MYCOM - WCDMA Fundamentals AndFunctionalities - For Handsout

8/13/2019 MYCOM - WCDMA Fundamentals AndFunctionalities - For Handsout

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Mycom Academy - Company Confidential 1

WCDMAWCDMA

FundamentalsFundamentals andand FunctionalitiesFunctionalities


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ModulesNetwork ArchitectureCDMA/WCDMA BasicsRAKE Receiver Link Budget CalculationLogical, Transport and Physical ChannelsRadio Resource Management

Power ControlHandover ControlLoad Control

Admission Control

Packet Scheduler Resource Manager Cell SynchronizationPagingCell Selection and Cell Reselection FundamentalsScrambling Code Planning


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Network ArchitectureNetwork Architecture


4/273Mycom Academy - Company Confidential 4

Agenda:Network Architecture

User EquipmentNode-BNode-B ConfigurationRNC



Learning Objectives:At the end of this module, you will be able to:

Name the new components in UTRANDescribe the upgrade path for Node-Bs



HLRMCEIR

SGSN GGSN

VLRMSC GMSC

RNC

RNC

BSC

PCU

BSC

NodeB

NodeB

BTS

BTS

MG AUC

BG

UTRAN CN

Iub

Iub

Iu

Iu

IuPS

IuPSIur

IuPS

IuPS

Abis

Abis

A

A

Gb

Gs

F

Gf

D

C

E

H

Gd

Gr Gc

GnGi

GpGp

Other PLMN

IntranetInternet

ISDNPSTN

UE

MG Mediation Device BG Border Gateway

*

*GSM/GPRS, Terminal



User Equipment (UE)

User Equipment can be any device that is utilized bysubscribers in the WCDMA Radio System as the mediumfor information exchanges.

Most popular: handheld mobile phones



Node-B

The Node-B is responsible for all interfaces required forcommunication between the RNC and the UE.


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Node-B Configuration

Typical configuration:

3 sectors1 carrier 20W256 - 384 channel elements


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Node-B Configuration

Configuration Number of

Cabinets

Output power per

carrier

HW channel

capacity(ERICSSON)

HW channel

capacity(NOKIA)

1+1+1 1 20 256

256

256

384

2+2+2 1 20 384

1+1+1+1+1+1 1 20 384


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Node-B Upgrade Path

1+1+11 carrier

20W50Erl

2+2+22 crs

2x10W80Erl

1+1+11 carrier

40W60Erl

1+1+11carrier/sec

20W150Erl

2+2+22 crs

2x20W100Erl

2+2+22crs/sec6x10W240Erl

2+2+22crs/sec6x20W300Erl

40 Erl/carrier 50 Erl/carrier 40 Erl/carrier 50 Erl/carrier

50 Erl/carrier 60 Erl/carrier


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Radio Network Controller (RNC):

The RNC is similar in function as the BSC would berecognized in the GSM Classic Network. RNCs areresponsible for Radio Resource Management. RNCsadditionally are the Radio Link that interface with existingNetworks from the radio resource.

RNC


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CDMA/WCDMA BasicsCDMA/WCDMA Basics


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Agenda:CDMA/WCDMA Basic

Multiple Access MethodsWCDMA Basic CharacteristicsCode CharecteristicsChannelization codesScrambling CodesSignal SpreadingCode UsageChannelization and Scrambling CodesSpreading and ScramblingDe-spreading and De-scramblingCode TreeCapacity Limitations


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Name the properties of an CDMA technologyDescribe the highlights of spread spectrum techniqueCalculate the Spreading FactorsUnderstand the ways a signal is spread


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Multiple Access Methods:

Frequency Division Multiple AccessOne user uses one frequency

Time Division Multiple Access

One users channel belongs to himunder a fraction of time and on certainfrequency

Code Division Multiple AccessEvery user is using the same resource buteach user has a code that identifies its

information

F r e q u e n c

y

T i m e

Power

FDMA

F r e q u e

n c yT i m e

Power

TDMA

F r e q u

e n c y

T i m e

Power

CDMA C O

D E


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WCDMA Basic Characteristics:

Wideband-Code Division Multiple Access

Duplex schemes:Frequency Division Duplex (FDD)Time Division Duplex (TDD)

Channel Spacing: 5MHz

Frequency band:FDD: UL:1920-1980 and DL: 2110-2170TDD: 1900-1920 and 2010-2025

Available channels: 12 for FDD and 7 for TDD


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WCDMA Basic Characteristics:User data rates: up to 2Mbit/s

Chip rate: 3.84Mcps

Modulation:

Data modulation: QPSK (Downlink); BPSK (Uplink)Spreading modulation: QPSK

Frame length: 10ms

Inter-BS synchronization:FDD: Asynchronous

TDD: Synchronous (GPS or common clock)


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WCDMA Basic Characteristics:Power versus Capacity

Capacity limited by interference rather than number ofchannels

Fast power control

1500Hz power control.

Spread spectrum technique:Information is transmitted at a bandwidth much wider thanthe information rate


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WCDMA Basic Characteristics:Continuous transmission

Code channels and not time slots

All users on the same frequencyCode channels and not separate carriers

Soft handover The mobile is connected to two or more base stations at thesame time


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WCDMA Basic Characteristics:Spread spectrum technique

Transmitting information at a bandwidth much wider thanthe information rate.

A signal is spread in the spectrum by artificially increasingthe modulation rate (chip rate).

The signal is later despread with the same spreading signalto retrieve the original signal.The user signal spreading is done with a spreadingsequence (code) having much higher bandwidth than theusers signal.Codes are unique for each channel.


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WCDMA Basic Characteristics:Spread spectrum technique

Transmitting and receiving sides have the same codehaving the same phase.The code to be used is determined by the transmitting sideand the receiving side will acquire the same code from thetransmitting signal.

Spreading Transmitter DespreadingReceiver

Spread signal

Inputnarrowbandsignal

Outputsignal


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WCDMA Basic Characteristics:Why would spreading the signal be good?

For a given information rate, the wider the bandwidth fortransmitting the information, the lower the required signal tonoise ratio would be.

This means that the wider the bandwidth is, the quality of thechannel can be lower.This would also mean that the system is tolerant tointerference.Information can be transmitted even if the received signal isbelow noise floor


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Spread Spectrum

A signal is spread in the spectrum by another signal

W-CDMA

X Code

5 MHz

270 kbit

GSM

200 kHz

3.84 Mcps


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Spread Spectrum

WBNB

A narrow band signal is spreadwith an orthogonal code .

Code

CodeThe signal is de-spreadwith the same spreading code.

