wcdma ran planning and optimization _book3_2_ features and algorithms

7/22/2019 WCDMA RAN Planning and Optimization _Book3_2_ Features and Algorithms

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WCDMA Load Control

The WCDMA system is a self interference system. As the load of the WCDMA system

increases, the interference rises. A relatively high interference may affect the coverage

and Quality of Service (QoS) of established services. Therefore, capacity, coverage and

QoS of the WCDMA system are mutually affected. The purpose of load control is tomaximize the system capacity while ensuring coverage and QoS.


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Objectives

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

Know load control principles

Know load control realization methods in WCDMA system

Know load control parameters in WCDMA system


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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

NodeB Transport resource

NodeB processing capability (NodeB credit)

Soft capacity

Cell Power (UL and DL)

WCDMA network load can be defined by 4 factors:

1,Power ,include DL transmitting power of cell and increased UL interference (RTWP).

2,DL OVSF code of a cell3,DL and UL NodeB processing capability which is defined by NodeB credit.

4,Iub transmission bandwidth of a NodeB

The power resource is related to the mobility, distribution of the UE and also effected by

the radio conditions. Therefore, for a fixed power resource, the numbers of service can

be supported is not a fix result. We believe the UL and DL power resources are soft.


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The Objectives of Load Control

Keeping system stable

Maximizing system capacity while ensuring coverage and

QoS

Realize different priorities for different service and different

user

WCDMA network load can be defined by 4 factors:

1,Power ,include DL transmitting power of cell and increased UL interference (RTWP).

2,DL OVSF code of a cell3,DL and UL NodeB processing capability which is defined by NodeB credit.

4,Iub transmission bandwidth of a NodeB

The power resource is related to the mobility, distribution of the UE and also effected

by the radio conditions. Therefore, for a fixed power resource, the numbers of service

can be supported is not a fix result. We believe the UL and DL power resources are

soft.


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Load Control Algorithms

The load control algorithms are applied to the different

UE access phases as follows:

PUC: Potential User Control CAC: Call Admission Control

IAC: Intelligent Admission Control LDB : Intra-frequency Load Balancing

LDR: Load Reshuffling OLC: Overload Control

The load control algorithms are applied to the different UE access phases as follows:

Before UE access: Potential User Control (PUC)

During UE access: Intelligent Access Control (IAC) and Call Admission Control (CAC)After UE access: intra-frequency Load Balancing (LDB), Load Reshuffling (LDR), and

Overload Control (OLC)


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Load Control Algorithms

Load control algorithm in the WCDMA system

The load control algorithms are built into the RNC. The input of load control comes

from the RNC and measurement information of the NodeB.

RNC can calculate hard resource load, that is OVSF ,NodeB credit, Iub occupancy.

The soft load need the NodeB reporting.


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Contents






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Soft Load MeasurementThe major measurement objects of the load measurement

Received scheduled Enhanced Dedicated Channel (E-DCH)power share (RSEPS)

Uplink Received Total Wideband Power (RTWP)

UL Load

HSDPA GBP

HSDPA PBR

Non-HSPA TCPDL Load

TCP

E-DCH Provided Bit Rate

The soft load control algorithms use load measurement values in the uplink and the

downlink. A common Load Measurement (LDM) algorithm is required to control load

measurement in the uplink and the downlink.

The NodeB and the RNC perform measurements and filtering in accordance with the

parameter settings. The statistics obtained after the measurements and filtering serve

as the data input for the load control algorithms.

The major measurement objects of the LDM are as follows:

Uplink Received Total Wideband Power (RTWP)

Received scheduled Enhanced Dedicated Channel (E-DCH) power share (RSEPS)

E-DCH Provided Bit Rate

Downlink Transmitted Carrier Power (TCP)

TCP of all codes not used for High Speed Physical Downlink Shared Channel (HS-

PDSCH), High Speed Shared Control Channel (Non-HSPA TCP)

Provided Bit Rate on HS-DSCH (PBR)

HS-DSCH required poweralso called Guaranteed Bit Rate (GBR) required power

(GBP)


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Based on the measurement parameters set on the NodeB Local Maintenance Terminal(LMT), the NodeB measures the major measurement quantities and then obtainsoriginal measurement values. After layer 3 filtering on the NodeB side, the NodeBreports the cell measurement values to the RNC.Based on the measurement parameters set on the RNC LMT, the RNC performssmooth filtering on the measurement values reported from the NodeB and then obtainsthe measurement values, which further serve as data input for the load controlalgorithms.

Filtering on the NodeB Side

A is the sampling value of the measurement.

B is the measurement value after layer 1 filtering.

C is the measurement value after layer 3 filtering ,which is the reported measurementvalue

Layer 1 filtering is not standardized by protocols and it depends on vendor equipment.

Layer 3 filtering is standardized. The filtering effect is controlled by a higher layer.


Load Measurement procedure

Smooth Window Filtering on the RNC Side

N : the size of the smooth window

: the reported measurement value

1

0( )

N

n i

i

P

P nN

==

nP


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The interval at which the NodeB reports each measurement quantity to the RNC is

configured by the Time unit and Report cycle on RNC LMT: SET LDM

The report interval = Time unit * Report cycle

By default, Time unit for all measurement are set to 10ms ;Report cycle for

RTWP is 100, that is 1s; Report cycle for TCP and Non HSPA TCP is 20 ,that is

200ms ;Report cycle for HSDPA GBP is 10, that is 100 ms; Report cycle forHSDPA PBR is 10, that is 100 ms

Smooth Window Filtering on the RNC Side

After the RNC receives the measurement report, it filters the measurement value

with the smooth window.

Assuming that the reported measurement value is Qn and that the size of the

smooth window is N, the filtered measurement value is :

Delay susceptibilities of PUC, CAC, LDBLDR, and OLC to common measurement

are different. The LDM algorithm must apply different smooth filter coefficients and

measurement periods to those algorithms , on RNC LMT, we can set the smooth

window length for different algorithms by SET LDM:

The following table lists the parameters :

251 to 32DlOLCAvgFilterLenDL OLC moving averagefilter length

251 to 32UlOLCAvgFilterLenUL OLC moving averagefilter length

31 to 32DlCACAvgFilterLenDL CAC moving averagefilter length

31 to 32UlCACAvgFilterLenUL CAC moving averagefilter length

251 to 32DlLdrAvgFilterLenDL LDR moving averagefilter length

251 to 32UlLdrAvgFilterLenUL LDR moving averagefilter length

321 to 32LdbAvgFilterLenLDB moving averagefilter length

321 to 32PucAvgFilterLenPUC moving averagefilter length

defaultValue

ValueRangeParameter IDParameter Name

Smooth window for GBP for all related algorithms are the same and the default setting is 1


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Contents






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Priority

The service of user with low priority will be affected by the

load control algorithms first

Three kinds of priorities

User Priority

RAB Integrate Priority

User Integrate Priority

User Priority: mainly applying to provide different QoS for different users. Eg., setting

different GBR according to the user priority for BE service. No consideration about the

service.

RAB Integrate Priority: Priority of a service, related to the service type, and the user

priority of the user.

