03nov_am1_umts introduction & basic algo

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Mohamed Arshad

MoAD RNE SSEAI

Kuala Lumpur

November 2008

Introduction to UMTS



All Rights Reserved © Alcatel-Lucent 20082 | UMTS Introduction | Nov 2008

Content

1. Introduction to UMTS Standard

2. W-CDMA Basic

3. Radio Environment4. Logical / Transport / Physical Channels

5. Basic Algorithm




IMT-2000

ITU: International Telecommunications Union

needs for a 3rd generation mobile system referred as IMT-2000 within ITU

IMT-2000 stands for International Mobile Telecommunications and 2000 for the year,the bit rate (2Mbps) and the frequency (2GHz)

High level requirements : world-wide standard supporting new advanced serviceswith high bit rates (up to 2 Mbps) in multiple environments

IMT-2000 spectrum band identified in 1992 (Conférence Mondiale des

Radiocommunications)


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2 Mbit/s 384 kbit/s 144 kbit/s

Indoorlow mobility

Urbanreduced mobility

Rural outdoorhigh mobility

• Variable bit rate capability

• Variable Quality Of Service (BER, delay)

• Support of asymmetric traffic• Service multiplexing

• High spectrum efficiency

• European objective: ensure compatibility with GSM

IMT-2000 objectives


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Integration with the Fixed Network

Satellite

Macro-Cell

Micro-Cell

Zone 2:Urban Zone 1:

In-Building

Pico-Cell

Zone 4: Global

Zone 3:Suburban

Basic TerminalPDA Terminal

Audio/Visual Terminal

Multi-environment




1850 1900 1950 2000 2050 2100 2150 2200 2250

1850 1900 1950 2000 2050 2100 2150 2200 2250

North

America

MSSPCS

Reserve

Europe UMTSGSM 1800 DECT MSS

1880 MHz 1980 MHz

Japan

Korea (w/o PHS)

MSSIMT 2000PHS MSSIMT 2000

2160 MHz1895 MHz

1918 MHz1885 MHz

ITU Allocations

1885 MHz 2025 MHz

IMT 2000

2010 MHz

2110 MHz 2170 MHz

China MSSIMT 2000IMT 2000

IMT 2000

MSSUMTS

2170 MHz

MSS

1885 MHz 1980 MHz

AA D B E F C AA D B E F C

MDS

GSM 1800

1850 MHz WLL WLL

Source: The UMTS Forum

3G Frequency Band World-Wide




IMT-2000 standards

Each worldwide standardization

body submitted their technology

candidate for IMT-2000 to ITU 5 interface standards:

IMT-SC: IMT Single Carrier (TDMA orGSM EDGE (IS-136) standard)

IMT-MC: IMT Multi Carrier (US CDMA

2000 standard) IMT-DS: IMT Direct Spread (WCDMA or

UMTS Frequency Division Duplex(FDD))

IMT-TC: IMT Time Code (UMTS TimeDivision Duplex (TDD))

IMT-FT: IMT Frequency Time (DECTstandard)




UMTS

UMTS : Universal Mobile Telecommunication System

UMTS was the 3G European standard

ETSI (European standardization body) selected its radio interface for UMTS

(UTRA) in January 1998 based on W-CDMA for FDD mode and TD-CDMA for TDD

mode

W-CDMA was also chosen by ARIB (Japan) and also in USA and Korea

Creation of 3GPP (3G Partnership Project) to join efforts on the

standardization of the UTRA (Universal Terrestrial Radio Access) solution:

ETSI (Europe), ARIB (Japan), TTA (Korea), TTC (Japan), T1P1 (USA) , CWTS(China)




UTRA - UMTS Terrestrial Radio Access

2 modes:

W-CDMA FDD mode for the paired band

uplink and downlink are separated in frequency

TD-CDMA TDD mode for the unpaired band

uplink and downlink are separated in time

flexible time duration for uplink and downlink for asymmetrical traffic

FDD Mode

FUL/DL

TDD Mode

1900 1920 1980

FDD ULTDDUL/D

L

TDDUL/DL

MSSUL

2010 2025

MSSDL

2110 2170 2200

FDD DL

FUL

FDL




Multiple Access Techniques

CDMA

time

p o w e r d e n s i t y

channel bandwidth

TDMA

channel bandwidth


time

TD/CDMA

time

channel bandwidth





UTRA FDD - Characteristics

W-CDMA multiple access

Frequency band Region 1 (Europe)

Uplink: 1920-1980 MHz

Downlink: 2110-2170 MHz

Carrier Bandwidth

2x5 MHz (theor. occupied bandwidth=Chiprate 3,84 Mcps)

Services

Both circuit and packet data and asymmetric bitrates

User bitrate up to 384 kbit/s

FDD foreseen for Macro- and Microcellular coverage




UMTS Radio Access Network

Internet

CoreNetwork

RNC

RNCISDN

Node B

Node B

Radio Access

Network

Node BNode B

Node B

Node B

Iub

Iu

Iur




User equipment

Uu

Uu is the UMTS air interface between the

terminal and the access network

ME-Mobile Equipment

The mobile equipment is the radio

terminal used for radio communication

over the Uu interface

USIM-UMTS Subscriber Identity Module

Smart card, which stores subscriber

identity and other information

USIM

M E

C u

U E

U u

U ser Equip m ent




UMTS radio access network

Node B

Node B

Iur

UTRAN

RNC

RNC

Node B

Node B

Iub

RNS

RNS


Iu Node B

radio station like the BTS in GSM.

