load control 2

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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential

Security Level: Confidentia

www.huawei.com

Load Control Strategys

for UMTS Network

UMTS Solution Test Department


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制作胶片应学会运用多种表现形式以丰富页面或使内容更条理化

V2.0在保留V1.0内容的基础上增加了部分新的图表内容

色调经过了调整，主要分公司的主色—“红黑灰白”系列和辅助色—“彩色”系列（供参考）

选用时，请保持胶片的统一风格（即同一胶片选用统一风格的图表表现）

图表颜色已经根据公司专色调配设置好，若想改变其颜色，请参照公司的颜色使用规范再自

行调配（看88页附件参考)

建议一套胶片里用色控制在4种以内

这些图库会在一定时期内更新，逐步规范和完善

Huawei conf idential


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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 3

Contents

Perface

Load Control Algorithm Overview

Auto-Adaptive Background Noise Algorithm

Potential User Control Algorithm

Call Admission Control Algorithm Intelligent Access Control Algorithm

Load Reshuffling Algorithm

Overload Control Algorithm

Dynamic Cell Shutdown Algorithm


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Contents

Perface


Load Control Introduction

Load Control algorithms in different UE access phases

Load Control algorithms used on different cell load levels

Priorities Involved in Load Control



Call Admission Control Algorithm

Intelligent Access Control Algorithm





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Load Control Introduction

Why we use load control algorithms?

The WCDMA system is a self-interfering system. As the load of the system increases, the

interference rises. A relatively high interference can affect the coverage and QoS of established

services. Therefore, the capacity, coverage, and QoS of the WCDMA system are mutually affected.

The destination of load control algotirhms

Through the control of key resources, such as power, downlink channelization codes, channel

elements (CEs), Iub transmission resources, which directly affect user experience, load control

aims to maximize the system capacity while ensuring coverage and QoS.

Differentiated services under load control algorithms

load control provides differentiated services for users with different priorities. For example,

when the system resources are insufficient, procedures such as direct admission, preemption,

redirection can be performed to ensure the successful access of emergency calls to the network.


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Load Control algorithms in different UE access phases

Before UE access: PUC

During UE access: CAC、IAC

After UE access: LDB、LDR 、OLC

Depending on the actual phase of UE access, different load control algorithms are

used, as shown in the following figure.

PUC = Potential User Control

IAC = Intelligence Admission Control

CAC = Call admission control

LDB = Load Control Balancing

LDR = Load Resuffling

OLC = Overload Control


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Load control algorithms used on different cell load levels

Start PUC: enable UEs in idle mode to camp on cells with light load

Start IAC: increase the access rate in cells with

heavy load by some actions while ensuring the QoS

Start LDR: check and relieve basic congestion in cells

NodeB TX

power (noise)

Cell load (number of subscribers)

Start OLC: check and relieve overload

congestion in cells

Icons for different load levels

Dynamically shut down or open up cells during the

effective period of the dynamic cell shutdown algorithm


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Resources used by different load control algorithms

Load Control

Algorithm

Resources

Power Code NodeB Credits Iub Bandwidth

CAC √ √ √ √

IAC √ √ √ √

PUC √ ‐ ‐ ‐

LDB √ ‐ ‐ ‐

LDR √ √ √ √

OLC √ ‐ ‐ √

Dynamic cell

shutdown√ ‐ ‐ ‐

NOTE

–: not considered √: considered

This table lists the resources that are considered by different load control

algorithms.


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Priorities Involved in Load Control

The priorities involved in load control are user priority, Radio Access Bearer (RAB)integrated priority, and user integrated priority.

User Priority

RAB Integrated Priority

User Integrated Priority


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User Priority

ARP 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

User

Priority ERROR 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3

There are three levels of user priority (1, 2, and 3), which are denoted as gold (high

priority), silver (middle priority) and copper (low priority) users. The relation between user

priority and Allocation Retention Priority (ARP) can be set through OM command; the

typical relation is shown in the following table.

Note:

ARP 15 is always the lowest priority and is not configurable. It corresponds to user priority 3 (copper).

If ARP is not received in messages from the Iu interface, the user priority is regarded as copper.

The levels of user priority are mainly used to provide different QoS for different users, for example, setting

different Guaranteed Bit Rate (GBR) values for BE services according to different priority levels.Changes in

the mapping between ARP and user priority have an influence on the following features:

High Speed Uplink/Downlink Packet Access (HSUPA /HSDPA)

Adaptive Multi Rate (AMR/ AMR-WB)

Iub overbooking

Load control


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RAB Integrated Priority

The values of RAB integrated priority are set according to the integrated priority

configuration reference parameter:

If the integrated priority configuration reference parameter is set to Traffi c Class , the integrated

priority abides by the following rules:

Traffic classes: conversational -> streaming -> interactive -> background =>

Services of the same class: priority based on Allocation/Retention Priority (ARP) values, that is, ARP1 ->

ARP2 -> ARP3 -> ... -> ARP14 =>

Only for the interactive service of the same ARP value: priority based on Traffic Handling Priority (THP),

that is, THP1 -> THP2 -> THP3 -> ... -> THP14 =>

Services of the same ARP, traffic class and THP (only for interactive services): HSPA or DCH service

preferred depending on the carrier type priority indicator parameter.

If the integrated priority configuration reference parameter is set to ARP , the integrated priority

abides by the following rules:

ARP: ARP1 -> ARP2 -> ARP3 -> ... -> ARP14 =>

Services of the same ARP: priority based on traffic classes, that is, conversational -> streaming ->interactive -> background =>

Only for the interactive service of the same ARP value: priority based on Traffic Handling Priority (THP),

that is, THP1 -> THP2 -> THP3 -> ... -> THP14 =>

Services of the same ARP, traffic class and THP (only for interactive services): HSPA or DCH service

preferred depending on the carrier type priority indicator parameter.


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User Integrated Priority

For multiple-RAB users, the integrated priority of the user is based on the service of thehighest priority. User integrated priority is used in user-specific load control.


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Contents

Perface










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Uplink background noise is sensitive to environmental conditions. Therefore, the

LDM algorithm incorporates an auto-adaptive update algorithm to restrict the backgroundnoise within a specified range:

If the temperature in the equipment room is constant, the background noise changes

slightly. In this case, the background noise requires no more adjustment after initial

correction.

If the temperature in the equipment room varies with the ambient temperature, the

background noise changes greatly. In this case, the background noise requires auto-

adaptive upgrade.


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Contents

Perface




Potential User Control Overview

Potential User Control Triggering

Potential User Control Procedure







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Potential User Control Overview

PUC algorithm is used to balance downlink traffic load between inter-

frequency cells.

This algorithm can be used for the UE which is in these state:

Idle mode

CELL_FACH

CELL_PCH

URA_PCH state

F2

F1

Heavy

Light

Potential UE cell selection

or reselection

This algorithm

can used intra

RNC


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Potential User Control Triggering

when the load is higher

than this threshold, it

will be consider heavy

when the load is lower

than this threshold, it

will be considered light

NOTE: PUC takes effect only in downlink.

Between the heavy

threshold and light

threshold, that means

the cell state is normal.


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Potential User Control Procedure

Depending on the load status of the current cell and neighboring cell, the cell reselection

parameters are adjusted，which are contained in SIB3 and SIB11.In this way, potential

user in heavy load cell reselects to the light load cell.

Note: The PUC algorithm consider the load of neighboring cell, if it is in heavy state, theadjusting will not happened.


