
channels). The connection will not achieve maximum performance.
GPRS master channels are distributed in all DSPs, in the DSP allocation there is not splitbetween GPRS and EDGE master channels
it is not possible to control which DSPs control GPRS master channels
The risk of one DSP controlling all EGPRS master channels of one connection depends on the
network configuration itselfwhen the second PCUPCM is full of EDAPs and/or GPRS channels EDGE master channels are packet
and allocated to the same DSP.
EDGE and GPRS master channels are allocated to DSPs after BCSU switchover and it is fixed.
it is not possible to control which DSPs control which master channels
Nokia 6630
Class 10
master channels on the MS (Class 10 connection)
DSP
5/21/2018 PCU Info Session v1
10/26
Company Confidential10 2005 Nokia PCU dimensioning / Raquel Sanchez
PCU dimensioning guidelinesLimiting factor:in order to achieve maximum performance in EDGE sites, in thePCUs controlling EDGE sites DSPs should not control more than 4 masterchannels.
Limiting the number of master channels (RTSLs) connected to the PCU Reducing the default territory and/or the number of BTSs connected to the PCU
Try to avoid one DSP controlling all master channels of the EDGE connection. This can beachieved by keeping the size of EDAPs small and the amount of GPRS channels low ordefining such EDAPs that they are located to the first PCU PCM
S16kbps)/BT(RTSLsTerritorydefaultX
/DSP(16kbps)channelsmaster4DSP/PCU16
/PCUBTSsofNumberMaximum2)
64/DSP(16kbps)channelsmaster4DSP/PCU16
/PCUchannelsmasterNr.Maximum1)
To say that only 64 master channels can be connected to the PCU
is aggressive. But this is the way to avoid that one EDGE
connection is not able to achieve maximum performance because
lack of DSP resources cause by the DSP sharing between GPRS
and EDGE master channels.
5/21/2018 PCU Info Session v1
11/26
Company Confidential11 2005 Nokia PCU dimensioning / Raquel Sanchez
PCU re-dimensioningResults
NET/Services/OSPP France
5/21/2018 PCU Info Session v1
12/26
Company Confidential12 2005 Nokia PCU dimensioning / Raquel Sanchez
Initial PCU configuration: 2 PCUs
PCU-1: 84 RTSLs (GPRS and EDGE)
10 BTSs EDGE,
11 BTSs GPRS
PCU-2: 84 RTSLs (GPRS and EDGE)
6 BTSs EDGE
11 BTSs GPRS
PCU configuration after re-dimensioning: 3 PCUs
PCU-1: 60 RTSLs (GPRS and EDGE)
6 BTSs EDGE,
9 BTSs GPRS
PCU-2: 52 RTSLs (GPRS and EDGE)
4 BTSs EDGE
9 BTSs GPRS
PCU-2: 56 RTSLs (GPRS and EDGE) 6 BTSs EDGE
8 BTSs GPRS
5/21/2018 PCU Info Session v1
13/26
Company Confidential13 2005 Nokia PCU dimensioning / Raquel Sanchez
DL FTP Application Throughput - Perfect Conditions
Point_1 (Roche Premarie_S1)
196.82203.52
181.36181.50200.56
142.56
0
50
100
150
200
250
Average Maximum Minimum
kbps
Mesuremants after new PCU dimensioning (POINT_1)Measurements before PCU changes (POINT_1)
DL FTP Application Throughput - Perfect Conditions,
Point_3 (Valdivienne_S0)
200.12 204.40
179.44171.54
200.56
113.36
0
50
100
150
200
250
Average Maximum Minimum
kbps
Mesuremants after new PCU dimensioning (POINT_3)Measurements before PCU changes (POINT_3)
DL Throughput Distribution perfect conditions
Com parison before-after New PCU dim ensioning
0
20
40
60
80
100
120
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
kbps
Freq
uency
0%
20%
40%
60%
80%
100%
All points before PCU changes All points a fte r new PCU dimensioning
Cumulative % Cumulative %
EDGE Golden Cluster, PCU re-dimensioning results
Almost 17%improvement ,
28.7 kbps moreAlmost 9%
improvement ,
15.32 kbps more
5/21/2018 PCU Info Session v1
14/26
Company Confidential14 2005 Nokia PCU dimensioning / Raquel Sanchez
