OWA200004 WCDMA Radio Resource Management ISSUE1.0

8/4/2019 OWA200004 WCDMA Radio Resource Management ISSUE1.0

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HUAWEI TECHNOLOGIES CO., LTD. All rights reserved

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OWA200004WCDMA Radio Resource

Management

ISSUE 1.0


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HUAWEI TECHNOLOGIES CO., LTD. All rights reserved Page 2

Chapter 1 Introduction to RRM

Chapter 2 Channel Configuration

Chapter 3 Power Control

Chapter 4 Mobility Management

Chapter 5 Load Control

Chapter 6 AMR Mode Control


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Introduction to RRM

RRM: Radio Resource Management

RRM is responsible for supplying optimum coverage, offering

the maximum planned capacity, guaranteeing the required

quality of service (QoS) and ensuring efficient use of physical

and transport resources.

Power is the ultimate radio resource. The best way to utilize

the radio resource is to control the power consumption strictly.

Increasing the transmission power of a certain user can

improve his QoS.

However, due to the self-interference, the increasing would

result in more interference on other users and consequently

reduce the receiving QoS.


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RRM Algorithms in the Call Flow (1)

CN

RNC

Iu

RAB ASSIGNMENTQoS)

QoS mapping

Admission control

Request ofcode resource

Configurationof access layer

Channel configuration--fundamental

channel configuration

Load control

--access control

Channel configuration--code resourcemanagement

Load control--load balance

Required QoS

Required Resource


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RRM Algorithms in the Call Flow(2)

Channel setup andcall initiated

Power control

Change ofservice rate

Handover

Call end

Resource release

End

Power controlclose loop

Power controlopen loop

Channel configuration--DCCC AMRC

Mobility management

Channel configuration--code resource management

Load control--load balance


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Classification of RRM

Based on the different objects, RRM is classified as:

Connection oriented RRM, which guarantees QoS of connection

and minimizes the radio resource allocated for the connection.

Channel configuration, power control, handover

A dedicated entity is created to manage the resource

configuration for each connection.

Cell oriented RRM, which maximizes users in cells and thus

increases system capacity while guaranteeing cell stability.

Code resource management, load controlA dedicated entity is created for each cell to manage its

resource.


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Procedure of RRM

Fundamental procedure of radio resource management

Measurement control

measurementUE, NodeB, RNC

Measurement report

Decision

The implementation of resource control


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2.1 Fundamental channel configuration

2.2 Dynamic channel configuration

2.3 Code resource management


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Fundamental Channel Configuration

Fundamental channel configuration is to map the RAB QoS features

requested by CN into the corresponding parameters and configurationmode on each AS layer

QoS requested by CN

Traffic Classes

Conversational

Streaming

Interactive

Background

Rate demand

Quality demandBLER


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QoS Mapping

DPDCH DPCCH

RAB

RB RB

DTCH DTCHDCCH

TrCHTrCHTrCH

CCTrCH

RLCentity

Mac-d Mac-c

Coding&RM&Mux

RadioBearers

RLCSublayer

Logical Channel

MACSublayer

Chansport Chanl

Physical Layr

DTCH

RB

Coding&RM&Mux

TrCH


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RB and RLC Parameter Configuration

RB parameters

RB number

RLC parametersDifferent RLC transfer modes

transparent mode

Unacknowledged mode

Acknowledged modeDifferent logic channel parameters


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MAC Parameter Configuration

MAC parameters

The mapping/multiplexing relation between logic channel

and transport channel

Different types and parameters of transport channel Dedicated channel

Common channel

Different configurations of MAC entity

MAC-d/MAC-c

Priority configuration of MAC sub layer

TFCS configuration


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PHY Parameter Configuration

PHY parameters

Mapping relation from transport channel to physical channel

Coding scheme

Convolutional

Turbo

Non

Interleaving length

Rate matching attribute

Spreading factor SF

Power offset

Other physical channel parameters, e.g., diversity mode, etc.


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BE Service

DCCC: Dynamic Channel Configuration Control

Object of DCCC: Best Effort (BE) service

Features of BE service

rate of service source changes largely

Less demand on time delay

More demand on bit error rate

RLC uses acknowledged mode, thus all data should be buffered inRLC Buffer.