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Contents

Perface





Call Admission Control Overview

CAC Based on power resource

CAC Based on Code Resource

CAC Based on CE Resource

CAC Based on Iub transmission Resource

CAC Based on Number of HSPA Users






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Call Admission Control Overview

Call Admission Control (CAC) is used to determine whether the systemresources are sufficient to accept a new user's access request. If the system

resources are sufficient, the access request is accepted; otherwise, the access

request is rejected.

The admission decision is based on the following resources:

Cell code resource

Cell power resource

NodeB credits resource

Iub transmission bandwidth resource

Number of HSDPA users (only for HSDPA services)

Number of HSUPA users (only for HSUPA services)

Note: A call can be admitted only when all of these resources are available. For CAC based on all the resources, uplink and downlink are independently.


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CAC based on power resource

For power resource admission, it can based on three kinds of algorithms to suit different

application scenarios.

Algorithm 1:

Power resource admission decision based on power or interference.

Depending on the current cell load (uplink load factor and downlink transmitted carrier power)

and the access request, the RNC determines whether the cell load will exceed the threshold or not

upon admitting a new call. If yes, the RNC rejects the request. If not, the RNC accepts the

request.

Algorithm 2:

Power resource admission decision based on the number of equivalent users.

Depending on the current number of equivalent users and the access request, the RNC determines

whether the number of equivalent users will exceed the threshold or not upon admitting a new

call. If yes, the RNC rejects the request. If not, the RNC accepts the request.

Algorithm 3:

The same as the Algorithm 1, the only difference is the estimated load increment always set to 0.

Note: For power resource, regardless of which the power algorithm is used, the RRC admission thresholdis always the cell OLC threshold.


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UL Power Admission based on algorithm 1&3 for R99 cell

In the formula, ηULcch is the value of the UL common channel load factor, which defines the factor

of UL common channel resources reserved.

By comparing the predicted uplink load factor ηUL , predicted with the corresponding threshold of

different service,the RNC decides whether to accept the access request or not.

The procedure for uplink power admission decision for R99 cells as follows:

The RNC obtains the uplink RTWP of the cell and uses the formula:

The threshold relationship of different services is set as follows

to calculate the current uplink load factor ηUL , where P N is the received uplink Background

noise.The RNC calculates the uplink load increment ΔηUL based on the service request.

For algorithm 3, ΔηUL is fixed to zero, this is the only difference between algorithm 1 and algorithm 3.

The RNC uses the following formula to predict the uplink load factor:

For HUSPA cells, theDCH UL power

admission formula is

different from R99

cells.


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Different threshold for different service

Threashold name Uplink Downlink

Overload trigger threshold 95 95

Total power threshold 83 90

Handover access threshold 80 85

AMR access threshold 75 80

Non-AMR access threshold 75 80

Other services access threshold 60 75

Load reshuffling trigger threshold 55 70

LDR

Other services

AMR&non-AMR

handover

Total power

OLC

High

Low

Cell power load

Threshold

The thresholds and coresponding algorithms are used for resource management and keep system stability.

Meanwhile,different threshold expresses different serivce priority. When the power resource is

insufficiency, the effect of these thresholds wiill be emerge: the higher the threshold is , the easier to

access the network.

Note:

For the RRC connection request for the reason of emergency call,detach or registration, direct admission is used.

For the RRC connection request for other reasons, UL/DL OLC Trigger threshold is used for admission.

For the serivce RB setup request admission,coresponding thresholds in the table will be used.

For the service handover in admission, handover access threshold will be used.

For the service upsize reconfiguration admisson, the load reshuffling trigger threshold will be used.

Baseline values for thresholds


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Type B: all UEs for which this cell is not the serving

E-DCH cell,the uplink load generated by the type B

of E-DCH scheduling services is defined by

ηUL,EDCH,f ,which is fixed to zero

UL Power Admission based on algorithm 1&3 for HSPA cell

Type A: All UEs for which cell is the serving E-

DCH cell, the uplink load generated by the type A of

E-DCH scheduling services is defined by

ηUL,EDCH,s

The uplink uncontrollable load is defined as follows:

ηUL,non-ctrl = ηUL - ηUL,EDCH,s - ηUL,EDCH,f

This result will be used to adminssion control.

Since the HSUPA scheduling algorithm consumes additional uplink power resources, the

power load of the WCDMA system is always relatively high. Therefore, the CAC algorithm

combines the PBR-based decision with the load-based decision to reduce the number of

potential erroneous rejections.

The power admission for HSUPA cell. If the RSEPS measurement is deactivated, the

admission algorithm automatically changes into algorithm 2.


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The PBR admission decision for HSUPA service

The PBR-based decision is used to check whether the QoS requirement of existing users

is fulfilled. The QoS is measured on the basis of the Provided Bit Rate (PBR) of theusers. If the QoS requirement is fulfilled, new users are allowed to access the network.

As shown in the previous figure, the Scheduling Priority Indicator (SPI) of a new HSUPA user

is SPI New user .


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The PBR admission decision for HSUPA service

Decision:

The RNC admits the HSUPAscheduling services in either of the

following cases:

Formula 1, 2, or 3 is fulfilled.

Formula 4 is fulfilled.

For HSUPA non-scheduling

services, the RNC admits the

HSUPA non-scheduling servicesin either of the following cases:

Formula 1, 2, or 3 is fulfilled.

Formulas 4 and 5 are fulfilled.Where

Note:

For HSUPA serivce, either PBR or power

resource admission descision is passed, the

serivce access will be allowed.

If the PBR measurement is deactivated, the

decision formulas that involve PBR are

regarded as unsatisfied.


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UL Radio Admission Decision for DCH RAB (for HSPA cell)

Where:

For HSUPA cells, the DCH service admission decision in uplink is different from R99

cells. Uncontrollable interference must be kept within a certain range. The purpose is to ensure the

stability of the system and to prevent non-scheduling services and DCH services from seizing the

resources of HSUPA services. In this regard, the CAC algorithm combines the uncontrollable part –

based decision and the total load – based decision.

When the admission of DCH services is implemented, the following formulas apply:

The RNC admits DCH services if formulas 1 and 2 are fulfilled.


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For HSDPA cells, the

DCH DL power

admission formula is

different from R99 cells.

DL Power Admission based on power algorithm 1&3 (for R99 cell)

In the formula, ηDL_cch is the value of DL common channel load reserved coefficient, which defines

the factor of DL common channel resources reserved.

By comparing the downlink load factor ηDL,predicted with the corresponding threshold, the RNC

decides whether to accept the access request or not.

The RNC calculates the downlink load increment ΔηDL based on the service request and the current

load.

The RNC uses the following formula to predict the downlink load factor:

The procedure for uplink power admission decision for R99 cells as follows:

The RNC obtains the cell downlink TCP and calculates the downlink load factor ηDL by dividingthe maximum downlink transmit power P max by this TCP.

Note: The downlink threshold for different service see the uplink part.


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DL PowerAdmission based on Algorithm 1&3 (for HSPA Cells)

Power Increment Estimation for DCH RABThe power increment estimation for the DCH RAB in the HSPA cell is similar to the DCH RAB

in the R99 cell.

Power Increment Estimation for HSDPA RAB

The power increment estimation for HSDPA RAB ΔPDL is made on the basis of GBR, Ec/N0,

non-orthogonal factor, and so on.

The detailed information

NEXT PAGE

For algorithm 3, ΔPDL is fixed to zero, this is the only difference between algorithm 1 and algorithm 3.


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DL Radio Admission Decision for DCH RAB (for HSPA cell)

Where:

When the admission of the DCH RAB is implemented in the HSDPA cells, the following

formulas apply:

Note:

If the GBP measurement is deactivated, the GBP

involved in the decision formulas is set to 0.