User Integrate Priority: Only used for multi-RAB user ,it is a temporary priority of an

ongoing-service user.


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User Priority

There are three levels of user priority

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

32kbps64kbps128kbpsUplink

CopperSilverGoldUser priority

32kbps64kbps128kbpsDownlink

gold

userPay $100

for 3G

services

In CN HLR, we can set ARP (Allocation Retention Priority ), during service setup, CN

sends ARP to RNC .Based on the mapping relation( configured in RNC), RNC can

identify the user is a gold, silver or copper one.

The user priority affect GBR of BE service in RAN, Iub transmission management and so

on.


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User Priority

The mapping relation between user priority and ARP

(Allocation/Retention Priority) is configured in RNC by SETUSERPRIORITY

The default relation is:

CopperSilverGoldUser

Priority

151413121110987654321ARP

The user priority mapping can be configured in RNC by SET USERPRIORITY

ARP 15 is always the lowest priority and it cannot be configured. It corresponds to

copper.

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

copper.


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RAB Integrate Priority

RAB Integrate Priority is mainly used in load control

algorithms

RAB Integrate Priority are set according to :

ARP

Traffic Class

THPfor interactive service only

HSPA or DCH

RAB Integrate Priority is mainly used in load control algorithms.

The values of RAB Integrate Priority are set according to the Integrate Prior ityConfigured Reference parameter as follows:

If Integrate Prior ity Configured Reference is set to Traffic Class, the integrate priorityabides 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, defined in CN , sent to RNC during service setup), that is,

THP1 -> THP2 -> THP3 -> ... -> THP14 =>

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

Speed Packet Access (HSPA) or Dedicated Channel (DCH) service preferred

depending on the value of the Indicator of Carrier Type Prior ity parameter.


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If Integrate Prior ity Configured Reference is set toARP, the integrate priority abides bythe following rules:

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

Traffic classes: 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, class and THP (only for interactive services): HSPA

or DCH service preferred depending on the value of the Indicator of CarrierType Prior ity parameter.

Integrate Prior ity Configured Reference and Indicator o f Carrier TypePriority are set by SET USERPRIORITY .

By default

Integrate Prior ity Configured Reference is set toARP

Indicator of Carrier Type Prior ity is set to NONE, that means HSDPA and DCHservices have the same priority.

ARP and THP are carried in the RAB ASSIGNMENT REQUEST message, and they are

not configurable on the RNC LMT.


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Example for RAB Integrate Priority

DCHBackground2D

DCHConversational2C

HSDPAInteractive1B

DCHInteractive1A

Bear

type

Traffic ClassARPService

ID

Services attribution in the cell

Based on ARP, HSDPA priority is higher

Based on Traffic Class, HSDPA priority is higher

DCHBackground2D

DCHConversational2C

DCHInteractive1A

HSDPAInteractive1B

Bear

type

Traffic ClassARPService

ID

Background

Interactive

Interactive

Conversational

Traffic Class

DCH2D

DCH1A

HSDPA1B

DCH2C

Bear

type

ARPService

ID

This example shows the RAB Integrate Priority calculation in 2 different conditions


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User Integrate Priority

When the user has one RAB, User integrate priority is the

same as the RAB integrate priority

For multiple RAB users, the integrate priority of the user is

based on the service of the highest priority

When the user has one RAB, User integrate priority is the same as the service of the

RAB integrate priority;

For multiple RAB users, the integrate priority of the user is based on the service of the

highest priority.

User integrate priority is used in user-specific load control. For example, the selection of

R99 users during preemption, the selection of users during inter-frequency load

handover for LDR, and the selection of users during switching BE services to CCH are

performed according to the user integrate priority.


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Integrate Priority Configured Reference

Parameter ID: PRIORITYREFERENCE

The default value of this parameter is ARP

Indicator of Carrier Type Priority

Parameter ID: CARRIERTYPEPRIORIND

The default value of this parameter is NONE

Key parameters of Priority

Integrate Priority Configured Reference

Parameter ID: PRIORITYREFERENCE

Value range: ARP, Traffic ClassContent: This parameter is used to set the criterion by which the priority is first sorted.

The default value of this parameter is ARP

Set this parameter through SET USERPRIORITY

Indicator of Carrier Type Priority

Parameter ID: CARRIERTYPEPRIORIND

Value range: NONE, DCH, HSPA

Content: This parameter is used to decide which carrier (DCH or HSPA) takes

precedence when ARP and Traffic Class are identical. When this parameter is set toNONE, the bearing priority of services on the DCH is the same as that of HSPA

services.

The default value of this parameter is NONE,

Set this parameter through SET USERPRIORITY


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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 Admission Control)

2.5 LDR (Load Reshuffling)

2.6 OLC (Overload Control)


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PUC Principles

The Potential User Control (PUC) algorithm controls the

Inter-frequency cell reselection of the potential UE, andprevents UE from camping on a heavily loaded cell.

Potential UE :

IDLE Mode UE

CELL-FACH UECELL-PCH UEURA-PCH UE

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 cell with light load. The UE may be in idle mode,

Cell_FACH state, Cell _PCH state, URA_PCH state


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PUC Load Judgment

Cell load for PUC is of three states: heavy, normal, and light

The RNC periodically monitors the downlink load of the cell and compares the

measurement results with the configured thresholds Load level division threshold 1 andLoad level division threshold 2, that is, load level division upper and lower thresholds.

If the cell load is higher than the load level division upper threshold plus the Load leveldivision hysteresis, the cell load is considered heavy.

If the cell load is lower than the load level division lower threshold minus the Load leveldivision hysteresis, the cell load is considered light.

Otherwise the cell load is considered normal


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PUC Procedure

NodeB UE

Heavy?

Light?

Normal?

Cell TCP

RNC

Threshold

cell reselection

parameters

Every 200ms

Every 30 minutes

System information

The parameters related to cell selection and cell reselection are Qoffset1(s,n) (load level

offset), Qoffset2(s,n) (load level offset), and Sintersearch (start threshold for inter-

frequency cell reselection).

The NodeB periodically reports the total TCP of the cell, and the PUC periodically triggers

the following activities:

Assessing the cell load level based on the total TCP

Configuring Sintersearch, Qoffset1(s,n), and Qoffset2(s,n) based on the cell load level

PUC can Modify inter-frequency cell reselection parameters based on the load:

1. Sintersearch :

when the load of a cell is Heavy, PUC will increase Sintersearch

when the load of a cell is Light, PUC will decrease Sintersearch

2. QOffset:when the load of current cell is Heavy and neighbor is Non heavy, PUC will decrease

QOffset

when the load of current cell is Non heavy and neighbor is Heavy, PUC will increase

QOffset

Updating the parameters of system information SIB3 and SIB11


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: indicates that the parameter value remains unchanged.

: indicates that the parameter value increases.

: indicates that the parameter value decreases.

