Adjustable TBF Multiplexing

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1/18

GSM/EDGE BSS, Rel.

RG20(BSS), Operating

Documentation, Issue 09

Feature description

RG301733: Adjustable TBF Multiplexing

Density

DN0999539

Issue 01A

Approval Date 2012-02-08

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Table of contentsThis document has 18 pages.

1 Summary of changes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2 Introduction to the feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3 Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4 Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.1 Software requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.2 Hardware requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

5 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

5.1 Functional details. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5.1.1 PCU2 Initiated Territory Upgrade procedure . . . . . . . . . . . . . . . . . . . . . 10

5.1.2 PCU2 Initiated Territory Downgrade procedure. . . . . . . . . . . . . . . . . . . 10

6 System impacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6.1 Impacts on network elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6.2 Impacts on interfaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6.2.1 BSC-NetAct interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6.3 Impacts on system performance and capacity. . . . . . . . . . . . . . . . . . . . 12

7 User interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.1 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.2 MML commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7.3 System response to failures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

8 Activating and configuring the feature . . . . . . . . . . . . . . . . . . . . . . . . . . 15

8.1 Configuring the Adjustable TBF Multiplexing Density . . . . . . . . . . . . . . 16

8.2 Deactivating the Adjustable TBF Multiplexing Density. . . . . . . . . . . . . . 17

9 Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

0 Z. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18


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List of tablesTable 1 Software requirements for different network elements . . . . . . . . . . . . . . 8

Table 2 Parameters for Adjustable TBF Multiplexing Density . . . . . . . . . . . . . . . 13

Table 3 Error code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14


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RG301733: Adjustable TBF Multiplexing Density Summary of changes

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1 Summary of changesChanges between document issues are cumulative. Therefore, the latest document

issue contains all changes made to previous issues.

Changes made between issues 01A and 01

Command has been updated in the chapter:Activating and configuring the feature.


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Introduction to the feature

2 Introduction to the featureThe feature RG301733 Adjustable TBF Multiplexing Density allows operator to control

upgrades/downgrades of the (E)GPRS territory at the cell level. This facilitates dynamic

variations in CS/PS territories in response to change in load conditions.

Operator controls the territory upgrade/downgrade procedures by modifying the follow-

ing parameters at cell level.

PCU PSW TBF upgrade threshold

PCU PSW TBF downgrade threshold

PCU PSW TBF density target

Adjustable TBF Multiplexing Density is an Application Software (ASW) feature that is

controlled with BSC licence key, ON/OFF. The operator modifies the parameters

through MML, FBPP or SendToNw for each segment. User-configurable parameters are

supported only in PCU2 segment.


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RG301733: Adjustable TBF Multiplexing Density Benefits

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3 Benefits

The feature provides the operator more flexibility to deploy data service at cell level

by providing option to configure parameters. The feature improves the channel efficiency.


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Requirements

4 Requirements

4.1 Software requirements

4.2 Hardware requirements

This feature does not require any new or additional hardware.

Network element Required software release

BSC S15 EP 2.1

NetAct OSS 5.4

Table 1 Software requirements for different network elements


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RG301733: Adjustable TBF Multiplexing Density Functional description

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5 Functional descriptionOperator controls the (E)GPRS territory upgrade/downgrade procedures by modifying

the parameters, PCU PSW TBF upgrade threshold, PCU PSW TBF downgrade thresh-

old, and PCU PSW TBF density target at the cell level. User activates the Adjustable

TBF Multiplexing Density feature before the modified parameters are used in PCU.

User-configurable parameters are used only in PCU2.

Operator defines separate values for threshold parameters, PCU PSW TBF upgrade

threshold and PCU PSW TBF downgrade threshold. A single value is defined for

upgrade and downgrade target parameter. This single value is termed as PCU PSW

TBF density target.

Parameter modification fails if the following rules are not satisfied.

PCU PSW TBF upgrade threshold PCU PSW TBF density target >= 50.

PCU PSW TBF density target PCU PSW TBF downgrade threshold >= 50.

User modifies PCU PSW TBF upgrade threshold, PCU PSW TBF downgrade threshold,

and PCU PSW TBF density target when (E)GPRS is disabled. The new parameters are

updated to the database.