Decision:The RNC admits the DCH RAB in

either of the following situations:

Formulas 1 and 2 are fulfilled.



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Downlink Radio Admission Decision for HSDPA RAB

Where：

Decision: The RNC admits the HSDPA

streaming RAB in any of the followingsituations:




The RNC admits the HSDPA BE RABin any of the following situations:


Formulas 3 and 4 are fulfilled. Formulas 3 and 5 are fulfilled.

Note:

If the GBP measurement is deactivated, the GBP

involved in the decision formulas is set to 0.

If the PBR measurement is deactivated, the

decision formulas that involve PBR are regarded

as dissatisfied.

For the first HSDPA service accessing the cell, the

decision formulas that involve PBR are regarded

as unsatisfied.


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Power admission decision based on algorithm 2

Definition

The 12.2 kbit/s AMR traffic is used to calculate the Equivalent Number of Users (ENU) of all other

services. The 12.2 kbit/s AMR traffic's ENU is assumed to be 1.

Admission procedure The RNC obtains the total ENU of all existing users ENUtotal = ∑all_exist_user ENUi.

The RNC gets the ENU of the new incoming user ENUnew.

The RNC uses the formula (ENU total + ENUnew)/ENUmax to forecast the ENU load, where ENUmax is the

configured maximum ENU.

By comparing the forecasted ENU load with the corresponding threshold, the RNC decides whether to acceptthe access request.

Different threshold parameters is set

for different types of service

Service Type Admission Threshold

UL DCH/HSUPA

UL threshold of Conv AMR service

UL threshold of Conv non_AMR service

UL threshold of other services

UL Handover access threshold

DL DCH

DL threshold of Conv AMR service

DL threshold of Conv non_AMR service

DL threshold of other services

DL Handover access threshold

HSDPA DL total power threshold

For example, the admission of a new AMR

service in the uplink based on algorithm 2will be successful if the following formula is

fulfilled:

(ENUtotal + ENUnew)/ENUmax ≤ UL thresholdof Conv AMR service


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Typical Equivalent Number of Users

ServiceENU

Uplink for DCH Downlink for DCH HSDPA HSUPA

3.4 kbit/s SIG 0.44 0.42 0.28 1.76

13.6 kbit/s SIG 1.11 1.11 0.74 1.89

3.4 + 12.2 kbit/s 1.44 1.42 - -

3.4 + 8 kbit/s (PS) 1.35 1.04 0.78 2.26

3.4 + 16 kbit/s (PS) 1.62 1.25 1.11 2.37

3.4 + 32 kbit/s (PS) 2.15 2.19 1.70 2.60

3.4 + 64 kbit/s (PS) 3.45 3.25 2.79 3.14

3.4 + 128 kbit/s (PS) 5.78 5.93 4.92 4.67

3.4 + 144 kbit/s (PS) 6.41 6.61 5.46 4.87

3.4 + 256 kbit/s (PS) 10.18 10.49 9.36 6.61

3.4 + 384 kbit/s (PS) 14.27 15.52 14.17 9.36

Typical equivalent number of users (with activity factor to be 100%)

In the upon table, for a 3.4+n kbit/s service of HSDPA or HSUPA

3.4 kbit/s is the rate of the signaling carried on the DCH.

n kbit/s is the GBR of the BE service, and the MBR of the RT service.

When calculate ENUs in RNC, the formula will be used: ∑ENUi*AFi. ENUi is the total equivalent number of different user priority users, as show in upon table;

AFi is the active factor for different user priority users;

???


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CAC Based on Code Resource

When a new service attempts to access the network, code resource admission is mandatory.

Code resource admission is implemented as follows:

For RRC connection setup requests, the code resource admission is successful if the current

remaining code resource is enough for the RRC connection.

For handover services, the code resource admission is successful if the current remaining code

resource is enough for the service.

For other R99 services, the RNC has to ensure that the remaining code does not exceed the

configurable OM threshold ( Dl HandOver Credit and Code Reserved SF ) after admission of the new

service.

For HSDPA services, the reserved codes are shared by all HSDPA services. Therefore, the

code resource admission is not needed.

For R99 PS BE serivce upsizing reconfiguration, the Cell LDR SF reserved threshold will be used.

Note: The spread factor code consume law and admission algorithm are similar to Node B credit resource,coresponding content see CAC based on Node B Credit part.


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CAC based on Node B Credit

Definition

CE stands for Node B credit on the RNC side and for Channel Element on the NodeB side. It

is used to measure the channel demodulation capability of the NodeBs.

How to calculate the CE resource

The resource of one equivalent 12.2 kbit/s AMR voice service, including 3.4 kbit/s signaling on the

Dedicated Control Channel (DCCH), consumed in baseband is defined as one CE.

one 12.2 kbit/s AMR voice service consumes one uplink CE and one downlink CE.If there is only

3.4 kbit/s signaling on the DCCH but no voice channel, one CE is consumed.

Channel elements provide either uplink or downlink capacity for services. There are two kinds of

CE.


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CAC based on Node B credit resource

When a new service tries to access the network, the credit resource admission is

implemented as follows:

For an RRC connection setup request, the credit resource admission is successful if the

current remaining credit resources of the local cell, local cell group (if any), and NodeB are

sufficient for the RRC connection.

For a handover service, the credit resource admission is successful if the current remaining

credit resources of the local cell, local cell group (if any), and NodeB are sufficient for the service.

For other services, the RNC has to ensure that the remaining credit of the local cell, local

cell group (if any), and NodeB does not exceed the configurable OM thresholds ( Ul HandOver Credit

Reserved SF/Dl HandOver Credit and Code Reserved SF ) after admission of the new services.

For R99 PS BE serivce upsizing configuration, the LDR reserved threshold will be used.

Notes: The credit resource admission is implemented in the uplink and downlink respectively.

For detailed information about local cell, local cell group, and capacity consumption law, refers to the3GPP TS 25.433.


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SF&CE DCH consume law

Stage Rate

(kbit/s)

Uplink Downlink

SFNumber of CEs

Consumed

Corresponding

Credits Consumed SFNumber of CEs

Consumed

Corresponding

Credits Consumed

RRC

3.4 256 1 2 256 1 1

13.6 64 1 2 128 1 1

RAB

8 64 1 2 128 1 1

16 64 1 2 128 1 1

32 32 1.5 3 64 1 164 16 3 6 32 2 2

128 8 5 10 16 4 4

144 8 5 10 16 4 4

256 4 10 20 8 8 8

384 4 10 20 8 8 8

AMR4.75

128 1 1 128 1 1

AMR

12.264 1 1 128 1 1

Note: For each rate and service, the number of UL credits is equal to the number of UL CEs multiplied by 2.


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SF&CE HSUPA consume law

Rate (kbit/s)Uplink

SF Number of CEs Consumed Corresponding Credits Consumed

8 64 1 2

16 64 1 2

32 32 1.5 3

64 32 1.5 3

128 16 3 6

144 16 3 6

256 8 5 10

384 4 10 20

608 4 10 20

1450 2SF4 16 32

2048 2SF3 32 64

2890 2SF2 32 64

5760 2SF2+2SF4 48 96

Note: There is no capacity consumption law for HS-DSCH in 3GPP TS 25.433, so certain creditsare reserved for HSDPA RAB, and credit admission for HSDPA channel is not needed.


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CAC Based on Iub transmission Resource

When a new service accesses the network, Iub interface resource admission is mandatory.

For the transmission admission control in Iub interface, as shown in the Figure, bottom-up Multi-

Level Admission Control Policy is used.

A user accessing the network from a path should go through the admission of the path,

resource group, and physical port in turn. The user that passes all the admission can be

successfully admitted by the transport layer.