Courtesy of Nortel


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Spread Spectrum

Signals from other users would be like noise (interference)

Receiver

Receiver

Transmitter

Codegenerato r

Codegenerator

Codegenerator

Code

generator

f

f

White noise

f

f

White noise

f

White noise

1 bit


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WCDMA Basic Characteristics:Processing gain/Spreading Factor

Processing Gain (G) is defined as

X Code (OVSF)

5 MHz3.84 Mcps

)log(10 RateService RateChip

G =

Courtesy of Nortel


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WCDMA Basic Characteristics:Processing gain differ for different services

As can be seen the wider the signal, the lower the power

intensity is. This is why the processing gain is lower

W

W

Packet Data user (384 kbps)

R

R

Voice user (12.2 kbps)

Spread wideband signal

Spread wideband signal

P o w e r

D e n s i

t y ( W / H z )

P o w e r

D e n s i

t y ( W / H z )

dB RW

G 25)102.121084.3

log(10 36

=

==

dB

R

W G 10)

10384

1084.3log(10 3

6=

==


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WCDMA Basic Characteristics:Spreading Factor

Spreading factor for different rates are:Higher bit rates = the lower processing gainLower bit rates = the higher processing gain

For 480kbps data rate, the spreading factor is 8

For 8kbps data rate, the spreading factor is 128

The higher the bit rate, the more power would be needed tomeet the quality requirements

As can be seen from the processing gain calculations, for ahigh bit rate service, the power needs to be increased.


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Codes Characteristics:In WCDMA two different codes are used:

Channalization codes (orthogonal codes)Scrambling codes

These codes have different properties and are suitable for

different purposes.Channelization Codes Scrambling Codes

Uplink : Separation of physical datachannel and control channels fromthe same mobileDownlink : Separation of downlinkconnections to different userswithin one cell

Uplink : Separation of mobilesDownlink : Separation of cells


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Codes Characteristics:Code correlation definitions:

Definition of Auto Correlation A measure that describes how similar a chip sequence and ashifted copy of the same signal are.

Definition of Cross Correlation A measure that describes how similar two different chipsequences are to each other.

Requirements in WCDMA:Good auto correlation properties are needed for separatingdifferent pathsGood cross correlation properties are needed for separatingdifferent channels.


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Codes Characteristics:The WCDMA receiver uses the cross correlation property ofthe codes to find out a specific signal out of a number ofdifferent various spread signals.

The WCDMA receiver uses the auto correlation property to

identify if the received signal frame is time aligned with thescrambling code before de-scrambling.

Two different codes are orthogonal if their cross correlationis equal to 0.


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Channelization Codes:Channelization codes:

Orthogonal codes based on Orthogonal Variable SpreadingFactor code (OVSF code) techniqueGood orthogonality properties: Cross correlation value foreach code pair in the code set equals to 0.The codes are fully orthogonal, i.e. they do not interfere witheach other as long as they are time synchronized.Thus, channelization codes can separate the transmissionsfrom a single source.Orthogonal codes have bad auto correlation properties andare therefore not good in a asynchronous environmentIn the downlink, it can separate different users within onecell/sector

In the uplink, it can only separate the physicalchannels/services of one user because the mobiles are notsynchronized in time.


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Channelization Codes:As orthogonal codes are not pseudo codes and do nothave noise like properties, another set of codes arerequired to scramble the signals as well.


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Scrambling Codes:Scrambling codes:

Scrambling codes are pseudo random codes and have anoise like spectral nature.Suitable for efficient use of the frequency spectrum.Good auto correlation properties and can be used in

asynchronous environment.Scrambling codes have sufficient cross correlationproperties to which is required to de-scramble a desiredchannel


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Signal Spreading:Spreading the signal done in two phases (both in UL andDL):

Phase 1 by using spreading codes (channelization codes):In uplink to separate users physical data and control dataIn downlink to separate common and dedicated channels inone cell for one specific mobile.

Phase 2 by using scrambling codesIn downlink it identifies the cellIn uplink is identifies the user (call)

The radio planners task is to plan the scrambling codes forthe downlink part only.The system allocates the spreading codes and thescrambling codes in uplink


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Code:

SC

C C 4, 2

C C 8, 1

C C 4, 3

SC=512 SC1

C C 4 , 2

SC2

C C 4 , 2

SC3

C C 4 , 2

CC=224

Downlink Uplink


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Channelization and Scrambling codes:Channelization Codes Scrambling Codes

Usage Uplink : Separation of physical datachannel and control channels fromthe same mobileDownlink : Separation of downlinkconnections to different userswithin one cell

Uplink : Separation of mobiles

Downlink : Separation of cells

Length 4-256 chipsDownlink also 512 chips

Different bit rates by changing thelength of the codes

Uplink : 10ms = 38400 chipsDownlink : 10ms = 38400chips

Number of codes Number of codes under onescrambling code = spreading factor

Uplink : 16.8 MillionDownlink : 512

Code Family Orthogonal Variable SpreadingFactor

Long 10ms code : Gold Code

Short code: Extended S(2)code family

Spreading Yes, increases the transmissionbandwidth

No, does not affecttransmission bandwidth


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Spreading and Scrambling:

Original information

Spreading Code

Result After Spreading

Scrambling Code

Result After Scrambling

Transmission through air interface


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De-spreading and De-scrambling:

Result from

previous slide

De-scrambling

Result After De-scrambling

De-spreading

Result


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Code Tree:Codes are selected from a code tree.As there are limited number of codes, the code tree is alsoa limitation to the capacity.

C1(0) = [1]

C2(1) = [1 0]

C2(0) = [1 1]

C3(0) = [1 1 1 1]

C3(1) = [1 1 0 0]

C3(2) = [1 0 1 0]

C3(3) = [1 0 0 1]

C4(0) = [1 1 1 1 1 1 1 1]

C4(1) = [1 1 1 1 0 0 0 0]

C4(2) = [1 1 0 0 1 1 0 0]

C4(3) = [1 1 0 0 0 0 1 1]

C4(5) = [1 0 1 0 0 1 0 1]

C4(6) = [1 0 0 1 1 0 0 1]

C4(7) = [1 0 0 1 0 1 1 0]

C4(4) = [1 0 1 0 1 0 1 0]

Spreading Factor:

SF = 1 SF = 2 SF = 4 SF = 16SF = 8


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Codes:The number of downlink orthogonal codes within onescrambling code is limited to the spreading factor.

With a spreading factor of X, the maximum number oforthogonal codes is X.

Some orthogonal codes must be used for:Common Channels (signaling)

Soft handover overhead, which is additional allocatedresources by the system.


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Capacity Limitations:Codes can be a limitation.

If for instance code C 3,1 is selected, codes C 4,2 and C 4,3cannot be used anymore. Hence lower level codes areblocked for usage as well.