S'intersearch = Sintersearch + Sintersearch offset 2Heavy

S'intersearch = SintersearchNormal

S'intersearch = Sintersearch + Sintersearch offset 1Light

Change ofSintersearch

SintersearchLoad of Current Cell


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PUC Principles

Freq1

Freq2

System InfoSIB3,11

System InfoSIB3,11

System InfoSIB3,11

Heavy load

Light load Normal load

Idle state CCH state

Modify

1.Easy to trigger reselection

2.Easy to select light load

Inter-freq neighbor Cell

Decrease the POTENTIAL load

Modify

1.Hard to trigger reselection

2.Easy to camp on the cell

Increase the POTENTIAL load

Stay

Based on the characteristics of inter-frequency cell selection and reselection.

Sintersearch

When this value is increased by the serving cell, the UE starts inter-frequency cellreselection ahead of schedule.

When this value is decreased by the serving cell, the UE delays inter-frequency

cell reselection.

Qoffset1(s,n): applies to R (reselection) rule with CPICH RSCP

When this value is increased by the serving cell, the UE has a lower probability of

selecting a neighboring cell.

When this value is decreased by the serving cell, the UE has a higher probability

of selecting a neighboring cell.

Qoffset2(s,n): applies to R (reselection) rule with CPICH Ec/I0

When this value is increased by the serving cell, the UE has a lower probability of

selecting a neighboring cell.

When this value is decreased by the serving cell, the UE has a higher probability

of selecting a neighboring cell.


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Cell LDC algorithm switch

Parameter ID: NBMLDCALGOSWITCH PUC

The default value of this parameter is Off

Load level division threshold 1 (Heavy)

Parameter ID: SPUCHEAVY

The default value of this parameter is 70(70%)

Load level division threshold 2 (Light)

Parameter ID: SPUCLIGHT


Key parameters PUC


Parameter ID: NBMLDCALGOSWITCH PUC

Value range: OFF, ONContent: This parameter is used to enable or disable the PUC algorithm..

The default value of this parameter is OFF

Set this parameter throughADD CELLALGOSWITCH / MOD CELLALGOSWITCH


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Load level division threshold 1 (Heavy)

Parameter ID: SPUCHEAVY

Value range: 0 to 100

Content: This parameter is one of the thresholds used to assess cell load level and to

decide whether the cell load level is heavy or not.

The default value of this parameter is 70%,

Set this parameter throughADD CELLPUC / MOD CELLPUC

Load level division threshold 2 (Light)

Parameter ID: SPUCLIGHT


Content: This parameter is one of the thresholds used to assess cell load level and todecide whether the cell load level is heavy or not.




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Load level division hysteresis

Parameter ID: SPUCHYST

The default value of this parameter is 5 (5%)

PUC period timer length

Parameter ID: PUCPERIODTIMERLEN

The default value of this parameter is 1800(s)

Key parameters PUC

Load level division hysteresis

Parameter ID: SPUCHYST

Value range: OFF, ONContent: This parameter specifies the hysteresis used during cell load level

assessment to avoid unnecessary ping-pong effect of a cell between two load levels

due to a little load change.

The default value of this parameter is 5 (5%)


PUC period timer length

Parameter ID: PUCPERIODTIMERLEN

Value range: 6 to 86400 sContent: This parameter specifies the period of potential user control. The higher the

parameter is set, the longer the period to trigger the PUC is.

The default value of this parameter is 1800(s)

Set this parameter through SET LDCPERIOD


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Sintersearch offset 1

Parameter ID: OFFSINTERLIGHT

The default value of this parameter is 2 (-4dB)


Parameter ID: OFFSINTERHEAVY

The default value of this parameter is 2 (4dB)

Key parameters PUC


Parameter ID: OFFSINTERLIGHT

Value range: 10 to 10 ,step:2dBContent: This parameter defines the offset of Sintersearch when the center cell load

level is "Light". It is strongly recommended that this parameter be set to a value not

higher than 0. The default value of this parameter is 2 (-4dB)



Parameter ID: OFFSINTERHEAVY

Value range: 10 to 10 ,step:2dB

Content: This parameter defines the offset of Sintersearch when the center cell loadlevel is "Heavy". It is strongly recommended that this parameter be set to a value not

lower than 0. The default value of this parameter is 2 (4dB)



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Qoffset1 offset 1

Parameter ID: OFFQOFFSET1LIGHT


Qoffset1 offset 2

Parameter ID: OFFQOFFSET1HEAVY


Key parameters PUC

Qoffset1 offset 1


Value range: 10 to 10 ,step:2dBContent: This parameter defines the offset of Qoffset1RSCP when the current

cell has heavy load and the neighboring cell has light or normal load. To enable the

UE to select a neighboring cell with relatively light load, it is strongly recommended

that this parameter be set to a value not higher than 0.

The default value of this parameter is -4 (-8dB)

Set this parameter throughADD CELLPUC/MOD CELLPUC

Qoffset1 offset 2



Content: This parameter defines the offset of Qoffset1RSCP when the load of a

neighboring cell is heavier than that of the center cell. To enable the UE to select a

neighboring cell with relatively light load, it is strongly recommended that this

parameter be set to a value not lower than 0.




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Qoffset2 offset 1



Qoffset2 offset 2



Key parameters PUC

Qoffset1 offset 1


Value range: 10 to 10 ,step:2dBContent: This parameter defines the offset of Qoffset1RSCP when the current cell

has heavy load and the neighboring cell has light or normal load. To enable the UE to

select a neighboring cell with relatively light load, it is strongly recommended that this

parameter be set to a value not higher than 0.

The default value of this parameter is -4 (-8dB)


Qoffset1 offset 2



Content: This parameter defines the offset of Qoffset2EcNo when the load of a

neighboring cell is heavier than that of the center cell. To enable the UE to select a

neighboring cell with relatively light load, it is strongly recommended that this

parameter be set to a value not lower than 0.




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Contents









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Intra-Frequency Load Balancing

Intra-frequency Load Balancing (LDB) is performed to adjust

the coverage areas of cells by modifying PCPICH power

LDB affect UEs in all states

Intra-frequency Load Balancing (LDB) is performed to adjust the coverage areas of

cells according to the measured values of cell downlink power load. RNC checks the

load of cells periodically and adjusts the transmit power of the P-CPICH in the

associated cells based on the cell load.

When the load of a cell increases, the cell reduces its coverage to lighten its load.

When the load of a cell decreases, the cell extends its coverage so that some traffic is

off-loaded from its neighboring cells to it.

Reduction of the pilot power will make the UEs at the edge of the cell handed over to

neighboring cells, especially to those with a relatively light load and with relatively high

pilot power. After that, the downlink load of the cell is lightened accordingly.


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LDB Procedure

NodeB UE

Heavy?

Light?

Normal?

Cell TCP

RNC

Threshold

Modify cell PCPICH

power

Updated PCPICH

POWER

Handover or

Cell Reselection

The NodeB periodically reports the total TCP of the cell, and the LDB periodically triggers

the following activities:

Assessing the cell load level based on the total TCP

If the downlink load of a cell is higher than the value of the Cell overload threshold, it isan indication that the cell is heavily loaded. In this case, the transmit power of the P-

CPICH needs to be reduced by a step, which is defined by the Pilot power adjustmentstep parameter. However, if the current transmit power is equal to the value of the Mintransmit power of PCPICH parameter, no adjustment is performed.