Physical link users consist of R99 users and HSPA users.

For R99 users, the UL and DL control admission together.

For HSPA users, the UL and DL control admission separately.

First the UL controls admission. If the UL admission for HSPA users is approved, the DL

controls admission and if the UL admission for HSPA users is rejected, the DL does not

control admission.

For BE service Iub

admisssion ,the GBR

rate is used.


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Bandwidth Reserved for Services

The RNC calculates the reserved bandwidth based on the activity factor and performs

admission control based on the reserved bandwidth. Different services use different policies.

RT services, including conversational and streaming services, are admitted at the MaximumBit Rate (MBR).

Reserved bandwidth for admission of an RT service = MBR * Activity factor, where the activity factor needs to be

set for each type of service.

NRT services, including interactive and background services, are admitted at the GBR.

Reserved bandwidth for admission of an NRT service = GBR * Activity factor

SRB services can be admitted at the GBR or 3.4 kbit/s.

Admission at 3.4 kbit/s: The bandwidth is fixed at 3.4 kbit/s. This admission mode is applicable to R99, HSDPA,

and HSUPA services.

Admission at the GBR: For R99 services, if the bandwidth of a transport channel varies between 3.4 kbit/s and 13.6

kbit/s, resource allocation and resource admission do not need to be performed again.

Reserved bandwidth for admission of SRB = 3.4k * Activity factor

In terms of common channels, EFACH services are admitted at the GBR, and other

common channel services are admitted at the MBR. Reserved bandwidth for admission of EFACH = GBR * Activity factor

Reserved bandwidth for admission of other common channel = MBR * Activity factor

Note: The activity factor can be set for different services relatively. The forward and backward activity factors cancongured independently!


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IUB bandwidth admission desicion For a new user, the following requirements apply:

Total bandwidth allocated to the users on the path + required bandwidth for the new user < total bandwidth

configured for the path – bandwidth reserved for handover.

Total bandwidth allocated to the users on the physical link + required bandwidth for the new user < total

bandwidth of the physical link – bandwidth reserved for handover.

For a handover user, the following requirements apply:

Total bandwidth allocated to the users on the path + required bandwidth for the handover user < total bandwidth

configured for the path.

Total bandwidth allocated to the users on the physical link + required bandwidth for the handover user < total

bandwidth of the physical link.

For a rate upsizing user, the following requirements apply:

Total bandwidth allocated to the users on the path + required bandwidth for the rate upsizing user < total

bandwidth configured for the path – congestion threshold.

Total bandwidth allocated to the users on the physical link + required bandwidth for the rate upsizing user < total

bandwidth of the physical link – congestion threshold.

Congestion clear bandwith

Congestion bandwidth

Handover resovered bandwidth

Total bandwidth

High

Low

Path/resource group/phycial port

Threshold

The forward and backward bandwidththresholds are set respectively. Also,

different level bandwidth threshold can be

set separately.


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IUB bandwidth admission procedure

Primary and secondary paths are used in admission control. According to the mapping between traffic

types and transmission resources, the RNC first selects the primary path for admission. If the

admission on the primary path fails, then the admission on the secondary path is performed.

The user tries to be admitted to available bandwidth 1 of the primary path, as shown in the Figure. The

procedure is as following:

If the admission on the primary path is successful, the user is carried on the primary path.

If the admission on the primary path fails, the user tries to be admitted to available bandwidth 2 of the secondary

path.

If the admission on the secondary path is successful, the user is carried on the secondary path. If not, the

bandwidth admission request of the user is rejected.

Admission decision for a new user :

Available bandwidth 1 = total bandwidth of the primary path - used bandwidth - handover reserved bandwidth

Available bandwidth 2 = total bandwidth of the secondary path - used bandwidth - handover reserved bandwidth

For a new user

admission,

bandwidth for

handover users

is reseved


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IUB bandwidth admission procedure

Admission procedure for a handover user

Available bandwidth 1 = total bandwidth of the primary path - used bandwidth

Available bandwidth 2 = total bandwidth of the secondary path - used bandwidth

Admission procedure for a rate upsizing user

Available bandwidth 1 = total bandwidth of the primary path - used bandwidth - congestion reserved bandwidth

Available bandwidth 2 = total bandwidth of the secondary path - used bandwidth - congestion reserved bandwidth

For handover users

admission,allocation of the

bandwidth is 100%!

For rate upsizing

users admission,

congestion reserved

bandwidth is reserved

Note: Therefor, the serivce priority is: handover users > new users> rate upsizing users


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CAC Based on the Number of HSPA Users

CAC 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

NodeB HsdpaMaxUserNum.

Otherwise, the algorithm rejects the service request.

CAC 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

NodeB HsupaMaxUserNum.

Otherwise, the algorithm rejects the service request.


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Contents

Perface Load Control Algorithm Overview





Intelligence Access Control Overview

IAC During RRC Setup Stage

IAC During RAB Setup Stage

IAC for Emergency Calls





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Intelligence Access Control Algorithm

IAC algorithm is used to increase the access success ratio with the currentQoS guaranteed through Rate Negotiation, Directed Retry Decision(DRD),

Preemption, Queuing and BE service Low-Rate Access.

RAB Rate

Negotiation

RAB Directed

Retry Decision

RAB

preemption

RAB

queuing

Low-RateAccess

RRC IAC


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Intelligence Access Control Overview

Admission

algorithmFails or not supported

Fails

Target cell

selected

Fails

Succeeds

RAB processing

RRC connection processing

Rate

negotiation

PS domain:

maximum rate

PS and CS

domains:

initial rate

Power

admission

Code admission

Iub resource

admission

Credit admission

FailsRRCconnection

request

Admissionalgorithm

DRD Redirection

RAB setup request

HSPA user

number admission

Succeeds

PS domain:GBR of PS

RT service

Service requestaccepted

Preemption

Queuing

Fails or not supported

Succeeds

Succeeds

Succeeds

Fails

NoYes

Service

steering DRD

Load balancing

DRD

DRD

algorithm

Is there any

cell not tried?

Service request

denied

Target Rate

Negotiation

Service-based RRC

redirection

Lead UE toanother cell

Access from another cell

Access from

current cell

Succeeds

Low-rateaccess

Fails or not supported

Succeeds


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IAC procedure supported by different services

ServiceType Low-Rate

Access

Rate Negotiation Preemption Queuing DRD

MB

R

Nego

tiatio

n

GBR

Nego

tiatio

n

Initial

Rate

Negotiat

ion

Target

Rate

Negotia

tion

Inter-

Freque

ncy

Inte

r-

RA

T

DCH √ √ √ √ √ √ √ √ √

HSUPA - √ √ √ √ √ √ √ –

HSDPA - √ √ – – √ √ √ –

Note: MBR stands for maximum bit rate


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IAC During RRC Setup Stage

RRC Direct

Retry

Decision

RRCRedirection

for Service

Steering

IAC duringRRC

SetupRRC

Redirection

After DRD

Failure

In the RRC connection setup stage, there arethree actions for intelligence access control

algorithm:

During the RRC connection setup, the

RNC implements service steering

between inter-frequency or inter-RAT

cells according to the cause of RRCconnection setup.

If the RRC CAC fails, RNC selects

inter-frequency, but intra-band blind

neighboring cells to do RRC DRD;

If RRC DRD fails, select inter-

freq/inter-RAT blind neighboring cellsto do redirection action;

For emergency call, different strategy is used for the RRC setup IAC !