RNC-Radio Network Controller

controls radio resources of several Node Bs

supports the Iu interface to the core network

RNS-Radio Network Subsystem

like BSS in GSM




UMTS radio access network interfaces

Node B

Node B

Iur

UTRAN

RNC

RNC

Node B

Node B

Iub

RNS

RNS


Iu Iur interface

logical interface between RNCs

basic inter RNC mobility (e.g. softhandover)

Iub interface

interface between RNC and Node B




Core network - circuit switched

MSC/VLR

CN

GMSC

GGSN

HLR

SGSN

Iu-CS

Iu-PS

Core Network

Iu-CS

for circuit switched services

MSC-Mobile Services switching Center

switch for circuit switched (CS) services

VLR-Visitor Location Register

register database for visitors of the radio

network

GMSC-Gateway MSC

switch from mobile network to external

networks for circuit switched services




Core network - packet switched

MSC/VLR

CN

GMSC

GGSN

HLR

SGSN

Iu-CS

Iu-PS

Core Network

HLR-Home Location Register

permanent database of subscriber data

Iu-PS

for packet switched services

SGSN-Serving GPRS Support Node

switch for packet switched (PS) services

GGSN-Gateway GPRS Support Node

switch from mobile network to external

networks for packet switched services




TE MT UTRAN CN IuEDGE

NODE

CN

Gateway

UMTS

“End-to-End Service” or “Teleservice”

TE/MT Local

Bearer ServiceUMTS Bearer Service External Bearer

ServiceUMTS Bearer Service

Radio Access Bearer Service(RAB) CN BearerService

Backbone

Bearer Service

Iu Bearer

Service

Radio Bearer

Service (RB)

UTRA FDD/TDD

Service(Radio PhysicalBearer Service)

Physical

Bearer Service

CN = Core networkTE = Terminal EquipmentMT = Mobile Termination

TE(e.g. UE)

e.g. UE

UMTS QoS Architecture TS23.107

Each bearer offers itsindividual services

Each bearer is usingthe services offeredby bearers below

QoS parameters aregiven by the core to

the RAN in radioaccess bearer set-up




Delay

sensitive

+

-

DataIntegrity

sensitive

-

+

QoS Classes

4 classes have been identified:

conversational

AMR speech service

Video telephony

– CS: H324

– PS: H323

streaming

interactive

location based services

computer games

background

e-mail delivery

SMS ...




Error

tolerant

Errorintolerant

Conversational

(delay <<1 sec)

Interactive Streaming

(delay <10 sec)

Background

(delay >10 sec)

ConversationalVoice and Video Voice Messaging

Streaming Audioand Video

Fax

E-mail arrivalnotification

FTP, still image,paging

E-commerce,WWW browsing,

Telnet,Interactive Games

(delay 1 sec)≈≈≈≈

Application Groups TS22.105




Bearer Service Attributes

The Attributes (QoS Parameters) of a Bearer Service can be negotiated at thebeginning of a connection and during a connection

Several different Bearer Services can be established simultaneously by one UE

Important Quality Parameters are

Maximum transfer delay

Delay variation

Bit error ratio

Data rate




Traffic class Conversational

class

Streaming

class

Interactive

class

Background

classMaximum

bitrate

X X X X

Delivery order X X X X

Maxum SDU size X X X X

SDU format

information

X X

SDU error ratio X X X XResidual bit

error ratio

X X X X

Delivery of

erroneous SDUs

X X X X

Transfer delay X X

Guaranteed bit

rate

X X

Traffic handling

priority

X

Allocation/

Retention

priority

X X X X

Source statistics

descriptor

X X Note: SDU = Service Data Unit

Radio Access Bearer (RAB) Service Attributes

The service attributes shown in the following table characterize a Radio

Access Bearer Service




QoS Examples for specific services (1) TS23.107

AMR (Adaptive Multi Rate) speech codec payload

Bit rate: 4,75 - 12,2 kbit/s

Delay: 100ms end-to-end delay at maximum

CODEC frame length is 20ms

BER:

10-4 for Class 1 bits (A,B)

10-3 for Class 2 bits (C)

FER < 0,5% (with degradation for higher erasure rates)




QoS Examples for specific services (2)

MPEG-4 video payload

Bit rate: variable, average rate scalable from 24 to 128 kbit/s and higher

end-to-end delay between 150 and 400ms

video CODEC delay is typically less than 200 ms

BER:

10-6 - no visible degradation

10-5 - little visible degradation

10-4 - some visible artefacts

> 10-3 - limited practical application



W-CDMA Basics

M lti l A T h i




Multiple Access Techniques

FDMA Frequency Division Multiple Access

uses band pass for carrier signal which are non-

overlapping in the frequency domain

TDMA Time Division Multiple Access

carrier signals are non overlapping in the timedomain

CDMA Code Division Multiple Access

spreads the signal over the entire available

bandwidth by using codes with good correlation

properties

FFrreeqquueennccyy

TTiimm ee

PPoowweerr

OO nnee UUsseerr

FFrreeqquueennccyy

TTiimm ee

PPooww eerr

UUsseerr

Power

Time

Frequency

One User

Carrier 1 Carrier 2




W-CDMA

W-CDMA = Wideband Code Division Multiple Access

Users are separated with code sequences (spreading/de-spreading technique)

All users are transmitting simultaneously on the same frequency

In FDD mode, different frequencies are used on uplink and downlink




Spread spectrum technique

The user bits are coded with a unique sequence (code).

The bits of the code are called chips and the chip rate is higher than the user

bit rate

Time

Domain

Bandwidth = 3.84 Mhz for UMTS

CodeCi(t)

Resulting spread signal

Di (t) = Si (t) x Ci(t)

Bit1 Bit2

Source signal Si (t)

before spreading

Frequency

Domain

Narrowband signal

Bit Rate =Rb

Chip Rate =Rc = 3.84 Mcps in UMTS

Chip Rate =RcSpreading Factor

SF =Rc/Rb




[1 1 -1 1 -1] [1 -1 -1 -1 1]

Spread Chip Sequence

c

sT

T L =

Spreading Factor

Spreading Chips

+1

-1

Symbol

+1

-1 -1 -1 -1

Ts

Tc

Direct Sequence Spread Spectrum




Spreading

SPREADING




Despreading

DESPREADING




Own and other signals




Spreading / Despreading

In the receiving path, de-spreading isachieved by auto-correlation with the samecode

Due to low cross-correlation properties with

other codes, the received signal energy isincreased compared to noise and othersignal interference

The gain due to despreading is calledprocessing gain

Example for 12.2 AMR speech:

dB kbps

kcps

Rate BitUser

RateChip PG 2575.314

2.12

3840================




Spreading and scrambling codes

Spreading codes (channelization codes)

used to differentiate mobiles and services

different lengths (spreading factor) according to service in UMTS

Orthogonal Variable Spreading Factor (OVSF) in UMTS

Scrambling codes

used to differentiate un-synchronized codes (from other UEs or Node-Bs)

1 scrambling code per sector on downlink

PN code family in UMTS

DL

UL UE

Descrambling Despreading

Spreading

OVSF

(Service identifier)

Scrambling

PN

(User identifier)

Node B

Spreading

OVSF(Service/ user identifier)

Scrambling

PN

(Cell identifier)