MCS Distribution (POINT1)
0
10
20
30
40
50
60
70
80
90
100
MCS_1 MCS_2 MCS_3 MCS_4 MCS_5 MCS_6 MCS_7 MCS_8 MCS_9
%
Before PCU changes (Point1) After PCU redimensioning (Point 1)
MCS Distribution (POINT3)
0
10
20
3040
50
60
70
80
90
100
MCS_1 MCS_2 MCS_3 MCS_4 MCS_5 MCS_6 MCS_7 MCS_8 MCS_9
%
Before PCU changes (Point3) After PCU redimensioning (Point 3)
EDAP/PCU performance (POINT 1)
DL FTP Perf.Cond. // Network Doctor report 280
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
Be fo re PCU changes (Po in t1 ) Af te r PCU redimensioning (Point 1 )
0
10
20
30
40
50
6070
80
90
100
%
TBF with inadeq EDAP DL TBF without EDAP DL Usage(%) DL Peak - 2nd ax is
EDAP/PCU performance (POINT 3)
DL FTP Perf.Cond. // Network Doctor report 280
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
200000
Before PCU changes (Point3) After PCU redimensioning (Point 3)
0
10
20
30
40
50
60
70
80
90
100
%
TBF with inadeq EDAP DL TBF without EDAP DL Usage(%) DL Peak - 2nd ax is
EDGE Golden Cluster, PCU re-dimensioning details
5/21/2018 PCU Info Session v1
15/26
Company Confidential15 2005 Nokia PCU dimensioning / Raquel Sanchez
Summary (1) - Guidelines
Suggestions for PCU dimensioning in large areas with mixed GPRS and EDGE:
Follow all recommendations in TN789 and in presented technical bulletin.
If maximum performance in EDGE is required extra PCU capacity is needed.
It is not possible to minimize the number of PCUs and maximize the performance of EDGE sites.
In areas where maximum performance is not a must, balance between number of PCUs and maximum
EDGE throughput/performance is recommended.
EDGE and GPRS BTSs are recommended to be connected to separate PCUs whenever possible.
When EDGE and GPRS BTSs cannot be connected to different PCUs, PCU capacity limitations
should be applied if maximum throughput is required.
If these rules are not followed the performance might be degraded.
To minimize the delay in cell-reselections adjacent BTSs should be connected to the same PCU.
Balance as much as possible the traffic between PCUs.
5/21/2018 PCU Info Session v1
16/26
Company Confidential16 2005 Nokia PCU dimensioning / Raquel Sanchez
Summary (2) - Strategies
BSS10.5-S11 PCU1 dimensioning strategies when having mixed EDGE and
GPRS:
In areas wheremaximum EDGE performance is not required
Strategy 1: Maximum connectivitytraditional rule
In mixed EDGE and GPRS scenarios this strategy allows good performance but does not
guarantee maximum throughput.
In spots where maximum EDGE performance is required
Strategy 2: Maximizing the performance of EDGE
Maximum 64 master channels (RTLSs) EDGE+ GPRS connected to the PCU
customerwithagreedpercentagenutilizatioPCUtheisUwhere
*64*31,
*128,
*64,
*64,
*16,
*256max
Ukbps
hputBHGbThroug
U
TRXs
U
SEGs
U
BTSobjs
U
EDAPs
U
AbischsroundupNrPCUs
5/21/2018 PCU Info Session v1
17/26
Company Confidential17 2005 Nokia PCU dimensioning / Raquel Sanchez
Summary (3) To know
We have done very simple document to explain how to do the PCU
dimensioning in BSS10.5-BSS11 when having mixed GPRS and EDGE in the
PCU and maximum performance in required
DSP allocation algorithm is improved in BSS11.5, more master channels can
be connected to the PCU controlling EDGE and GPRS without performance
degradation due to internal PCU capacity
PCU2 increases the capacity of the DSPs, this brings the possibility of
increasing as well the number of master channels connected to PCU without
performance degradation
5/21/2018 PCU Info Session v1
18/26
Company Confidential18 2005 Nokia PCU dimensioning / Raquel Sanchez
Questions ?