RRC R di ti f S i St i


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RRC Redirection for Service Steering

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. The procedure

of RRC redirection for service steering is as follows:

If the switch of RRC direction for service steering (RedirSwitch) is set to

ONLY_TO_INTER_FREQUENCY or ONLY_TO_INTER_RAT , based on the cell load and the

redirection factors, RNC decides whether to perform RRC redirection for service

steering acconding to the cause of the service requested by UE and the capability of

UE. If the switch is off or the RNC fails to determine the service type, the RNChandles the RRC connection setup request of the UE in the current cell.

Based on the setting of Redirection Switch, the RNC takes the corresponding actions:

If RedirSwitch is set to ONLY_TO_INTER_FREQUENCY , the RNC sends an RRC

CONNECTION REJECT message to the UE, redirecting the UE to the destination

frequency carried in the message. .

If RedirSwitch is set to ONLY_TO_INTER_RAT , the RNC sends an RRC CONNECTION

REJECT message to the UE. The message carries the information about inter-RAT

neighboring cells.


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RRC Redirection for load balancing

In addition, the RNC considers the load of the cell for access and the redirection factors

to control the degree of load balancing. If the cell is normal, the RNC generates a random number between 0 and 1 and

compares it with the corresponding unconditional redirection factor. If the random

number is smaller than this factor, the RNC performs the redirection action

according to the setting of Redirection Switch . Otherwise, the RNC handles the

RRC connection setup request of the UE in the current cell.

If the cell is in the basic congestion or overload state, the RNC generates a random

number between 0 and 1 and compares it with the corresponding LDR-triggered

redirection factor. If the random number is smaller than this factor, the RNC

performs the redirection action according to the setting of Redirection Switch .

Otherwise, the RNC handles the RRC connection setup request of the UE in the

current cell.

Note: The RRC redirection action needs inter-frequency or inter-RAT blind neighboring cells. If

this condision don’t meet, the RRC redirection will not happened.


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RRC DRD after CAC failure

If the RRC setup is CAC failure as the resource insufficient, and the RRC DRD

switch is open, the following procedure will be implemented: The RNC selects intra-band inter-frequency neighboring cells of the current

cell. These neighboring cells are suitable for blind handovers.

The RNC generates a list of candidate DRD-supportive inter-frequency cells

according to the singal quality.

The RNC selects a target cell from the candidate cells for UE access. If the

candidate cell list contains more than one cell, the UE tries a cell randomly. If the admission is successful, the RNC initiates an RRC DRD procedure.

If the admission to a cell fails, the UE tries admission to another cell in the

candidate cell list. If all the admission attempts fail, the RNC makes an RRC

redirection decision.

If the candidate cell list does not contain any cell, the RRC DRD fails. The

RNC performs the next step, that is, RRC redirection.

Note: If the RRC DRD switch is closed, the RRC redirection action based on RRC CAC

failure will be performed.


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RRC Redirection After DRD Failure

The RNC performs the following steps when the RRC DRD swtich is off for the RRC DRD

procedure fails:

The RNC selects all intra-band inter-frequency neighboring cells of the current cell as the candidate

cells.

The RNC selects a cell from candidate cells. The candidate cells are the cells selected in step 1 but

exclude the cells that have carried out inter-frequency RRC DRD attempts.

If more than one candidate cell is available, the RNC selects a cell randomly and redirects the UE to

the cell.

If no candidate cell is available,

If the switch of RRC redirection after DRD failure is set to Only_To_Inter_Frequency, the RRC connection

setup fails.

If the switch of RRC redirection after DRD failure is set to Allowed_To_Inter_RAT , then:

If a neighboring GSM cell is configured, the RNC redirects the UE to that GSM cell.

If no neighboring GSM cell is configured, the RRC connection setup fails

Note: If the RRC recirection switch is OFF, then the RRC Connection procedure stage fails.


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IAC During RAB Setup Stage

During the RAB setup stage, several IAC actions will be attempted orderly to

increase the access success radio: RAB Rate Negotiation

RAB Direct Retry Decision(DRD)

RAB Preemption

RAB Queuing

RAB Low-Rate Access for BE service

RAB IAC actions work as following:

RAB Rate

Negotiation

RAB Direct

Retry

Decision

RAB

Preemption

RAB

QueuingLow-Rate

Access

Service Access

Failure

Service access success


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RAB Rate Negotiation

Maximum rate negotiation

When setting up, modifying, or admitting a PS service, and the 'Alternative RAB Parameter Values' of IE is present in theRANAP RAB ASSIGNMENT REQUEST or the RELOCATION REQUEST message, the RNC and the CN negotiate the rate

according to the UE capability to obtain the maximum expected rate while ensuring a proper QoS.

GBR rate negotiation

During the setup, modification, or handover of real-time PS services, if the RAB assignment message includes multiple

alternative guaranteed bit rates, the RNC selects the smallest one as the negotiated guaranteed rate and responds to the CN.

Initial rate negotiationFor a non-real-time service in the PS domain, the RNC selects an initial rate to allocate bandwidth for the service before

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

Uplink and downlink radio bearer status of the cell

Minimum spreading factor supported

HSPA capability

Target rate negotiation

For a non-real-time service in the PS domain, if cell resource admission fails, the RNC chooses a target rate to allocate

bandwidth for the service based on cell resource in following cases:

Service setup

Soft handover

DCCC rate upsizing


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D t il d i f ti f l d b l DRD l ith


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Detailed information for load balance DRD algorithm

Algorithm 1

The load balancing DRD is performed according to the cell measurement values about the DL non-HSDPA

power and DL HS-DSCH required power. For DCH service, the RNC sets up the service on a carrier with a light load of non-HSDPA power to achieve load

balancing among the cells on the different frequencies.

For HSDPA service, the RNC sets up the service on a carrier with a light load of HS-DSCH required power to

achieve load balancing among the cells on different frequencies.

Algorithm 2

The load balancing DRD is performed according to the DCH Equivalent Number of Users (ENU) and

HSDPA user number.

For DCH service, the RNC sets up the service on a carrier with a light load of DCH ENU to achieve load balancing

among the cells on different frequencies.

For HSDPA service, the RNC sets up the service on a carrier with a light load of HSDPA user to achieve load

balancing among the cells on different frequencies.

The effect of the algorithm as shown in the previous page:

Cell B has a lighter load of non-HSDPA power than Cell A. If the UE requests a DCH service in Cell A, preferably,the RNC selects Cell B for the UE to access.

Cell A has the lighter load of HS-DSCH required power than Cell B .If the UE requests an HSDPA service in Cell B,

preferably, the RNC selects Cell A for the UE to access.

Note: The calculation of the DCH Equivalent Number of Users is the same as rules of call admission control part.


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Inter-Frequency DRD due to CAC failure

The precondition is that it is covered by multiple frequencies when the UE

requests a service in an area.The RNC selects a suitable cell in candidate cell. The

CAC algorithm makes an admission decision based on the resource status of the cell.

If the admission attempt is successful, the RNC initiates an inter-frequency blind

handover to the cell.

If the admission attempt fails, the RNC removes the cell from the candidate cells and

then checks whether all candidate cells are tried.

If there is any candidate cell not tried, the algorithm goes back to try this cell.

If all candidate cells haven been tried, then:

• If the service request is an HSPA one, the HSPA request falls back to a DCH one. Then, the

algorithm goes back to step 1 to retry admission based on R99 service priorities.

• If the service request is a DCH one, the RNC initiates an inter-RAT DRD.

Note: If there is no inter-frequency neighboring cells exist or the inter-frequency handover procedure is failure for all the attempts, the inter-RAT DRD may be happened.

I RAT DRD d CAC f il


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Inter-RAT DRD due to CAC failure

When all admission attempts for inter-frequency DRD during RAB processing fail, theRNC determines whether to initiate an inter-RAT DRD.

