b12 fsm reduction of transmitted pddcb ed01 rel

8/11/2019 B12 FSM Reduction of Transmitted PDDCB ED01 Rel

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COPYRIGHT 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED.

ALCATEL-LUCENT CONFIDENTIAL SOLELY FOR AUTHORIZED PERSONS HAVING A NEED TO KNOW PROPRIETARY USE PURSUANT TO COMPANY INSTRUCTION

Reduction of transmitted PDDCBFeature introduction Strategy & Monitoring

Raluca IOVANAS

MGR TIPS/ Network Engineering & Assurance (NEA)


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ALCATEL-LUCENT CONFIDENTIAL SOLELY FOR AUTHORIZED PERSONS HAVING A NEED TO KNOW PROPRIETARY USE PURSUANT TO COMPANY INSTRUCTION

PUBLICATION INFORMATION

Author

Raluca IOVANAS

Reference documentation

Reduction of transmitted PDDCB MEMO 211175

Publication history

September 2012 ED 01


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CONTENTS



3 | TEST STRATEGY



6 | CONCLUSION


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1.1 | INTRODUCTION

1 | Reduction of transmitted PDDCB DESCRIPTION


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Reduction of transmitted PDDCB

TECHNICAL DESCRIPTION

The Reduction of transmitted PDDCB is an optional feature and it wasrequested by CMCC in order to reduce the interference in the network

According to 3GPP, the transmission of Packet Downlink Dummy ControlBlock is not mandatory

When there is no RLC/MAC data or control block to transmit, but thenetwork decides to transmit on downlink, it will transmit RLC/MAC controlblocks containing PDDCB message

However, from the total number of PDDCB messages sent , only a smallpercentage contains useful information the rest of them have no content

Therefore, the goal of this feature is to remove the RLC/MAC control blocks

which contain a PDDCB message without carrying useful information


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Packet Downlink Dummy Control Block (PDDCB) message is sent on thePDCHs by the network to the mobile station as a fill message with:

optional parameters - PAGE_MODE and PERSISTENCE_LEVEL

no content

However, the PERSISTENCE_LEVEL is not sent by ALU BSS ( it is alwaysset to 0)

The PAGE_MODE parameter is only useful in case of paging reorganization

(reconfiguration of paging channel), which is related to PCCCH

Today, PCCCH is not used/activated, therefore there is no need to sendPDDCB with paging reorganization


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According to 3GPP, it is not required to transmit PDDCB messagescontinuously on active PDCH when no other PDU is to be sent

The network will send the PDDCB messages, needed by the MS, in the

following two cases:

USF signaling

MS-BSS synchronization for PR mode B

For MS- BSS synchronization, the network will ensure that each MS with anactive TBF in uplink or downlink receives at least one valid radio blocktransmitted with a coding scheme and a modulation that can be decoded by

that MS every 360 millisecond interval

PR mode B - the network will use the same P0 value for all the MS with aTBF established on the same PDCH, therefore the dynamic power reductionvalue shall be calculated relative to this P0 value


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P0 - is a constant power reduction relative to BCCH level

If downlink power control is used, in PR mode B, this valid radio block sentat every 360 milliseconds shall contain a usable PR field and does notnecessarily have to be addressed to any particular MS

This PR field is set according to the dynamic power reduction valuescomputed by RLC/MAC depending on the radio link conditions reported bythe MS

However, PDDCBs, like all RLC/MAC control blocks, do not contain a PR fieldand are sent at BCCH power

Hence, PDDCBs are sent for PR mode B synchronization, without a PR field,at BCCH power


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TECHNICAL DESCRIPTIONExpected gains

Gains expected in CMCC network

From the trace collected from Nanjing/Shanghai/Jinhua, the percentage ofuseless PDDCB messages is a little bit less than 48% of all downlink frames sent

However, from the total number of PDDCB messages sent , only a smallpercentage (3.5%) contains useful information and cannot be removed

Hence, the activation of Reduction of transmitted PDDCB feature is expected tobring a PDDCB reduction of approximately 45% of all DL frames sent

* Note that a change in some BSS parameter may modify the PDDCB ratio,independently of this improvement


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Gain estimation for any other traffic model

The BSS sends PDDCB messages when no data or other control message has tobe sent

We can assume that the proportion of useless PDDCBs roughly corresponds to aproportion of time during which a PDCH carries TBF which are all in delayed DL