If the downlink load of a cell is lower than the value of the Cell underload threshold, it isan indication that the cell has sufficient remaining capacity for more load. In this case, the

transmit power of the P-CPICH increases by a step, which is defined by the Pilot poweradjustment step parameter, to help to lighten the load of neighboring cells. However, ifthe current transmit power is equal to the value of the Max transmit power of PCPICHparameter, no adjustment is performed.


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Parameter ID: NBMLdcAlgoSwitch LDB

The default value of this parameter is Off

Intra-frequency LDB period timer length

Parameter ID: IntraFreqLdbPeriodTimerLen

The default value of this parameter is 1800 (s)

Key parameters LDB


Parameter ID: NBMLdcAlgoSwitch LDB

Value range: OFF, ONContent: This parameter is used to enable or disable the LDB algorithm..


Set this parameter throughADD CELLALGOSWITCH / MOD CELLALGOSWITCH

Intra-frequency LDB period timer length

Parameter ID: IntraFreqLdbPeriodTimerLen


Content: This parameter specifies the length of the intra-frequency LDB period.

The default value of this parameter is 1800 (s)

Set this parameter through SET LDCPERIOD


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Cell overload threshold (Heavy)

Parameter ID: CellOverrunThd


Cell underload threshold (Light)

Parameter ID: CellUnderrunThd


Key parameters LDB

Cell overload threshold

Parameter ID: CellOverrunThd


Content: If the downlink load of a cell exceeds this threshold, the algorithm can

decrease the pilot transmit power of the cell so as to extend the capacity of the whole

system.


Set this parameter throughADD CELLLDB / MOD CELLLDB

Cell underload threshold

Parameter ID: CellUnderrunThd


Content: If the downlink load of a cell is lower than this threshold, the algorithm can

increase the pilot transmit power of the cell so as to share the load of other cells.




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Pilot power adjustment step

Parameter ID: PCPICHPowerPace

The default value of this parameter is 2 (0.2dB)

Max transmit power of PCPICH

Parameter ID: MaxPCPICHPower

The default value of this parameter is 346 (34.6dBm)

Key parameters LDB

Pilot power adjustment step

Parameter ID: PCPICHPowerPace

Value range: 0 to 10 , Step 0.1dBContent: This parameter defines the step for the adjustment to the pilot power.

The default value of this parameter is 2, 0.2dB


Max transmit power of PCPICH

Parameter ID: MaxPCPICHPower

Value range: 100 to 500 ,Step 0.1dB

Content: This parameter defines the maximum transmit power of the P-CPICH in a cell.

This parameter has to be set according to the actual system environment, that is, for

example, cell coverage (radius) and geographical environment. If the maximum transmitpower of the P-CPICH is set too low, the cell coverage decreases. When a certainproportion of soft handover area is ensured, any more increase in the pilot powerachieves no improvement on the performance of the downlink coverage.


Set this parameter throughADD PCPICH / MOD PCPICHPWR


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Min transmit power of PCPICH

Parameter ID: MinPCPICHPower


Key parameters LDB

Min transmit power of PCPICH

Parameter ID: MinPCPICHPower

Value range: -100 to 500Content: This parameter defines the minimum transmit power of the P-CPICH in a cell.

This parameter has to be set according to the actual system environment, that is, forexample, (radius) and geographical environment. If the minimum transmit power of theP-CPICH is set too low, the cell coverage will be affected. The parameter has to be setunder the condition that a certain proportion of soft handover area is ensured or theoccurrence of coverage hole can be prevented.


Set this parameter throughADD PCPICH / MOD PCPICHPWR


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Contents









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Why we need CAC?

WCDMA is an interference limited system, after a new call is

admitted, the system load will be increased

If a cell is high loaded, a new call will cause ongoing user

dropped

We must keep the coverage planned by the Radio Network

Planning

CAC is needed under such scenarios:

1. RRC connection setup request

2. RAB setup and Bandwidth increasing3. Handover

4. RB reconfiguration


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Flow chart of CAC

The admission decision is based on:

Cell available code resource: managed in RNC

Cell available power resource, that is DL/UL load : measured in NodeB NodeB resource state, that is, NodeB credits : managed in RNC

Available Iub transport layer resource, that is, Iub transmission bandwidth:

managed in RNC

HSPA user number (only for HSPA service)


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Admission control Switches can be set on RNC LMT:

Power CAC

Uplink CAC algorithm switch

Downlink CAC algorithm switch

NodeB Credit CAC

CAC algorithm switch : CacSwitch

Cell CAC algorithm switch: CRD_ADCTRL

HSDPA user number CAC

CAC algorithm switch :HSDPA_UU_ADCTRL

HSUPA user number CAC

CAC algorithm switch: HSUPA_UU_ADCTRL

Algorithm Switch of CAC

Except the mandatory code and Iub resource admission con trol , the admission control based

on power and NodeB credit ,HSDPA User Number can be disabled through the LMT command:

Power CAC can be switched off byADD CELLALGOSWITCH / MOD CELLALGOSWITCH

Uplink CAC algorithm switch (NBMULCACALGOSELSWITCH ) specifies the algorithm used

for power admission in the uplink.

Downlink CAC algorithm switch (NBMDLCACALGOSELSWITCH) specifies the algorithm

used for power admission in the downlink.

NodeB Credit CAC can be switched off by SET CACALGOSWITCH or ADD

CELLALGOSWITCH / MOD CELLALGOSWITCH

CAC algorithm switch (CacSwitch) specifies the NodeB level credit CAC algorithm

Cell CAC algorithm switch (CRD_ADCTRL) specifies the Cell level credit CAC algorithm

HSDPA user number CAC switched off byADD CELLALGOSWITCH / MOD

CELLALGOSWITCH

HSDPA_UU_ADCTRL specifies whether to enable or disable the HSDPA admission control

algorithm.

HSUPA user number CAC switched off byADD CELLALGOSWITCH / MOD

CELLALGOSWITCH

HSUPA_UU_ADCTRL specifies whether to enable or disable the HSUPA admission control

algorithm


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CAC Based on Code Resource

Code Resource CAC functions in:

RRC connection setup

Handover

R99 services RAB setup

Note: RRC connection setup and Handover have higher priority

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

mandatory.

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

current remaining code resource is enough for the RRC connection.

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

remaining code resource is enough for the service.

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

exceed the configurable threshold after admission of the new service.

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

the code resource admission is not needed.

So the RRC connection setup and Handover has higher priority to access a cell


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CAC Based on Power Resource

UL and DL Power Resource CAC functions in:

R99 cell

RRC connection setup

R99 RAB setup

Handover

HSPA cell

RRC connection

R99 RAB setup

HSPA RAB setup

Handover

Note: RRC connection setup and Handover have higher priority

The UL CAC and DL CAC are independent .

The basic principle of Power CAC is: RNC predict the cell power load after the access. If

the load will be higher than a threshold, the admission is failed.

So, by setting different threshold for different access, we can realize different priorities.


