wcdma load control workshop.ppt

Apr. 2006

Node B Products of Huawei

May 2008

WCDMA Load Control

HUAWEI TECHNOLOGIES CO., LTD.

www.huawei.com

HUAWEI TECHNOLOGIES Co., Ltd. HUAWEI Confidential

Overview

PUC

CAC

IAC

LDR

OLC


Load Control exists in all phases

Load Control is used to keep system stable, maximize system capacity while ensuring the coverage and QoS.

Different load control algorithms according to different phases provided:- Before UE access: Potential User Control (PUC)- During UE access: Call Admission Check (CAC) and Intelligent Access Control (IAC)- After UE access: Load Reshuffling (LDR), and Overload Control (OLC)

3. After UE access2. During UE access1. Before UE access

Time

• LDRCACPUC• OLC

•• IAC

PUC: Potential User Control CAC: Call Admission ControlIAC: Intelligent Admission Control LDR: Load ReshufflingOLC: Overload Control


Load control features

PUC

The function of PUC is to balance traffic load among inter-frequency cells. By modifying

cell selection and reselection parameters and broadcasting them through system

information, PUC leads UEs to cells with light load. The UEs may be in idle mode,

CELL_FACH state, CELL_PCH state, or URA_PCH state.

CAC

The function of CAC is to decide on resource requests from UEs, such as access,

reconfiguration, and handover requests, according to the resource status of the cell.

IAC

The function of IAC is to increase the access success rate with the current QoS assured

through rate negotiation, queuing, preemption, and Direct Retry Decision (DRD).


Load control features

LDR

The function of LDR is to reduce the load of a cell when the available resources of the

cell reach the specified alarm threshold. The purpose of LDR is to increase the access

success rate in the following ways:

Inter-frequency load handover

Code reshuffling

BE service rate reduction

AMR voice service rate reduction

Uncontrolled realtime traffic QoS renegotiation

CS inter-RAT load handover

PS inter-RAT load handover

OLC

The function of OLC is to reduce the cell load rapidly by restricting the Transport Format

(TF) of the BE service or releasing UEs when the cell is overloaded. The purpose of OLC

is to ensure the stability of the system and the QoS of most UEs.


Load Control for different cell load level


Thresholds and actions of the load control algorithms


RAB integrate priority

If the value of the parameter is set to Traffic Class, the integrate

priority abides by the following rules:

Classes of services: conversational -> streaming -> interactive ->

background

Services of the same class: priority based on Allocation/Retention Priority

(ARP) values

Only for the interactive service of the same ARP value: priority based on

THP

Services of the same class and priority: HSDPA or DCH service preferred

on the basis of the value of the Indicator of Carrier Type Priority

parameter


RAB integrate priority

If the value of the parameter is set to ARP, the integrate priority

abides by the following rules:

ARP1 -> ARP2 -> ARP3 … -> ARP14

Same ARP value: conversational -> streaming -> interactive ->

background

Only for the interactive service of the same ARP: priority based on THP

Services of the same ARP, class and THP (only for interactive service ):

HSDPA or DCH service preferred on the basis of the value of the

Indicator of Carrier Type Priority parameter


Priority Definition - Example

RAB ID ARP Traffic Class THP Bear Type

A 1 Interactive 3 DCH

B 1 Interactive 3 HSDPA

C 2 Conversational DCH

D 2 Background DCH

E 2 Background HSDPA

F 2 Streaming DCH

Services with different ARP/TC/THP/Bear：

ARP is the top-priority, and HSDPA over DCH

TC is the top-priority, and HSDPA over DCH

RANK ARP Traffic Class THP Bear Type

B 1 Interactive 3 HSDPA

A 1 Interactive 3 DCH

C 2 Conversational DCH

F 2 Streaming DCH

E 2 Background HSDPA

D 2 Background DCH

RANK Traffic Class ARP THP Bear Type

C Conversational 2 DCH

F Streaming 2 DCH

B Interactive 1 3 HSDPA

A Interactive 1 3 DCH

E Background 2 HSDPA

D Background 2 DCH


Priority Definition in Huawei Implementation

User Priority

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

User Priority

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

User Integrate Priority:

- For multiple-RAB users, determined by the service with the highest

RAB Integrate Priority.

User Priority: ☺ Gold (1) ☺ Silver (2) ☺ Bronze (3)

Typical Mapping of “ARP” and “User Priority”


GBR Configuration in Huawei Implementation

– For R99 I/B services Uplink BE Guarantee Bitrate and Downlink BE Guarantee Bitrate are configurable

respectively per cell. Uplink BE Guarantee Bitrate is used in BE downsizing due to uplink cell basic congestion. Downlink BE Guarantee Bitrate is used in BE downsizing due to downlink coverage and

downlink cell basic congestion.

– For R99 and HSDPA RT services GBR is in accordance with the requested guaranteed bit rate in RAB parameters.

– For HSDPA I/B services Different GBRs are configured for Gold/Silver/Copper user.

Gold Silver Copper

Uplink 64kbps 64kbps 64kbps

Downlink 64kbps 64kbps 64kbps


Overview

PUC

CAC

IAC

LDR

OLC


Potentioal User Control

The PUC algorithm controls the cell selection of a potential UE and prevents an idle UE from

camping on a heavy load cell.


Potentioal User ControlCell load comes with three levels: heavy, normal, and light.

When cell load is higher than the load level division upper threshold plus the load level division

hysteresis, it is decided to be heavy.

When cell load is lower than the load level lower threshold plus the load level division hysteresis, it

is decided to be light.


Potentioal User Control

Based on the cell load, PUC works as follows:

If the cell load becomes heavy, PUC modifies cell selection and reselection

parameters and broadcasts them through system information. In this way, PUC

leads UEs to neighboring cells with light load.