The inter-RAT DRD procedure is as follows:

If the current cell is configured with any neighboring GSM cell suitable for blind handover,

and the RNC performs this action.

The RNC generates a list of candidate DRD-supportive inter-RAT cells that fulfill the

singal quality requirement.

The service request then tries admission to a target GSM cell in order of blind handover

priority.

Note: If there is no suitable handover cells exist or the inter-RAT handover procedure is failurefor all the attempts, the service request undergoes preemption and queuing.

RAB preemption


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RAB preemption

Why we use preemption function

Preemption guarantees the success in the access of a higher-priority user by forcibly

releasing the resources of a lower-priority user. We support the preemption scenarios in

following cases:

Setup or modification of a service

Hard handover or SRNS relocation

UE state transits from CELL_FACH to CELL_DCH

Preemption preconditions

RNC performs preemption if the following conditions are met:

New serivce have the preemption capacity

The destination service can be preempted

User priority are satisfied.

USERUSER

1 2 3 N

USERUSERS USER

K

END

High LowUser Integration priority

VIP USER

Preemption of different service on different resources


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Preemption of different service on different resources

Service Resource Service That can Be Preempted

R99 HSUPA HSDPA R99 + HSPA Combined

R99 service Code √ - - √

Power √ - √ √

CE √ √ - √

Iub bandwidth √ √ √ √

HSDPA service Code - - - -

Power √ - √ √

CE - - - - Iub bandwidth √ - √ √

Number of users - - √ √

HSUPA service Code - - - -

Power - √ - -

CE √ √ - √

Iub bandwidth √ √ - √

Number of users - √ - √

Note: The preemption function is controlled by corresponding algorithm switch on the RNC.

RAB Queuing


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RAB Queuing

After the admission of a service fails, the service request is put into a specific queue

to increase the access success radio. Admission attempts for the service request are made

periodically during a defined period of time.

USER

1 2 3 K N

USERUSER USERS USER

NEW

USER

END

Heartbeat

timer

Queue

When timer expires, select the

request with the highest

integrate priority for an attempt

of resource allocation.

Note:

RNC performs queuing when the service has the queue capacity.

The Preemption and queuing capacity is difined in RANAP RAB ASSIGNMENT

REQEST message on the IU interface.

Detailed information for RAB Queuing


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Detailed information for RAB Queuing

When a new queuing request is received, the queuing algorithm will do some decision:

If the queue is not full, then the queqing algorithm will put this request into the quque and start the

heartbeat timer if it is not started.

If the queue is full, then the queuing algorithm check out whether there are have requests whose

intergate priorities are lower than that of new request

• If yes, then preemption occurs in the queue,that is lower request are took out and

rejected,New request are put into the queuing.

• If no,then the queing algorithm rejects the new request directly.

After the heartbeat timer(500ms) expires, the queuing algorithm proceeds as follows:

Rejects the request which the actual waiting time of is longer than the value of the Max queuing

time length parameter.

Selects the request with the highest integrate priority for an attempt of resource allocation.

• If the attempt is successful, the heartbeat timer is restarted for the next processing upon

expiry of this timer.

• If the attempt fails, the queuing algorithm puts the service request back into the queue with

the time stamp unchanged for the next attempt.


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Low-Rate Access of the PS BE Service

If a preemption or queuing failure, the PS BE service can access the target cell at a low

rate to increase the access success rate. Low-rate access means access from the DCH at 0kbit/s, FACH, or enhanced FACH (E-FACH).

Low-rate access is used in the following scenarios:

RAB setup

Hard handover or relocation

After an appropriate access action is determined, the service attempts to access the

network

If the action of access from the DCH at 0 kbit/s is determined, the service attempts to access

the network at 0 kbit/s for traffic and at the normal rate for signaling.

If the action of access from the FACH/E-FACH is determined, the service attempts to access

the network from the FACH/E-FACH.

If the access attempt fails, this service is rejected.

For the service that accesses the network at 0 kbit/s, the rate up timer is started after the

service rate fails to increase for the first time. If the rate fails to increase even when the timer

expires, the service is released, and the connection is also released for a single service.

L t ti i diff t i


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Low-rate access actions in different scenarios

Scenario Scenario Description FACH/E_FACH DCH at 0 kbit/s

RAB setup

The RRC connection is set up on the FACH or E-FACH. √ ×

The RRC connection is set up on the DCH. × √

The RRC connection is set up on the HSPA channel. × √

Combined

services

Hard handover or relocation is performed for the CS+PS

combined services.× √ (Note 1)

Hard handover or relocation is performed for the PS+PS

combined services.× √

The CS service is set up, and a new PS service is to be set up. × √

The existing PS service is set up on the FACH/E-FACH, and a

new PS service is to be set up.√ ×

The existing PS service is set up on the DCH, and a new PS

service is to be set up.× √

The existing PS service is set up on the HSPA channel, and a

new PS service is to be set up.

× √ (Note 2)

The PS service is set up, and a new CS service is to be set up. × ×

Note:

Note 1: In this scenario, only the PS service can be admitted at 0 kbit/s.

Note 2: In this scenario, the new PS service can be admitted at 0 kbit/s, and the existing service are not affected.

IAC f E C ll


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IAC for Emergency Calls (RRC setup stage)

To guarantee successful access of emergency calls, the RNC takes special measures for

emergency calls.

Resource admission in RRC setup stage

For power resource, the emergency call is admitted regardless of whether the CAC algorithm is

enabled or not..

For hard resources (that is, code, Iub, CE), preemption will always happened due to admission

failure.

RRC connection

setup request

Admission

algorithmPreemption DRD Redirection

RAB process

Fails

Succeeds

Fails Fails

Succeeds Succeeds

Note: To guarantee a successful admission of an emergency call, the RNC does not

perform RRC redirection for service steering.

IAC f E C ll


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IAC for Emergency Calls (RAB setup stage)

Resource admission in RAB setup stage

For power resource, when the admission switch for emergency call is enabled, power-based

admission fails if the system is in the overload congestion state. Otherwise, the admission

succeeds.

For hard resources (that is, code, Iub, and CE), the resource-based admission is successful if the

current remaining resources are sufficient for the request. Otherwise, the admission fails.

Preemption procedure The emergency calls that trigger preemption have the highest priority, the preempted users have

the lowest priority.

preemption is performed regardless of whether the preempt algorithm is enabled or not.

The range of users that can be preempted is specified by the specific switch, that is whether the

emergecy call can preempt the users which have preemption-prohibited attribute.

Note: The emergency calls can only preempt the non-emergency users.


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Contents

Perface







Load Reshuffling Algorithm Overview

Load reshuffling triggering

Load reshuffling actions



L d R h ffli Al ith O i


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Load Reshuffling Algorithm Overview

When the usage of cell resource exceeds the basic congestion triggering threshold, the

cell enters the basic congestion state. In this case, LDR is required to reduce the cell loadand increase the access success ratio.

Four resources can trigger the basic congestion of the cell:

power resource,

code resource,

Iub resource,

NodeB credit resource.

Load reshuffling algorithm procedure has three stages, that is:

Basic Congestion Triggering

LDR Procedure

LDR Actions

Tiggering style

For power resource, the RNC performs periodic measurement and checks whether the

cells are congested.

For code, Iub, and NodeB credit resources, event-triggered congestion applies, that is,

the RNC checks whether the cells are congested when resource usage changes.

LDR Triggering for power resource


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LDR Triggering for power resource

For an R99 cell:

If the current UL/DL load of the R99 cell is higher than or equal to the basic congestion trigger

threshold in UL/DL for 1000ms, the cell works in the basic congestion state. If the current UL/DL load of the R99 cell is lower than the UL/DL LDR Release threshold for

1000ms, the cell returns to the normal state.

