PCU Info Session v1

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



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



DL FTP maximum performance degradationPCU capacity

BSS10.5-PCU1




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


k

bps

Best

conditions

There were clearly twopoints performing worse:Point 1 and Point 3.



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

%


DL FTP Perf.Cond. 20-06-2005

PCU statistics

Network Doctor report 280

0

20000

40000

6000080000

100000

120000

140000

160000

180000

200000


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


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.


7/26


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


8/26


Practical PCU dimensioning guidelines for S10.5and S11



9/26


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


10/26


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.


11/26


PCU re-dimensioningResults



12/26


Initial PCU configuration: 2 PCUs

PCU-1: 84 RTSLs (GPRS and EDGE)

10 BTSs EDGE,

11 BTSs GPRS


6 BTSs EDGE

11 BTSs GPRS

PCU configuration after re-dimensioning: 3 PCUs


6 BTSs EDGE,

9 BTSs GPRS


4 BTSs EDGE

9 BTSs GPRS

PCU-2: 56 RTSLs (GPRS and EDGE) 6 BTSs EDGE

8 BTSs GPRS


13/26


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


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


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


14/26


MCS Distribution (POINT1)

0

10

20

30

40

50

60

70

80

90

100


%

Before PCU changes (Point1) After PCU redimensioning (Point 1)

MCS Distribution (POINT3)

0

10

20

3040

50

60

70

80

90

100


%


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


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


15/26


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.


16/26


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


17/26


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


18/26


Questions ?


19/26


Annex 1: PCU detailsMixed GPRS and EDGE configurations in

BSS10.5 and S11 releases

Product Line


20/26


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


21/26


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


22/26


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


23/26


Annex 2

PCU dimensioning exampleBSS10.5/BSS11, PCU1NET/Services/OSPP France


24/26


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


25/26


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.


26/26


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)

Documents

PCU Info Session v1