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Dynamic Channel Configuration

MAC-d

DL Transport

Channel TrafficVolume

Threshold

Configuration in L2

RLC

Signalingbearer

DCH1

RLC

TFC Select

DCH2

ChannelSwitching

DCCH DTCH

Objective of DCCC

Meet bandwidth requirement of

users to the greatest degree

Make best use of resource on air

interface

Meet the fluctuant requirement for

data rate

Save downlink channel code (OVSF

code) resource

Achieve bandwidth on demand


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Decision of DCCC

Decision of DCCC

Measurement report on traffic volume of RLC Buffer

Decide whether to change the bandwidth used by UE

dynamically based on the measurement result.

Consider whether there is limitation on air interface during

the decision of reconfiguration. This is done by measuring

the transmitting power of UE in both downlink and uplink.

The uplink & downlink DCCC decisions are the same, but areexecuted respectively.


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Implementation of DCCC

Implementation of DCCC

RB reconfiguration/ transport channel reconfiguration

Cell-FACH-->Cell-DCH Cell-DCH-->Cell-DCH, include

reduction/increment of bandwidth

Cell-DCH-->Cell-FACH

DCCC also restricts the selection of TF at MAC layerbased on the request of congestion control.


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Effect of DCCC Bandwidth Allocation on Demand

System capacity

Traditional channel

configuration

Rate of service source

DCCC


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OVSF

OVSF code tree

SF = 1 SF = 2 SF = 4

Cch,1,0 = (1)

Cch,2,0 = (1,1)

Cch,2,1 = (1,-1)

Cch,4,0 =(1,1,1,1)

Cch,4,1 = (1,1,-1,-1)

Cch,4,2 = (1,-1,1,-1)

Cch,4,3 = (1,-1,-1,1)


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C(8,0)

C(8,1)

(,

(,

(,

(,

C(4,0)

C(8,0)

C(8,1)

(,

(,

(,

(,

C(8,0)

C(8,1)

(,

(,(,

(,

C(4,0) Higher usage

Usage of Code Resource


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C(8,0)

C(8,1)

(,

(,

(,

(,

C(4,0)

C(8,0)

C(8,1)

(,

(,

(,

(,

C(8,0)

C(8,1)

C(4,0)

C(8,0)

C(8,1)

single code channel transmission

multiple code channel transmission

Complexity Requirement of Code


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OVSF code allocation

Principles of code allocation

Increase the usage of code

Reduce the complexity of code allocation scheme

Increase system capacity


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Near-far effect in CDMA

A B

P()

P()

P()

P()

Receivedpower fromuser A

P()

Despreading

Transmissionpower of user A

Received powerby NodeB

The user A can communicatesuccessfully

Received

power fromuser B

Transmissionpower of user B

The user B is submergedbecause of strong interference

from user A


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Classification of Power Control

Power Control

Uplink power control

Open loop power control

Inner loop power control

Outer loop power control

Downlink power control

Open loop power control

Inner loop power control

Outer loop power control

Compared with open loop

power control, inner loopand outer loop powercontrol are called closedloop power control


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Open Loop Power Control for DPCH

Accurately calculate initial

transmitting power of inner

loop needed to lessen the

time of convergence

Reduce the impact on

system load

Convergence of innerloop power control

time

power

time

power


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NodeB UERACH

BCH: CPICH channel powerUL interference level

Open-loop power control is

used to decide the initial powerof PRACH preamble accordingto the path loss.

The path loss is figured outaccording to the CPICHtransmission power andreceived power.

Open Loop Power Control for PRACH


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Uplink Close Loop Power Control

NodeB UE

Transmit TPC

Measure&compare

SIR of received signal

Inner loop

Set SIRtar

Traffic data withsteady BLER can

be acquired

Measure BLER oftransport channel

Outer loop

RNC

Measure&compare BLERof received data

Set BLERtar

10-100Hz


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BLER--SIR

The aim of the outer-loop PC algorithm is to maintain the quality of the

connection at the level defined by the quality requirements of the

bearer severce.

According to principles of wireless communication, BLER may change

with the wireless environment under fixed SIR.

BLER

SIR

BLER

Different curvescorrespond withdifferent multi-path

environment.