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Power CAC Algorithms

Algorithm 1: based on UL/DL load measurement and load

prediction (RTWP and TCP)

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

Algorithm 3: loose call admission control algorithm

Huawei provide 3 Power CAC Algorithms

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

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.Based on Huawei testing and experience, The 12.2 kbit/s AMR traffic is used to

calculate the Equivalent Number of Users (ENU) of all other services in UL and DL. The

12.2 kbit/s AMR traffic's ENU is assumed to be 1. Depending on the current number of

equivalent users and the access request in UL and DL, the RNC determines whether the

number of equivalent users will exceed the threshold upon admitting a new call. If yes, the

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

Algorithm 3: power resource admission decision based on power or interference, but withthe estimated load increment always set to 0.Depending on the current cell load (uplink load

factor and downlink TCP) and the access request, 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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Basic principle of Uplink CAC Algorithm 1

Get current RTWP, and calculate thecurrent load factor

Admission request

Get the traffic characteristic, and

estimate the increment of load factor

Calculate the predicted load factor

admitted rejected

End of UL CAC

Y NSmaller than

the threshold?

RTWPPNUL = 1

CCHULpredictedUL ++=_

Pn is uplink receive background noise.

The procedure for uplink power resource decision is as follows:

1. The RNC obtains the uplink RTWP of the cell, and calculate the current uplink loadfactor.

2. The RNC calculates the uplink load incrementUL based on the service request.

3. The RNC uses the formulaUL,predicted=UL +UL to forecast the uplink load

factor.

4. By comparing the forecasted uplink load factorUL,predicted with the corresponding

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


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Basic principle of Downlink CAC Algorithm1

The procedure for downlink power resource decision is as follows:

1. The RNC obtains the cell downlink TCP, and calculates the downlink load factor by

multiplying the maximum downlink transmit power by this TCP.

2. The RNC calculates the downlink load incrementP based on the service request and

the current load.

3. The RNC forecasts the downlink load factor.

4. By comparing the downlink load factor with the corresponding threshold (DL threshold

of Conv AMR service, DL threshold of Conv non_AMR service, DL threshold of other

services, DL Handover access threshold), the RNC decides whether to accept the

access request or not.


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Basic principle of CAC Algorithm 2

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

iitotal ENUNENU 1)(

newENU

newtotaltotal ENUNENUNENU +=+ )()1(

max/)1( ENUNENUENULoad total +=

The procedure for ENU resource decision is as follows:

1. The RNC obtains the total ENU of all exist users ENUtotal.

2. The RNC get the ENU of the new incoming user ENUnew.3. The RNC forecast the ENU load.

4. By comparing the forecasted ENU load with the corresponding threshold (the same

threshold as power resource), the RNC decides whether to accept the access request

or not.

The ENUmax can be set by LMT, the ENUnew and ENUi is determined by Huawei

algorithm, there is an example in next slide.


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Power CAC for RRC connection Setup

For the RRC connection request is, tolerance principles are

applied : Emergency call, Detach , Registration

Direct Admission

RRC connection request for other reasons

UL/ DL OLC Trigger threshold Admission

To ensure that the RRC connection request is not denied by mistake, tolerance principles

are applied.

The admission decision is made for the following reasons of the RRC connection request:

1. For the RRC connection request for the reasons of emergency call, detach or

registration, direct admission is used ,that is no limitation.

2. For the RRC connection request for other reasons, UL/DL OLC Triggerthreshold is used for admission. By default, the OLC trigger threshold isrelatively high (DL/UL 95%), which make the RRC connections are easily set

up.


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UL Power CAC for R99 Cell (Algorithm1)

For R99 DCH RAB Setup, The RNC uses the following formula

to predict the uplink load factor :

Where the

By comparing the predicted uplink load factorUL,predicted with the

corresponding threshold ,the RNC decides whether to accept the

access request or not

CCHULULULpredictedUL ++= _

RTWP

PNUL =1

The threshold for Conv AMR service , Conv non_AMR service , Other R99 services ,Handover are set independently, which provide different priorities.

Normally, Other R99 services < Conv non_AMR service services < Conv AMRservice < Handover

The uplink load incrementUL is determined by :

1. The Eb/No of the new incoming call

2. The uplink load increment is proportional to the value of Eb/No.

3. UL neighbor interference factor

4. Active Factor of the new incoming call


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DL Power CAC for R99 Cell (Algorithm1)

For R99 DCH RAB Setup, The RNC uses the following formula to

predict the downlink load factor :

Where the

By comparing the predicted downlink load factorDL,predicted with

the corresponding threshold ,the RNC decides whether to accept

the access request or not

CCHDLDLDLpredictedDL ++= _

maxP

TCPDL =

maxP

DLDL

=

The threshold for Conv AMR service , Conv non_AMR service , Other R99 services ,Handover are set independently, which provide different priorities.

Normally, Other R99 services < Conv non_AMR service services < Conv AMR service RRC connection setup and

Services RAB setup


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CAC Based on Iub Interface Resource

Iub Overbooking

The Iub overbooking feature considers the statistic multiplexing

of service activities and multiple users

Admit more users, increases the resource utilization on the Iub

interface.

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.

If the RNC allocates the maximum bandwidth to the subscriber when a service is

established, a large proportion of the Iub transmission bandwidth is unused. For example,

downloading a 50 KB page takes only about one second, but reading this page needs

dozens of seconds. Thus, over 90% of the Iub transmission bandwidth is not used.

To save the Iub transmission bandwidth for operator use, Huawei provides the Iub

overbooking function, which applies an admission control mechanism to access the

service.


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Iub Overbooking

CS voice services

Service rate:12.2 kbit/s

SID

PS interactive and background services

Download time

Reading time

The UMTS supports four traffic classes: conversational, streaming, interactive, and

background.

The transmission rate varies with the traffic class as follows:

For Circuit Switched (CS) conversational services, the channel transmits voice signals at

a certain rate (for example, 12.2 kbit/s) during a conversation and only transmits Silence

Descriptors (SIDs) at intervals when there is no conversation.

For Packet Switched (PS) interactive and background services, such as web browsing,

there is data transmitted during data downloading. After a web page has been

downloaded, and when the user is reading the page, however, there is very little data to

transfer.


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Iub Overbooking

CS voice services

Activity Factor

PS interactive and background services

GBR

MML

SET DEFAULTFACTORTABLE

SET USERGBR

SET CORRMALGOSWITCH (IUB_OVERBOOKING_SWITCH)

ADD AAL2PATH

ADD IPPATH

Use SET DEFAULTFACTORTABLE to set a default of Activity Factor table for all the

services.

Use SET USERGBR to set GBR for BE services

Use SET CORRMALGOSWITCH (IUB_OVERBOOKING_SWITCH) to define the switch

of Iub overbooking


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CAC Based on Number of HSPA Users

HSPA user number can be limited 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

When the HSDPA_UU_ADCTRL is on, the HSDPA services have to undergo HSDPAuser number admission decision.

When a new HSDPA service attempts to access the network, it is admitted if the number

of HSDPA users in the cell and that in the NodeB do not exceed the associated

thresholds

When the HSUPA_UU_ADCTRL is on, the HSUPA services have to undergo HSUPAuser number admission decision.