DescramblingDespreading




Channelization codes

Orthogonal Variable Spreading Factor (OVSF) are used for channelization, that

means for spreading

The codes are mutually orthogonal, if they are synchronized in the timedomain

Codes are taken from the OVSF code tree

Following codes are not allowed to be used: Codes between a used code and the code tree root

Codes following a used code




1c4,1=

c4,2=

c4,3=

c4,4=

c2,1=

c2,2=

c1,1

= 1

1 1

1 -1

11

1 1

1 -1

1 -1

reverse

copy 1 1

copy

reverse

-1 -1

1 -1

-1 1

reverse

SF= 4SF= 1 SF= 2

1 1 1 1 1 1 1

1 1 1 1 -1 -1 -1 -1

1 1 1 1-1 -1 -1 -1

1 1 1 1-1 -1 -1 -1

1 1-1 -1 1 1-1 -1

1 1-1 -1 1 1-1-1

1 -1 -1 1 1 -1 -1 1

1 -1 -1 1 -1 1 -11

…

Up to SF=256

Spreading codes: OVSF code tree

S di d




Code tree organisation

C256, 0

P-CPICHC256,1

P-CCPCH

C256, 2

PICH

C256, 3

AICHC64, 1

S-CCPCH

…x 16

SF256

SF128

SF64

SF32

SF16

Not available

Available

Used by DL DPCH

Spreading codes

OVSF O th lit t




1c4,1=

c4,2=

c4,3=

c4,4=

c2,1=

c2,2=

c1,1= 1

1 1

1 -1

11

1 1

1 -1

1 -1

1 1

-1 -1

1 -1

-1 1

1 1 1 1 1 1 1

1 1 1 1 - 1 - 1 - 1 - 1

1 1 1 1-1 -1 -1 -1

1 1 1 1- 1 - 1 - 1 - 1

1 1-1 -1 1 1-1 -1

1 1-1 -1 1 1-1-1

1 - 1 - 1 1 1 - 1 - 1 1

1 - 1 - 1 1 -1 1 -11Codes free

Codes used

OVSF : Orthogonality property

S bli g d




Long scrambling codes

Improved cross correlation

Uniform distribution of the interference

A Gold sequence is used with length of 38400 chips

In case of Multi-User detection (MUD), short scrambling codes (differentfamily of codes) can be used (easier computations)

Scrambling codes

Downlink Scrambling Code




RNCSC#0SC#1

SC#2

Node

B

Node

B

SC#128 SC#129

SC#130

SC: Scrambling Code

Downlink Scrambling Code

Downlink scrambling code

One code per cell (sector/carrier) : Configurable by operator

512 sets of 16 codes each (1 primary and 15 secondary) Only the primary scrambling code is used for all Common Channels

Uplink scrambling code groups




o UE uses scrambling code from 0 to max 241-1

o The network assigns the scrambling code to be used by the UE

Done on RNC basis

Groups per RNC to be planned

o The uplink scrambling codes are divided into 512 code groups

o Each code group has max 232 codes

o These 512 code groups match to the 512 primary codes of the downlink

Uplink scrambling code groups

Interference limited system




Interference limited system

Thanks to spreading/de-spreading

Desired signal is raised

Interference signals are kept low

However the level of interference must be controlled to to avoid receiving

too much interference and not being able to discriminate useful signal

spreadingspreading DespreadingDespreading

BB

ChannelChannel

WW

Thermal NoiseThermal Noise

BB

Processinggain

“Near-Far-Problem”




UE 1

UE 2

Before despreading After despreading

Near Far Problem

Up to around 80 dB attenuation between UE1 and UE2

If UE1 and UE2 transmitted with the same power, UE1 would jam UE2 : so-

called “near-far” effect

Solution : power control

Need for an efficient power control able to fight against slow AND fast

fading!

Power Control




Power Control

TX Power is adjusted regularly so that each connection is received with the

required Eb/Nt of its service

Uplink: Avoid „Near-Far-Problem“

Downlink: Power share allocation

Policy: “No one gets a higher quality (Eb/Nt) than he needs. Everyone getsexactly the required quality or is not served at all“

no unnecessary increase of interference for other mobiles

no waste of common power resource in the downlink

Interference limited




When the number of users in the cell increases, the interference levelincreases (noise rise), the required received power at the base stationto reach a given Eb/Nt (quality) increases

For high interference level, the required received power becomesinfinite: power control is unstable pole capacity

Coverage and capacity are linked in CDMA systems

0

2

4

6

8

10

12

14

16

18

20

0 10 20 30 40 50 60 70

Number of simultaneous users per sector

I n t e r f e r e n c e l e

v e l r e l a t i v e t o

N o i s e

l e v

e l

( d B )

Cell breathing




Considering the limitation of maximal transmit power, the increase of

required received power due to high traffic will lead to decrease the

cell range

The cell coverage decreases when the traffic increases : so-called “cell

breathing” phenomenon

Coverage and capacity are linked in CDMA systems

Load control




T r a f f i c

d e

n s i t

y

i n c

r e a s

e s

Deployed intersite distanceDeployed intersite distance

In order to avoid power control instability and coverage holes due to high

traffic level, the level of interference received by a base station should be

controlled by means of admission and load control algorithms



Uplink Cell load (monoservice)




Interference level as a function of capacity

0

5

10

15

20

25

30

35

0 10 20 30 40 50 60 70 80 90 100

Cell loading (%)

50% of cell load

(3dB of interference)

max loading : 75%

I

n t er f er en c e

l ev el

( d B )

)1log(10 UL X NoiseRise −−−−−−−−====

Note:For cell load above 75 %, thesystem gets unstable

The UL cell load is directly linked to the so called ‘Noise Rise’ or interference

level

100 % UL cell load means infinite mobile power required

monoservice

CDMA downlink




Downlink particularities

The downlink signals of the Node-B are synchronised

In W-CDMA, OVSF spreading codes have orthogonality properties : less

intracell interference The total transmit power of Node-B is shared between traffic channels and

common channels (pilot, paging, synchronisation)

A constant part of power is dedicated to common channels

Downlink traffic channels are power controlled. The maximal transmit powerand the dynamic of power have to be parameterized for each service

The maximal total downlink power is the limiting factor



UMTS Radio Environment

Propagation model




o No special propagation model currently used for broadband signals at 2GHz

o Standard propagation model based on Hata-Okumura model for macrocellular

COST-HATA is only valid for 1500-2000 MHz

Calibration of morpho correction factors required




Shadowing and Fast fading (2)




