36255366 wcdma ran planning and optimization book1 wrnpo basics

7/16/2019 36255366 WCDMA RAN Planning and Optimization Book1 WRNPO Basics

1/283

www.huawei.com

Copyright 2008 Huawei Technologies Co., Ltd. All rights reserved.

WCDMA RAN

Fundamental


2/283

Page1Copyright 2008 Huawei Technologies Co., Ltd. All rights reserved.

Objectives

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

Describe the development of 3G

Outline the advantage of CDMA principle

Characterize code sequence

Outline the fundamentals of RAN

Describe feature of wireless propagation


3/283


Contents

1. 3G Overview

2. CDMA Principle

3. WCDMA Network Architecture and protocol structure

4. WCDMA Wireless Fundamental


4/283


Contents

1. 3G Overview

2. CDMA Principle




5/283


Different Service, Different Technology

AMPS

TACS

NMT

Others

1G 1980s

Analog

GSMGSM

CDMACDMAIS-95IS-95

TDMATDMA

IS-136IS-136

PDCPDC

2G 1990s

Digital

Technologies

drive

3G

IMT-2000

UMTSUMTS

WCDMAWCDMA

cdmacdma

20002000

Demands

drive

TD-

SCDMA

TD-

SCDMA

3G provides compositive services for both operators and subscribers

z The first generation is the analog cellular mobile communication network in the time

period from the middle of 1970s to the middle of 1980s. The most important

breakthrough in this period is the concept of cellular networks put forward by the BellLabs in the 1970s, as compared to the former mobile communication systems. The

cellular network system is based on cells to implement frequency reuse and thus

greatly enhances the system capacity.

z The typical examples of the first generation mobile communication systems are the

AMPS system and the later enhanced TACS of USA, the NMT and the others. The

AMPS (Advanced Mobile Phone System) uses the 800 MHz band of the analog

cellular transmission system and it is widely applied in North America, South America

and some Circum-Pacific countries. The TACS (Total Access Communication System)

uses the 900 MHz band. It is widely applied in Britain, Japan and some Asian

countries.

z The main feature of the first generation mobile communication systems is that they

use the frequency reuse technology, adopt analog modulation for voice signals and

provide an analog subscriber channel every other 30 kHz/25 kHz.

z However, their defects are also obvious:

Low utilization of the frequency spectrum

Limited types of services

No high-speed data services

Poor confidentiality and high vulnerability to interception and numberembezzlement

High equipment cost


6/283

z To solve these fundamental technical defects of the analog systems, the digital

mobile communication technologies emerged and the second generation mobile

communication systems represented by GSM and IS-95 came into being in the

middle of 1980s. The typical examples of the second generation cellular mobile

communication systems are the DAMPS of USA, the IS-95 and the European GSMsystem.

z The GSM (Global System for Mobile Communications) is originated from Europe.

Designed as the TDMA standard for mobile digital cellular communications, it

supports the 64 kbps data rate and can interconnect with the ISDN. It uses the 900

MHz band while the DCS1800 system uses the 1800 MHz band. The GSM system

uses the FDD and TDMA modes and each carrier supports eight channels with the

signal bandwidth of 200 kHz.

z The DAMPS (Digital Advanced Mobile Phone System) is also called the IS-54 (NorthAmerica Digital Cellular System). Using the 800 MHz bandwidth, it is the earlier of the

two North America digital cellular standards and specifies the use of the TDMA mode.

z The IS-95 standard is another digital cellular standard of North America. Using the

800 MHz or 1900 MHz band, it specifies the use of the CDMA mode and has already

become the first choice among the technologies of American PCS (Personal

Communication System) networks.

z Since the 2G mobile communication systems focus on the transmission of voice and

low-speed data services, the 2.5G mobile communication systems emerged in 1996to address the medium-rate data transmission needs. These systems include GPRS

and IS-95B.

z The CDMA system has a very large capacity that is equivalent to ten or even twenty

times that of the analog systems. But the narrowband CDMA technologies come into

maturity at a time later than the GSM technologies, their application far lags behind

the GSM ones and currently they have only found large-scale commercial

applications in North America, Korea and China. The major services of mobile

communications are currently still voice services and low-speed data services.

z With the development of networks, data and multimedia communications have also

witnessed rapid development; therefore, the target of the 3G mobile communication is

to implement broadband multimedia communication.

z The 3G mobile communication systems are a kind of communication system that can

provide multiple kinds of high quality multimedia services and implement global

seamless coverage and global roaming. They are compatible with the fixed networks

and can implement any kind of communication at any time and any place with

portable terminals.