When a new HSUPA service attempts to access the network, it is admitted if the number

of HSUPA users in the cell and that in the NodeB do not exceed the associated

thresholds


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HSDPA_UU_ADCTRL

Parameter ID: HSDPA_UU_ADCTRL

Maximum HSDPA user number

Parameter ID: MaxHSDSCHUserNum

The default value of this parameter is 64

HSDPA_UU_ADCTRL

Parameter ID: HSUPA_UU_ADCTRL

Maximum HSUPA user number

Parameter ID: MaxHsupaUserNum


Key parameters

Maximum HSDPA user number

Parameter ID: MaxHSDSCHUserNum


Content: This parameter specifies the maximum number of HSDPA users in a cell.


Set this parameter throughADD CELLCAC/MOD CELLCAC

HSDPA_UU_ADCTRL


Value range: 0 ,1

Content: This parameter specifies whether to enable or disable the HSDPA admission control algorithm.

Set this parameter throughADD CELLALGOSWITCH / LST CELLALGOSWITCH/MODCELLALGOSWITCH

HSUPA_UU_ADCTRL


Value range: 0 ,1

Content: This parameter specifies whether to enable or disable the HSDPA admission control algorithm.

Set this parameter throughADD CELLALGOSWITCH / LST CELLALGOSWITCH/MODCELLALGOSWITCH

Maximum HSUPA user number

Parameter ID: MaxHsupaUserNum


Content: This parameter specifies the maximum number of HSDPA users in a cell.


Content: This parameter specifies the maximum number of HSUPA users in a cell.

Set this parameter throughADD CELLCAC / LST CELLCAC / MOD CELLCAC


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Contents









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Why we need IAC?

The disadvantage 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

CAC limits the setup of RRC and RAB . When the cell is overloaded , the CAC will cause

access failure.

In order to improve the access success rate the Intelligent Access Control (IAC) algorithm is

used to improve the access success rate. The IAC procedure includes rate negotiation,

Call Admission Control (CAC), preemption, queuing, and Directed Retry Decision (DRD).


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IAC Overview

The access procedure (include the IAC)

As shown in the Figure, the procedure for the UE access includes the procedures for RRC

connection setup and RAB setup. The success in the RRC connection setup is one of the

prerequisites for the RAB setup.

During the RRC connection processing, if resource admission fails, DRD and redirection apply.

During the RAB processing, the RNC performs the following steps:

Performs RAB DRD to select a suitable cell to access, for service steering or load balancing.

Performs rate negotiation according to the service requested by the UE.

Performs cell resource admission decision. If the admission is passed, UE access is granted.

Otherwise, the RNC performs the next step.

Selects a suitable cell, according to the RAB DRD algorithm, from the cells where no admission

attempt has been made, and then goes to rate negotiation and cell resource admission again. If

all DRD admission attempts to the cells fail, go to the next step.

Makes a preemption attempt. If the preemption is successful, UE access is granted. If the

preemption fails or is not supported, the RNC performs the next step, queuing.

Makes a queuing attempt. If the queuing is successful, UE access is granted. If the queuing fails

or is not supported, the RNC Rejects UE access.


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IAC - RRC Connection Processing

When a new service accesses the network, an RRC connection must be set up first. If the

RRC connection request is denied, DRD is performed. If DRD also fails, RRC

redirection is performed to direct the UE to an inter-frequency or inter-RAT cell

through cell reselection.

After the RNC receives the RRC CONNECTION REQUEST message, the CAC algorithm

decides whether an RRC connection can be set up between the UE and the current

cell.

If the RRC connection can be set up between the UE and the current cell, the RNC sends

an RRC CONNECTION SETUP message to the UE. If the RRC connection cannotbe set up between the UE and the current cell, the RNC takes the follow ingactions:

RRC DRD :

If the DRD_SWITCH is set to 0, the RRC DRD fails, and RRC redirection is performed.Else, the RNC performs the following steps:

1. The RNC selects inter-frequency neighboring cells of the current cell. These

neighboring cells are suitable for blind handovers.

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

quality of the candidate cell meets the requirements of inter-frequency DRD:

(CPICH_Ec/No)RACH > DRD_Ec/No nbcell

where

(CPICH_Ec/No)RACH is the cached CPICH Ec/N0 value included in the RACH

measurement report.

DRD_Ec/No nbcell is the DRD Ec/N0 Threshold set for the inter-frequencyneighboring cell.


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3. 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.

1. If the admission is successful, the RNC initiates an RRC DRD procedure.

2. 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.4. If the candidate cell list does not contain any cell, the RRC DRD fails. The RNC performs the next

step, that is, RRC redirection.

5. RRC redirection, the RNC performs the following steps:

1. The RNC selects all inter-frequency cells of the local cell.

2. The RNC selects candidate cells. That is, exclude the cells to which inter-frequency RRC

DRD attempts have been made from the cells selected in the previous step.

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

the UE to the cell.


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Key parameters

RRC redirect switch

Parameter ID: RrcRedictSwitch

The default value of this parameter is

Only_To_Inter_Frequency

DRD Ec/N0 threshold

Parameter ID: DRDEcN0Threshhold

The default value of this parameter is -18-9 dB

RRC redirect switch

Parameter ID: RrcRedictSwitch

Value range: OFF, Only_To_Inter_Frequency, Allowed_To_Inter_RATContent: This parameter specifies the RRC redirection strategy.

The default value of this parameter is Only_To_Inter_Frequency

Set this parameter through SET DRD

DRD Ec/N0 threshold

Parameter ID: DRDEcN0Threshhold


Content: If the measured Ec/N0 value of the neighbor cell is less than this

parameter, this neighboring cell cannot be selected to be the candidate DRDcell.

The default value of this parameter is -18-9 dB

Set this parameter throughADD INTERFREQNCELL


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IAC PS Rate Negotiation

PS Service Rate Negotiation Includes:

Maximum expected rate negotiation

Initial rate negotiation

Target rate negotiation

Rate negotiation includes the maximum expected rate negotiation, initial rate negotiation, and target rate negotiation.

When setting up, modifying, or admitting a PS service (conversational, streaming, interactive, or background service)

the RNC and the CN negotiate the rate according to the UE capability to obtain the maximum expected rate while

ensuring a proper QoS.

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

when Setup or UE state transits from CELL_FACH to CELL_DCH based on cell code and credit resource

The Initial rate selection is affected by 2 algorithm switches: RAB Downsizing Switch, DCCC Switch

For DCH For HSUPA

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 Service setup or Soft handover


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Key parameters

RAB_Downsizing_Switch

Parameter ID: RAB_DOWNSIZING_SWITCH

The default value of this parameter is 1 (on)

UL/DL BE traffic Initial bit rate

Parameter ID:

ULBETRAFFINITBITRATE / DLBETRAFFINITBITRATE

The default value of this parameter is D64 64k

RAB_Downsizing_Switch

Parameter ID: RAB_DOWNSIZING_SWITCH

Value range: (0,1)Content: This parameter specifies whether to support the RAB downsizing function.

The default value of this parameter is 1 (on)

When this parameter is set to 1, the RAB downsizing function is applied to

determine the initial bit rate based on cell resources (code and credit). .