BSC throws an error when the user modifies the parameter through MML, when

(E)GPRS is enabled. Modifying new parameters through SendToNw or FBPP, disables

(E)GPRS automatically.

BSC checks the Adjustable TBF Multiplexing Density feature licence while (E)GPRS is

enabled in the segment where the feature is used. Licence state is not checked during

(E)GPRS enabling when default values are used for parameters. If any one of the three

parameter values is different from the default value, then (E)GPRS is enabled in the

segment only if licence is in ON state.

In Automatic PCU selection case, if the parameters have values other than default and

the license state is not ON, then activation of GPRS fails.

When licence state is changed to CONF or OFF, (E)GPRS enabling in segment fails, if

PCU PSW TBF density target, PCU PSW TBF upgrade threshold or PCU PSW TBF

downgrade threshold parameter values are different from the default values. When

licence state is CONF or OFF, default values should be defined for the parameters to

enable the (E)GPRS in a segment.

However if (E)GPRS is enabled in segment before the licences state is changed to

CONF or OFF then, the parameter values are in use in PCU until (E)GPRS is disabled

in segment.The parameter values in database are sent irrespective of the licence state when

(E)GPRS is enabled in a segment and created to PCU after PCU restart, BCSU switcho-

ver, BSC restart, and PCU pool reallocation.

If the licence state of Adjustable TBF Multiplexing Density is ON or CONF, the new

parameters are displayed in execution printouts.

This chapter is divided into the following section:

Functional details
http://x%3Dd%3Do%3Dc/s-000483.pdfhttp://x%3Dd%3Do%3Dc/s-000483.pdf


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Functional description

5.1 Functional details

5.1.1 PCU2 Initiated Territory Upgrade procedure

PCU2 initiates territory upgrade if average TBF amount per PDCH is higher than PCU

PSW TBF upgrade threshold or less number of timeslots are allocated to Mobile Station

(MS) as per its multislot capability. During channel allocation algorithm, if channels are

not allocated to MS as per its multislot capability then PCU2 insets MS in deprived list

and requests for upgrade in the territory. PCU2 calculates the number of channels to be

upgraded based on PCU PSW TBF density target parameter value. PCU2 requests for

territory upgrade if resources are available.

For more details on territory method, see Radio resource management in BSS09006:

GPRS System Feature Description.

Example:

Size of GPRS territory=2 TSLs, MS multislot class =5, PCU PSW TBF Upgrade Thresh-

old =1.5, PCU PSW TBF Upgrade Target =1.

Number of channels allocated is 2 and hence, average number of TBFs per TSL = (2/2)

= 1. If a new MS having the same multislot class 5 requests for channel then, the

average number of TBFs per TSL becomes = (4/2) = 2 .This value is greater than the

PCU PSW TBF Upgrade Threshold. Now the territory upgrade is initiated and the

amount of additional channels required depends on the value of PCU PSW TBF

Upgrade Target set for that segment. Hence PCU2 requests 2 additional timeslot.

Example:

Territory size = 2 RTSL. There are two DL TBFs allocated 2 RTSL/TBF. PCU PSW TBF

Downgrade Threshold = 1.5 PCU PSW TBF Density Target = 2, PCU PSW TBF

Upgrade Threshold = 2.5.

If a new MS having multislot class 8 and allocated to RTSL then, the average number

of TBFs per TSL becomes = (6/2) = 3. PCU requests 2 RTSL for upgrade. After territory

upgrade, PS territory has 4 RTSL.

5.1.2 PCU2 Initiated Territory Downgrade procedure

Whenever a TBF is released by PCU2, it checks whether a downgrade is needed by cal-

culating the average number of TBFs per PDCH. PCU2 checks the PS territory for addi-

tional channels and if the average number of TBFs per PDCH is less than PCU PSW

TBF downgrade threshold value, then PCU2 sends territory downgrade request

message only if guard timer is not running. PCU2 then starts the guard timer. Whenever

a TBF is deallocated, PCU checks whether a downgrade is needed based on current

resource usage. If a downgrade is required, it calculates the number of channels to be

downgraded based on PCU PSW TBF density target parameter value. When TBF

amount is small, PCU adjusts territory downgrade request to keep the TSL amount of

largest allocation. PCU2 evaluates the downgrade criteria and sends a request for

downgrade. Now PCU2 starts the update guard timer and the territory downgrade pro-

cedure starts. On receiving downgrade request, PCU2 stops the update guard timer and

proceeds as per the normal downgrade procedure.