C1(0) = [1]

C2(1) = [1 0]

C2(0) = [1 1]

C3(0) = [1 1 1 1]

C3(1) = [1 1 0 0]

C3(2) = [1 0 1 0]

C3(3) = [1 0 0 1]

C4(0) = [1 1 1 1 1 1 1 1]

C4(1) = [1 1 1 1 0 0 0 0]

C4(2) = [1 1 0 0 1 1 0 0]

C4(3) = [1 1 0 0 0 0 1 1]

C4(5) = [1 0 1 0 0 1 0 1]

C4(6) = [1 0 0 1 1 0 0 1]

C4(7) = [1 0 0 1 0 1 1 0]

C4(4) = [1 0 1 0 1 0 1 0]

Spreading Factor:

SF = 1 SF = 2 SF = 4 SF = 16SF = 8


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RAKE Receiver RAKE Receiver


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Agenda:RAKE Receiver

Propagation EnvironmentRAKE Receiver Effect of DiversityRake Receiver FingersSignal Processing


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Describe what RAKE receiver is

Explain the benefits of a RAKE receiver Name the signal combination methods


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Propagation Environment


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RAKE ReceiverMultipath signals and signals from different Node-Bs canbe combined using a RAKE receiver.

RAKE receiver uses a technique, which uses severalbaseband correlators to identify the strongest multi-pathsignals for individual processing

The correlators outputs are combined to produce onesignal with less fading.


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RAKE process:Identifies the time delay position at which significantenergy arrives and allocates correlation receiver i.e. theRAKE finger Passes this processed information to the decoder forsignal processing

RAKE Receiver


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Effect of Diversity Combining

1-path

2-paths

4-pathsMacro diversityMultipath diversity

Antenna diversity

More diversity means

Less fading andtherefore less marginsneeded


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RAKE Receiver FingersA RAKE receiver typically have 4 fingers:

Search finger: finds new channel paths, assign finger to thepathsTracker: tracks small changes in the finger positions

Both Node B and MS receivers use RAKE receiver techniques.

Typically Node B receivers have 6 RAKE-receiver fingers.


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RAKE ReceiverUEs RAKE receiver at any given time is looking at signalsfrom:

CellsNeighbor list

The Search finger:Looks for the Pilot Symbols in pilot channels of each cellFinds signal strength from different Node Bs for softhandover

Rake Receiver ImprovesReliabilityPerformance

Provides strongest signalReduces the transmitter power


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Signal ProcessingPrimary methods used to combine the RAKE-receiverfingers outputs are:

Equal-gain combining method: All fingers outputs are weighted equally and then simply added

Maximal-Ratio combining Method (MRC) / Maximum Likeli-hood

Combining will apply a weighting to each result depending onthe probability of that result being correct before they arecombined

In practice, both combining techniques are often usedtogether


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Channel can rotate the signal to any phase and to anymagnitude

Maximum ratio combining corrects channel phaserotation and weights component with channelamplitude estimates

Signal Processing


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Link Budget CalculationsLink Budget Calculations


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Agenda:Power Budget Calculations

Link BudgetUplink Link BudgetDownlink Link BudgetCPICH Link Budget


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Outline the different parameters in a link budget path.

Name the unique parameters for WCDMA.Describe the E b/No and the requirements for higher bit rates.


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Link Budget:Link budget is used to define the cell range and path lossLink budget process in WCDMA:

Start looking at the uplink. Uplink is the limiting path (noisefrom other mobiles)UE transmit power Define data ratesDecide on E b/No targets for each data rateGather vendor specific data such as:

BTS output power

Receiver sensitivity levels Antenna typesUse of mast head amplifier Cable losses

Body loss figure


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Link Budget:Link Budget process in WCDMA:

Penetration loss definition

Propagation environmentMobile speedSystem loading factor Estimated mobile speed

Fast fading marginSlow fading marginLink losses & margins

Predefined parameters

Processing gainChip rateThermal noise densitySoft handover gain


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Link Budget:Definition E b /N o of is:

Energy per user information bit divided by noise powerspectral density

Required E b /N o means that for some quality target (BLER) a

certain average bit-energy over total noise+interferencespectral density (E b /N o) is required.

The value depends on the service and the speed of themobile.


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Link Budget - Uplink

Mobiles with data capability might have a higher output power (3GPP TS 25.101)


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Link Budget:Maximum transmit power:

Maximum power of the mobile. The standard defines four

power classes:1/8W 21dBm1/4W 24dBm1/2W 27dBm2W 33dBm

Transmit antenna gain:0dB for speech terminals2dB for data terminals

Body loss:Different values from vendorsTypically 3dB0 dB for data services


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Link Budget:Required Eb/No:

Required signal to noise ratio per data bit at the receiver

Depends on:Data rateCoding schemeInterleaving depthFading environmentDiversity

Thermal noise figure is a constant derived from Boltzmansconstant and temperature in Kelvin.

Receiver noise figure:Noise contributed by Node-B receiver itself. Typically:

Base station: 3dB-5dBMobile: 8dB


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Link Budget:Chip rate:

A scaling factor for WCDMA carrier bandwidth into account.

Chip rate expressed in dB relative to 1Hz.

Processing gain:The gain obtained by spreading the signal.The L2 user data rate is taken for this value.

Noise rise due to interference:

Extra noise due to other mobiles

Receiver sensitivity:Minimum detectable received signal level at the receiver.


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Link Budget:Building and vehicle penetration loss:

Typical values:Building 10-18dBCar 5-8dB

Not required if the calculation is for on-the-street levels.

Soft handover gain:Gain against shadowing.

A gain due to soft handover


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Link Budget:Fast fading margin

A margin against fast fading (when slow mobile)

At cell edge the mobile does not have enough power tofollow the fast fading.For fast mobiles, the figure should not be applied.

Cell edge when the mobilereaches its maximum power level

Power

Quality


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Link Budget:Slow fading:

Compensation against log-normal fading.

Depends on the environment


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Link Budget:The reason why E b /N o requirement is lower for higher bitrates is:

DPDCH and DPCCH are sent together.DPCCH includes the overhead information bits.When sending data, the DPDCH will require higher power.The amount of overhead information does not increaseproportionally with information bit rate.

As DPDCH will have higher power when sending withhigher bit rates, DPCCH will enjoy higher power as well.Therefore lower quality requirement will be put on DPCCHchannel.Thus lower E b/No for higher data rates.


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Link Budget - Downlink


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Link Budget - CPICH


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CPICH Link BudgetSoft handover gain:

Set to 0 as the signals from different cells have tobe processed separately

Fast fading:Set to 0 as CPICH does not use fast powercontrol.


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LogicalLogical , Transport, Transport andand PhysicalPhysical ChannelsChannels


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Agenda:Logical, Transport and Physical Channels

Channel Mapping

Logical ChannelsTransport ChannelsPhysical Channels


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Understand the mapping between the different channels.

Understand the usage of the different channels.


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Channel MappingThe signaling information and data are fed through thenetwork on Logical Channels.

The content of the logical channels is mapped into physicalchannels with the help of transport channels.