In UMTS, power control will fight against shadowing and fast fading

-20

-15

-10

-5

0

5

10

15

20

25

0 1000 2000 3000

Slot Number (0,666 ms)

P o w e r ( d B m )

F a s t f a d i n g v a l u e s

( d B )

Fast fading samples (dB)

Transmit power (dBm)

0 1000 2000 3000


R e c e i v e d P o w e r a t N o

d e - B ( d B m )

Transmit power

Received power


Shadowing




Same as in GSM

Slow fading variations due to obstacles (buildings, hills,…) are called

shadowing

Shadowing can be modeled as a random variable with log-normal distribution

of 0 mean and standard deviation that is characteristic of the environment

Normal/Gaussian Distribution

0

0.05

0.1

0.15

0.2

0.25

0.3

0 2 4 6 8 10 12

Fade Level

P r o b a b i l i t y D e n s i t i y F u n c t i o n


Multipath Diversity




Due to Reflection and diffraction of the transmit signal on obstacles there is

not only one path but a large number of paths with different delays and

amplitudes

In W-CDMA, due to larger bandwidth, RAKE receiver will take benefit of this

diversity

Multipath profile


RAKE receiver (1)




RAKE receiver is a spread-spectrum receiver that is able to track and

demodulate resolvable multipath components :

It takes benefit of multipath diversity

In W-CDMA, with 3.84 Mcps, a RAKE receiver will be able to discriminate

multipath having delays higher than one chip duration (0.26 s)

RAKE receiver

combining


RAKE receiver (2)




It combines the delayed replicas of the transmitted signal to improve

reception quality : time-diversity technique:

Identify the delay positions on which significant energy arrives and allocate

correlation receivers (RAKE fingers) to those peaks

Within each correlation receiver, track the changing phase and amplitude

values and correct them (thanks to pilot symbol estimation)

Combine the demodulated and phase-adjusted symbols across all active

fingers and present them to the decoder for further processing (maximal

ratio combining)


Typical multipath channels (1)




o Typical multipath channels can be derived from measurement campaigns

o ITU defined such typical profiles and they were used during the UMTS radio

interface evaluation process:

Vehicular A & B,

Outdoor to Indoor A & B,

Indoor Office A & B


Typical multipath channels (2)




Pedestr ian A V e h icu lar A

Tap Relat ive

D elay (ns)

Ave r a ge

P ow e r ( dB )

Rela t ive

D elay (ns)

Ave r a ge

P ow e r ( dB )

1 0 0 0 0

2 11 0 -9 .7 31 0 -1 .03 19 0 -19 .2 71 0 -9 .0

4 41 0 -2 2 .8 1 09 0 -10 .0

5 - - 1 73 0 -15 .0

6 - - 2 51 0 -20 .0

0 t [ns]110 190 410

Power

t [ns]

0 310 710 1090 1730 2510

Power

Environment

Channel power

variance for 1

antenna (dB)

Power control gainInterchip

interference

Pedestrian A 24.5Large gain can be expected at low

speeds (<10 km/h)Small

Vehicular A 8.5 Medium Large




Fast fading (2)




-15

-10

-5

0

5

10

0 100 200 300 400 500 600 700 800 900 1000

Slot number (every 0,666ms)

F a s t F a d i n g v a l u e ( d B )

Vehicular A 3 km/h

Vehicular A 50 km/h

Vehicular A

Tap Relativedelay (ns)

Averagepower (dB)

1 0 0

2 310 -1

3 710 -9

4 1090 -10

5 1730 -15

6 2510 -20

6 paths with

2 main pathsVeh. A : Half a wavelength between 2 fading holes (90 ms for

3km/h, 5.4 ms for 50km/h)


C/I and Eb/No




o Eb/Nt target = minimum required power density (or energy per bit) over theinterference (or noise) power density to reach target BER/BLER after decoding

C/I = (Eb*Rb)/(No*W) = (Eb*Rb)/(No*Rc) = Eb/No * Rb/Rc

o Example of speech : (Eb/No)target around 6 dB for good BER means a

(C/I)target of 6-25= -19 dB (GSM : 9-12 dB)

(C/I)target dB = (Eb/No)target dB - PG dB(C/I)target dB = (Eb/No)target dB - PG dB

RF Filter60MHz

DownConverter

LP Filter3.84 MHz

D.A.C Digital FilterNyquist

DescramblingDespreading

C/I Eb/No

chips chips bits

DEMODULATOREc/Io

Decoder


Link level simulations




o Eb/No figures gives performance for dimensioning

o Eb/No figures depend on service, mobile speed, multipath channel profile,

diversity technique used

o Link level simulations model the transmitter and receiver channels (coding,

decoding, spreading, despreading, demodulation, power control…)

o Link level simulations enable to derive Eb/No figures according to required

BLER target


Eb/No measurements




o Eb/No can also be measured on the equipment:

on lab tests

on the field (“on-air” network)

o Note that specific test conditions have been defined by 3GPP to characterize

the performances of the Node-B:

specific channel mapping

specific multipath channel

without power control

Not suited for

dimensioning purpose


Receiver Sensitivity




Reference SensitivityReference Sensitivity = (C/I) +NF + 10log(NtW)

= NF +10log(Nt)+ 10log[(Eb /N0)] + 10log(Rb)

Service dependent

in dBm

in dB

Rx Sensitivity calculation : minimum required C level to reach a given quality

(C/I target) when facing only thermal noise

Where:

Nt Thermal Noise density, 10log(Nt) =-174 dBm/Hz

(Eb/No) : Service target Eb/No (here: non-logarithmic)

Rb: Service bit rate

NF: Node-B Noise figure in dB



Logical/Transport/PhysicalChannels

Logical, Transport, Physical channels




Logical Channels

are defined by the kind of information transported

signaling, system information, user data, …

Transport Channels

are defined by how and with what characteristics data is transported

max delay, type of coding, required BER, transport format, ...