TBF mode, except for the polling messages used to keep the TBF alive

In this case, for each TBF the MFS sends a DL dummy LLC everyT_DELAYED_DL_TBF_POL (default=200ms), the remaining are PDDCBs

For the case of one PDCH per MS in average (for example, 3 MSs per PDCH and3 PDCHs per MS) there would be on each PDCH one DL LLC PDU every 200ms,which means 10% of radio blocks


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The remaining 90% of radio blocks are carrying PDDCB messages, if all MS are

in TBF DL delayed state

If MSs are in average delayed state 50% of time (this can happen with bursty

traffic such as IM), then with this particular PDCH allocation and TBF multiplexing,

the transmission of PDDCB messages roughly takes 45% of radio blocks (50% x

90%)


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CONTENTS



3 | TEST STRATEGY



6 | CONCLUSION


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2.1 | reduction of transmitted PDDCB activation



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FEATURE ACTIVATION STRATEGY

Reduction of transmitted PDDCB Activation The activation of this feature is provided at cell level from OMC-R

The feature can be activated through the EN_RED_PDDCB parameter which is

sent to the MFS EN_RED_PDDCB = 0 or 1 ( 0 disabled , 1 enabled )

Feature optionality

The Reduction of transmitted PDDCB feature is optional for the network(TRX

quantity controlled) The optionality management will be done in two ways:

All the logical TRXs of the cell where the feature is activated will be counted

Minimum between the number of TRXs configured for PS and the number of

EGPRS-capable TRE of the cell where the feature is activated will be counted Feature availability

This feature is available starting with B12.2 Ed.1 release in TDM only

reduction of transmitted PDDCB will be allowed in IP transport later on


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Interaction with TRX Dynamic Power Save

The principle of this feature is to switch-off the PA (power amplifier) bias of agiven TRX when there is nothing to transmit over the air

The feature is activated as soon as one radio timeslot is not transmitting and itis independent of the type of traffic: voice, packet, or signaling

Therefore, the activation of Reduction of transmitted PDDCB feature isexpected to increase the efficiency of the TRX Dynamic power save feature


Interaction with other features


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Interaction with GPRS UL Power Control

The MS measures the DL power received either on PDCH or on BCCH dependingon the system parameter PC_MEAS_CHAN

The MS uses this measurement for UL power control

If the BSS does not transmit PDDCB when no data has to be sent, then therewill be few measurements to rely on and it may disturb UL power control

Therefore, if Reduction of transmitted PDDCB feature is activated, it would bebetter that the MS relied on the BCCH level to make measurement

Consequently, the PC_MEAS_CHAN parameter has to be set so that the MStakes the measurement on BCCH (PC_MEAS_CHAN = 0)




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Interaction with GPRS DL Power Control

When packet downlink power control is activated, PC_MEAS_CHAN in BSC andMFS shall be set to 0 (downlink measurements for power control shall be madeon BCCH)

Fortunately, this rule is coherent with the requirement for UL power control and

PDDCB reduction

Interaction with measurements at MS side

Together with other measurement of signal quality, the MS reports the varianceof the received signal level (SIGN_VAR parameter)

The absence or rarity of PDDCB may make this measurement meaningless, but

because this value is not anymore used by ALU BSS no problem is raised




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Interaction with GCH statistical multiplexing

In TDM mode, the MAC layer is located in the MFS

The PDDCB are transferred on Abis and Ater interfaces

Not sending the useless PDDCB may diminish the load of the GCH layer

Activating the feature will bring no gain in term of GCH allocation request

Nevertheless, in case of GCH congestion, the available throughput will be better

used (only useful radio blocks)

Today the PDDCB are transmitted in a compressed mode between MFS and BTS(padding bits are inserted by the BTS), hence the PDDCB dont consume muchbandwidth




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2.3 | HW Support



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HW SupportThe following is required by product management for hardwaresupport:

BTS: SUMP, SUMA, SUMX, A9100 (Evolium standard)*, A9110-E (M5M)*

A9110 (M4M) does not support this feature

TRE: G4*, G5 TRE (TWIN)* and G6 TRE(MC-TRE and MC-RRH)*

TREs older than G4 do not support this feature

BSC generation: G2, Evolution BSC (MxBSC) with TPV1/ TPV3

TC: not impacted

O&M: OMC-R*, POLO*, NPO*

MFS: Evolution MFS (MxMFS)* - GP2 and GP3

* The feature is supported on the NE with software impacts


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2.4 | NEW PARAMETERS



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NEW PARAMETERS

Parameter

NameDefinition

Sub-

System

Instan

ce

Category/OMC-R

access

TypeRange/Default

value

EN_RED_PDDCBEnables/disables the reduction of useless

PDDCB in a cell MFS CellSite (CAE)/Changeable Flag

0 or 1 / 0(disabled)


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CONTENTS



3 | TEST STRATEGY



6 | CONCLUSION

7 | APPENDIX A: XXXX


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3.1 | REMOVAL OF USELESS PDDCB TEST STRATEGY

3 | TEST STRATEGY


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TEST STRATEGY

OVERVIEW The goal of the feature is to reduce the interference in the network by removing

the RLC/MAC control blocks which contain a PDDCB message without carryinguseful information

The following selected KPIs are verified before and after the feature activation QoS KPIs:

CS

Voice Quality distribution

Delta MOS RxLev, RxQual

Call Drop due to interference, Call Drop Radio

PS

TBF establishment success rate

GPRS/ EDGE throughput

GCH_Erlang_Total

GPRS_GPU_Ater_cong_time

No possible degradations caused by this feature are expected


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TEST STRATEGY

REQUIREMENTS

Two categories of tests are required:

Statistical and unitary tests have to be performed

QoS follow up - at least 1 week for the reference period and 1 week forobservation

Voice Quality evaluation through drive tests

Required tools:

NPO or AnaQoS (if NPO is not available) to follow up the QoS KPIs

DT tool chain including VQ support to asses the VQ scores before and after feature

activation (e.g. QVoice from ASCOM, VQ tool from SwissQual, Nemo from Anite) Deutrip


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TEST STRATEGY

PREREQUISITES

2 BTSs (at least 3/4 cells) for the pilot area

PS uplink and downlink power control to be activated in the pilot area

RMS measurements have to be activated when starting the reference period

Reference & verification tests made with same parameter setting

Pilot area selection:

Dense urban area with high level of interference due to a low frequency reuse factorshould be chosen

High PS traffic load (UL and DL)


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TEST STRATEGY

PLANNING SUMMARY

Test Category Test Type Trial PeriodNeeded

resources

Statistical

Non Regression1 week reference

+ 1 week

observation

1 RNE/NEA expert

for QoS follow-up+ analysis/

troubleshootingImprovement

after reduction oftransmitted

PDDCB activation

1 week reference+ 1 week

observation

Unitary Drive tests 3 Days2 Drive testengineers


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TEST STRATEGY

STATISTICAL TESTS MAIN KPIs PS KPIs are the main ones impacted by the feature and should be monitored

This feature may also have impact on voice quality, therefore some CS KPIs willbe monitored

Main KPIs include the following categories:

GPRS Establishment phase - GPRS_GPU_TBF_establishment_request,

GPRS_GPU_TBF_establishment_success_rate

Data throughput - GCH_Erlang_Total, GPRS throughput, EDGE throughput

Data Transfer - GPRS_DL / UL_TBF_drop_rate

GCH Congestion - GPRS_GPU_Ater_cong_time

RMS indicators - Average RxQuality, Average RxLevel, RMS_DL_Power_avg,RMS_DL_Power_avg_per_RxLevel, RMS_DL_Power_avg_per_RxQuality

Voice quality - Delta MOS

Call Drop Call_Drop_DL_Interference, Call_Drop_Radio


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TEST STRATEGY

UNITARY TESTS Stationary tests -Voice quality assessment in medium radio conditions

Mobility tests - Voice quality assessment with 2 MSs (medium radio condition)moving around in the selected area

Reference test (for both stationary and mobility tests) - reduction of transmitted PDDCBfeature disabled in all the cells

Observation test (for both stationary and mobility tests) - reduction of transmitted

PDDCB feature enabled in all the cells

Expected outcome:

Comparison of average MOS, RxLev, RxQual values with and without this feature activated

Comparison of VQ scores before and after feature activation


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TEST STRATEGY

UNITARY TESTS PS end-user performance tests are performed in two situations

Stationary and mobility tests in good and medium radio conditions

Reference test - reduction of transmitted PDDCB feature disabled in all the cells