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Downlink Power Control

NodeB

Set SIRtar

Transmit TPC

Measure and compare SIR

Measure and compare BLER

Outerloop

Inner loop UE physical layer

UE Layer 3

Downlink inner loop and outer loop power control

10-100Hz1500Hz


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UE Working Modes and states

The UE has no relation to UTRAN, only to CN. For data transfer, a

signalling connection has to be established

UE camps on a cell

It enables the UE to receive system information from the PLMN

UE can receive "paging" message from control channels of the cell.

It enables the UE to receive cell broadcast services.

Idle Mode


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In active state

Communicating via its dedicated channels

UTRAN knows which cell UE is in.

Cell-DCH

Cell-FACH

In active state

Few data to be transmitted both in uplink and in downlink. There is

no need to allocate dedicated channel for this UE. Downlink uses FACH and uplink uses RACH.

UE need to monitor the FACH for its relative information.



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No data to be transmitted or received.

Monitor PICH, to receive its paging.

lower the power consumption of UE.


UTRAN have to update cell information of UE when UE roamsto another cell

Cell-PCH


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No data to be transmitted or received.

Monitor PICH.

UTRAN only knows which URA (UTRAN Registration Area,

which consists of multiple cells) that UE is in.

UTRAN update UE information only after UE has roamed to

other URA.

A better way to lower the resource occupancy and signaling

transmission

URA-PCH


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Classification of Handover

Hard handover

Soft handover

Intra-frequency

hard handover

Inter-frequency

hard handover

Inter-system

handover Softer handover


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Soft Handover

Features of soft handover

Seamless handover with no disconnection of the radio access bearer.

To enable a sufficient reception level for maintaining communications by

combining the received signal at symbol level from multiple cells in case

the UE moves to the cell boundary areas.

The macro diversity gain achieved by combining the received signal in the

NODEB (softer handover) or in the RNC (SHO) improves the uplink signal

quality and thus decrease the required transmission power of the UE.

UE move

Target BSSource BS

time

Data UE

received/ sentN o GAP of communication


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Softer Handover

For soft handover, the combination of multiple RL uses

maximum ratio combination (RAKE combination) in downlink

and selection combination in uplink.

When the two cells in soft handover belong to the same NodeB,maximum ratio combination could be used in uplink. In this

case the handover is softer handover.

Softer handover has higher priority in handover schemes

because maximum ratio combination has larger gain than

selection combination.


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Soft Handover Measurement

Active set

Including all cells currently participating in a SHO

connection of a terminal.

Neighbor Set/Monitored Set

This set includes all cells being continuously

monitored/measured by the UE and which are not currently

included in the active set.


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Soft Handover Measurement


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Power Control in Soft Handover (SSDT)

In conventionaldownlink powercontrolalgorithm,all basestationstransmit signalto UE

UE choosesthe cell withthe smallestpath loss and

the best signalto transmitDPDCH

SSDT: Site Selection Diversity Transmit

All cells in active set transmit DPCCH in downlink. The cell transmitting

DPDCH is chosen by UE per 10ms or a longer period of time.


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Hard Handover

Features of hard handover:

HHO causes a temporary disconnection for RT radio

access bearer and is lossless for NRT bearers.

The UE must either be equipped with a second receiver or

support compressed mode to execute inter-system/inter-

system measurement.

UE move

Target BSSource BS

time

Data UEreceived/sent

GAP of communication


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Application of Hard Handover in 3G

Intra-frequency hard handover

When inter-RNC SHO cant be executed or is not allowed.

Inter-frequency hard handover

Needed in certain areas due to network planning

Load balance between frequencies

Inter-system handover

2G-3G smooth evolutionThe finite coverage range of initial phase of 3G


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Introduction of Compressed Mode

Compressed Mode

Intra-frequency neighbors can be measured simultaneously

with normal transmission by UE using a RAKE receiver.

Inter-frequency or inter-system neighbors measurements

require the UE measuring on a different frequency, this has

either to be done with multiple receivers in the UE or in the

compressed mode.

CM is to stop the normal transmission and reception for acertain period of time, enable the UE to measure on the

other frequency.