5/21/2018 PCU Info Session v1
19/26
Company Confidential19 2005 Nokia PCU dimensioning / Raquel Sanchez
Annex 1: PCU detailsMixed GPRS and EDGE configurations in
BSS10.5 and S11 releases
Product Line
5/21/2018 PCU Info Session v1
20/26
Company Confidential20 2005 Nokia PCU dimensioning / Raquel Sanchez
Mixed GPRS/EDGE configuration algorithms
There are two internal E1 PCMs (32 * 64kbit/s TSLs
each) connected to each PCU (NSEI) in both ANSI
and ETSI configurations.
The PCU PCM subTSL allocation algorithm works so
that EGPRS channels are divided between the first
and the second PCUPCM for getting better PCU DSP
channel distribution. Dividing of EGPRS channels is done so that RTSL7 is
first located to the first PCU PCM and other channels
from the same TRX to the second PCU PCM.
EDAPs are connected to the end of the second PCU
PCM.
GPRS only channels are normally connected to the
second PCU PCM starting just above the EDAPs.
Same 64kbit/s TSL from PCU PCMs cannot be used
for GPRS only and EGPRS channels at the same
time.
PCU PCM 0 PCU PCM 1
E E E = EGPRS master channel
E E
E E S = EGPRS slave channel (EDAP channel)
E EE E G = GPRS only channel
E E
E E
E E
G G G G
G G G G
G G G G
G G G G
G G G G
G G G G
G G G G
G G G G
S S S S
S S S S
S S S S
S S S S
S S S S
S S S S
S S S S
S S S S
S S S S
S S S S
S S S S
S S S S
S S S S
S S S S
S S S S
S S S S
5/21/2018 PCU Info Session v1
21/26
Company Confidential21 2005 Nokia PCU dimensioning / Raquel Sanchez
Mixed GPRS/EDGE configuration limitations (1/2)
If the second PCU PCM is full of either
EDAPs or EDAPs and GPRS only channelreserved 64 kbit/s timeslots (for example 3* 8 EDAP timeslots and 18 GPRS PCUPCM timeslots), the EGPRS channels arepacked to the first PCU PCM.
This means in practice that all channels ofone EDGE TRX are often connected tosame 64kbit/s PCU PCM timeslot andtherefore they are handled by the sameDSP inside the PCU.
In picture 72 GPRS channels are dividedbetween 16 DSPs. Basically this meansthat each DSP has either five or four GPRS
default channels. Six DSPs out of 16 have four EDGE
channels.
PCU PCM 0 PCU PCM 1
E E E E G G G G E = EGPRS master channel
E E E E G G G GE E E E G G G G S = EGPRS slave channel (EDAP channel)
E E E E G G G G
E E E E G G G G G = GPRS only channel
E E E E G G G G
G G G G
G G G G
S S S S
S S S S
S S S S
S S S S
S S S S
S S S S
S S S SS S S S
S S S S
S S S S
S S S S
S S S S
S S S S
S S S S
G G G G S S S S
G G G G S S S S
G G G G S S S S
G G G G S S S S
G G G G S S S S
G G G G S S S S
G G G G S S S S
G G G G S S S S
G G G G S S S S
G G G G S S S S
5/21/2018 PCU Info Session v1
22/26
Company Confidential22 2005 Nokia PCU dimensioning / Raquel Sanchez
Each PCU has 16 DSPs.