Physical Channels are defined by

information transported

– stand alone (Layer 1 support)

– signaling, common and dedicated channels

slot format

Mapping between different channel types in FDD

MAC d f




CCCH

CPCH DCH

DCCHDTCH

PCH BCH FACH DSCH DCH

PCCH BCCH CCCH CTCHDCCHDTCH

UPLINK DOWNLINK

LOGICALCHANNELS

TRANSPORTCHANNELS

DPCCHDPDCH

SCCPCH PCCPCH PDSCHDPCCHDPDCH

PHYSICALCHANNELS

PCPCH

SCH CPICH AICH PICH CSICH CD/CA-ICHStandalone physical channelswithout connection to transport layer

RACH

PRACH

RLC Layer

MAC Layer

PHY Layer

MAC data transfer

services providedon logical channelsControl ChannelsTraffic Channels

PHY datatransferservices

provided on

transportchannels

DedicatedTransportChannels

CommonTransportChannels

Variable bitrate support

andmultiplexing

Mapping between different channel types in FDD

Dedicated Paging and Point to




CCCH

CPCH DCH

DCCHDTCH

PCH BCH FACH DSCH DCH

PCCH BCCH CCCH CTCHDCCHDTCH

UPLINK DOWNLINK

LOGICALCHANNELS

TRANSPORTCHANNELS

DPCCHDPDCH

SCCPCH PCCPCH PDSCHDPCCHDPDCH

PHYSICALCHANNELS

PCPCH

SCH CPICH AICH PICH CSICH CD/CA-ICHStandalone physical channelswithout connection to transport layer

RACH

PRACH

Control infobw UE and

network

Dedicated

channels

Paging and

broadcast

Point-to-

multipointchannel

Randomaccess

Common controlphysicalchannels

Synchro PilotAcquisitionIndicator

PagingIndicator

Logical channels




PCCH - Paging control Channel (DL)

DL Paging information

BCCH - Broadcast Control Channel (DL)

DL System control information

e.g. Cell identity, UL interference level

CCCH - Common control Channel (UL/DL)

For transmitting control information between the network and Ues. The CCCH iscommonly used by UEs having no RRC connection and after cell reselection

e.g. initial access (RRC connection request, cell update)

Logical channels




CTCH - Common Traffic Channel (DL)

channel to transfer dedicated user information to all or a group of UEs

e.g. SMS Cell broadcast

DCCH - Dedicated Control Channel (UL/DL)

transmits dedicated control information between UE and UTRAN

e.g. measurement reports, radio bearer setup

DTCH - Dedicated Traffic Channel (UL/DL)

The DTCH carries user data

e.g. speech, Fax, video, web, ...

Transport Channels

Why?




A transport channel offers flexibility to arrange information on any service-

specific rate, delay or coding before mapping it on a physical channel:

• provides flexibility in traffic variation

• enables multiplexing of transport channels on the same physical channel

• Provide flexibility in supporting different technologies: ATM, IP, ADSL, etc

Transport Channels




Definition

Services provided by PHY layer to higher layers

Defined by how and with what characteristics data is transferred over the air

Dedicated Channels

Common Channels

Dedicated Channels

DCH - Dedicated to a single UE

Uplink or Downlink

Common Channels

BCH – Broadcast (DL, system and cell information, single TF)

FACH – Forward Access Channel (DL)

PCH – Paging Channel (DL)

RACH – Random Access Channel (UL)

CPCH – Common Packet Channel (UL)

DSCH – Downlink Shared Channel (DL)

Transport Channels




General Concepts

Transport Block: Basic unit b/w MAC and Layer 1, Layer 1 adds a CRC to eachTransport Block

Transport Block Set: Set of TB exchanged at the same time using the sameTransport Channel

Transmission Time Interval: MAC delivers one Transport Block Set per TTI (multipleof 10ms) to Layer 1

Transport Format: Information describing a TBS and how it has to be delivered Transport Format Set: Set of Transport Formats associated to a Transport Channel

Transport Format Combination: Authorized combination of TF that can besimultaneously submitted to Layer 1

Transport Format Combination Set: Set of TFC on a CCTrCH

Transport Format Indicator: Label for a TF within a TFS

Transport Format Combination Indicator: Representation of the TFC

Transport Channels




Transport Channels




General Concepts

MAC indicates the TFI to L1 at each delivery of TBS on each Transport Channel

L1 builds the TFCI from all TFI from parallel Transport Channels

L1 processes the Transport Blocks appropriately

L1 appends the TFCI to the physical control channel



Transport Channels




DCH - Dedicated Channel

DCH is the only Dedicated Transport Channel

Channel dedicated to one UE

Supports

– Fast Power Control, variable bit rate, SHO, transmit diversity, beamforming

DSCH - Downlink Shared Channel

Similar to the FACH

Carries dedicated user data and/or control information

Always associated with a downlink DCH (with SF of 256)

DSCH supports– sharing between different users

– no SFH, but Fast PC due to associated DCH

Transport Channels




RACH - Random Access Channel

carries control information or small amounts of packet data

– e.g. for initial access or non-real-time dedicated control or traffic data

transmitted over entire cell supported by open loop power control

CPCH - Common Packet Channel

Similar to DSCH in DL, used for transmission of bursty data traffic

possibility to– transmit over part of the cell (beam forming)

– change rate fast

– fast power control

initial risk of collision, but collision detection (CD/CA-ICH) Is shared by the UEs in a cell -> common resource

Physical Channels (TS25.211)




Channels without connection to transport channels are called Stand-alone

channels

All Stand-alone channels exist in DL only

Stand alone channels are

CPICH Common Pilot Channel

SCH Synchronization Ch (Primary & Secondary)

AICH Acquisition Indication Channel

PICH Paging Indicator Channel

CSICH CPCH Status Indicator Channel

CD/CAICH Collision Detection / Channel Assignment

Indicator Channel

Physical Channels

Uplink DPDCH and DPCCH




p

DPDCH carries the DCH transport channel

DPCCH carries L1 control information

I/Q multiplexed

Pilot

Npilot bits

TPC

NTPC bits

Data

Ndata bits

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

Tslot = 2560 chips, 10 bits

1 radio frame: Tf = 10 ms

DPDCH

DPCCHFBI

NFBI bitsTFCI

NTFCI bits

Tslot = 2560 chips, Ndata = 10*2k

bits (k=0..6)Channel

estimation

TransportFormat

CombinationIndicator

FeedbackInformation for

closed-loopTxDiv

Power Controlcommand

DPCCH: Fixed spreading factor of 256

Physical Channels




Downlink DPDCH and DPCCH

One radio frame, Tf = 10 ms

TPC

NTPC bits


Tslot = 2560 chips, 10*2k bits (k=0..7)

Data2

Ndata2 bits

DPDCH

TFCI

NTFCI bits

Pilot

Npilot bits

Data1

Ndata1 bits

DPDCH DPCCH DPCCH

Physical Channels




PRACH: Physical Random Access Channel Based on slotted ALOHA with fast acquisition indication