For an HSPA cell:

In the uplink, the object to be compared with the associated threshold for decision is the

uncontrollable load.

In the downlink, the object to be compared with the associated threshold for decision is the sum

of the non-HSDPA power and the Power Requirement for GBR (GBP).

LDR Thresholds for power resource


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LDR Thresholds for power resource

LDR trigger

Other services

AMR&non-AMR

Handover access

Total power

OLC

High

Low

Cell power load

Threshold

LDR state

Normal stateLDR release

Threshold Name Uplink Downlink

Overload trigger threshold 95 95

Overload release threshold 85 85

Total power threshold 83 90

Handover access threshold 80 85

AMR access threshold 75 80 Non-AMR access threshold 75 80

Other services access threshold 60 75

Load reshuffling trigger threshold 55 70

Load reshuffling release threshold 45 60

When the cell enters the basic

congestion state, the maximum

target rate is GBR for BE RAB.Therate upsizing exceed GBR is

forbidden!

They are baseline values of

coresponding threshold in huawei

RNC.These valuses are notrecommended modified in live

network, but can be modified in the

testbed to help testing easier when

verify the load control algorithms.


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LDR Triggering for Code Resource

Congestion control algorithm based on code resource can be enabled through the

specific parameter on RNC Local Maintenance Terminal.

If the SF corresponding to the current remaining code of the cell is larger than Cell

LDR SF reserved threshold, code congestion is triggered.

When the code resource congestion triggered, that means the spread code resourceis insufficient, and the access success raido maybe lower than the normal state.

Note: Only the downlink spread code may be insufficient and triggerr the code resource load

reshuffling, the code in uplink always sufficient and never trigger the LDR state.

LDR T i i f N d B C dit R


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LDR Triggering for Node B Credit Resource

The basic congestion for NodeB credit is of the following types:

Type A: Basic congestion at local cell level

If the cell UL/DL current remaining SF (mapped to credit resource) is higher than UL LDR

Credit SF reserved threshold/DL LDR Credit SF reserved threshold, credit congestion at cell

level is triggered.

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

The same as the basic congestion at Node B level.

Type C: Basic congestion at NodeB level

If the cell group or NodeB UL/DL current remaining SF (mapped to credit resource ) is higher

than UL LDR Credit SF reserved threshold/DL LDR Credit SF reserved threshold, credit

congestion at cell group or NodeB level is triggered.

Note: When RNC performs Load reshuffling actions for the CE reource, the range of UEs to be

sorted by priority is different from other resources, all the UEs in the normal-state cells that belong to the

cell group or NodeB will be sorted based on the integrated priority.

LDR Triggering for Iub Bandwidth Resource


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Congestion detection can be triggered in any of the following conditions:

Bandwidth adjustment because of resource allocation, modification, or release Change in the configured bandwidth or the congestion threshold

Fault in the physical link

Assume that the forward parameters of a port for congestion detection are

defined as follows:

Configured bandwidth: AVE

Forward congestion threshold: CON

Forward congestion clear threshold: CLEAR (Note that CLEAR is greater than CON.)

Used bandwidth: USED

Then, the mechanism of congestion detection on the port is as follows:

Congestion occurs on the port when CON + USED ≥ AVE.

Congestion disappears from the port when CLEAR + USED < AVE.

i i f i


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The congestion detection for a path or a resource group is similar to that for a port.

Generally, congestion thresholds need to be set for only ports or resource groups. If

different types of AAL2 paths or IP paths require different congestion thresholds, the

associated parameters need to be set for the paths as required.

If ATM LPs or IP LPs are configured, congestion control is also applicable to the LPs.

The congestion detection mechanism for the LPs is the same as that for resource

groups.

Load Reshuffling Actions


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Load Reshuffling Actions

Procedure: As showed in the illustration, if the inter-frequencyhandover action succeeds, the determination of whether the systemis congested continues. If the system is still congested, the inter-frequency load handover is initiated again.

If the handover fails, code reshuffling is performed:If the code reshuffling succeeds, the determination of whether thesystem is congested continues. If the system is still congested, thecode reshuffling is initiated first.

If the code reshuffling fails, the next action, that is, BE ratereduction, is taken.

… …

Code reshuffling

Inter-frequency load handover

BE service rate reduction

Uncontrolable realtime

Qos renegotiation

AMR rate reduction

Inter-system load handover

in the CS domain

Inter-system load handover

in the PS domain

MBMS power reduction

L o a

d R e s u

f f l i n g

A c

t i o n s

Actions: As the illustration, the sequence of the LDR actions isfixed to Inter-freq load handover, code reshuffling, BE rate reduction,

Uncontrolable realtime Qos renegotiation, AMR rate reduction,

Inter-system handover in CS domain, Inter-system handover in PS

domain, and MBMS power reduction.

Occasion: When the cell is in basic congestion state, the RNCtakes one of the following actions in each period until the congestionis resolved

Order: The sequence of the LDR actions can be changed throughthe ADD CELLLDR command, and the waiting timer for LDR period is defined by the LDR period timer length parameter through

the SET LDCPERIOD command.

LDR actions performed for different resources


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ResourceUL/

DL

Channel

LDR Actions

Inter-

Frequency

Load

Handover

BE Rate

Reduction

Inter-RAT

Handover inCS Domain

Inter-RAT

Handover inPS Domain

AMR Rate

Reduction

Iu QoS

Renegotiation

Code

Reshuffling

MBMS

PowerReduction

Power

UL

DCH √ √ √ √ √ √

HSUPA √ √

DL

DCH √ √ √ √ √* √

HSDPA √ √ FACH

(MBMS) √*

Iub

UL

DCH √ √ √

HSUPA √

DL

DCH √ √ √ HSDPA √ FACH

(MBMS)



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ResourceUL/

DLChannel

LDR Actions

Inter-

Frequency

LoadHandover

BE Rate

Reduction

Inter-RAT

Handover in

CS Domain

Inter-RAT

Handover in

PS Domain

AMR Rate

Reduction

Iu QoS

Renegotiatio

n

Code

Reshuffling

MBMS

Power

Reduction

code

– –

DL

DCH √ √ √

HSDPA

FACH

(MBMS)

credit

UL

DCH √ √ √ √

HSUPA √ √

DL

DCH √ √ √ √

HSDPA

FACH

(MBMS)

Note: Whether the gold users perform the LDR actions is controled by specific switch on RNC

Loal Maintenance Terminal.

Action 1: Inter Frequency Load Handover


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Action 1: Inter-Frequency Load Handover

Inter-FrequencyLoad Handoveraction performed

Power resource LDR…

The UL/DL HO load space threshold for the target cell

must be satified

Target Cell condition

… The neighbouring cell must be the inter-frequency blind

handover cell，and the measured signal quality can meet

…

After actions performed, all of the resources in the target

cell do not trigger basic congestion

Service condition…

For the selected UE, its UL/DL current bandwidth has to be

less than the UL/DL HO maximum bandwidth

…

The LDR algorithm selects one UE to perform the actions

according to the user integrate priority.

Code resource LDR…

The minimum SF of target cell mustn’t greater then thecurrent cell

… The difference of code occupy rate must meet the

InterFreq HO code used ratio space threshold

If the conditions are not

meet or the action fails, the

algorithm will go to next

action desicion

All the conditons must

be satified, then the

action will be

performed

Action 2: BE Rate Reduction


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Baise principle

BE Rate Reduction action of

basic congestion algorithm

Service

condition

•This action is used for DCH

RAB and HSUPARAB .Only BE service will

be considered.