In other words:Logical channels define what type of data that is to betransferredTransport channels define how and with what properties thedata is transferred when on physical layer.Physical channels define the physical characteristics of theradio channel.


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Channel Mapping - Uplink

Logical

Channels

Physical

Channels

Transport

Channels

CCCH DCCH DTCH

PRACH

DCHCPCH

PCPCH DPDCH DPCCH

RACH

3GPP TS 25.211


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Channel Mapping - Downlink

Logical

Channels

PhysicalChannels

Transport

Channels

PCCH DCCH DTCH

S-CCPCH

FACHBCH

P-CCPCH

DPCCH

DPDCH

PCH

BCCH CCCH CTCH

DSCH DCH

PDSCH

CPICH

SCHCD/CA-ICH

CSICH AICH

PICH

3GPP TS 25.211


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3GPP TS 25.211

Logical Channel


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Logical ChannelsBCH Broadcast Channel

Carries system and cell-specific information; always

transmitted over the entire cell with a low fixed bit ratePCH Paging Channel

For messages to the mobiles in the paging area

FACH Forward Access ChannelCarries control information from base station to mobile inone cell when the system knows the location cell of themobile

May also carry short user packetsMay be transmitted over whole cell or over a portion usinglobe-forming antennas


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Logical ChannelsRACH Random Access Channel

Uplink channel used to carry control information from the

mobile stationMay also carry short user packets

Always received from the entire cell

CPCH Common Packet ChannelCarries small and medium-sized packets

A contention-based, random access channel used fortransmission of bursty data traffic

Associated with a dedicated channel on the downlink, whichprovides power control for the uplink CPCH


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Logical ChannelsDCH Dedicated Channel

A downlink or uplink channel used to carry user or control

information between the network and the UECorresponds to three channels:

DTCH Dedicated Traffic ChannelSDCCH Stand-Alone Dedicated Control Channel

ACCH Associated Control ChannelTransmitted over the whole cell or only a part using lobe-forming antennasMay have fast rate changes (even every 10 ms), and fastpower control

Transport Channels:


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Logical channels are mapped onto transport channels

Physical Channels:


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Physical ChannelsDPCH - Dedicated Physical Channel

A downlink or uplink dedicated physical channel used to

carry user or control information to User Equipment (UE)over an entire or cell or part of the cell that usesbeamforming antennas

PRACH - Physical Random Access Channel A common uplink physical channel used to carry controlinformation or short user packets from the UE

PCPCH - Physical Common Packet Channel

A common uplink physical channel used to carry short andmedium-sized user packets. Its always associated with adownlink channel for power control


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Physical ChannelsCPICH - Common Pilot Channel

A fixed-rate downlink physical channel that carries a

predefined bit/symbol sequenceP-CCPCH Primary Common Control Physical Channel

A fixed-rate downlink channel used to broadcast system andcell-specific informationThe P-CCPCH is not transmitted during the first 256 chips ofeach slot (I.e., it maintains a 90% duty cycle)

S-CCPCH Secondary Common Control Physical Channel

A downlink physical channel used to carry the FACH andPCH transport channel


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Physical ChannelsSCH Synchronization Channel

A downlink signal used for cell search. The SCH consists of

two subchannels, the primary and secondary SCH, whichare transmitted during the P-CCPCH idle periodPDSCH

A downlink channel used to carry the DSCH transport

channelAICH Acquisition Indicator Channel

A fixed-rate downlink physical channel used to carry accesspreamble acquisition indicators for the random access

procedure

h l h l


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Physical ChannelsAP-AICH Access Preamble Acquisition Indicator Channel

A fixed-rate downlink physical channel used to carry access

preamble acquisition indicators of CPCHPICH Paging Indicator Channel

A fixed-rate downlink physical channel used to carry thepaging indicators which disclose the presence of a pagemessage on the PCH

CSICH - CPCH Status Indicator Channel A fixed-rate downlink channel used to carry CPCH status

information A CSICH is always associated with a physical channel usedfor transmission of CPCH AP-AICH, and uses the samechannelization and scrambling codes

Ph i l Ch l


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Physical ChannelsCD/CA-ICH Collision-detection/Channel-Assignment IndicatorChannel

A fixed-rate common downlink physical channel used tocarry CD indicator only if the CA is not active, or a CD/CAindicator at the same time if the CA is active


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Radio Resource ManagementRadio Resource Management

Ag d


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Agenda:Radio Resource Management

Radio Resource Management Overview

RRM - Cell Based FunctionsRRM - Connection Based Functions

Learning Objectives:


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Understand the reasons behind Radio ResourceManagement functionalitiesName the different Radio Resource Managementfunctionalities

Radio Resource Management (RRM) Overview


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Radio Resource Management (RRM) - OverviewThe RRM is responsible to ensure:

The planned coverage for each targeted service

High capacity by minimizing the blockingThe required Quality of Service is metPrioritise the usage of the resources so that the capacity is

maximised

This is done by continuously monitoring and measuring theavailable resources based on the requests



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Radio Resource Management (RRM) - OverviewThe RRM covers covers all functionalities for handling theair interface.

The RRM must be able to:Estimate the impact on interference of allowing new usersinto the systemProvide different Quality of Service for different type of usersTake appropriate measures in accordance with the loadsituationTake appropriate action when load is exceeded in the

system


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Radio Resource Management (RRM) - OverviewThe functions together are responsible for providing

Optimum Coverage

Maximum capacityQuality of ServiceEnsuring sufficient use of physical and transport resources

RRM Cell Based Functions


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RRM Cell Based FunctionsAdmission Control (AC)

Performs the admission control for new bearers to enter the

networkPredicts interference caused by the bearer and decideswhether the bearer can be admitted

Allocates powerDefines the transport channels

Packet Scheduler

Scheduling packets on the radio interfaceEnsures fast allocation of resources for non-real time traffic

RRM Cell Based Functions


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RRM Cell Based FunctionsLoad Control

Takes care of radio network stability

Gathers interference information and provides cell loadstatus to Admission Control and Packet Scheduler

Resource managerManages the physical resourcesMaintains the code tree and code allocation

RRM Connection Based Functions


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RRM Connection Based FunctionsPower Control

Continuously monitors the quality of the radio link and adjusts themobiles and base stations powers

Sets an absolute minimum transmission power used to maintainrequired qualityDivided into:

Closed Loop Power ControlOpen Loop Power ControlOuter Loop Power Control

Handover ControlManages the mobility

Ensures that the mobile is connected to the best cell which wouldgive least interferenceCan be divided into:

Intra-frequency Handover Inter-frequency Handover

Inter-system Handover

Parameter Distribution Overview


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Parameter Distribution Overview

Functionalities # in RNC # in BTS # in Cell Total

HC 6 - 8 14

PC 16 1 19 36

AC 29 6 23 58

LC 1 6 6 13

PS 51 4 19 74


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Power ControlPower Control

Agenda:


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g :Power Control

Power Control

Open Loop Power ControlRandon Access ProcedureOuter Loop Power ControlUplink Outer Loop Power ControlDownlink Outer Loop Power ControlOuter Loop Power Control Quality DeteriorationInner Loop Power Control (Closed Loop)

Learning Objectives:


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g jAt the end of this module, you will be able to:

Describe the role of power controlName the different power control typesExplain the reasons for the different types

Power Control


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The functions of power control are:To maintain the link quality in the uplink and downlink by

adjusting the powersMitigate the near-far effect by providing minimum requiredpower level for each connectionProtection against shadowing and fast fadingMinimizing the interference in the network.By minimizing the interference, provide a higher capacityand better quality.