For more details on territory method, see Radio resource management in BSS09006:

GPRS System Feature Description.
http://dn7036138.pdf/http://dn7036138.pdf/http://dn7036138.pdf/http://dn7036138.pdf/http://dn7036138.pdf/http://dn7036138.pdf/http://dn7036138.pdf/http://dn7036138.pdf/


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Example:

Size of GPRS territory=6 TSLs, MS multislot class =5, PCU PSW TBF Downgrade

Threshold =0.5, PCU PSW TBF Downgrade Target =1, No of MS = 3.

The average number of TBFs is 6/6=1. If two MSs are released then, the averagenumber of TBFs becomes 2/6 = 0.33 . This value is less than the PCU PSW TBF Down-

grade Threshold. The amount of channels to be downgraded depends on the value of

PCU PSW TBF Downgrade Target. Hence the PCU2 initiates the downgrade of 4

channels to achieve the target.

Example:

Default territory size = 1 RTSL, Territory size= 8 RTSL. There are two DL TBF allocated

4 RTSL/TBF. PCU PSW TBF Downgrade Threshold = 2.5, PCU PSW TBF Density

Target = 3, PCU PSW TBF Upgrade Threshold = 3.5.

If PQ is not overloaded, PCU searches largest MS allocation. Based on TBF Density

Target, territory downgrade needs 5 TSLs, but because largest allocation is 4 TSLs,PCU sends territory downgrade request for 4 TSLs. After territory downgrade, PS terri-

tory has 4 TSLs.

If PQ is overloaded, TBF Density Target 1 is used and PCU do not send territory down-

grade request.


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System impacts

6 System impactsThis chapter is divided into the following sections:

Impacts on network elements Impacts on interfaces

6.1 Impacts on network elements

NetAct

New parameters, PCU PSW TBF Density Target, PCU PSW TBF Upgrade Threshold,

and PCU PSW TBF Downgrade Threshold are supported by NetAct.

6.2 Impacts on interfaces

6.2.1 BSC-NetAct interface

FBPP and SendToNW support for new parameters are provided.

6.3 Impacts on system performance and capacity

Additional checks are required in PCU to maintain the values of the parameters for each

segment and accordingly (E)GPRS territory upgrade/downgrade procedure is initiated

at cell level.

Additional checks are required in PCU to calculate TBFs or RATs per TSL for each

segment and accordingly (E)GPRS territory upgrade/downgrade procedure is initiated

at cell level.

The default values of the parameters are adjusted in order to serve end user on best

possible resources and with best possible throughput. This means that PCU tries to

increase/decrease the territory size in level, approximately one TBF per radio channel

when there are unused radio channel(s) available. By doing the territory handling in this

way the MSs would potentially have radio resources of their own and the multiplexing

of multiple TBFs per radio channel happen only in the higher traffic load situations. The

limiting factor for territory expansion is CS traffic load and the upper limit of the PS ter-

ritory size (CMAX). In other words the default values will provide best throughput for the

end-users and increase the radio channel efficiency at the cost of PDCH efficiency.

When the PCU PSW TBF upgrade/downgrade thresholds and PCU PSW TBF densitytarget parameters are adjusted to allow more multiplexing then, the impacts on system

performance is that the PDCH efficiency increases meanwhile, the end-user experi-

ences a throughput degrade (when more than one TBFs per radio channel) likewise the

radio channel efficiency.


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7 User interfaceThis chapter is divided into the following sections:

Parameters MML commands

System responses to failures

7.1 Parameters

The following tables show the parameters implemented for the feature Adjustable TBF

Multiplexing Density. The parameters are subject to change.