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Compressed Mode

Objective of compressed mode: for UE to realize measurement and

synchronization to target cell when inter-frequency handover andinter-system handover is required.


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Classification of Compressed Mode

Downlink compressed mode

To create time for UEs measurement and synchronization.

3 optional schemes -- SF/2, rate matching/puncturing,

higher layer scheduling

Uplink compressed mode

To avoid the interference on its own downlink measurement

and synchronization when UE is measuring certain target

cells.

Whether compressed mode is needed is determined byUEs capacity.

2 optional schemes -- SF/2, higher layer scheduling.


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Features of Compressed Mode

Features of compressed mode

All parameters of compressed mode are configured by UTRAN.

The usage of compressed mode would reduce the system

performance.

Complex algorithm is needed to decide when to enter compressedmode.

Complex algorithm is needed to decide what parameters areneeded in the compressed mode.


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SRNS Relocation

Advantage of SRNS relocation

Reducing data flow on Iur interface

Improving the systems adaptability.

Reducing the time delay

Problem of SRNS Relocation: a large amount of signaling is

needed to interact.

CN

SRNS DRNS

CN

RNS SRNS


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Classification of Load Control

Technical classification of load control:

Call Admission Control

Load balance between cells

Congestion control


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Admission Control (AC)

AC is used to decide whether a new RAB is admitted

or a current RAB can be modified.

Admission control is done in uplink and downlinkseparately.

The strategy is that a new bearer is admitted only if

the total load after admittance stays below the

threshold defined by RNP.


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Load Balance

Load balance between cells

Load balance between intra-frequency cells

Cell breathing

Load balance between inter-frequency cells

Inter-frequency load balance

Potential user control


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Cell Breathing

CRNC

The objective of loadThe objective of load

banlance is to share thebanlance is to share theload of some "hot" cellsload of some "hot" cells

in surrounding cells within surrounding cells with

low load, thus tolow load, thus to

increase the usage ofincrease the usage of

system capacity.system capacity.

cell breathing


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Potential User Control

Potential user control

To avoid the load imbalance effectively when UE enters

DCH state by making UE in idle mode or non-DCH

connected mode camp in cells with low load in advance

To achieve the objective by changing the cell selection and

re-selection parameters dynamically

Potential user control is done by using system message


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Congestion Control

The measures to make full use of system resource admission

control, load balance between cells, packet scheduling are not

enough to guarantee the absolute stabilization, hence congestion

control technology must be introduced.

Objective of congestion control

To ensure the system load is below the absolutely steady

threshold.

Methods of congestion control

Temporarily reducing the QoS of traffic with low priority

Temporarily reducing the QoS of CS traffic in some extreme

conditions


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AMR Coding

WCDMA system uses Adaptive Multi-Rate (AMR) speechcode, which is linear prediction coding.

Rateno.

Sub-flow 1block size

bit


bit


bit

Combinationblock size

bit

rate

kbps

0 0 0 0 0 No data1 39 0 0 39 SID2 42 53 0 95 4.753 49 54 0 103 5.154 55 63 0 118 5.95 58 76 0 134 6.76 61 87 0 148 7.47 75 84 0 159 7.958 65 99 40 204 10.29 81 103 60 244 12.2


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MOS--CIR


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AMR Speech

Features of AMR speech:

At a certain load level (which corresponds with SIR of UE),

the Mean Opinion Score (MOS) the users experience does

not increase linearly with the speech rate which UE uses.

That is, at a certain load level, the most appropriate AMRspeech rate used to acquire the highest MOS does not

refer to the highest rate, but an appropriate middle rate.

The limitation of UEs maximum transmitting power restricts

the coverage of uplink AMR speech. To increase the uplink

coverage of AMR speech, uplink rate should be reduced

without worsening the UEs speech quality.


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AMR Mode Control

Hence, AMR mode control is to weigh the load level, and:

Reduce AMR speech rate on heavy load condition,

thus reduce the system load and improve speech

quality relatively.

Increase AMR speech rate on light load condition, thus

improve QoS.

The AMR speech mode control can be done every 20ms!

Reducing of AMR speech rate can widen the uplinkcoverage effectively.


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OWA200004 WCDMA Radio Resource Management ISSUE1.0

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