One PCU DSP can handle up to 20 x 16kbit/s channels. 16 of these channels can
be GPRS, EGPRS or PCCCH channels and rest 4 can be used only for EDAP
slave channels
One master channel and its slaves needs to be located in one DSP.
Default and dedicated GPRS and EGPRS channels consumes DSP channels
statically and reserve those DSP channels even without GPRS or EDGE traffic.
If the default channel load of DSP is high DSPs have less possibilities to allocate
slave channels.
It also means that PCU has fewer possibilities to divide the channel load between
DSPs. PCU PCM allocation example presented in last slide leads to the following DSP
channel configuration in six out of 16 DSPs.
Because only two slave channels per EGPRS channels available, only MCS-6
allocations are possible for these EGPRS channels .
E E E E E = EGPRS master
S S S S G = GPRS only
S S S S S = EGPRS slave
S S S SS S S S
E E E S
S S S S
S S S S
S S S G
G G G G
E E S S
S S S S
S S G G
G G G G
G G G G
E S S SS G G G
G G G G
G G G G
G G G G
Mixed GPRS/EDGE configuration limitations (2/2)
Other examples about other
possible DSP channels
configurations:
DSP 1:
E E E E E = EGPRS master channel
G G G G
G S S S S = Available for slave allocation
S S S S
S S S S G = GPRS only channel
5/21/2018 PCU Info Session v1
23/26
Company Confidential23 2005 Nokia PCU dimensioning / Raquel Sanchez
Annex 2
PCU dimensioning exampleBSS10.5/BSS11, PCU1NET/Services/OSPP France
5/21/2018 PCU Info Session v1
24/26
Company Confidential24 2005 Nokia PCU dimensioning / Raquel Sanchez
EXAMPLE (1/3)
Requirement : Maximize the EDGE performance (maximum throughput)
14 Sites, 37 BTSs, 4 TSL default territory.
6 Sites EDGE, 16 BTSs, 1 TRX (EGENA=Y) per BTS
EDAP 8 TSLs per EDAP
8 Sites GPRS, 21 BTSs, 1 TRX (GENA=Y) per BTS
required.arePCUs3TSsB37areThere
BTSs16/BTSRTSLs)kbps(16Territorydefault4
/DSP(16kbps)channelsmaster4DSP/PCU16
/PCUBTSsofNumberMaximum
64/DSPchannelsmaster4DSP/PCU16
/PCUchannelsmasterNr.Maximum
EDGE site
GPRS site
EDGE site
GPRS site
5/21/2018 PCU Info Session v1
25/26
Company Confidential25 2005 Nokia PCU dimensioning / Raquel Sanchez
EXAMPLE (2/3)
Is is possible to reduce the number of PCUs?
Try to separate EDGE and GPRS in different PCUs
6 EDAPs * 8 PCUPCM TSLs/EDAP = 48 PCUPCM TSLs
16 EGPRS BTSs * 4 RTSLs Default Territory/BTS = 64 channels (16kbps) 16
PCUPCM TSLs (64 kbps).
One PCU has 64 PCU PCM TLSs
2 PCUs must have EDGE traffic, all EDGE cells can not be allocated to one PCU.
1 PCU controlling EDGE can handle maximum 16 BTS/PCU (if maximum
performance for EDGE is required in this configuration)
2 PCUs can control 32 BTS, so the third PCU is needed.
5/21/2018 PCU Info Session v1
26/26
Company Confidential26 2005 Nokia PCU dimensioning / Raquel Sanchez
1
5
3
2
4
7
13
14
PCU-1
11
9
8
10
PCU-2
PCU-3
6
12
PCU-3
EDGE sit e
GPRS site
1
5
3
2
4
7
13
14
PCU-1
11
9
8
10
PCU-2
PCU-3
6
12
PCU-3
EDGE sit e
GPRS site
Master channels
connected to PCU
BTSs connected to
PCU
PCU-1 48 12
PCU-2 52 13
PCU-3 48 12
EXAMPLE (3/3)