wcdma load control algorithm and parameters

8/10/2019 WCDMA Load Control Algorithm and Parameters

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Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved.

WCDMA Load Control

Algorithm and

Parameters


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Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved. Page2

Foreword

The WCDMA system is a self-interfering system, so the

capacity, coverage, and QoS are mutually affected

The target of load control is to maximize the system

capacity while ensuring coverage and QoS, and providedifferentiated services for users


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References

3GPP TS 25.133: Requirements for Support of Radio Resource

Management (FDD)

3GPP TS 25.215: Physical Layer - Measurements (FDD)

3GPP TS 25.304: UE Procedures in Idle Mode and Procedures

for Cell Reselection in Connected Mode

3GPP TS 25.321: Medium Access Control (MAC) Protocol

Specification

3GPP TS 25.331: Radio Resource Control (RRC)

3GPP TS 25.413: UTRAN Iu Interface RANAP Signaling


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Objectives

Upon completion of this course, you will be able to:

Outline the principle of load control

Describe the realization method of load control

Perform the parameter adjustment of load control


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Contents

1. Load Control Overview

2. Load Control Algorithms


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Contents


1.1 Load Control Algorithms Overview

1.2 Load Measurement

1.3 Priorities Involved in Load Control


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Load Definition

Load: the occupancy of capacity

Two kinds of capacity in WCDMA system:

Hard capacity:

Cell DL OVSF code

Iub transport resource

NodeB processing capability (NodeB credit)

Soft capacity: Cell power (UL and DL)


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Load Control Algorithms (Cont.)

Load Control AlgorithmResources

Power Code NodeB Credits Iub Bandwidth

PUC - - -IAC

CAC

LDB - - -

LDR

OLC - -

: not considered; : considered

Resources considered by different load control algorithms:


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Contents






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Load Measurement

Load control function in the WCDMA system:


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Load Measurement Quantities

The major load-related measurement quantities are as follows:

Uplink Received Total Wideband Power (RTWP)

Downlink Transmitted Carrier Power (TCP)

Non-HSPA power: TCP excluding the power used for transmission

on HSPA channels

Provided Bit Rate (PBR) on HS-DSCH

PBR on E-DCH

Power Requirement for GBR (GBP) on HS-DSCH: minimum power

required to ensure the GBR on HS-DSCH

Received Scheduled E-DCH Power Share (RSEPS): power of the E-

DCH scheduling service


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Reporting Period

The NodeB periodically reports each measurement quantity to the

RNC.

The reporting period parameters for setting different measurement

quantities:

Measurement Reporting Period Parameter

RTWP ChoiceRprtUnitForUlBasicMeasTenMsecForUlBasicMeas

MinForUlBasicMeasChoiceRprtUnitForDlBasicMeasTenMsecForDlBasicMeasMinForDlBasicMeas

RSEPS

TCP

Non-HSDPA power

GBP ChoiceRprtUnitForHsdpaPwrMeasTenMsecForHsdpaPwrMeasMinForHsdpaPwrMeas

HS-DSCH PBR ChoiceRprtUnitForHsdpaRateMeasTenMsecForHsdpaPrvidRateMeasMinForHsdpaPrvidRateMeas

E-DCH PBR ChoiceRprtUnitForHsupaRateMeasTenMsecForHsupaPrvidRateMeasMinForHsupaPrvidRateMeas


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Contents






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Priority

The QoS of the services or users with low priority will be

affected by the load control algorithms first

Three kinds of priorities involved in load control:

User priority

RAB integrated priority

User integrated priority


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User Priority

There are three levels of user priority:

gold (high priority), silver (middle priority) and copper (low

priority) users

User priority Gold Silver Copper

Uplink 384kbps 128kbps 64kbps

Downlink 384kbps 128kbps 64kbps

gold

user


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User Priority (Cont.)

The mapping relation between user priority and ARP isconfigured in RNC by SET UUSERPRIORITY

Typical relation between user priority and ARP:

ARP 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

User

Priority Gold Silver Copper


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RAB Integrated Priority

RAB integrated priority is mainly used in load control

algorithms

RAB integrated priority are set according to :

ARP

Traffic Class

Traffic Handling Priority (THP, only for interactive services)

Carrier types: HSPA or DCH


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An Example for RAB Integrated Priority

Service

ID

ARP Traffic ClassBear

typeA 1 Interactive DCH

B 1 Interactive HSDPA

C 2 Conversational DCH

D 2 Background DCH

Services attribution in the cell

Based on ARP, HSPA priority is higher

Based on Traffic Class, HSPA priority is higher

Service

IDARP Traffic Class

Bear

type

B 1 Interactive HSDPA

A 1 Interactive DCH

C 2 Conversational DCH

D 2 Background DCH

Service

IDTraffic Class ARP

Bear

type

C Conversational 2 DCH

B Interactive 1 HSDPA

A Interactive 1 DCH

D Background 2 DCH


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User Integrated Priority

For single-RAB user, the user integrated priority is the

same as the RAB integrated priority

For multiple-RAB user, the user integrated priority is

based on the highest priority of RAB


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Parameters of Priority

PriorityReference

Parameter name: Integrate Priority Configured Reference

Recommended value: ARP

CarrierTypePriorInd

Parameter name: Indicator of Carrier Type Priority

Recommended value: NONE


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Contents


2.1 PUC (Potential User Control)

2.2 LDB (Intra-Frequency Load Balancing)

2.3 CAC (Call Admission Control)

2.4 IAC (Intelligent Access Control)

2.5 LDR (Load Reshuffling)

2.6 OLC (Overload Control)


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PUC Principle

The Potential User Control (PUC) algorithm only controls

the Inter-frequency cell reselection of the potential UE,

and prevents UE from camping on a heavily loaded cell

The PUC is valid only for inter-frequency cells, and ittakes effect only in the downlink

Potential UE:

UE in idle mode

UE in Cell-FACH, Cell-PCH and URA-PCH


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PUC Load Judgment


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PUC Load Judgment

For a cell not supporting DC-HSDPA, the RNC periodically

monitors the downlink load of the cell.