Set this parameter through SET CORRMALGOSWITCH

UL/DL BE traffic Initial bit rate

Parameter ID: ULBETRAFFINITBITRATE / DLBETRAFFINITBITRATE

Value range: D8, D16, D32, D64, D128, D144, D256, D384, D768, D1024, D1536,D1800, D2048 k

Content: This parameter defines the uplink initial access rate of background and

interactive services in the PS domain.

The default value of this parameter is D6464k

Set this parameter through SET FRC


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IAC RAB Directed Retry Decision

RAB Directed Retry Decision (DRD) is used to select a

suitable cell for the UE to try an access

Inter-frequency DRD

Service Steering

Load Balancing

Inter-RAT DRD

Through the RAB DRD procedure, the RNC selects a suitable cell for RAB processing

during access control. RAB DRD is of two types: inter-frequency DRD and inter-RAT

DRD. For inter-frequency DRD, the service steering and load balancing algorithms are

available.

After receiving a RANAP RAB ASSIGNMENT REQUEST, the RNC initiates an RABDRD procedure to select a suitable cell for RAB processing during access control.

The RNC performs inter-frequency DRD firstly. If all admission attempts of inter-

frequency DRD fail, the RNC performs an inter-RAT DRD. If all admission attempts of

inter-RAT DRD fail, the RNC selects a suitable cell to perform preemption and

queuing .

Relation Between Service Steering DRD and Load Balancing DRD

When both service steering DRD and load balancing DRD are enabled, the general

principles of inter-frequency DRD are as follows:

Service steering DRD takes precedence over load balancing DRD. That is,preferably take service priorities into consideration.

To services of the same service priority, load balancing applies.


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IAC RAB Directed Retry Decision

RAB Directed Retry Switchs

DRD is applicable to RAB setup only when this

switch is on.

RAB_SETUP_DRD_SWITCHRAB setup

DRD is applicable to traffic-volume-based

DCCC procedure or UE state transition, only

when this switch is on.

RAB_DCCC_DRD_SWITCHDCCC

DRD is applicable to RAB modification only


RAB_MODIFY_DRD_SWITCHRAB modification

DRD is applicable to HSUPA services only


HSUPA_DRD_SWITCHHSUPA service

DRD is applicable to HSDPA services only


HSDPA_DRD_SWITCHHSDPA service

DRD is applicable to combined services only


COMB_SERV_DRD_SWITCHCombined

services

This is the primary DRD algorithm switch. The

secondary DRD switches are valid only when

this switch is on.

DRD_SWITCHDRD switch

DescriptionSwitchScenario

DRD algorithm switch

Parameter ID: DRDSWITCH

The default value of this parameter is off

Set this parameter through SET CORRMALGOSWITCH


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IAC Inter-frequency DRD

Inter-Frequency DRD for Service Steering

DRD for Service Steering is based on Service priorities of

cells ,include:

R99 RT services pr iority

R99 NRT services pr iorit y

HSPA services priority

Other services priority

Called Service priority group

If the UE requests a service in an area covered by multiple frequencies, the RNC selects

the cell with the highest service priority for UE access, based on the service type of

RAB and the definitions of service priorities in the cells.

Cell service priorities help achieve traffic absorption in a hierarchical way.

The priorities of specific service types in cells are configurable. If a cell does not support a

service type, the priority of this service type is set to 0 in this cell.

The service priorities in each cell is called Service priority group , which is identified bythe Service priority group Identity parameter.

Service priority groups are configured on the LMT. In each group, priorities of R99 RT

services, R99 NRT services, HSPA services, and other services are defined.

When selecting a target cell for RAB processing, the RNC check the service type firstly ,

then, selects a cell with a high priority for the service, that is, a cell that has a small

value of service priority.


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Inter-Frequency DRD for Service Steering

An example of service priority group

00212

01121

Servicepriority of

other service

Service priorityof HSPAservice

Service priorityof R99 NRT

service

Service priorityof R99 RT

service

Servicepriority group

Identity

Cell A and cell B are of different frequencies.

Assume that the service priority groups given in the table are defined on an RNC, 2groups of service priorities are defined.

Then ,Cell A is configured with service priority group 1. Cell B is configured with service

priority group 2

If UE requests a R99 RT service in cell A ,Cell B has a higher service priority of the R99

RT service than cell A. If the UE requests an RT service in cell A, preferably, the RNC

selects cell B for the UE to access.


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Inter-Frequency DRD procedure for Service Steering

The procedure for the service steering DRD is as follows:

1The RNC determines candidate cells to which blind handovers can be performed and sorts the

candidate cells into a descending order according to service priority.

A candidate cell must meet the following conditions:

The frequency of the candidate cell is within the band supported by the UE.

The quality of the candidate cell meets the Ec/No requirements of inter-frequency DRD (DRDEc/N0 Threshold )

The candidate cell supports the requested service.

2The RNC selects a target cell from the candidate cells in order of service priority for UE access.

3The CAC algorithm makes an admission decision based on the status of the target cell.

If the admission attempt is successful, the RNC accepts the service request.

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

choose next candidate cell.

4If admission decisions have been made in all the candidate cells

For HSPA access, the HSPA request falls back to a DCH one. Then, the algorithm goes back

to Step 1 to make an admission decision based on R99 service priorities.

For DCH access, the RNC initiates an inter-RAT DRD.


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Key parameters

Service differential drd switch

Parameter ID: ServiceDiffDrdSwitch


Service priority group Identity

Parameter ID: PriorityServiceForR99RT

Service differential drd switch

Parameter ID: ServiceDiffDrdSwitch

Value range: ON, OFFContent: This parameter specifies whether to enable the service steering DRD algorithm

The default value of this parameter is OFF.

Set this parameter throughADD CELLDRD

Service priority of R99 RT service

Parameter ID: SpgId

Value range: 1 to 8

Content: This parameter uniquely identifies a group of service priorities that map to cells

and indicate the support of each cell for the following service types: R99 RT service,R99 NRT service, HSPA service, and other services.

Set this parameter throughADD SPG


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Parameter ID: SpgId

Service priority of R99 NRT service

PriorityServiceForR99NRT

Service priority of HSPA service

PriorityServiceForHSPA

Service priority of Other service

PriorityServiceForExtRab

Key parameters


Parameter ID: PriorityServiceForR99RT

Value range: 0 to 7

Content: This parameter specifies the support of the cells with a specific Service prioritygroup Identity for R99 RT services.

The value 0 means that these cells do not support R99 RT services.

For the values 1 through 7, the service priority is inversely proportional to the value, that is,the value 7 indicates the lowest service priority, whereas the value 1 indicates the highest.



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Service priority of R99 NRT service

Parameter ID: PriorityServiceForR99NRT

Value range: 0 to 7

Content: This parameter specifies the support of the cells with a specific Service priority

group Identity for R99 NRT services.The value 0 means that these cells do not support R99 NRT services.



Service priority of HSPA service

Parameter ID: PriorityServiceForHSPA

Value range: 0 to 7

Content: This parameter specifies the support of the cells with a specific Service prioritygroup Identity for HSPA services.