Message partPreamble

4096 chips 10 ms (one radio frame)

Preamble Preamble

Message partPreamble

4096 chips 20 ms (two radio frames)

Preamble Preamble

Pilot

Npilot bits

Data

Ndata bits


Tslot = 2560 chips, 10*2k bits (k=0..3)

Message part radio frame TRACH = 10 ms

Data

ControlTFCI

NTFCI bits

Repetitionof a 16 chipsignature

Data partmapped tothe RACH

Control partfor channelestimationand TFCI

Physical Channels




AICH: Acquisition Indicator Channel Fixed rate (SF=256)

Carries Acquisition Indicators (AI)

An AI corresponds to a signature on the PRACH

1024 chips

Transmission Off

AS #14 AS #0 AS #1 AS #i AS #14 AS #0

a1 a2a0 a31a30

AI part = 4096 chips, 32 real-valued symbols

20 ms

Physical Channels

l h l




CPICH: Common Pilot Channel Fixed rate (30Kbps, SF=256)

Aid the channel estimation at UE

Provide phase reference for the common channels

Used for measurements in case of hand-over and cell selection/re-selection

Pre-defined bit sequence


Tslot = 2560 chips , 20 bits


Physical Channels

P CCPCH P i C C l Ph i l Ch l




P-CCPCH: Primary Common Control Physical Channel Fixed rate (30Kbps, SF=256)

Carries BCH

Data

Ndata1=18 bits


Tslot = 2560 chips , 20 bits


(Tx OFF)

256 chips

Time-multiplexed

with SCH

Physical Channels

S CCPCH S d C C t l Ph i l Ch l




S-CCPCH: Secondary Common Control Physical Channel Carries FACH and PCH


Tslot = 2560 chips, 20*2k

bits (k=0..6)

Pilot

Npilot bits

Data

Ndata1 bits


TFCI

NTFCI bits

Physical Channels

SCH S h i ti Ch l




SCH - Synchronization Channel Time multiplexed with PCCPCH

first 256 chips of slot SCH, rest PCCPCH

Primary SCH Consists of a a fixed 256 chips code Primary Synchronization Code (PSC)

The PSC is the same for every cell in the system

The PSC is repeated in each slot

Secondary SCH

Transmitted in parallel to the Primary SCH

In each of the 15 slots a different Secondary Synchronization Code SSC istransmitted

The SSC sequence indicates the used downlink scrambling code set (8 codes) out of

64 scrambling code groups

Physical Channels

AICH Acquisition Indication Channel




AICH - Acquisition Indication Channel SF256, Frame length 20ms 5120 chips/slot

Used to confirm reception of (P)RACH

PICH - Paging Indicator Channel SF=256, carries the paging indicators

associated with an SCCPCH to which a PCH transport channel is mapped

Once a PI message has been detected on the PICH, the UE decodes the next PCH

frame transmitted on the SCCPCH whether there is a paging message intended forit.

CSICH - CPCH Status Indication Channel

CD/CA-ICH - CPCH Collision Detection/Channel Assignment Indicator Channel All CPCH related physical channels support the operation of the UL CPCH transport

channel



Basic Algorithms

Interfaces to Layer 1




Physical Layer

Medium Access Control

Radio Resource Control

Layer 1

Layer 2

Layer 3

PHY primitives

CPHY primitivesControl of the

configuration

↓ Transfer of transport blocks

↑ Status of Layer 1↑ Transport blocks and error indication

Layer 1 Functions

FEC encoding/decoding of transport channels

M




Measurements

Macro-diversity distribution/combining and soft-handover

Error detection on transport channels

Multiplexing of transport channels and de-multiplexing of CCTrCh

Rate matching

Mapping of CCTrCh on PHY channels

Modulation/de-modulation and spreading/de-spreading of PHY channels Frequency and time synchronization

Closed-loop power control

Power weighting and combining of PHY channels

RF processing

Cell Search

Cell Search




Step 1: Slot synchronization

UE uses SCH primary synchronization code

Primary synchronization code is common to all cells The primary synchronization code is the same in every slot slot boundary

Step 2: Frame synchronization and code-group identification

UE uses the SCH secondary synchronization code

Correlation with all possible 64 secondary synchronization codes

Step 3: Scrambling code identification

Correlation over the CPICH with all (8) codes of the code-group

P-CCPCH can be detected

Random Access

o UE randomly selects an access slot and a signature




o It transmits a Preamble with Preamble_Initial_Power

o If no answer, it chooses a new slot and a new signature; power is increased

by Power_Ramp_Step

o In case of positive answer, message part is transmitted

“Near-Far-Problem”




Up to around 80 dB attenuation between UE1 and UE2

If UE1 and UE2 transmitted with the same power, UE1 would jam UE2 :

so-called “near-far” effect

Solution : power control

Need for an efficient power control able to fight against slow AND fast

fading!

UE 1

UE 2

Before despreading After despreading

Power control




In UMTS FDD, all users are sharing the same frequency band

W-CDMA requires power control to minimize the level of interference

(interference-limited system) Power control is applied on both uplink and downlink

Power control minimizes the transmission power to match the quality target

for each radio access bearer service No one should get more power than necessary to reach the required QoS

Avoids near-far problem on uplink

Power Control

Need for a fast power control (1)

Th t it t




o The transmit power must vary

in time to compensate for the

variations of the attenuation

over the air interface: attenuation due to distance,

Slow attenuation (shadowing

due to obstacles)

fast attenuation (fast fading).