If the cell load is higher than the upper threshold

(SpucHeavy) plus the load level division hysteresis

(SpucHyst), the cell load is considered heavy.

If the cell load is lower than the lower threshold (SpucLight)

minus SpucHyst, the cell load is considered light.


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PUC Load Judgment

For a cell supporting DC-HSDPA, the RNC concurrentlymonitors the load state of each single cell and load state of the

cell group.

The determination of load state of a single cell is the same as that

of a cell not supporting DC-HSDPA

The determination of load state of the cell group is as follows:

If the load of the two cells is higher than their upper thresholds

(SpucHeavy) plus their load level division hystereses (SpucHyst), the load

of the cell group is considered heavy.

If the load of the two cells is lower than their lower thresholds (SpucLight)

minus their load level division hystereses (SpucHyst), the load of the cell

group is considered light.


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PUC Procedure

NodeB UE

Heavy?

Light?

Normal?

Cell TCP

RNC

Threshold

cell reselection

parameters

System

information


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PUC Procedure (Cont.)

Freq1

Freq2

System Info

SIB3,11

System Info

SIB3,11

System Info

SIB3,11

Heavy load

Light load Normal load

Idle state CCH state

Modify1.

Sintersearch2. Qoffset

Modify 1. Sintersearch

2. QoffsetStay


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Parameters of PUC

NBMLdcAlgoSwitch-PUC

Parameter name: Cell LDC algorithm switch for PUC

Recommended value: OFF

SpucHeavy Parameter name: Load level division threshold 1

Recommended value: 70, namely 70%

SpucLight

Parameter name: Load level division threshold 2



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Parameters of PUC (Cont.)

SpucHyst

Parameter name: Load level division hysteresis


PucPeriodTimerLen

Parameter name: PUC period timer length

Recommended value: 1800, namely 1800s


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OffSinterLight

Parameter name: Sintersearch offset 1

Recommended value: -2, namely -4dB

OffSinterHeavy

Parameter name: Sintersearch offset 2

Recommended value: 2, namely 4dB


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OffQoffset1Light(for RSCP)

Parameter name: Qoffset1 offset 1


OffQoffset1Heavy(for RSCP)

Parameter name: Qoffset1 offset 2

Recommended value: 4, namely 4dB


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Contents









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LDB Principle

Intra-frequency Load Balancing (LDB) is performed to

adjust the coverage areas of cells by modifying PCPICH

power

LDB affect UEs in all states


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LDB Procedure


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Parameters of LDB

NBMLdcAlgoSwitch-INTRA_FREQUENCY_LDB

Parameter name: Cell LDC algorithm switch for LDB


IntraFreqLdbPeriodTimerLen

Parameter name: Intra-frequency LDB period timer length



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Parameters of LDB (Cont.)

CellOverrunThd

Parameter name: Cell overload threshold


CellUnderrunThd Parameter name: Cell underload threshold


PCPICHPowerPace

Parameter name: Pilot power adjustment step

Recommended value: 2, namely 0.2dB


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Parameters of LDB (Cont.)

PCPICHPower

Parameter name: PCPICH transmit power

Recommended value: 330, namely 33dBm

MaxPCPICHPower Parameter name: Max transmit power of PCPICH

Recommended value: 346, namely 34.6dBm

MinPCPICHPower

Parameter name: Min transmit power of PCPICH

Recommended value: 313, namely 31.3dBm


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Contents









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Contents



2.3.1 CAC Overview

2.3.2 CAC Based on Code Resource

2.3.3 CAC Based on Power Resource

2.3.4 CAC Based on NodeB Credit Resource

2.3.5 CAC Based on Iub Resource

2.3.6 CAC Based on the Number of HSPA Users


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Why We Need CAC?

WCDMA is an interference limited system, after a new

service is admitted, the system load will be increased

If a cell is high loaded, a new service will affect the QoS

of ongoing user, even result in call drop

CAC is used to determine whether the system resources

are sufficient to accept a new user's access request or

not


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CAC Procedure


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CAC Algorithm Switches

Power CAC Uplink CAC algorithm switch: ALGORITHM_SECOND

Downlink CAC algorithm switch: ALGORITHM_FIRST

NodeB credit CAC

CAC algorithm switch: ON

Cell CAC algorithm switch-CRD_ADCTRL: ON

HSDPA user number CAC

Cell CAC algorithm switch-HSDPA_UU_ADCTRL: OFF

HSUPA user number CAC

Cell CAC algorithm switch-HSUPA_UU_ADCTRL: OFF


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Contents



2.3.1 CAC Overview







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CAC Based on Code Resource

Code resource CAC is involved in:

RRC connection setup

Handover

R99 services setup

RRC connection setup and handover have higher priority


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Parameter of CAC Based on Code

Resource

DlHoCeCodeResvSf

Parameter name: DL handover credit and code reserved SF

Recommended value: SF32


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Contents



2.3.1 CAC Overview







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CAC Based on Power Resource

Power resource CAC is involved in:

RRC connection setup

Handover

Services setup



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Power CAC ProcedureRequest initiation

Uplink call

admission decision

Admitted?

Downlink calladmission desicion

Admitted?

Request accepted Request rejected

No

No

Yes

Yes


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Power CAC Algorithms

Algorithm 1: based on UL/DL load measurement andload prediction (RTWP and TCP)

Algorithm 2: based on Equivalent Number of User (ENU)

Algorithm 3: loose call admission control algorithm


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Power CAC for RRC Connection Setup

For the RRC Connection Setup Request for the reason ofemergency call, detach, or registration: Direct Admission

For the RRC connection setup request for other reasons:

When power-based admission is based on power (algorithm 1 and

algorithm 3), the UL or DL OLC trigger threshold (UlOlcTrigThd orDlOlcTrigThd) is used for admission.