Power Control


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There are three power control types defined in WCDMA:1 Open Loop Power Control

Used in uplink and downlinkUsed for initial power settingBetween the mobile and the RNCPerformed only at call setup

Power Control


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There are three power control types defined in WCDMA:2 Closed Loop Power Control (Fast Power Control)

Used in uplink and downlinkFast Power Control

Performed 1500 times a second Compensates fading dips

Adjusting the Eb/No requirements Minimises the interference

Slow Closed Loop Power Control in Downlink Performed only for common channels in downlink direction

Prevents for power drifting in downlink direction Between the mobile and the RNCDuring a connection

Power Control


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There are three power control types defined in WCDMA:3 Closed Loop Power Control

Used in uplink and downlink Performed at a much lower rate: (10-100 times per second) Performed in order to adjust the Signal to Interference Ratio

targets to achieve a target Block Error Ratio

During a connection

Open LoopPower Control


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RNCRNC

Open LoopAt call setup

Inner LoopDuring a connection

Outer LoopQuality target

Open Loop Power ControlO l l i d i d h i i i l


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Open loop power control is done in order to set the initialpower transmission to the network at a call setup

The mobile estimates the access power level by sending apreamble message at an estimated power level. If the basestation does not respond to the mobile, the mobile waits acertain period of time and retransmits at a higher powerlevel. The mobile continues doing so until it receives aresponse from the base station.

Uplink + DownlinkMeant for the following channels:

PRACH (UL): First transmission preamblePCPCH (UL): First transmission preambleDPCCH (UL): At establishment of the first DPCCHDPDCH (DL): At the setup of the first bearer

Random Access ProcedureWh bil i ll R d A Ch l


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When a mobile is to set up a call, Random Access Channel,RACH, is used to access the network.

The Physical Random Access Channel, PRACH, is used tocarry the RACH.

The random access transmission procedure consists of:One or more preamble transmission attemptsMessage part

Preamble parts are sent till the network sees them andresponds to the mobile through Acquisition Channel, AICH.

Random Access Procedure


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One access slot

p-a

p-mp-p

Pre-amble

Pre-amble

Message part

Acq.Ind.

AICH accessslots RX at UE

PRACH accessslots TX at UE

Power Ramp step

Power Ramp

3GPP TS 25.2113GPP TS 25.211

Random Access ProcedureS t d


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Setup procedurePreamble TX power is first set to Preamble Initial Power .

UE waits for the AICH response (either +1 or -1)If no response

the UE increases the power with an amount equal to PowerRamp Step and decreases the Preamble Retransmission Maxvalue by 1.UE repeats this till it reaches the Preamble RetransmissionMax value is 0 or it receives an AICH response.

If Preamble Retransmission Max value is 0, the UE sends aNo ACK on AICH to higher layers.If -1 received, a NACK on AICH received is sent to higherlayers.

Random Access ProcedureThe UE stops transmitting preambles upon:


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The UE stops transmitting preambles upon: An ACK has been received on AICH

An NACK has been received on AICHMaximum number of preambles set by PreambleRetransmission Max have been received within a cycle.The maximum allowed power has been reached for PRACHon the mobile.

The RACH process is stopped if a max number of RACH

transmit has been reached.UE will send a RACH failure message to the network.

RACH Preamble partPreamble Part Frame Structure


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Preamble

RACH Preamble partEach preamble is of length 4096 chips and consists of 256

repetitions of a signature of length 16 chips. There are amaximum of 16 available signatures, see 3GPP TS 25.213for more details.

Message partPreamble

4096 chips10 ms (one radio frame)

Message part

4096 chips 20 ms (two radio frames)

Preamble

Preamble PreamblePreamble

3GPP TS 25.2113GPP TS 25.211

Message Part Frame StructureRACH Message part


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RACH Message partMessage part can be either 10ms or 20ms long.

Each 10ms has 15 slots and each slot consists of two parts;Data part to which the RACH transport channel ismappedControl part that carries Layer 1 control information.

Data and control parts are transmitted in parallel.

Pilot N pilot bits

Data N data bits

Slot #0 Slot #1 Slot #i Slot #14

T slot = 2560 chips,10*2

k bits (k=0..3)

Message part radio frame T RACH = 10 ms

Data

ControlTFCI

N TFCI bits

3GPP TS 25.2113GPP TS 25.211

Open Loop Power Control (UL)Open loop power control uses the path loss estimation in


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Open loop power control uses the path loss estimation inthe downlink direction

Estimated by knownCPICH power from the base stationCPICH RSCP of the mobile

Initial power setting for PRACH and PCPCH is determinedby:

Received total wideband power (uplink interference measures)Required uplink quality figures (in 3GPP denoted as constant value)CPICH power from the base stationCPICH RSCP of the mobile

Preamble_initial_power [dBm] = UL_interference [dBm]+ CPICH_Tx_Power [dBm]- CPICH_RSCP [dBm]+ UL_Required_CI [dB]

Open Loop Power Control (UL)Initial power setting for DPDCH is determined by:


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Initial power setting for DPDCH is determined by:Received total wideband power (uplink interference measures)

SIR values of DPCCHCPICH power from the base stationCPICH RSCP of the mobileContribution of the spreading factor for DPCCH

DPCCH_initial_power [dBm] = UL_interference [dBm]+ CPICH_Tx_Power [dBm]+ DPCCH_SIR [dB]- 10 log (SF DPCCH ) [dB]- CPICH_RSCP [dBm]

Calculated by

Admission Control

Outer Loop Power ControlOuter loop power control is performed to adjust the SIR


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p p p jtarget according to the conditions and the requirements ofthe radio links:

Changes in the radio environmentThe speed of the mobileThe mobiles power control dynamicsSoft handover branches

Data rate

Signal to Interference Ratio, SIR, level is constantlyadjusted to an optimum value so that the link quality is

maintained at a constant level. This is usually defined as acertain BLER target for the provided service.

Higher speed, higher target levels.