-70

-60

-50

-40

-30

-20

-10

0

0 . 1

2 . 8

5 . 4

8 . 0

1 0 . 6

1 3 . 2

1 5 . 9

1 8 . 5

2 1 . 1

2 3 . 7

2 6 . 3

2 9 . 0

3 1 . 6

3 4 . 2

3 6 . 8

3 9 . 4

4 2 . 1

4 4 . 7

4 7 . 3

4 9 . 9

Distance [m]

R e c e i v e d P o w e r [ d B m ]

Lognormal fading

Raleygh fading

Power Control

Need for a fast power control (2)




o Half a wavelength between 2 fading holes

o Mean time between 2 fading holes at 2 GHz:

90 ms at 3 km/h

5 ms at 50 km/h

2.25 ms at 120 km/h

o In W-CDMA UMTS FDD, the rate of power control is equal to one power

control command every 0.666 ms (1500Hz vs. 2Hz in GSM)

6 paths with2 main pathsVeh. A : Half a wavelength between 2 fading holes (90

Power ControlExample of Fast fading according to speed




-15

-10

-5

0

5

10

0 100 200 300 400 500 600 700 800 900 1000

Slot number (every 0,666ms)

F a s t F a d i n g

v a l u e ( d B )

Vehicular A 3 km/h

Vehicular A 50 km/hVehicular A

Tap Relative

delay (ns)

Average

power (dB)

1 0 0

2 310 -1

3 710 -9

4 1090 -10

5 1730 -15

6 2510 -20

2 main pathsms for 3km/h, 5.4 ms for 50km/h)

Power ControlPower Control behaviour

I UMTS t l ill fi ht i t h d i d f t f di




In UMTS, power control will fight against shadowing and fast fading

-20

-15

-10

-5

0

5

10

15

20

25

0 1000 2000 3000


P o w e r ( d B

m )

F a s t f a d i n g v a l u e s ( d B )

Fast fading samples (dB)

Transmit power (dBm)

0 1000 2000 3000


R e c e i v e d P o w e r a t

N o d e - B ( d B m )

Transmit power

Received power



Power ControlOpen loop

No feedback whether the transmit power setting was ok or not




No feedback whether the transmit power setting was ok or not

Uplink

Node-B sends:

output power

needed SIR

uplink interference level

UE calculates output power from:

Node-B output power

Measured received signal

needed SIR

uplink interference level

Downlink

UE sends:

measurement reports

UTRAN calculates output

power from:

UE measurement reports

Node-B output power

needed SIR

TPC d

Power ControlUplink closed loop




TPC commands SIR target (FP)

UE

• Adjusts Tx powerbased on receivedTPC commands

NODE B• SIR measurement on UL DPCCH

• Generate TPC commands bycomparing the measured SIR to

SIR target• Decode data blocks and generate

CRCI

UL DPCCH/DPDCH

INNER-LOOP

Transport blocks + CRCI (FP)

SRNC• Adjusts SIR target based

on CRCI to reach thetarget BLER (given by CN

at RAB assignmentrequest)

OUTER-LOOP

Node B

Serving RNC

Power ControlUplink inner loop

o TPC command generation every 0.666ms (1500 times per second)




If SIRmeas > SIRtarget, TPC command = power down one step

If SIRmeas < SIRtarget, TPC command = power up one step

o The step adjustment size is 1dB by default

o SIRtarget is estimated by the outer loop to reach the target BLER specified for

each service

The SIR target is typically determined 10-100 times per second

Power ControlUplink inner loop

o Algorithm 1:If SIR t SIRt t TPC d i 1




o If SIRest > SIRtarget TPC command is -1

o If SIRest < SIRtarget TPC command is +1

o Upon reception of more than one command: Algorithm 1 is based on soft

symbol decision on each commando Algorithm 2: after 5 slots

o if all 5 TPC commands are 1 resulting TPC command is +1

o if all 5 TPC commands are 0 resulting TPC command is –1

o otherwise resulting TPC command is 0o Upon reception of more than one command:

o For each link, compute TPC_cmd(i) as previously over 5 slots

o if 1/N Σ TPC_cmd(i) > 0.5 resulting TPC command is +1

o if 1/N Σ TPC_cmd(i) < -0.5 resulting TPC command is –1

o otherwise resulting TPC command is 0

Power ControlUplink outer loop

o The following algorithm is used :




At each received block:

Nblocks = Nblocks + 1

If CRCI = ‘fail’ Nerrors = Nerrors +1

If Nblocks ≥ Ntb

If Nerrors > Nerror_up increase SIRtarget by SIR_up

If Nerrors < Nerror_down decrease SIRtarget by SIR_down

Nblocks = 0, Nerrors = 0o The parameters of the algorithm can be configured (one value per service)

o Thanks to the outer loop, the system will be able to adapt the Eb/No target (for a

target BLER) according to the environment moving conditions (multipath, speed for

instance)

Node BDLDPCCH/DPDCH Serving

RNC

Power ControlDownlink closed loop

Target BLER




UE

• SIR measurement on DL

DPCCH

• Generate TPC commandsby comparing the measuredSIR to the SIR target

• Decode data blocks andgenerate CRCI

• Adjusts SIR target to reachthe target BLER

NODE B

• Adjusts Tx powerbased on received TPCcommands

Node B

TPCcommands

INNER-LOOP

RNC

SRNC

• Signals the target BLERto the UE via RRCsignaling

Outerloop

withinUE

Power ControlNeeds for Power Balancing

o For the DL power control, the UE sends the same TPC command to all cells inthe active set:




When a new link is added the initial DL transmit power is not aligned with the othercells in the Active Set

When some errors occur during UL transmission, different cells in the active setmay interpret the command differently

o This will cause a decrease of the soft-handover gain since this gain is thelargest when the receive powers from all cells in the active set are equal.

o Thus, a mechanism, known as Power balancing, is required

o Alcatel-Lucent claims 10-15% gain on capacity with power balancing

Node B

DL Power control (NBAP)Serving

RNC

Power ControlPower balancing algorithm




UE

• CPICH_Ec/Io isregularly measured by theUE for all cells in theactive set and reported to

the CRNC via RRCsignaling.

NODE B

• Change the DL DPCCHtransmit power of each cellsin the UE active set whenreceiving a ‘DL powercontrol’ command from theCRNC

• A correction is periodicallyperformed towards thereference power

RNC

SRNC

• Regularly computesthe DL DPCCH power asfor the initial power

• Regularly sends a ‘DLpower control’ commandto all Nodes B in the UE

active set (only for UE inSHO) DL referencepower

Measurement report (RRC)

Goal = align Node Bs transmitter powers involved in a Soft HO with a UE

Soft Handover (SHO)Principles

Connection is shifted softly from one cell toanother cell on the same carrier

RNC




All Node Bs, which are involved in soft/softerhandover belong to the Active Set (AS) of the communication

The decision to change the AS will mainly relyon the measured PCPICH level of the cell

Max AS size is limited by parameter settings

All Node Bs from the AS process the signalfrom the UE

A softer handover is a soft handover betweendifferent sectors of the same Node B

The UE receives the ‘same’ signal fromdifferent cells and therefore from differentpaths diversity gain

N

Macrodiversity

Received

PilotSignal

Node-B 2

3 dB

Node-B 1

In UL selection of the best signal on a frame basis at RNC level -

Soft HO

Soft Handover (SHO)Macrodiversity gain




In UL selection of the best signal on a frame basis at RNC level

‘selection diversity’