When power-based admission is based on the ENU (algorithm 2),

the admission decision is made as follows:

When UL_UU_OLCor DL_UU_OLCis set to 1, RRC connection setup

request is rejected when the cell is in the overload state. If the cell is not inthe overload state, the UL or DL OLC trigger threshold is used for power-

based admission.

When UL_UU_OLCor DL_UU_OLCis set to 0, the UL or DL OLC trigger

threshold is used for power-based admission.

P B d Ad i i Al ith 1


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Power-Based Admission Algorithm 1

for RAB Setup

Power-based admission decision based on algorithm 1consists of uplink power-based admission decision and

downlink power-based admission decision procedures:

Uplink admission decision:

R99 cell

HSPA cell

Downlink admission decision:

R99 cell

HSPA cell


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Algorithm 1 - Uplink for R99 Cell


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Parameters of Power CAC

UlCCHLoadFactor

Parameter name: UL common channel load reserved

coefficient


UlNonCtrlThdForHo/UlNonCtrlThdForAMR/UlNonCtrlThdF

orNonAMR/UlNonCtrlThdForOther

Parameter name: UL threshold of handover/Conv AMR/Conv

non_AMR/other service

Recommended value: 80%, 75%, 75%, 60%


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Algorithm 1 - Uplink for HSPA Cell

1. The RNC obtains the uplink RTWP of the cell andcalculates the current uplink load factor.

After the Received Scheduled E-DCH Power Share (RSEPS)

measurement is introduced, the UL RTWP is divided into

two parts:

Controllable part

Uncontrollable part


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2. The RNC calculates the uplink load increment ULbased on the service request using Ec/N0 of the GBR of

the service, neighboring interference factor, and AF of

the service


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3. The RNC determines whether to grant the UE admission:

1).

2).

3). 4).

5).


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3. The RNC determines whether to grant the UE admission: The RNC admits the HSUPA scheduling services in either of the

following cases:

Formula 1, 2, or 3 is fulfilled.

Formula 4 is fulfilled.

The RNC admits the HSUPA non-scheduling services in either of the

following cases:

Formula 1, 2, or 3 is fulfilled.

Formulas 4 and 5 are fulfilled.

The RNC admits the DCH services when formulas 4 and 5 are

fulfilled

If the access request is rejected, the RNC performs the next step


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4. The RNC checks whether the Control RTWP Anti-interference function switch (RsvdBit1subparameter of

the RsvdPara1parameter) is enabled. If it is enabled, the

RNC checks whether the uplink equivalent user load

proportion of the cell is lower than 40%. If it is lower

than 40%, the RNC accepts the access request.

Otherwise, the RNC rejects the access request.


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Parameters of Power CAC

UlHsDpcchRsvdFactor

Parameter name: UL HS-DPCCH reserve factor


UlCellTotalThd

Parameter name: UL total power threshold



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Parameters of Power CAC (Cont.)

HsupaLowPriorityUserPBRThd

HsupaEqualPriorityUserPBRThd

HsupaHighPriorityUserPBRThd

Parameter name: Low/Equal/High priority HSUPA user PBR

threshold

Recommended value: 100%, 100%, 100%


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Algorithm 1 - Downlink for R99 Cell


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DlCCHLoadRsrvCoeff

Parameter name: DL common channel load reserved

coefficient


DlHOThd/DlConvAMRThd/DlConvNonAMRThd/DlOtherTh

d

Parameter name: DL threshold of handover/Conv AMR/Conv

non_AMR/other service

Recommended value: 85%, 80%, 80%, 75%


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Algorithm 1 - Downlink for HSPA Cell

1. The RNC calculates the downlink power incrementPDLfor new service request

The power increment estimation for the DCH RAB in the

HSPA cell is similar to the DCH RAB in the R99 cell

The power increment estimation for HSDPA RAB PDLis

made on the basis of GBR, Ec/N0, non-orthogonal factor,

and so on


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2. The RNC determines whether to grant the UEadmission:

Admission Decision for DCH RAB in the Downlink:

1).

2).

3).


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Admission Decision for DCH RAB in the Downlink:

If the current cell does not support DC-HSDPA, the RNC admits

the DCH RAB when either of the following conditions is met:

Condition A: Formulas 1 and 2 are fulfilled

Condition B: Formulas 1 and 3 are fulfilled


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Admission Decision for HSDPA RAB in the Downlink:

1).

2).

3).

4).

5).


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Admission Decision for HSDPA RAB in the Downlink:

If the current cell does not support DC-HSDPA, the RNC admits

the HSDPA RAB when any of the following conditions is met:

Condition C: Formula 1 (for streaming service) is fulfilled or Formula 2

(for BE service) is fulfilled

Condition D: Formulas 3 and 4 are fulfilled

Condition E: Formulas 3 and 5 are fulfilled


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DlCellTotalThd

Parameter name: DL total power threshold


DlHSUPARsvdFactor

Parameter name: DL HSUPA reserved factor



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HsdpaStrmPBRThd

Parameter name: HSDPA streaming PBR threshold


HsdpaBePBRThd

Parameter name: HSDPA best effort PBR threshold




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for RAB Setup

When the CAC function uses algorithm 2, the admissionof uplink/downlink power resources uses the algorithm

depending on the Equivalent Number of Users (ENU)


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Equivalent Number of Users

The 12.2 kbit/s AMR traffic is defined as one ENU. Thus,the 12.2 kbit/s AMR traffic can be used to calculate the

ENU of all other services. The calculation is related to the

following factors:

Cell type, such as urban or suburban

Traffic domain, CS or PS

Coding type, turbo code or 1/2, 1/3 convolutional code

Traffic QoS, that is, Block Error Rate (BLER)


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Power CAC Algorithm 2 Procedure

Get current total ENU

Admission request

Get the traffic characteristic, and

estimate the increment of ENU

Calculate the predicted ENU

admitted rejected

End of UL/DL CAC

Y NSmaller than

the threshold?