If the cell load becomes normal, PUC uses the cell selection and reselection

parameters configured on the LMT.

If the cell load becomes light, PUC modifies cell selection and reselection

parameters and broadcasts them through system information. In this way, PUC

leads UEs to this cell.


Overview

PUC

CAC

IAC

LDR

OLC


Resource Admission Check Overview

Affected users Users in connected mode

Procedure Make decision whether to admit

new users or service upgrade

according to the available system

resources.

Resources to

check

1. DL Channelization Code

2. Radio Resource: Power /

Interference

3. Credit: Resource

4. Iub transmission bandwidth

For

HSDPA/HSUPA

Maximum user number per Cell /

NodeB

Admission request

Code resource based admission?

Credit resource based admission?

Iub resourcebased admission?

Resource admission passed

Power resource based admission?

Yes

Yes

Yes

Yes

Yes

Resource admission denied

No

No

No

No


Admission Check of Radio Resource

UL and DL independently

On the basis of TCP / RTWP

On the basis of equivalent user number

Request initiation

Uplink calladmission desicion

Admitted?

Downlink calladmission desicion

Admitted?

Request admitted Request rejected

End

No

No

Yes

Yes


Admission Algorithm Selection

Algorithm 1: based on TCP/RTWP measurement and load increment estimation

Downlink:

Load level definition: TCP (Transmitted Carrier Power)

Uplink:

Load level definition: load factor

Load increment of the new request is taken into consideration.

Algorithm 2: based on static Equivalent Number of Users calculation

Standard user: 12.2kbps AMR with active factor 100%.

Algorithm 3: based on current TCP/RTWP measurement

Based on TCP/RTWP measurement;

Load increment of the new request is not taken into consideration

RTWP

PNUL 1


Uplink Admission Algorithm 1 & 3

)/( NoEcFun

Uplink admission control request

Get measured RTWP and calculatethe current uplink load factor.

Calculate the increment of theuplink load due to the request.

Get the predicted uplink loadfactor.

RTWPPN

UL 1

LUULpredictedUL ,

Compare the predicted value withadmission threshold

! Increment is always equal to ZERO when

algorithm 3 is applied


Downlink Admission Algorithm 1&3

)/_,/( NoEcCPICHNoEcFunP

Downlink admission control request

Get measured current TCP

Calculate the increment of thedownlink power due to the request.

Get the predicted downlink totalpower

Compare the predicted power withadmission threshold

TCP

PTCPP predicted

! Increment is always equal to ZERO when

algorithm 3 is applied

)()1()/_(/1

/)1(

1010

10 NPNECPICH

P

NE

NENP

Nc

CPICH

Nc

Nc ）（


Priority Handling of Admission Check

Parameters Default value

UL Handover access threshold 80％

UL threshold of Conv AMR service 75％

UL threshold of Conv non_AMR service 75％

UL threshold of other services 60％

• Threshold for uplink radio resource admission check

Parameters Default value

DL Handover access threshold 85％

DL threshold of Conv AMR service 80％

DL threshold of Conv non_AMR service 80％

DL threshold of other services 75％

•Threshold for downlink radio resource admission check


Code Management

Code management is used to manage the code resource between all the physical channels, including common channel (CCH) e.g. PCPICH and PCCPCH, dedicated channel (DPCH), and shared channel (HSDPA).

DPCHCCH

SF=16SF=8

SF=4

HSDPA

Code for DPCH:- Dynamically allocated

Code for common channel:- Reserved

Code for HSDPA:- Shared with R99 (Refer to HSDPA part)


Code Allocation Mechanism

Reserve the codes with smallest SF to improve utilization rate of whole code tree.

On the basis of maximum free sub-tree

Less code fragments are left

SF=256SF=128 ┏ ━ ●C(256, 0): PCPI CH

┏ 0 ┫SF=64 ┃ ┗ ━ ●C(256, 1): PCCPCH

┏ 0 ┫┃ ┃ ┏ ━ ●C(256, 2): AI CH┃ ┗ 1 ┫

SF=32 ┃ ┗ ━ ●C(256, 3): PI CH┏ 0 ┫

SF=16 ┃ ┗ ━ ●C(64, 1): SCCPCH┏ 0 ┫┃ ┃ ┏ ━ ●C(128, 2): DPCH┃ ┃ ┏ ━ 2 ┫┃ ┃ ┃ ┃┃ ┗ 1 ┫ ┗ ━ ○ 3

SF=8 ┃ ┗ ━ ○3┏ 0 ┫

SF=4 ┃ ┗ ━ ○1┏ 0 ┫┃ ┗ ━ ○1┃┗ ━ ○1

┏ ━ ○2┃ ● Occupi ed code┗ ━ ○3 ○ Non-occupi ed code


Admission Check of Iub Bandwidth

DPCH Service

Bandwidth consumption:

MBR * Active factor

HSDPA Service

Bandwidth consumption:

GBR * Active factor

Traffic ClassActive Factor

Scope

Common Channels 1

NodeB

SRB 0.9

Telephony (AMR&VOIP) 0.7

R99 Conversational (VP) 1

R99 Streaming 1

R99 Interactive 0.9

R99 Background 0.9

HSDPA Streaming 1

HSDPA Interactive 0.9

HSDPA Background 0.9

Configurable per service type


Admission Check of NodeB Credit

Admission Check:

Credits of local cell

Credits of local cell group

Credits of NodeB

Credit Consumption Law:

Reported from NodeB

In terms of SF

HSDPA is not involved

wcdma load control workshop.ppt

Documents

huawei confidential

traffic load

load control features

load control features

load reshufflingolc

light load

load reshuffling ldr

phasesload control