Introduction to the RAN14.0 Feature–CE Overbooking 20120112

8/10/2019 Introduction to the RAN14.0 FeatureCE Overbooking 20120112

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Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.

Confidentiality: INTERNAL

Introduction to the RAN14.0

Feature CE Overbooking


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Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page 2

About This Course

This course is based on the radio access network (RAN)

14.0 version. Before you learn this course, ensure that you

have completed the following courses based on the RAN

13.0 version: Dynamic channel element (CE) resource management

Load control

Dynamic selection of the transmission time interval (TTI)


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Objectives

After completing this course, you will be able to:

Understand the values and application scenarios of the CE

Overbooking feature.

Explain the basic principles of the CE Overbooking feature.

Enable and verify the CE Overbooking feature based on

manuals.


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Contents

1 Feature Desc riptio n

2 Feature Planning

3 Feature Deployment

4 Performance Monitoring

5 Reference Document and Acronyms & Abbreviations


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Feature Description

Background

Benefit

The transmission rates of HSUPA UEs are low in most cases due to thehigh penetration rate of smart phones. In this case, if the RNC reserves a

certain amount of credit resources for each admitted UE, the RNC rejects

new UE access attempts due to congested uplink credit resources. However,

the actual CE usage of the NodeB is low.

This problem can be resolved by enabling the TTI switching algorithm.

However, if the TTI of most UEs is switched from 2 ms to 10 ms, thebenefits of using a 2 ms TTI, such as the peak rate, short delay, and quick

scheduling, are unavailable. This reduces user experience.

The CE Overbooking feature provides the following benefits when thepenetration rate of smart phones with an HSUPA TTI of 2 is high and the

average uplink throughput is low:

Relieves CE congestion during UE access.

Increases the number of admitted UEs and the number of UEs with a 2 ms

TTI.

Increases cell throughput when Uu resources are sufficient.


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Technical PrinciplesWith this feature, the NodeB adjusts the credit resource usage of admitted UEs based on the

actual CE usage, includes the credit resource usage in a private information element (IE) in a

measurement report, and sends the report to the RNC every measurement report period. TheRNC then directly uses the reported credit resource usage. The following figure shows the

implementation principle of this feature.

This feature applies only to uplink CE resources.

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NodeB CN

Uu Iub Iu

RNCUE

Processing on the RNC:

The RNC receives information aboutconsumed credit resources that is

reported by the NodeB using proprietary

IEs of Iub-interface messages. TheRNC performs CAC, LDR, or TTI

selection based on the information.

Processing on the NodeB:The credit resources that are consumed by

admitted HSUPA UEs are adjusted periodically

based on whether the amount of CE resourcesthat are available for HSUPA UEs is smaller

than the CE resource usage calculated with the

following formula:CE resource usage = Max (CE resources

required for ensuring the GBR, CE resources

required for transmitting one RLC PDU)


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Functions

Whether CE Overbooking

Is EnabledMethod for Calculating the Credit Resource Usage

Not enabled

The RNC calculates the credit resource usage as follows:

For R99 UEs, the RNC calculates the credit resource usage of admitted UEs based on the maximum bit

rate (MBR).

For HSUPA UEs, the RNC calculates the credit resource usage of admitted UEs by using the following

formula:

Credit resource usage = Max (Credit resources required for ensuring the GBR, Credit resources required for

transmitting one RLC PDU)

Enabled

The NodeB calculates the credit resource usage as follows:

For R99 UEs, the RNC calculates the credit resource usage of admitted UEs based on the MBR.

For HSUPA UEs, the NodeB adjusts the credit resource usage of admitted UEs to be less than or equal to

the calculation result of the following formula:

Credit resource usage = Max (Credit resources required for ensuring the GBR, Credit resources required for

transmitting one RLC PDU)

If the UEs use a 10 ms TTI, the adjustment is based on the UE rate.

If the UEs use a 2 ms TTI, the adjustment is based on the UE rate and the REVDPARA4 parameter.

When dynamic CE resource management is implemented, the CE resources that are available

for HSUPA UEs are managed dynamically. That is, idle CEs are recycled when the datatransmission rates of HSUPA UEs are low, or no data is transmitted. When this feature is enabled,

the credit resource usage of HSUPA UEs with low transmission rates is calculated based on the

actual CE usage.

The following table lists the methods for calculating consumed credit resources before and after

the CE Overbooking feature is enabled.

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RelatedFeature

Required Features

This feature depends on the feature WRFD-010638 Dynamic CE

Resource Management.

When CE Overbooking is enabled, it is recommended that

DRA_BASE_ADM_CE_BE_TTI_RECFG_SWITCH under DraSwitch

be turned on.

Mutually Exclusive Features

None

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Impact of CE Overbooking

Impact on resource consumption

Congestion of credit resources on the RNC is reduced.

Impact on the system capacity

Enabling this feature affects system capacity as follows:

Relieves congestion of credit resources on the RNC.

Increases the number of admitted UEs and online UEs.

Increases the average cell throughput when Uu resources are sufficient.

When CE resources are insufficient, enabling this feature reduces the resources available to each

user, leading to lower per user throughput.