N

i

itotal ENUNENU

1

)(

newENU

newtotaltotal ENUNENUNENU )()1(

max/)1( ENUNENUENULoad total


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UlTotalEqUserNum

Parameter name: UL total equivalent user number

Recommended value: 80

DlTotalEqUserNum

Parameter name: DL total equivalent user number




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Power Based Admission Algorithm 3

for RAB Setup

Algorithm 3 is similar to algorithm 1. The difference isthat the estimated load increment in algorithm 3 is

always set to 0

In accordance with the current cell load (uplink load

factor and downlink TCP), the RNC determines whether

the cell load will exceed the threshold, with the

estimated load increment set to 0. If yes, the RNC rejects

the request. If not, the RNC accepts the request


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Contents



2.3.1 CAC Overview






C


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NodeB Credit

CE is used to measure the channel demodulationcapability of the NodeBs. On the RNC side, it is referred

to the NodeB credit. On the NodeB side, it is the Channel

Element (CE)

The resource of one equivalent 12.2 kbit/s AMR voice

service, including 3.4 kbit/s signaling on DCCH, is defined

as one CE

There are two kinds of CE, that is, uplink CE supportinguplink services and downlink CE supporting downlink

services. Therefore, one 12.2 kbit/s AMR voice service

consumes one uplink CE and one downlink CE

N d B C di CAC


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NodeB Credit CAC

NodeB credit CAC is involved in: RRC connection setup

Handover

Services setup


P t f N d B C dit CAC


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Parameter of NodeB Credit CAC

UlHoCeResvSf Parameter name: UL handover credit reserved SF


DlHoCeCodeResvSf

Parameter name: DL handover credit and code reserved SF


HsupaCeConsumeSelection

Parameter name: HSUPA Credit Consume Type

Recommended value: MBR

C t t


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Contents

2. Load Control Algorithms2.3 CAC (Call Admission Control)

2.3.1 CAC Overview






I b R CAC


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Iub Resource CAC

Iub overbooking The Iub overbooking feature considers the statistic

multiplexing of service activities and multiple users

Through the admission of more users, Iub overbooking

increases the resource utilization on the Iub interface

I b R CAC (C t )


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Iub Resource CAC (Cont.)

Activity factor RT services, including conversational and streaming services,

are admitted at the Maximum Bit Rate (MBR):

Admission bandwidth = MBR x activity factor

NRT services, including interactive and background services,

are admitted at the GBR:

Admission bandwidth = GBR x activity factor

I b R CAC P d


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Iub Resource CAC Procedure

For handover of a user, the following requirements apply: Load of the path + Bandwidth required by the user < Total

configured bandwidth of the path

For a new user, the following requirements apply:

Load of the path + Bandwidth required by the user < Total

configured bandwidth of the path - Bandwidth reserved for

handover

For rate upsizing of a user, the following requirementsapply:

Load of the path + Bandwidth required by the user < Total

configured bandwidth of the path - Congestion threshold

P t f I b R CAC


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Parameters of Iub Resource CAC

FWDHORSVBW/BWDHORSVBW

Parameter name: Forward/Backward handover reserved bandwidth

Recommended value: 0, namely 0Kbit/s

FWDCONGBW/BWDCONGBW

Parameter name: Forward/Backward congestion threshold


FWDCONGCLRBW/BWDCONGCLRBW

Parameter name: Forward/Backward congestion clear threshold


C t t


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Contents

2. Load Control Algorithms2.3 CAC (Call Admission Control)

2.3.1 CAC Overview






HSPA U N b CAC


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HSPA User Number CAC

HSPA user number CAC is involved in: Cell level

Maximum number of HSPA users in a cell

NodeB level

Maximum number of HSPA users in all the cells configured in one

NodeB

CAC f HSDPA U


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CAC of HSDPA Users

When HSDPA_UU_ADCTRLis set to 1, the HSDPA services have

to undergo admission decision based on the number of HSDPA

users.

When a new HSDPA service attempts to access the network,

the algorithm admits the service if the following conditions are

met:

The number of HSDPA users in the cell does not exceed the

maximum value specified by MaxHsdpaUserNum.

The number of HSDPA users in the NodeB does not exceed the

maximum value specified by NodeBHsdpaMaxUserNum.

Otherwise, the HSDPA service is degraded to R99 service to

retry admission.

CAC of HSUPA Users


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CAC of HSUPA Users

When HSUPA_UU_ADCTRLis set to 1, the HSUPA services have to

undergo admission decision based on the number of HSUPA users

When a new HSUPA service attempts to access the network, the

algorithm admits the service if the following conditions are met:

The number of the HSUPA users in the cell does not exceed the maximum

value specified by MaxHsupaUserNum.

The number of the HSUPA users in the NodeB does not exceed the

maximum value specified by NodeBHsupaMaxUserNum.

Otherwise, the HSUPA service is degraded to R99 service to retry

admission

Parameters of HSPA User Number


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CAC

MaxHsdpaUserNum Parameter name: Maximum HSDPA user number


NodeBHsdpaMaxUserNum Parameter name: NodeB Max HSDPA User Number


Parameters of HSPA User Number


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CAC (Cont.)

MaxHsupaUserNum Parameter name: Maximum HSUPA user number


NodeBHsupaMaxUserNum Parameter name: NodeB Max HSUPA User Number


Contents


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Contents

2. Load Control Algorithms2.1 PUC (Potential User Control)






Why Do We Need IAC?


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Why Do We Need IAC?

The disadvantages of CAC: For PS NRT (Non-Real Time) services, CAC is not flexible

No consideration about the priority of different users

No consideration about Directed Retry after CAC rejection

Intelligent means the algorithm can increase admission

successful rate

IAC Procedure


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IAC Procedure

Contents


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Contents

2. Load Control Algorithms2.4 IAC (Intelligent Access Control)

2.4.1 IAC During RRC Connection Setup

2.4.2 Directed Retry Decision During RAB Procedure

2.4.3 Rate Negotiation at Admission Control

2.4.4 Admission Decision

2.4.5 Preemption

2.4.6 Queuing

2.4.7 Low-Rate Access of the PS BE Service

2.4.8 IAC for Emergency Calls

IAC RRC Connection Setup


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IAC - RRC Connection Setup

.