Outer Loop Power ControlIn uplink:


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up :Located in serving RNC

The initial E b/No set-point and changes to that are sent fromRNC to the base station for the use in the inner loop powercontrolThe SIR target is then updated for each mobile according tothe BLER or BER figures for the connection.

Uplink Outer Loop Power Control


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RNCRNC

SIR target for fast

power control10-100Hz

Uplink Outer Loop Power Control

Algorithm for calculating the changes of the SIR target is


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g g g gbased on BLER estimation:

SIR Target (i+1) = SIR Target (i) + SIR [dB]

SIR = step_size * (BLER_estimation BLER_target)

BLER_estimation = _TBIstotal_n_of

RCsn_of_nok_C

Downlink Outer Loop Power Control

In downlink:


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Implemented in mobile

The mobile sets the SIR target on each CCTrCH used forthe downlink closed loop power controlQuality target: BLER of each transport channel as set by theRNC

Admission control determines the value of DL BLER targetfor each DCH mapped on DPCH and are sent to the mobile.No SIR target changes if the the power of the base stationreaches a maximum or network congestion occurs thoughthe quality gets worse.

Outer Loop Power Control Quality Deterioration

If the uplink SIR target has reached the maximum and the


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uplink SIR target modification commands are all greaterthan zero, a quality deterioration report is sent to handovercontrol.

SIRTarget

Time

Max SIR Target

Max SIR Target

Quality deterioration report to HC

Repeated Quality deterioration report to HC

Actual SIR Target

Time to trigger (defined by a parameter)

Inner Loop Power Control (Closed Loop)

During a connection:


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Power adjustment at a rate of 1500 times/second betweenthe mobile and the base station.The RNC sets the target BLER level for the service. Fromthis BLER, it derives a SIR target and sends it to the basestation.The base station estimates an UL SIR level and decides ifthe power of the mobile has to be increased or decreased(this part is called for Inner Loop ).If the SIR level is higher than the target, a TPC is sent to themobile to decrease its power.If the SIR level is lower than the target, a TPC is sent to themobile to increase its power.In DL the AC decides the levels of the initial, minimum andmaximum power levels for DPDCH.

Inner Loop Power Control

Power is increased only if all links report an TPC =1


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TPC = 0

TPC = 1TPC = 1

No power increased but decreased


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Handover ControlHandover Control


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Handover ControlHandover Control

Agenda:

Handover TypesS f H d


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Softer Handover Soft Handover Hard Handover Handover ControlEvent 1A

Event 1BEvent 1CSHO SummaryEvent 1EEvent 1FIF/IS HHOReporting Events 6A, 6B and 6D

Load Based HO GSM WCDMA


Name the different type of handovers


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Name the different type of handoversExplain the reasons for each handover typeUnderstand and be able to explain the most importantevents: event 1A, event 1B, event 1C, event 1E and event1F.

Handover

Handover types:


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Soft Handover

Softer Handover Hard Handover

Handover

WCDMA soft handover types:Soft Handover


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Soft Handover Intra-frequency handover The mobile will be connected to several cellssimultaneouslyThe mobile estimates the suitability of a candidate

Softer Handover Intra-frequency handover The mobile will be connected to two or three cells fromthe same site simultaneously.

Softer Handover


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RNCRNC

Softer Handover

Characteristics and purpose:M bil t d t t ll th ll f th


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Mobiles are connected to two cells or three cells from thesame siteMobile Evaluated Handover (MEHO)

According to simulations 5%-10% probability.No extra transmission neededProvides additional diversity gainCreates additional interference

Soft Handover (SHO)


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Soft Handover (SHO)

Characteristics and purpose:Mobiles are connected to two or more cells from different


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Mobiles are connected to two or more cells from differentsites.Mobile Evaluated Handover (MEHO)Seamless handover without any disconnection between themobile and the RNC.Except the power control commands, exactly the sameinformation is sent.

According to simulations 20%-40% probability.It is required to avoid near-far effects

Extra transmission across I ub is needed.More channel elements are needed.Can create additional interference

Handover

WCDMA hard handover types:Intra Frequency Hard Handover


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Intra Frequency Hard Handover When SHO is not possible e.g. lack of I ur interfaceThe mobile measurement and reporting is the same as SHOMobile estimates the handoverRNC controlled

Inter Frequency Hard Handover Handover from one cell to another from different carriersRNC makes the decisionReal time users will be temporarily disconnected but this is notperceived by the user.

Handover

WCDMA handover types are:Inter System Hard Handover


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Inter System Hard Handover

Handover between two different systems e.g. WCDMA toGSMThe network evaluates the handover

Hard Handover (HHO)GSMGSM


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WCDMAWCDMA

Hard Handover (HHO) Inter System/Frequency

Characteristics and purpose:Mobiles are handed over from one system to another.


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yNetwork Evaluated Handover (NEHO)During the handover, there is an idle time where the mobilecan measure on other systems. This is called CompressedMode (CM).CM was introduced in WCDMA to allow inter-frequency(system) handovers (3GPP TS 25.215)

As some amount of data is sent in a shorter time, morepower is needed during CM (both in the mobile and thebase station). This affects the WCDMA coverage.Fast power control information might be lost during the gapwhich means that higher E b/No values are needed.

As higher E b/No values, the capacity of WCDMA is affected

Handover Control

Why are SHO and Softer HO required?In order to avoid near-far effect for circuit switched


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o de to avo d ea a e ect o c cu t sw tc edconnectionsMacro diversity gain gives larger cell range compared toHHO (gain against shadowing ~ 1dB to 3dB gain)Can give up to 10%-40% extra coverage

The SHO probability should be below 30%-40% in order tokeep the capacity overhead at an optimum level

Handover Control

Handover measurement:The handover measurements are based on CPICH E c/Io


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levels only.CPICH E c/Io is the received energy per chip divided by thepower density in the band.The accuracy of CPICH E c/Io measurements is important forhandover performance.The accuracy of the measurements depend on the mobilespeed and the filtering length

An optimum long filtering length is good for slow movingmobiles or stationary mobiles so that the errors caused by fastfading is minimized.