7/283


3G Evolution

z Proposal of 3G

IMT-2000: the general name of third generation mobile

communication system

The third generation mobile communication was first proposed

in 1985and was renamed as IMT-2000 in the year of 1996

Commercialization: around the year of 2000

Work band : around 2000MHz

The highest service rate :up to 2000Kbps

z Put forward in 1985 by the ITU (International Telecommunication Union), the 3G

mobile communication system was called the FPLMTS (Future Public Land Mobile

Telecommunication System) and was later renamed as IMT-2000 (InternationalMobile Telecommunication-2000). The major systems include WCDMA, cdma2000

and UWC-136. On November 5, 1999, the 18th conference of ITU-R TG8/1 passed

the Recommended Specification of Radio Interfaces of IMT-2000 and the TD-SCDMA

technologies put forward by China were incorporated into the IMT-2000 CDMA TDD

part of the technical specification. This showed that the work of the TG8/1 in

formulating the technical specifications of radio interfaces in 3G mobile

communication systems had basically come into an end and the development and

application of the 3G mobile communication systems would enter a new and essential

phase.

z The 3GPP is an organization that develops specifications for a 3G system based on

the UTRA radio interface and on the enhanced GSM core network.

z The 3GPP2 initiative is the other major 3G standardization organization. It promotes

the CDMA2000 system, which is also based on a form of WCDMA technology. In the

world of IMT-2000, this proposal is known as IMT-MC. The major difference between

the 3GPP and the 3GPP2 approaches into the air interface specification development

is that 3GPP has specified a completely new air interface without any constraints from

the past, whereas 3GPP2 has specified a system that is backward compatible with IS-

95 systems.


8/283


3G Spectrum Allocation

z ITU has allocated 230 MHz frequency for the 3G mobile communication system IMT-

2000: 1885 ~ 2025MHz in the uplink and 2110~ 2200 MHz in the downlink. Of them,

the frequency range of 1980 MHz ~ 2010 MHz (uplink) and that of 2170 MHz ~ 2200

MHz (downlink) are used for mobile satellite services. As the uplink and the downlink

bands are asymmetrical, the use of dual-frequency FDD mode or the single-frequency

TDD mode may be considered. This plan was passed in WRC92 and new additional

bands were approved on the basis of the WRC-92 in the WRC2000 conference in the

year 2000: 806 MHz ~ 960 MHz, 1710 MHz ~ 1885 MHz and 2500 MHz ~ 2690 MHz.


9/283


Bands WCDMA Used

z Main bands

1920 ~ 1980MHz / 2110 ~ 2170MHz

z Supplementary bands: different country maybe different

1850 ~ 1910 MHz / 1930 MHz ~ 1990 MHz (USA)

1710 ~ 1785MHz / 1805 ~ 1880MHz (Japan)

890 ~ 915MHz / 935 ~ 960MHz (Australia)

. . .

z Frequency channel numbercentral frequency5, for mainband:

UL frequency channel number96129888

DL frequency channel number : 1056210838

z The WCDMA system uses the following frequency spectrum (bands other than those

specified by 3GPP may also be used): Uplink 1920 MHz ~ 1980 MHz and downlink

2110 MHz ~ 2170 MHz. Each carrier frequency has the 5M band and the duplex

spacing is 190 MHz. In America, the used frequency spectrum is 1850 MHz ~ 1910

MHz in the uplink and 1930 MHz ~ 1990 MHz in the downlink and the duplex spacing

is 80 MHz.


10/283


3G Application Service

Time Delay

ErrorRatio

background

conversational

streaming

interactive

z Compatible with abundant services and applications of 2G, 3G system has an open

integrated service platform to provide a wide prospect for various 3G services.

z Features of 3G Services

z 3G services are inherited from 2G services. In a new architecture, new service

capabilities are generated, and more service types are available. Service

characteristics vary greatly, so each service features differently. Generally, there are

several features as follows:

Compatible backward with all the services provided by GSM.

The real-time services (conversational) such as voice service

generally have the QoS requirement.

The concept of multimedia service (streaming, interactive,

background) is introduced.