RRC Redirection based on


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Distance

Target service: UE-originating AMR services

RNC estimates the distance between the UE and the cell

center by considering the propagation delay

RNC determines whether to perform RRC redirectionbased on the estimation result

RRC Redirection for Service Steering


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RRC Redirection for Service Steering

Purpose: Enable the successful RRC connection setup by

selecting an appropriate cell for the UE based on the requested

service.

During the RRC connection setup, the RNC implements service

steering between inter-frequency or inter-RAT cells according

to the cause of RRC connection setup. In addition, the RNC

considers the load of the cell for access and the redirection

factors to control the degree of load balancing

Algorithm switch: DrSwitch-DR_ RRC_DRD_SWITCH

Triggering factor: RedirFactorOfNormor RedirFactorOfLDR

Target cell: RedirSwitch

Parameters of RRC Redirection


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Parameters of RRC Redirection

DrSwitch-DR_ RRC_DRD_SWITCH Parameter name: DRD switch for RRC connection

Recommended value: ON

RedirSwitch

Parameter name: Redirection Switch


RedirFactorOfNorm/RedirFactorOfLDR

Parameter name: Redirection Factor Of Normal/LDR

Recommended value: 0, 100

RRC DRD


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RRC DRD

Purpose: Instruct the UE to set up an RRC connection inan inter-frequency neighboring cell with better signal

quality


Target cell: same-coverage inter-frequency neighboring

cells, which quality is large than threshold:

Parameters of RRC DRD


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Parameters of RRC DRD

DRDEcN0Threshhold Parameter name: Drd Ec/N0 threshold


RRC Redirection after DRD Failure


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RRC Redirection after DRD Failure


ConnectFailRrcRedirSwitch

Target cell: inter-frequency neighboring cells or inter-RATneighboring cells

Parameters of IAC RRC


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Redirection

ConnectFailRrcRedirSwitch Parameter name: RRC redirect switch

Recommended value: Only_To_Inter_Frequency


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IAC - RAB DRD


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IAC - RAB DRD

Purpose

Select a suitable cell for a UE to access according to the HSPA+

technological satisfaction, service priority, and cell load

Scenario

RAB setup

RAB modification

DCCC channel reconfiguration

Non-periodic DRD:

Inter-frequency DRD Inter-RAT DRD.

Contents


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Contents







2.4.5 Preemption

2.4.6 Queuing



IAC - Rate Negotiation


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IAC Rate Negotiation

Rate negotiation includes: PS MBR negotiation

PS GBR negotiation

Initial rate negotiation

Target rate negotiation

PS MBR Negotiation


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PS MBR Negotiation

If the IE "Alternative RAB Parameter Values" is present inthe RANAP RAB ASSIGNMENT REQUEST or the

RELOCATION REQUEST message when a PS service is set

up, reconfigured, or handed over, then the RNC and the

CN negotiate the rate according to the UE capability to

obtain the MBR while ensuring a proper QoS

Parameters of PS MBR


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Negotiation PsSwitch-PS_STREAM_IU_QOS_NEG_SWITCH

Parameter name: PS rate negotiation switch for Streaming service


PsSwitch-PS_ BE_IU_QOS_NEG_SWITCH

Parameter name: PS rate negotiation switch for BE service


PsSwitch-PS_BE_STRICT_IU_QOS_NEG_SWITCH

Parameter name: PS rate negotiation switch for strict BE service


PS GBR Negotiation


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PS GBR Negotiation

During the setup, reconfiguration, or handover of a real-time PS service, if the RAB assignment message carries

multiple alternative GBRs and

PS_STREAM_IU_QOS_NEG_SWITCHsubparameter of the

PsSwitchparameter is set to 1, the RNC selects the

maximum rate as the GBR of this RAB and sends it to the

CN

Initial Rate Negotiation


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Initial Rate Negotiation

For a BE service in the PS domain, the RNC selects an initial rate to

allocate bandwidth for the service before the admission request based

on cell resources in the following cases:

A service is set up

The UE state changes from CELL_FACH to CELL_DCH

Purpose: Enable UE admission at an appropriate rate based on the

service requested by the UE and the signal quality of the cell

The negotiation is based on the cell load information, which includes:

Uplink and downlink radio bearer status of the cell

Minimum spreading factor (SF) supported

HSPA capability

Initial Rate Negotiation (Cont )


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Initial Rate Negotiation (Cont.)

DCCCSwitch

PS BE Initial Rate DynamicConfiguration Switch

Actual Initial Rate

ON ON

In the uplink, the initial rate is the smaller oneof the MBR and 384 kbit/s.In the downlink, the initial rate is dynamicallyset on the basis of Ec/N0.

ON OFF

In the uplink, the initial rate is the smaller oneof the MBR and the initial rate of the uplink BEservice (UlBeTraffInitBitrate).In the downlink, the initial rate is the smallerone of the MBR and the initial rate of the

downlink BE service (DlBeTraffInitBitrate)OFF - MBR

Initial rate definition for DCH services:

Parameters of Initial Rate Negotiation


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DraSwitch-DRA_DCCC_SWITCH Parameter name: Dynamic resource allocation switch for

DCCC


PsSwitch-PS_BE_INIT_RATE_DYNAMIC_CFG_SWITCH

Parameter name: PS rate negotiation switch for initial rate

reconfiguration




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EcN0EffectTime

Parameter name: Ec/N0 effective time

Recommended value: 30000, namely 30000ms

EcN0Ths

Parameter name: Ec/N0 threshold

Recommended value: 41, namely -4dB

DlBeTraffInitBitrate

Parameter name: DL BE traffic Initial bit rate

Recommended value: D64, namely 64kbit/s



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Initial rate of HSDPA services: GBR

Initial rate definition for HSPA services:

If the DRA_HSUPA_DCCC_SWITCHsubparameter of the

DraSwitchparameter is set to 1, the actual initial rate is the

initial rate of the HSUPA BE service (HsupaInitialRate).