A long filtering length will cause handover to be delayed for fastmoving mobiles

Handover Control

Handover measurement:Event triggered measurements and reporting


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Event 1A: A primary CPICH enters the reporting rangeEvent 1B: A primary CPICH exits the reporting rangeEvent 1C: A none active primary CPICH becomes better thanan active primary CPICHEvent 1D: Change the best cell

Event 1E: A primary CPICH becomes better than an absolutethresholdEvent 1F: A primary CPICH becomes worse than an absolutethreshold

Event 6F: The UE RX-TX time difference for a radio linkincluded in the active set becomes larger than an absolutethresholdEvent 6G: The UE RX-TX time difference for a radio linkincluded in the active set becomes less than an absolutethreshold

Event 1A: A Primary CPICH Enters the Reporting

RangeCell A Cell BEc /N o

Addition


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Cell C

Time

AdditionWindow

Addition Time

E1a

Event 1B: A Primary CPICH Leaves the Reporting

RangeCell A Cell BEc /N o

Drop


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Cell C

Time

DropWindow

Drop Time

E1b

Event 1C: A Non-active CPICH Becomes Better

Than an Active Primary CPICHCell A Cell BEc /N o


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Cell D

TimeReplacement Time

E1c

Cell C

SHO Summary

Event ReportingCell Status

TriggeringCondition

Reporting Range /Hysteresis

Time toTrigger


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y gg

E1aActive set cells+ 2 monitor set

cells

Monitor setcells

Addition Window4dB

AdditionTime

0s

E1b Active set cells Active set cellsDrop Window

6dB

Drop Time

320ms

E1cActive set cells+ 2 monitor set

cells-

Replacement Window4dB

ReplacementTime

0

Event 1E: A Primary CPICH Exceeds an Absolute

ThresholdCell A Cell BEc /N o


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HHO Cancel Time

HHO Cancel Threshold

HHO threshold

Time

E1e

E1f

Event 1F: A Primary CPICH Falls Below an

Absolute ThresholdCell AEc /N o


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HHO Cancel Time HHO Time Hysterisis

Cell B

HHO Cancel Threshold

HHO threshold

Time

E1e

E1f

IF/IS HHO

Measurement Triggering for E c /Io :RNC starts IF/IS HHO measurements when event 1F occursf ll ll i h i


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for all cells in the active set.RNC stops IF/IS measurements when event 1E occurs forat least one cell of the active set.IF/IS measurements can be stopped if event 1Fs are

cancelled by event 1E only when IFHO/ISHO was notsuccessful and only inside the time between CMmeasurements, which is governed by parameters.

IF/IS HHO

Measurement Triggering for RSCP:The mobile continuously monitors the pilot channels of theb t ti i th th ti t


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base station in the the active setsIf the RSCP of a cell falls below a threshold (e.g. NOKIAparameter HHoRscpThreshold ), the mobile sends event 1Freport.

RNC starts IF/IS HHO measurements when event 1F occursfor all cells in the active set.RNC stops IF/IS measurements when event 1E occurs forat least one cell of the active set.

IF/IS measurements can be stopped if event 1Fs arecancelled by event 1E only when IFHO/ISHO was notsuccessful and only inside the time between CMmeasurements, which is governed by parameters.

Reporting Events 6A, 6B and 6D

UE TX

power

6A: The UE Tx power exceeds an absolute threshold6B: The UE Tx power falls below an absolute threshold6D: The UE Tx power reaches its maximum value


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Time Hysterisis Time to trigger

Time

E6a

E6b

E6d

p

UE Transmitted power

IF/IS HHO

Measurement Triggering: UL CoverageRNC orders IF/IS measurements when one of the followingevent occurs:


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event occurs:Event 6A: The UE Tx power becomes larger than an absolutevalueEvent 6D: The UE Tx power reaches its maximum value

Also GSM measurements could be measured firstdepending on UE Tx power values in IFHO and ISHOparameters

Only lower threshold is sent to UE, so either WCDMA or GSM

is measured first, but also other RAT could be measured if notgood enough neighbour is found

IF/IS HHO

Measurement Triggering: UL CoverageRNC stops the inter-frequency measurements when theevent 6B occurs i e when the Tx power of the UE becomes


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event 6B occurs i.e.when the Tx power of the UE becomesless than an absolute value.Not all of the available mobiles in the market support theE6a.

Usually time to trigger for events 6a and 6d are set to 0s.Time to trigger event 6a = 0sTime to trigger event 6d = 0s

IF/IS HHO

Measurement Triggering: DL CoverageRNC orders UE to make IF/IS measurements when DL Txpower of a single radio link reaches threshold defined as:


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power of a single radio link reaches threshold defined as:DL_Code_PWR PowerOffset_DLdpcchPilot > CPICH Pwr + DL Tx Pwr

+ DL_TPCH_TXPWR_Threshold

DL_Code_PWR = measured DL code power

PowerOffset_DLdpcchPilot = power offset for the DPCCHpilot bits relative to the DPDCHs power.

Default value = 3dB

DL Tx Pwr (DPCH) = measurement on DPCH Tx power

(reported by BTS)

IF/IS HHO

Measurement Triggering: DL CoverageCPICH Pwr = Tx power of the CPICH of an active cell

Usually set to 30dBm or 33dBm


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Usually set to 30dBm or 33dBm

DL_TPCH_TXPWR_Threshold = depends on the type ofservice

AMR/CS/RTPS/NRTPS -1/-3/-3/-1dB

IF/IS HHO

Measurement Triggering: UL QualityRNC starts IF/IS measurements based on UL


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outer-loop power control reports.The option must be set in RNC by activating parameter(EnableULQualDetRep , by default 0=no)Time duration for which BER/BLER target has not beenreached, despite SIR target at maximum level(ULQualDetREpThreshold )Periodic report, for certain period while BLER/BER target

is not reached


WCDMA could be used to relieve GSM overloadGSM can be used to extend the WCDMA coverage


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area.

GSMGSMGSM

WCDMA WCDMA

Load Based HO Coverage Based HOCoverage Based HO


100%Speech to WCDMA

Only with high GSM LoadMore Capacity


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0%

80%Only with high GSM Load

For Speech

All Packet Data to WCDMA Higher Bit Rates

Load Based Handover Process : GSM WCDMAHandover Triggering Thresholds are set in BSC

Inter-RAT measurements starts in case the RXLEV


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of the serving cell is above or below a threshold

Handover decision is done in case of load of

the serving cell > Load_thresholdand

CPICH Ec/No > min Ec/No Threshold

MS selects the target UTRAN cell

Handover command is sent to MSC


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Load ControlLoad Control


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Agenda:

Load ControlLoad Control


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Why there is a need for load control.Describe what Controllable and Non-controllable traffic is.


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Describe how P trx_total and P rx_total are calculated.

Load Control

Important to keep the air interface load under the plannedthresholds.


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Load controls has two main functions:Preventive control

Prevent the system from being overloaded

Overload controlReturning the system from an overloaded state to a normalstate

Load control measures both UL and DL interference periodically

Load Control

Load Control is a cell based Radio Resource Managementfunction and utilizes:

Thresholds set by radio planners


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Load measurements based on powerAdmission Control & Packet Scheduler & Load Controlalgorithms

Admission Control

Packet Scheduler

Load Control

Load Status

Load Change

NRT Load

Load Control

Load control takes the interference coming from other cellsinto account as well.