7.2 MML commands

The following MML commands are used to handle the feature:

TheEQV

command for modifying GPRS parameters The EQOcommand for printing BTS parameters

Name Object Description Range Default value

PCU PSW TBF Density

Target

(TBFT)

BTS/

SEG

With this parameter you can define the

target value for the TBF multiplexingdensity in an upgrade and downgrade ter-

ritory operations initiated by the PCU.

Based on this parameter PCU determines

the number of channels, to be

requested/offered from/to the Radio

Resource Manager in an upgrade/down-

grade request.

100(Mini-

mum) ,

500 (Maxi-

mum)

Step size :

100

100 (1 TBF)

PCU PSW TBF Upgrade

Threshold

(TBFU)

BTS/

SEG


upper threshold limit for the TBF multi-

plexing density which describes the mean

number of TBFs multiplexed on the sametimeslot. If the TBF multiplexing density

exceeds the value of this parameter, then

PCU asks for more channels from the

Radio Resource Manager provided that it

already has all the default channels.

150 (Mini-

mum), 550

(Maximum)

Step size :

50

150 (1.5 TBF)

PCU PSW TBF Down-

grade Threshold

(TBFD)

BTS/

SEG


lower threshold limit for the TBF multiplex-

ing density, which describes the mean

number of TBFs multiplexed on the same

timeslot. If the TBF multiplexing density

becomes smaller than the value of thisparameter, then PCU requests a down-

grade territory operation to the Radio

Resource Manager provided that it has

some additional channels.

50 (Mini-

mum), 450

(Maximum)

Step size :

50

50 (0.5 TBF)

Table 2 Parameters for Adjustable TBF Multiplexing Density
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User interface

7.3 System response to failures

This feature introduces the error code shown in the following table.

Output Name Number Description

ADJUSTABLE

TBF

MULTIPLEXING

DENSITY

FEATURE IS

NOT IN USE

IN BSC

option_adjtbf_mux_not_in_us

e_ec

00701H /

1793d

Adjustable TBF Multiplexing Density feature

license is not enabled in BSC.

Table 3 Error code


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8 Activating and configuring the featureThis chapter provides the procedures to operate the feature Adjustable TBF Multiplex-

ing Density.


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Activating and configuring the feature

8.1 Configuring the Adjustable TBF Multiplexing Density

Prerequisites

Install S15 EP 2.1 release to the BSC.

Install and configure any BTS site.

Install the license for the feature Adjustable TBF Multiplexing Density and set the

licence state as ON.

Disable (E)GPRS on the cell where the parameters are to be configured.

Check the license state of the features with the command W7I

ZW7I:FEA,FULL:FEA=3476;

2 If the license is not active, enter the following command to activate the licenseZW7M:FEA=3476:ON;

3 Modify BTS/SEG and configure the feature parameters using MML/NetActZEQV:BTS=10:RAC=255,::DCENA=N,:TBFT=200,TBFU=250,TBFD=150;

ZEQV:SEG=1:RAC=100,:::TBFT=200,TBFU=250,TBFD=150;

4 Output BTS/SEG parameters and check if parameters are modifiedZEQO:BTS=10:GPRS;

ZEQO:SEG=1:GPRS;

5 Enable (E)GPRS

End


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8.2 Deactivating the Adjustable TBF Multiplexing Density

g Please note that when the licence of this feature is disabled, the feature continues towork in those segments in which the feature is in use until reconfiguration.

The following are the steps to deactivate the feature at cell level.

Disable (E)GPRS on the cell

2 Configure the feature parameters to default valuesZEQV:BTS=10:RAC=255,::DCENA=N,:TBFT=100,TBFU=150,TBFD=50;

End

To deactivate the feature at BSC level, the licence state for the feature is set to OFF.


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Abbreviations

9 Abbreviations

0 ZBSC Base Station Controller

CS Circuit Switched

DLDC DownLink Dual Carrier

(E)GPRS Enhanced General Packet Radio Service

PCU2 2nd Generation Packet Control Unit in BSC

PCUPCM Internal PCM of PCU2 in BSC

PS Packet Switched

RAT Resource Allocation for a TBF

TBF Temporary Block Flow

Documents

Adjustable TBF Multiplexing