Impact on network performance

This feature relieves congestion of credit resources on the RNC and therefore affects network

performance as follows: Increases the success rates for RRC connection setups, RAB setups, and handovers.

Increases the call drop rate due to insufficient CE resources on the NodeB when multiple UEs

transmit data simultaneously.

Possibly increases the call drop rate due to increased Uu load when more UEs are admitted.

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Application Scenarios and Benefits

Application scenarios There is a large number of 2 ms HSUPA smart phones in the network.

Credit resources are congested on the RNC.

The average HSUPA throughput is low.

The CE usage on the NodeB is lower than the credit resource usage on the RNC.

Benefits

When the CE usage on the NodeB is low due to the low average throughput of 2 ms

HSUPA smart phones, this feature provides the following benefits:

Reduces the congestion of credit resources on the RNC. This increases the success

rate of access based on CE resources, and reduces the number of CE resource

request failures, probability of TTI switching triggered by CE congestion, and CE-

based load reshufflings (LDRs).

Increases the number of admitted UEs and the number of HSUPA UEs with a 2 ms

TTI.


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Contents

1 Feature Description

2 Feature Plann ing





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Activation Suggestion and Information

Collection

Activation suggestionActivate CE overbooking when one of the following conditions is met:

There is a large number of 2 ms HSUPA smart phones in the network.

Credit resources are congested on the RNC.

The average HSUPA throughput is low.

The CE usage on the NodeB is lower than the credit resource on the RNC.

Information collection

Check the following counters:

VS.LC.ULCreditUsed.Mean: credit resource usage on the RNC

VS.LC.ULMean.LicenseGroup: CE usage on the NodeB

VS.RRC.Rej.ULCE.Cong and VS.RAC.NewCallReq.Fail.ULCE.Cong: whether credit

resources on the RNC are congested

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You are advised to enable this feature when credit resources are congested, and the

CE usage on the NodeB is much lower than the credit resource usage on the RNC.


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Version/LicensePlanning

Version

RAN14.0 or later versions

License

The license contolling the CE Overbooking feature is activated on the

M2000.Required feature

WRFD-010638 Dynamic CE Resource Management


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Contents


2 Feature Planning

3 Feature Deplo ym ent




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Feature Deployment

Deployment Requirements The license controlling the CE Overbooking feature must be obtained.

The feature WRFD-010638 Dynamic CE Resource Management must be enabled.

The requirements on NodeB hardware deployment are as follows:

The BTS3812E, BTS3812A, and BTS3812AE must be configured with the EBBI, EBOI,

EULP, or EULPd.

The DBS3800 must be configured with the EBBC or EBBCd. The BBU3806C must be

configured with the EBBM.

The 3900 series base stations must be configured with the WBBPb, WBBPd, or WBBPf.

Activation/Initial Configuration

Activate the license and parameter settings for this feature on the M2000.

Feature Verification

Check the VS.NodeB.ULCreditUsed.Mean counter introduced for this feature. If the

value is not 0, this feature takes effect.

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Contents


2 Feature Planning


4 Performance Monitor in g



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Performance Monitoring

Check whether the CE Overbooking feature takes effect based onthe following counters:

VS.NodeB.ULCreditUsed.Mean: added on the RNC and used to measure the credit

resource usage at the NodeB level when this feature is enabled

VS.LC.ULCreditUsed.Mean: used to measure the credit resource usage on the

RNC

When th is feature takes effect, the value of the

VS.NodeB.ULCredi tUsed.Mean cou nter on th e NodeB is smal ler than the

sum of th e value of the VS.LC.ULCredi tUsed.Mean c oun ter in al l the cel ls

und er the NodeB .

When this feature takes effect, i f CE con gestion (wh ich caus es access

rejects) st i l l exists, and the stat ist ic resu l t of the coun ters added for this

feature is clo se to the Licens ed CE capabi l i ty, capaci ty expans ion is

recommended.


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Performance Monitoring

When CE usage is low due to a large number of 2 ms HSUPA smart

phones in the network, and the average uplink throughput is low, check

the following counters to observe performance changes:

VS.RRC.Rej.ULCE.Cong, VS.RAC.NewCallReq.Fail.ULCE.Cong, and

VS.HSUPA.RAB.FailEstab.ULCE.Cong: whether the success rate of

access based on CE resources increases, and whether the number of

CE resource request failures decreases. VS.HSUPA.TTI2to10.Succ: whether the probability of TTI switching

triggered by CE congestion decreases

VS.MeanRTWP: whether Uu load increases

VS.HSUPA.MeanBitRate: whether the average cell throughput

increases

VS.HSUPA.UE.Mean.TTI2ms: number of HSUPA UEs with a 2 ms TTI


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Contents


2 Feature Planning



5 Reference Document and Acro nym s & Abb reviat ions


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Reference Document

WCDMA RAN CE Overbooking Feature Parameter Description


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Acronyms & Abbreviations

CE: channel element

GBR: g uaranteed bit rate

HSUPA: h igh s peed up l ink packet access

MBR: maximum bi t rate

PDU: packet data un it

RLC: radio l ink contro l

RNC: radio netwo rk contro l ler

TTI: transm ission t ime interval


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Documents

Introduction to the RAN14.0 Feature–CE Overbooking 20120112