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Traffic definition:Non-controllable traffic = Real time users + Other-cell users

+ Noise

+ Non-real time users (minimum bit rate)Controllable traffic = Non-real time users

Load Control

Traffic classes:Non-controllable traffic: Conversational or Streaming

Delay sensitive


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Controllable traffic: Interactive or BackgroundNot sensitive to delays

Conversational Streaming

Real Time Traffic

Interactive Background

Non-real Time Traffic

CS Domain PS Domain

Load Control

Some portions of the capacity must be reserved for realtime traffic so that mobility is taken into account.


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The ratio between real time traffic and non-real time trafficvaries in time.

Load target

Overload area

Overload margin

Non-controllable traffic

Extra capacity for controllable traffic

Load ControlUplink radio planning thresholds for load control are:

Noise [dB]


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Uplink received power:P rx_Total = P rx_own cell + P rx_others + P noise = P rx_NC + P rx_NRT

Load

Prx_target + Prx_offset

Prx_target Prx_Target ~ 3dB-4dBPrx_Offset ~ 1dB

Load ControlDownlink radio planning thresholds for load control are:

Power [dB]


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Downlink transmission power:P tx_Total = P tx_NC + P tx_NRT

Load

Ptx_target + Ptx_offset

Ptx_target Ptx_Target ~ 40dBPtx_Offset ~ 1dB

Load Control

Load control measures the load and passes the informationto Admission Control and Packet Scheduler

Ad i i C t l ti t th ff t f dditi l l d


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Admission Control estimates the effect of additional load

Load Control actions are performed by Admission Control

and Packet Scheduler.

Load Control updates the load status of the cell based onmeasurements and estimations provided by AC and PS.


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Admission ControlAdmission Control


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Agenda:

Admission Control Admission Control and Other Functions Admission Control (AC)

Uplink Admission Control


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Uplink Admission ControlUplink Admission Control Case Study 1Uplink Admission Control Case Study 2Uplink Admission Control Case Study 3Uplink Admission Control Case Study 4Downlink Admission ControlDownlink Admission Control Case Study 1

Downlink Admission Control Case Study 2Downlink Admission Control Case Study 3Downlink Admission Control Case Study 4


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Admission Control and Other Functions

Load ControlCell load status

Load change informationLoad information


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Admission ControlLoad change estimation

RAB Admission Decision

DL Power AllocationProducing TFS

L2 parameters

Handover Control Active state mobility control

Packet Scheduler

Radio resource scheduling

Resource Manager Code allocation

Transport resource allocation info

Power ControlUL outer loop power control

Active set

information

Load change informationLoad information

Target BLER, SIR

RB information

Load information

Resource requestResource information

Admission Control (AC)

AC handles new incoming traffic to the RAN byEstimating the total load caused by adding a new RAB inuplink and downlinkAnd decides whether the new RAB can be admitted


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And decides whether the new RAB can be admittedReal time traffic admission to the network is decidedNon-real time traffic after RAB has been admitted the optimumscheduling is determined by Packet Scheduler.

Used for power decision at:Call setupModified

During handover


The load is measured by:PrxTotal received by the base station in the uplinkPtxTotal transmitted by the base station in the downlink


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The decision procedure of AC will use:Thresholds defined by the radio planner

Uplink interference and downlink transmission levels


Important measures and parameters:Uplink:

PrxTotal received by the base station in the uplinkPrxOffset, the maximum margin by which PrxTarget can be


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, g y gexceeded

DownlinkPtxTotal transmitted by the base station in the downlinkPtxOffset, the maximum margin by which PtxTarget can beexceeded


The load change depends on: At attribute of the RABTraffic typeQuality parameters


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Quality parameters

AC is located in RNC. In RNC the load information from

several cells can be obtained.

Power increase estimation or load increase estimation ishandled by the AC functionality (for own and neighbours)

AC requests logical resources from Resource Manager(RM).


OverloadOverload

StateState

No New RAB

Drop RT bearers

Overloadactions

Decreased bit rates

NRT bearersto FACH

Drop NRT bearersP T P Off

AC LC PS


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NormalNormalStateState

PreventivePreventiveStateState

StateState

Only new RTbearers if RT load

below PrxTarget or PtxTarget

Preventive load

control actions

No new capacityrequest scheduled

Bit rate notincreased

AC admitsRABs normally No action

PS Schedules

packet trafficnormally

PrxTarget + PrxOffsetPtxTarget + PtxOffset

PrxTargetPtxTarget


Uplink interferenceNew users blocked above this point

Max planned power


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New users added = IMax planned load

LoadNoise floor

I total_old

Uplink Admission Control (AC)

In uplink the total received interference power indicates theload.

Criteria that have to be fulfilled before an real time RAB can


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be admitted are: Prx_NC + I P rx_target

Prx_total

P rx_target + P rx_offset

P rx_total = P rx_NC + P rx_NRT

P rx_NRT Is determined by Packet Scheduler and deliveredto AC through Load Control


Uplink interference

New users blocked above this point

P l BS

After this point theload control actionsare started to restore


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LoadNoise floor

Prx_total_BS

Prx_target Prx_offsetnormal load.

Uplink Admission Control Case Study 1

Prx_total_BS

Prx_target

packet Prx_NC


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Prx_NC

PP rx_targetrx_target PP rx_NCrx_NC ++ P P rx_NCrx_NCPP rx_totalrx_total PP rx_total_BSrx_total_BSPP rx_totalrx_total == PP rx_NCrx_NC ++ P P rx_NCrx_NC ++ PP rx_NRTrx_NRT

Admission is given to RT and NRT RAB request


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Prx_total_BS

Prx_targetPrx_NRT

Prx_NC


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Prx_NC


No Admission is given to any type of traffic


Prx_total_BS

Prx_target

Prx_NRT Prx_NC


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Prx_NC


No Admission is given to RT RAB traffic butNRT RAB can be admitted or downgraded

Downlink Admission Control (AC)

In downlink the total transmitted powers are used insteadof measured total power.

Criteria that have to be fulfilled before a real time RAB canb d itt d


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be admitted are: Ptx_NC + Ptx_NC P tx_Target

Ptx_Total

P tx_target_BS = P tx_target + P tx_offset

P tx_total = P tx_NC + P tx_NRT

Downlink Admission Control

Uplink interference

New users blocked above this point

Prx_target_BS

Absolute maximum Tx power in the cell After this point the

load control actionsare started to prevent


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Load

Prx_target Prx_offset

poverload.

Downlink Admission Control (AC)

For each RAB request, AC has to estimate the increase inthe total NC transmission power

The task is to estimate the increase in the total non-controllable transmission power: P tx_NC


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It is calculated in:

Estimation of Tx power increase based on admission of areference RAB (AMR 12.2kbps)For other RAB, the power of the reference RAB is multipliedby a factor based on the requested RABs properties (Eb/No

and etc.) = P txPower of inactive RT users (still in establishment phase

MYCOM - WCDMA Fundamentals AndFunctionalities - For Handsout

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Transcript of MYCOM - WCDMA Fundamentals AndFunctionalities - For Handsout