If the DRA_HSUPA_DCCC_SWITCHsubparameter of the

DraSwitchparameter is set to 0, the actual initial rate is the

MBR.



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a a ete s o t a ate egot at o

DraSwitch-DRA_HSUPA_DCCC_SWITCH

Parameter name: Dynamic resource allocation switch for

HSUPA DCCC


HsupaInitialRate

Parameter name: Initial rate of HSUPA BE traffic

Recommended value: D256, namely 256kbit/s

Target Rate Negotiation


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Target Rate Negotiation

For a BE service in the PS domain, if the cell resource-

based admission at the initial rate fails, the RNC selects a

target rate to allocate bandwidth for the service based

on cell resource in following cases:

Service setup

Soft handover

DCCC rate upsizing

Contents


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Contents







2.4.5 Preemption

2.4.6 Queuing2.4.7 Low-Rate Access of the PS BE Service


Admission Decision


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After rate negotiation, RNC makes admission decision.

The admission decision performed by CAC is based on

resources, such as code resources, power resources,

NodeB credits, and Iub resources

If the admission is successful, UE access is granted.

Otherwise, the RNC performs the next step

Contents


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2.4.5 Preemption

2.4.6 Queuing2.4.7 Low-Rate Access of the PS BE Service



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Preemption Procedure


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p

1. The RNC selects the target cell for preemption

For non-DC-HSDPA services: the RNC selects a suitable cell

according to the settings of the DRD functions

For DC-HSDPA services: the RNC selects the two cells in the

DC-HSDPA cell group as the target cell

Preemption Procedure


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p

2. The RNC selects a service for preemption

3. The preemption algorithm determines the radio link

sets to be preempted

a. Selects SRNC users first. If no user under the SRNC is

available, the algorithm selects users under the DRNC.

b. Sorts the preemptable users by user integrated priority,

or sorts the preemptable RABs by RAB integrated priority.

c. Determines candidate users or RABs

Parameters of Preemption


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p

PreemptAlgoSwitch

Parameter name: Preempt algorithm switch


Contents


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2.4.5 Preemption

2.4.6 Queuing



IAC - Queuing


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g

For PS services, after preemption fails, the RNC performs

queuing if the following conditions are met:

The RNC receives a RAB ASSIGNMENT REQUEST message

indicating that queuing is supported

The queuing algorithm switch (QueueAlgoSwitch) is set to

ON

The queuing function is triggered by the heartbeat timer

that is set by the PollTimerLenparameter. Each time the

timer expires, the RNC selects the service that meets the

requirement to make an admission attempt

Parameters of Queuing


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Copyright 2009 Huawei Technologies Co., Ltd. All rights reserved.Page135

g

QueueAlgoSwitch

Parameter name: Queue algorithm switch


MaxQueueTimeLen

Parameter name: Max queuing time length


Contents


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2.4.5 Preemption

2.4.6 Queuing



IAC - Low-Rate Access of the PS BE

Service


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Service

Low-rate access means access from the DCH at 0 kbit/s,

FACH, or enhanced FACH (E-FACH)

Low-rate access is used in the following scenarios:

RAB setup

Hard handover or SRNS relocation

Parameters of Low-Rate Access of the

PS BE Service


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PS BE Service

PsSwitch-PS_BE_EXTRA_LOW_RATE_ACCESS_SWITCH

Parameter name: PS rate negotiation switch for low rate

access


ZeroRateUpFailToRelTimerLen

Parameter name: Release 0 kbit/s Timer length for failed to

rate up


Contents


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2.4.5 Preemption

2.4.6 Queuing



IAC for Emergency Calls


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RRC connection setup process of emergency calls:

No admission on power resource

Admission is successful if the current remaining hard

resources are sufficient

If the hard resource admission failspreemption is

performed regardless of the preemption switch

RRC connection

setup request

Admission

algorithmPreemption DRD Redirection

RAB process

Fails

Succeeds

Fails Fails

Succeeds Succeeds

IAC for Emergency Calls (Cont.)


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RAB Admission of Emergency Calls :

For power resource admission:

When EMC_UU_ADCTRLis on, power admission fails if the

system is in overload. Otherwise, the admission succeeds

If the CAC algorithm switch is off, the emergency calls are directly

admitted

Admission is successful if the current remaining hard

resources are sufficient

IAC for Emergency Calls (Cont.)


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Preemption of Emergency Calls

If cell resource-based admission fails, preemption is

performed regardless of whether the preempt function is

enabled or not.

If EmcPreeRefVulnSwitchis set to ON, all non-emergency

users that have accessed the network can be preempted,

regardless of the preemption-prohibited attribute of the

users.

If EmcPreeRefVulnSwitchis set to OFF, only the non-

emergency users with preemption-allowed attribute can be

preempted.

Parameters of IAC for Emergency Calls


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EmcPreeRefVulnSwitch

Parameter name: Preemptvulnerability for Emergency call

switch


NBMCacAlgoSwitch-EMC_UU_ADCTRL

Parameter name: Cell CAC algorithm switch for UU resource

of emergency call


Contents


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Contents


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2.5.1 Basic Congestion Triggering

2.5.2 LDR Procedure

2.5.3 LDR Actions

LCC (Load Congestion Control)


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Overload state: OLC

Load

THLDR

THOLC

100%

section A

section B

section C Normal state

Basic congestion state: LDR

LDR Principle


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Reason:

When the cell is in basic congestion state, new coming calls

could be easily rejected by system

Purpose:

Optimizing cell resource distribution

Decreasing load level, increasing admission successful rate

Triggering:

Power, code, Iub or NodeB credit

LDR Triggering - Power Resource


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Hysteresis time: 1000ms

UL/DL load

Cell in the basic congestionstate

Basic congestionrelieved

RNC periodic check

LDR trigger

threshold

LDR release

threshold

Time


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LDR Triggering - Code Resource


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Congestion control based on code resource can be

enabled through the CELL_CODE_LDRsubparameter of

the NBMLdcAlgoSwitchparameter

If the SF corresponding to the current remaining code of

the cell is larger than the value of CellLdrSfResThd, code

congestion is triggered and the related load reshuffling

actions are taken


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LDR Triggering - Iub Resource


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Congestion control based on Iub resource can be enabled

through the IUB_LDRsubparameter of the

NodeBLdcAlgoSwitchparameter

Iub congestion control in both the uplink and downlink is

NodeB-oriented. So for the basic congestion caused by

Iub resource, all UEs under the NodeB are the objects of

related LDR actions

Parameters of LDR (Cont.)