Observation test - reduction of transmitted PDDCB feature enabled in all the cells

Requirements:

Gb trace available

FTP server inside the PLMN with access rights

SIM cards

BTS locations (Google Earth), with cells orientations

Expected outcome:

Comparison of the reactivity/accessibility of the network(GPRS/EDGE) to PS requests before andafter the feature activation

Comparison of the download throughput, success rate and duration

Comparison of DL average power before and after feature activation


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TEST STRATEGY

UNITARY TESTSDescription Number of samples TechnologyStationary tests

FTP DL 3 Mbytes 10 FTP transfers EDGE

FTP UL 1 Mbytes 10 FTP transfers EDGE

FTP DL 1 Mbytes 10 FTP transfers GPRS

FTP UL 500 Kbytes 10 FTP transfers GPRS

Ping 32 bytes pause 5s 100 iterations EDGE

Ping 32 bytes pause 5s 100 iterations GPRS

Ping 1460 bytes pause 0s 100 iterations EDGEPing 1460 bytes pause 5s 100 iterations EDGE

WEB/WAP 20 iterations GPRS

WEB/WAP 20 iterations EDGE

Mobility tests

FTP DL 1 Mbytes 10 FTP transfers EDGE

FTP UL 1 Mbytes 10 FTP transfers EDGE

FTP DL 500 Kbytes 10 FTP transfers GPRS

FTP DL 500 Kbytes 10 FTP transfers GPRS


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CONTENTS



3 | TEST STRATEGY



6 | CONCLUSION


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4.1 | NEW COUNTERS



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PERFORMANCE EVALUATION

NEW COUNTERS

Counternumber

Mnemonic Definition / Trigger(s)Measured

object

P51 NB_USEFUL_PDDCB_SCHEDULED

Number of useful PDDCB scheduled / Whenever a useful PDDCBis scheduled, this counter is increased. It corresponds to:- USF signalling to MS- PR_MODE_B synchronization

Cell

P52 NB_USELESS_PDDCB_SCHEDULED

Number of useless PDDCB scheduled / Whenever a uselessPDDCB is scheduled, this counter is increased. It corresponds toPDDCB not counted in P51 and it includes next UL blocksignalling to BTS

Cell

These new counters are incremented whether the feature is activated or not in thecell

They might be useful for the customers who would like to experiment this feature


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4.2 | NEW INDICATORS



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PERFORMANCE EVALUATION

NEW INDICATORS

NPO indicatorref name

NPO Long Name NPOFormula

Description

GTRPAUFDN GPRS_Useful_PDDCB_Scheduled P51 Number of useful PDDCB scheduled

GTRPAUSDN GPRS_Useless_PDDCB_Scheduled P52 Number of useless PDDCB scheduled


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CONTENTS



3 | TEST STRATEGY



6 | CONCLUSION

i i / O h


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Restrictions / Other Issues

A degradation of QoS has been observed in Telecom load when Reduction oftransmitted PDDCB is activated on GP3 (issue is not observed on GP2)

Consequently, the feature is opened for lab only on GP3 until QoS issue is

clarified

CONTENTS


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Conclusion

The Reduction of transmitted PDDCB is an optional feature and it wasrequested by CMCC in order to reduce the interference in the network

When there is no RLC/MAC data or control block to transmit, but thenetwork decides to transmit on downlink, it will transmit RLC/MACcontrol blocks containing a PDDCB message

According to 3GPP, the continuous transmission of Packet DownlinkDummy Control Block is not mandatory

However, from the total number of PDDCB messages sent , only a smallpercentage contains useful information the rest of them have no

content

Hence, the goal of this feature is to remove the RLC/MAC control blockswhich contain a PDDCB message without carrying useful information

C l i


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Conclusion

The activation of Reduction of transmitted PDDCB feature in CMCC isexpected to bring a PDDCB reduction of approximately 45% of all DLframes sent

Nevertheless, the feature can still be used in any other traffic model,different than the CMCC conditions

Its efficiency might be different, depending on the given trafficconditions

There are specific indicators which an operator interested in this featurewill have to use before the introduction, in order to assess its efficiency

in the network


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b12 fsm reduction of transmitted pddcb ed01 rel

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