In DL Maximum Ratio combining due to RAKE receiver at UE

For UL & DL good decorrelation due to different locations of Node

Bs many multipaths

In UL Maximum. Ratio Combining at Node B

In DL Maximum Ration combining due to RAKE receiver at UE

For UL & DL less decorrelation due to “same” location of sectors

less multipaths

Softer HO

RNC

RNC

Soft Handover (SHO)Events vs. Periodic Reporting

o The UE is told by the UTRAN, which events shall trigger a measurement report less reports than every 480 ms in GSM




o The report is evaluated by the HO algorithm

o For Release 99 only intra frequency events are defined:

1A - a PCPICH enters the reporting range

1B - a PCPICH leaves the reporting range

1C - a non–active PCPICH becomes better than an active primary CPICH

1D - change of best cell (Primary)

1E - a PCPICH becomes better than an absolute threshold

1F - a PCPICH becomes worse than an absolute threshold

Soft Handover (SHO)Algorithm example

CPICH 1

Measurement ∆T ∆T ∆T




Cell 1Cell 2

Cell 3

Event 1AAdd Cell 2

Event 1CReplace Cell 1

with Cell 3

Event 1BRemove Cell 3

As_Th + As_Th_Hyst

AS_Th –As_Th_HystAs_Rep_Hyst

CPICH 2

CPICH 3

Time

Only cell 1 in AS

Only cell 2 in AS

Soft Handover (SHO)UL closed loop Power Control and SHO

o In SHO, more than one TPC commands are sent to the UE




o The UE must combine all received TPC commands and get a single TPC value.

If at least one of the Node-Bs in the active set is sending a power down

command, the UE will reduce its output power.

TPC = Down TPC = Up

TPC = Down

Soft Handover (SHO)DL closed loop Power Control and SHO

Received TPC = Sent TPC ?




o As each Node-B processes the UE TPC command independently power drifting

is possible

o One Node-B performs “power up” while another one performs “power down”

o This would degrade the SHO performance and should be avoided with slower powercontrol:

o UE sends 3 times the same TPC and Node-B combines all the 3 to improve accuracy

TPC

Inter-Frequency handoverHard handover

o RNC can trigger blind hard hand-over or Compress Mode HHOo The terminal must make measurements on other frequencies while still




q

having the connection running on the current frequency:

Dual receiver

simple handover operation, but expensive receiver

Compressed mode (or slotted mode)

simple receiver, but complicated handover operation

o The information is compressed time periodically (a few ms), in order to

perform measurements on the other frequencies

Downlink

10ms frame Idle period

Compressedframe

UTRA cell GSM cell


o Blind hand-over: requires overlapping of the source cell by the target cell




o Compressed mode:

o Transmission and/or reception is stopped during few ms

o UE can do measurements on another frequency

o Frames are compressed to create transmission gaps


o 3GPP has defined three methods for compressed mode:

o Higher layer scheduling: through reduction of the data rate

d d




o Spreading factor reduction: PHY data rate is increased

o Puncturing: symbol rate reduction at PHY layer

o Measurements types:

o GSM Initial BSIC identification

o GSM BSIC reconfirmation

o GSM carrier RSSI

o WCDMA carrier RSSI

Call Admission ControlPrinciple

CAC (Call Admission Control)

• Rejects all calls requesting UTRAN resources above the existing hw/sw limits• Applies to all types of traffic (CS & PS)




Other features acting during Call admission in case of lack of UTRAN resources:

• HSPA2DCH Fallback: HSPA call can be reconfigured to DCH if no HSPA resources.

• iMCTA CAC – allows to redirect a call on another Frequency or RAT if no resources available onthe current primary cell

• iRM CAC – part of larger set of iRM

algorithms (intelligent resourcesmanagement)

• Performs PS RABs downsize at admission accordingto the load level of different resources monitored(RF Power, Codes, CEM, Iub…) and also RL quality.

• Applies only on R99 PS traffic.

Call Admission ControlHigh traffic load behaviour

UE requests an UTRAN resource (Power, Codes, CEM, Iub…) and is not getting it becausethe resource is not available => resource Blocking

Blocking can impact different phases of the call:




Blocking during Call Admission phase as it is considered the most impacting for callintegrity (direct impact on call success).

The only solutions against blocking:

• Additional hw resources

• Resources management features activation (iRM, HSDPA fallback, iMCTA CAC)

Additional RL not added in the ActiveSet (risk of call drop)

Call is not reconfigured (impact on userthroughput)

Call admission failure

Effect

Lack of resources to perform iRM transitions(RB Adaptation Upsize, iRM Sched Upgrade…)

Call Reconfiguration

No resources available for additional RLMobility

Lack of resources at call setupCall Admission

Blocking CauseCall Phase

• Resources management features (iRM…) usage is highly recommendedin order to avoid useless hw upgrade

RAB Allocation ProcedureRAB Allocation ProcedureSuccessful PS RAB Allocation

RAB Assignment Request

UE CNBTS RNC

PS call initial connection (RRC phase) …




RAB Assignment Response (Success)

Radio Link Reconfiguration Prepare

Radio Link Reconfiguration Ready

Radio Bearer Setup

Radio Bearer Setup Complete

UP / DL Synchronization

UP / UL Synchronization

Radio Link Reconfiguration Commit

RNC CAC

BTS CAC

iRM CACRNC mechanisms

BTS mechanism

• BTS and RNC CAC mechanisms are involved in different call establishment phases.

• iRM CAC is a specific RNC mechanism

RAB Allocation ProcedureRAB Allocation ProcedureSuccessful PS RAB Allocation

Main UTRAN Resources that can trigger CAC action (call admission blocking):

BTS Channel Elements – Resource managed by BTS CAC

Blocking of this resource ⇒ RB rejection or RL Setup/Reconfiguration failures




Iub ATM – Resource managed by RNC CAC

Blocking of this resource

⇒RB rejection

RF power – Resource managed by RNC CAC

Blocking of this resource ⇒ RB rejection

UL load (RTWP) – Resource managed by BTS CAC

Blocking of this resource ⇒ RB rejection or RL Setup/Reconfiguration failures

OVSF Codes – Resource managed by RNC CAC

Blocking of this resource ⇒ RB rejection

RNC CPU – Resource managed by the RNC

Blocking of this resource ⇒ Overload mechanism => RB rejection




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