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NodeBLdcAlgoSwitch-IUB_LDR

Parameter name: NodeB LDC algorithm switch for LDR


LDR Triggering NodeB Credit

Resource


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esou ce

The basic congestion caused by NodeB credit resource is

of the following types:

Type A: Basic congestion at local cell level

Type B: Basic congestion at local cell group level (if any)

Type C: Basic congestion at NodeB level



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Parameter Parameter name Recommended value

Type A:

CELL_CREDIT_LDRCell LDC algorithm switch for LDR OFF

Type A:

UlLdrCreditSfResThdUL LDR credit SF reserved threshold SF8

Type A:

DlLdrCreditSfResThd

DL LDR credit SF reserved threshold SF8

Type B:

LCG_CREDIT_LDR

NodeB LDC algorithm switch for

LDROFF

Type C:

NODEB_CREDIT_LDR

NodeB LDC algorithm switch for

LDROFF

Type B/C:

UlLdrCreditSfResThdUL LDR credit SF reserved threshold SF8

Type B/C:

DlLdrCreditSfResThdDL LDR credit SF reserved threshold SF8



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If the congestion of all resources is triggered in a cell, the

congestion is relieved in order of resource priority for load

reshuffling as configured through the SET ULDCALGOPARA

command

Recommended setting is as follows:

The first priority for load reshuffling (LdrFirstPri) is set to IUBLDR

The second priority for load reshuffling (LdrSecondPri) is set to

CREDITLDR

The third priority for load reshuffling (LdrThirdPri) is set to

CODELDR

The fourth priority for load reshuffling (LdrFourthPri) is set to

UULDR

Contents


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2.5.2 LDR Procedure

2.5.3 LDR Actions

LDR Procedure


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The RNC periodically takes actions if the basic congestion

is detected:

Inter-frequency load handover

Code reshuffling

BE service rate reduction AMR rate reduction

Inter-RAT load handover in the CS domain

Inter-RAT load handover in the PS domain

QoS Renegotiation for Uncontrollable Real-Time Services

LDR Procedure


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LDR Actions Intended for Different

Resources


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When the basic congestion is triggered by different

resources, the congestion can be relieved in a order set

by running the SET ULDCALGOPARAcommand

LDR actions intended for different resource table (See the

notes)



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LdrPeriodTimerLen

Parameter name: LDR period timer length


GoldUserLoadControlSwitch

Parameter name: Gold user load control switch




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DlLdrFirstActionto DlLdrTenthAction

Parameter name: DL LDR first action to DL LDR tenth action

Recommended value: CodeAdj, InterFreqLDHO, BERateRed

UlLdrFirstActionto UlLdrEighthAction

Parameter name: UL LDR first action to UL LDR eighth

action

Recommended value: InterFreqLDHO, BERateRed

Contents


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2.5.2 LDR Procedure

2.5.3 LDR Actions

LDR Actions - Inter-Frequency Load

Handover


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Inter-Frequency Load Handover

Based on Blind Handover

Based on Measurement

InterFreqLDHOMethodSelection

Parameter name: InterFreq Load Handover Method

Selection

Recommended value: BLINDHO


Handover


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Inter-Frequency Load Handover Based on Blind Handover

1. Check whether cells for inter-frequency blind handover are

available. If available, go to the next step. Otherwise, the action

fails

2. The algorithm selects the target cell according to the type of

resource that causes the basic congestion:

the basic congestion is caused by power resource

the basic congestion is caused by code resource

3. The algorithm selects the UEs to be handed over according tothe setting of InterFreqLdHoForbidenTC and NbmLdcUeSelSwitch


Handover


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Inter-Frequency Load Handover Based on Measurement: Only for

power congestion

1. The RNC selects the UE whose service types are not forbidden for LDR

handover by parameterInterFreqLdHoForbidenTC

2. The RNC selects the candidate cells

3. The RNC issues a measurement control message to the UE, requesting

the UE to measure the signal quality of all candidate cells

4. The UE measures the RSCP and Ec/No of the candidate cells and

periodically reports the measurement results to the RNC

5. Based on the received measurement results, the RNC selects the

candidate target cells

6. The RNC selects the cell with the highest priority from the candidate

target cells to perform inter-frequency hard handover



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InterFreqLdHoForbidenTC

Parameter name: Forbidden Traffic Class for inter-freq HO

Recommended value: None

NbmLdcUeSelSwitch

Parameter name: Inter-freq Handover Select User algorithm

switch

Recommended value: NBM_LDC_MATCH_UE_ONLY


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UlInterFreqHoBWThd/DlInterFreqHoBWThd

Parameter name: UL/DL HO maximum bandwidth

Recommended value: 200000bit/s, 200000bit/s

LDR Actions - BE Rate Reduction


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Target RAB:

The RAB with the lowest integrated priority

The current rate is higher than GBR

Number:

UlLdrBERateReductionRabNum/DlLdrBERateReductionRabNum

The RNC sends a RADIO BEARER RECONFIGURATION

message to the UE



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UlLdrBERateReductionRabNum/DlLdrBERateReductionRa

bNum

Parameter name: UL/DL LDR-BE rate reduction RAB number


LDR Actions - QoS Renegotiation


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QoS renegotiation function switch:

DRA_IU_QOS_RENEG_SWITCH

Target RAB:


Number:

UlLdrPsRTQosRenegRabNum/DlLdrPsRTQosRenegRabNum

The RNC sends a RAB MODIFY REQUEST message to the

CN



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DraSwitch-DRA_IU_QOS_RENEG_SWITCH

Parameter name: Dynamic resource allocation switch for IU

QoS RENEQ


UlLdrPsRTQosRenegRabNum/DlLdrPsRTQosRenegRabNu

m

Parameter name: UL/DL LDR un-ctrl RT Qos re-nego RAB

num


LDR Actions - Inter-RAT Handover


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Target user:

The user with the lowest integrated priority

Service handover indicator:

HO_TO_GSM_SHOULD_BE_PERFORM

HO_TO_GSM_SHOULD_NOT_BE_PERFORM

WCDMA cell

GSM cell



167/192


Parameter Parameter nameRecommended

value

UlCSInterRatShouldBeHOUeNum UL CS should be HO user number 3

DlCSInterRatShouldBeHOUeNum DL CS should be HO user number 3

UlCSInterRatShouldNotHOUeNumUL CS should not be HO user

number3

DlCSInterRatShouldNotHOUeNumDL CS should not be HO user

number3

UlPSInterRatShouldBeHOUeNum UL PS should be HO user number 1

DlPSInterRatShouldBeHOUeNum DL PS should be HO user number 1

UlPSInterRatShouldNotHOUeNumUL PS should not be HO usernumber

1

DlPSInterRatShouldNotHOUeNumDL PS should not be HO usernumber

1

LDR Actions - AMR Rate Reduction


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Target RAB:


Number:

UlLdrAMRRateReductionRabNum/DlLdrAMRRateReductionRabNum

In downlink:

The RNC sends the Rate Control Request message through the Iu

interface to the CN

In uplink:

The RNC sends the TFC CONTROL command to the UE



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UlLdrAMRRateReductionRabNum/DlLdrAMRRateReductio

nRabNum

Parameter name: UL/DL LDR-AMR rate reduction RAB

number


LDR Actions - Code Reshuffling


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CellLdrSfResThd

Parameter name: Cell LDR SF reserved threshold


MaxUserNumCodeAdj

Parameter name: Max user number of code adjust


LdrCodePriUseInd

Parameter name: LDR code priority indicator

Recommended value: FALSE

Contents


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Contents


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2.6.1 Overload Triggering

2.6.2 General OLC Procedure

2.6.3 OLC Actions

OLC Principle


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Reason:

In overload congestion state, the system is not stable

Purpose:

Ensuring the system stability and making the system back to

the normal state as soon as possible

Triggering:

Power resource and interference

OLC Load Judgment

/ l d


175/192


State transition hysteresis threshold

UL/DL load

Cell in overloadOverload released

RNC periodic check

OLC trigger

threshold

OLC release

threshold

time

Parameters of OLC


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NBMLdcAlgoSwitch-UL_UU_OLC/DL_UU_OLC

Parameter name: Cell LDC algorithm switch for OLC

Recommended value: OFF, OFF

UlOlcTrigThd/DlOlcTrigThd

Parameter name: UL/DL OLC trigger threshold Recommended value: 95%, 95%

UlOlcRelThd/DlOlcRelThd

Parameter name: UL/DL OLC release threshold

Recommended value: 85%, 85%

Contents


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2.6.3 OLC Actions

OLC Procedure


178/192


Parameters of OLC (Cont.)


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OlcPeriodTimerLen

Parameter name: OLC period timer length

Recommended value: 3000, namely 3000ms

Contents


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2.6.3 OLC Actions

OLC Actions - Performing TF Control of

BE ServicesOLC l ith f TF t l i th d li k


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OLC algorithm for TF control in the downlink:

Select RABs with the lowest integrated priority

The RNC sends the TF control indication message to the MAC

The MAC restricts the TFC selection: TFmax(N+1) = TFmax(N) x

Ratelimitcoeff

OLC algorithm for TF control in the uplink:

Select RABs with the lowest integrated priority

the RNC sends a TRANSPORT FORMAT COMBINATION CONTROL

message to the UE

The UE restricts the TFC selection

Example of TF Control


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DlD R t Thd


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DlDcccRateThd

Parameter name: Downlink Bit Rate Threshold For DCCC

Recommended value: D64, namely 64Kbit/s

DlOlcFTFRstrctRabNum

Parameter name: DL OLC fast TF restrict RAB number


DlOlcFTFRstrctTimes

Parameter name: DL OLC fast TF restrict times

Recommended value: 3, namely 3 times


i i


184/192


RateRstrctTimerLen/RateRecoverTimerLen

Parameter name: DL TF rate restrict/recover timer length

Recommended value: 3000ms, 5000ms

RateRstrctCoef/RecoverCoef

Parameter name: DL TF rate restrict/recover coefficient

Recommended value: 68%, 130%


UlD R t Thd


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UlDcccRateThd

Parameter name: Uplink Bit Rate Threshold For DCCC

Recommended value: D64, namely 64Kbit/s

UlOlcFTFRstrctRabNum

Parameter name: UL OLC fast TF restrict RAB number


UlOlcFTFRstrctTimes

Parameter name: UL OLC fast TF restrict times

Recommended value: 3, namely 3 times

OLC Actions - Switching BE Services

to Common Channels

T t


186/192


Target user:

Select users with the lowest integrated priority

The users with the DCH or HSPA BE services in PS domain

Execution:

The RNC sends RB Reconfiguration message to UE

The UE makes a response by RB Reconfiguration Complete


T C hU N


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TransCchUserNum

Parameter name: Transfer Common Channel User number


OLC Actions - Adjusting the Maximum

FACH TX Power

T t FACH h l


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Target FACH channel:

During an OLC period, the OLC can adjust the power of only

one FACH. If multiple FACHs meet the conditions, the OLC

adjusts them one by one in different OLC periods

Execution:

The cell adjusts the maximum FACH TX power:

arg maxt etP P Delta


M F hP


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C

wcdma load control algorithm and parameters

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