•The selected RAB bit ratemust greater than GBR.

Rate downsizing Rate recovery

•If the selected RAB is a DCH RAB, only3-rate downsizing applies.

•If the current rate is MBR, the rate is

downsized to Uplink mid bit rate threshold.•If the current rate is higher than GBR butlower than MBR, the rate is downsized to

GBR.

•In the LDR state, the rate upsizingtarget rate is GBR.

•After basic congestion is cleared, the

rate upsizing target rate is MBR rate.•If the rate upsizing will trigger the

basic congestion,the action should not

be happened.

•User selection based on theintegrate priority, the lowest RAB

will be processed first .

•The number of RABs to select isdetermined by the UL/DL LDR-BE

rate reduction RAB number

parameter .

Action 2: BE Rate ReductionIn the same environment, different rates consume different resource. The higher the rate is, the more

resource will be needed. Therefore, the load can be reduced by bandwidth reconfiguration. The BE ratereduction action is based on DCCC algorithm. When admission control of Power/NodeB Credit is disabled,it is not recommended that the BE Rate Reduction be configured as an LDR action in order to avoid ping-

pong effect.

For HSUPA service, this action is

just used for CE resource LDR, and

the rate variety depends on HSUPA

UpLink rate adjust set parameter

The reconfiguration is completed

as indicated by the RB

RECONFIGURATION message

on the Uu interface and through

the RL RECONFIGURATION

message on the Iub interface.

Note: If the conditions are not meet or action fail, the algorithm will go to next action decision.

Action 3：

Uncontrolled Real-Time QoS Renegotiation


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Based on this action, the RNC can adjust the rate of real-time services to reduce theload of the current cell.

Q g

Baise Principle

Service

Pondition

Uncontrolled Real-

Time QoS

Renegotiation

Renegotiation

Procedure

The target rate is the GBR rate which is indicated on

Iu interface when the serivce setup.

The RNC initiates the RAB renegotiation procedure

through the RAB MODIFICATION REQUEST

message on the Iu interface.

The Core Network sends the RAB ASSIGNMENT

REQUEST message to the RNC for RAB parameterreconfiguration.

• This action is just used forDCH RAB.

• Only the real-time services inthe PS domain will be

considered. For example, the

streaming service.

•User selection based on theintegrate priority, the lowest

RAB will be processed first .

•The number of RABs toselect is determined by the

UL/DL LDR un-ctrl RT Qos

re-nego RAB num parameter .

Note: If the conditions are not meet or actions fails, the algorithm will go to next action decision.

This action is not recommended

to be configured when there are

no steaming traffic calss

subscribed in live network.

Action 4: Inter-RAT Handover in the CS Domain


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According to the different “service-handover” IE in the RAB ASSIGNMENT REQ message onthe IU interface,this action is divided into two types: Inter-RAT Should Be Load Handover in the CS Domain

Inter-RAT Should Not Be Load Handover in the CS Domain

The two actions have completely similar parameters and procedures, therefore, we just introducethe “Inter - RAT Should Be Load Handover in the CS Domain” action here as an example.

Service

condition

… −The UE can support inter-RAT compress mode.

… The AMR DCH service in the CS domain, which the

“service-handover” IE is set to "handover to GSM should be performed" in RAB ASSIGNMENT REQ message.

…

The algorithm selects RAB to perform this action according to

integrate priority. the lowest RAB will be selected first. Basic

principle

… The number of UEs which are selected is controled by the UL/DL

CS should be ho user number parameter.

Environment

condition

…

The CS inter-rat handover algorithm switch and the CS inter-

rat handover algorithm parameter are both enabled.

… The GSM neighbouring cells are configured properly.

Note: If the conditions are not meet or actions fails, the algorithm will go to next action decision.

Inter-RAT

Handover in the

CS Domain

performed

Action 5: Inter-RAT Handover in the PS Domain


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The action procedure of I nter -RAT H andover in the PS Domain is similar to that of Inter- RAT H andover in the CS Domain .

Action 5: Inter RAT Handover in the PS Domain

Actions 6: AMR Rate Reduction


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Actions 6: AMR Rate Reduction

In the WCDMA system, voice services work in eight AMR modes. Each mode has its own rate.

Therefore, mode control is functionally equal to rate control.

The LDR algorithm operates in the downlink as follows:

In the downlink direction

Based on the integrate priority, the LDR sorts the RABs in descending order. RABs with AMR

services (conversational) and with the bit rate higher than the GBR are selected. The number of

RABs to select is determined by the DL LDR-AMR rate reduction RAB number parameter.

The RNC sends the Rate Control request message through the IuUP to the CN to adjust the

AMR rate to the GBR.

If the RNC cannot find an appropriate RAB for the AMR rate reduction, the action fails. The

LDR takes the next action.

In the Uplink direction

The only difference from downlink is on the step 2: The RNC sends the TFC CONTROL command to

the UE to adjust the AMR rate to the GBR..

Note: This action is just suitable for CS AMR service which is canrried on the DCH.

Action 7 Code Reshuffling


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Principle

When the cell is in basic congestion for shortage of code resources, sufficient code resources can be

reserved for subsequent service access through code reshuffling. Code subtree adjustment refers to the

switching of users from one code subtree to another. It is used for code tree defragmentation, so as to free

smaller codes first.

The algorithm operates as follows:

Step 1 : Initialize the SF_Cur of the root node of subtrees to Cell LDR SF reserved threshold.

Step 2 : Traverse all the subtrees with this SF_Cur at the root node. Leaving the subtrees

occupied by common channels and HSDPA channels out of account, take the subtrees in which

the number of users is not larger than the value of the Max user number of code adjust parameter

as candidates for code reshuffling.

Step 3: Select a subtree from the candidates to perform the action

Step 4: Treat each user in the subtree as a new user and allocate code resources to each user.

Step 5: Initiate the reconfiguration procedure for each user in the subtree and reconfigure thechannel codes of the users to the newly allocated code resources.

Action 7：Code Reshuffling

Note: If no such candidate is available in step 2, subtree selection fails. This procedure ends.

Code Reshuffling Procedure


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Code Reshuffling Procedure

The reconfiguration procedure on the UU interface is implemented through thePHYSICAL CHANNEL RECONFIGURATION message and that on the Iubinterface through the RL RECONFIGURATION message.

In the Step 3 in previous page, subtree select principle according to the setting

of the LDR code priority indicator parameter:

If this parameter is set to TRUE, select the subtree with the largest code number from thecandidates.

If this parameter is set to FALSE, select the subtree with the smallest number of users from

the candidates. In the case that multiple subtrees have the same number of users, select the

subtree with the largest code number.

The following figures show an example of code reshuffling. In this example, Cell

LDR SF reserved threshold is set to SF8 and Max user number of code adjust is

set to 1.

Action 8: MBMS Power Reduction


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Action 8: MBMS Power Reduction

The downlink power load can be reduced by lowering power on MBMS traffic

channels.

The algorithm operates as follows:

Based on the integrated priority, the algorithm sorts the RABs in descending order.

The algorithm selects a RAB with the lowest integrated priority and with the

current power higher than the minimum transmit power of the corresponding

MTCH. That is, it selects a RAB of which the ARP value is higher than

MbmsDecPowerRabThd.

The algorithm triggers a reconfiguration procedure to set the power to the

minimum transmit power of the FACH onto which the MTCH is mapped.

The reconfiguration procedure on the Iub interface is implemented through the

COMMON TRANSPORT CHANNEL RECONFIGURATION REQUEST

message.

C t t


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Contents

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load control 2

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