The value 0 means that these cells do not support HSPA services.



Service priority of Other service

Parameter ID: PriorityServiceForExtRab

Value range: 0 to 7

Content: This parameter specifies the support of the cells with a specific Service prioritygroup Identity for Other services .

The value 0 means that these cells do not support Other service .




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Inter-Frequency DRD for Load Balance

The resources triggering DRD for Load Balance include:

DL Power

OVSF code

Any of these 2 resources can trigger inter-frequency DRD for

Load Balance

Load balancing considers two resources: power, and code.

If both are activated, power-based load balancing DRD takes precedence over code-

based load balancing DRD.

Code-based load balancing DRD is applicable to only R99 services because HSDPA

services use reserved codes.


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IAC Inter-frequency DRD Inter-Frequency DRD procedure for DL Power Load Balance

The procedure for the service steering DRD is as follows:

1The RNC determines candidate cells to which blind handovers can be performed and sortsthe candidate cells into a descending order according to service priority.

A candidate cell must meet the following conditions:

The frequency of the candidate cell is within the band supported by the UE.

The quality of the candidate cell meets the Ec/No requirements of inter-frequency

DRD (DRD Ec/N0 Threshold )

The candidate cell supports the requested service.

2The RNC determines whether the DL radio load of the current cell is lower than thepowerthreshold for load balancing DRD (condition 1 )

power threshold for load balancing DRD is CAC parameter.

If the DL load of the current cell is lower than the threshold, the service tries admission tothe current cell.

If the DL load of the current cell is equal to or higher than the threshold, the RNC checksthe candidate cells to try to find out a target cell for UE access.

RNC will check if there is a candidate cell will meet the following condition (condition 2 ) :

Ptotal_thd,nbcell is DL total power threshold for the inter-frequency neighboring cell.

Pload,nbcell is total power load of the inter-frequency neighboring cell. For a R99 cell, it isthe Downlink Transmitted Carrier Power of the cell, and for an HSPA cell, it is the non-HSDPA power and GBP.

Ptotal_thd,cutcell is DL total power threshold for the current cell.

Pload,cutcell is the total downlink load of the current cell.

Ploadoffset is the Power balancing drd offset of the current cell.


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Then, the RNC selects the target cell as follows:

If there is only one inter-frequency neighboring cell that meets the load balancing DRDconditions, the RNC selects this cell as the target cell.

If there are multiple such cells, the RNC selects the cell with the lightest load as the

target cell. If there is no such cell, the RNC selects the current cell as the target cell.

3The CAC algorithm makes an admission decision based on the status of the target cell.

If the admission attempt is successful, the RNC accepts the service request.

If the admission attempt fails, the RNC removes the cell from the candidate cells andthen choose next candidate cell.

4If admission decisions have been made in all the candidate cells

For HSPA access, the HSPA request falls back to a DCH one. Then, the algorithm goesback to Step 1 to make an admission decision based on R99 service priorities.

For DCH access, the RNC initiates an inter-RAT DRD.


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Power balance DRD switch on DCH

Parameter ID: LdbDrdSwitchDCH


Power balance DRD switch on HSDPA

Parameter ID: LdbDrdSwitchHSDPA


Max transmit power of cell

Parameter ID: MaxTxPower

The default value of this parameter is 430 (43dBm)

Dl power balancing drd power threshold for DCH

Parameter ID: LdbDRDOffsetDCH

The default value of this parameter is 10%

Dl power balancing drd power threshold for HSDPA

Parameter ID: LdbDRDOffsetHSDPA


Key parameters

Power balancing drd switch

Parameter ID: PowerBalancingDrdSwitch

Value range: ON, OFFContent: This parameter specifies whether to enable the power-based loadbalancing DRD algorithm .


Set this parameter through SET DRD /ADD CELLDRD

Max transmit power of cell

Parameter ID: MaxTxPower

Value range: 0 to 500 , step:0.1dBm

Content: This parameter specifies the sum of the maximum transmit power ofall the downlink channels in a cell.

The default value of this parameter is 430 (43dBm).

Set this parameter through MOD CELL

Power balancing drd offset

Parameter ID: LoadBalanceDRDOffset

Value range: 0% to 100%

Content: This parameter specifies the load offset threshold of the current celland the inter-frequency cell when power balancing drd algorithm is applied.Only when the cell load offset reaches this threshold, the inter-frequency cellcan be selected to be the target drd cell.


Set this parameter through SET DRD / ADD CELLDRD


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IAC Inter-frequency DRD Inter-Frequency DRD procedure for Code Load Balance

The procedure of load balancing DRD based on code resource is similar to that based on power

resource.

1The RNC determines whether the minimum remaining spreading factor of the current cell is

smaller than Minimum SF threshold for code balancing drd.

If the minimum SF is smaller than Minimum SF threshold for code balancing drd, theRNC tries the admission of the service request to the current cell.

If the minimum SF is not smaller than Minimum SF threshold for code balancing drd,the RNC performs the next step .

2The RNC determines whether the code load of the current cell is lower than Code occupiedrate threshold for code balancing drd . .

If the code load is lower than Code occupied rate threshold for code balancing drd,the service tries the admission to the current cell.

If the code load is not lower than Code occupied rate threshold for code balancing

drd, the RNC selects the cell with the lightest code load or the current cell as the targetcell.

3The RNC selects the cell as follows:

If the difference between the code resource occupancies of the cell and the current cell

is larger than the value of Delta code occupied rate , the RNC selects the cell with thelightest code load as the target cell. Otherwise, the RNC selects the current cell as the

target cell.


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Code balancing drd switch

Parameter ID: CodeBalancingDrdSwitch


Minimum SF threshold for code balancing drd

Parameter ID: CodeBalancingDrdMinSFThd

The default value of this parameter is SF8

Key parameters

Code balancing drd switch

Parameter ID: CodeBalancingDrdSwitch

Value range: ON, OFFContent: This parameter specifies whether to enable the code-based load

balancing DRD algorithm.



Minimum SF threshold for code balancing drd

Parameter ID: CodeBalancingDrdMinSFThd

Value range: SF4, SF8, SF16, SF32, SF64, SF128, SF256

Content: If the downlink minimum SF of the best cell is below this threshold,the code-based load balancing DRD is not triggered.

The default value of this parameter is SF8 .



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Code occupied rate threshold for code balancing drd

Parameter ID: CodeBalancingDrdCodeRateThd


Delta code occupied rate

Parameter ID: DeltaCodeOccupiedRate


Key parameters

Code occupied rate threshold for code balancing drd

Parameter ID: CodeBalancingDrdCodeRateThd

Value range: 0% to 100%Content: This parameter specifies the code occupancy threshold of the current cell for

code-based load balancing DRD.Only when the code occupancy of the best cell

reaches this threshold can code-based load balancing DRD be triggered.

The default value of this parameter is 13%.


Delta code occupied rate

Parameter ID: DeltaCodeOccupiedRate

Value range: 0% to 100%

Content: This parameter specifies the code occupied rate offset threshold of the

current cell and the inter-frequency cell when code

wcdma ran planning and optimization _book3_2_ features and algorithms

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