11/283


The Core technology of 3G: CDMA

CDMA

WCDMAWCDMA

CN: based on MAP and GPRSRTT: WCDMA

TD-SCDMACN: based on MAP and GPRS

RTT: TD-SCDMA

cdma2000CN: based on ANSI 41 and MIP

RTT: cdma2000

z Formulated by the European standardization organization 3GPP, the core network

evolves on the basis of GSM/GPRS and can thus be compatible with the existing

GSM/GPRS networks. It can be based on the TDM, ATM and IP technologies to

evolve towards the all-IP network architecture. Based on the ATM technology, the

UTRAN uniformly processes voice and packet services and evolves towards the IP

network architecture.

z The cdma2000 system is a 3G standard put forward on the basis of the IS-95

standard. Its standardization work is currently undertaken by 3GPP2. Circuit Switched

(CS) domain is adapted from the 2G IS95 CDMA network, Packet Switched (PS)

domain is A packet network based on the Mobile IP technology. Radio Access

Network (RAN) is based on the ATM switch platform, it provides abundant adaptationlayer interfaces.

z The TD-SCDMA standard is put forward by the Chinese Wireless Telecommunication

Standard (CWTS) Group and now it has been merged into the specifications related

to the WCDMA-TDD of 3GPP. The core network evolves on the basis of GSM/GPRS.

The air interface adopts the TD-SCDMA mode.


12/283


Contents

1. 3G Overview

2. CDMA Principle




13/283


Multiple Access and Duplex Technology

z Multiple Access Technology

Frequency division multiple access (FDMA)

Time division multiple access (TDMA)

Code division multiple access (CDMA)

z In mobile communication systems, GSM adopts TDMA; WCDMA, cdma2000 and TD-

SCDMA adopt CDMA.


14/283


Multiple Access Technology

Frequ

ency

Time

Power

FDMA

Frequ

encyTime

Power

TDMA

Power

Time

CDMA

Frequency

z Frequency Division Multiple Access means dividing the whole available spectrum into

many single radio channels (transmit/receive carrier pair). Each channel can transmit

one-way voice or control information. Analog cellular system is a typical example of

FDMA structure.

z Time Division Multiple Access means that the wireless carrier of one bandwidth is

divided into multiple time division channels in terms of time (or called timeslot). Each

user occupies a timeslot and receives/transmits signals within this specified timeslot.

Therefore, it is called time division multiple access. This multiple access mode is

adopted in both digital cellular system and GSM.

z CDMA is a multiple access mode implemented by Spreading Modulation. Unlike

FDMA and TDMA, both of which separate the user information in terms of time and

frequency, CDMA can transmit the information of multiple users on a channel at the

same time. The key is that every information before transmission should be

modulated by different Spreading Code to broadband signal, then all the signals

should be mixed and send. The mixed signal would be demodulated by different

Spreading Code at the different receiver. Because all the Spreading Code is

orthogonal, only the information that was be demodulated by same Spreading Code

can be reverted in mixed signal.


15/283


Multiple Access and Duplex

Technology

z Duplex Technology

Frequency division duplex (FDD)

Time division duplex (TDD)

z In third generation mobile communication systems, WCDMA and cdma2000 adopt

frequency division duplex (FDD), TD-SCDMA adopts time division duplex (TDD).


16/283


Duplex Technology

Time

Frequency

Power

TDD

USER 2

USER 1

DL

UL

DL

DLUL

FDD

Time

Frequency

Power

UL DL

USER 2

USER 1


17/283


Contents

1. 3G Overview

2. CDMA Principle




18/283


WCDMA Network Architecture

RNS

RNC

RNS

RNC

Core Network

Node B Node B Node B Node B

Iu-CS Iu-PS

Iur

Iub IubIub Iub

CN

UTRAN

UEUu

CS PS

Iu-CSIu-PS

CSPS

z WCDMA including the RAN (Radio Access Network) and the CN (Core Network). The

RAN is used to process all the radio-related functions, while the CN is used to

process all voice calls and data connections within the UMTS system, and

implements the function of external network switching and routing.

z Logically, the CN is divided into the CS (Circuit Switched) Domain and the PS (Packet

Switched) Domain. UTRAN, CN and UE (User Equipment) together constitute the

whole UMTS system

z A RNS is composed of one RNC and one or several Node Bs. The Iu interface is

used between RNC and CN while the Iub interface is adopted between RNC and

Node B. Within UTRAN, RNCs connect with one another through the Iur interface.

The Iur interface can connect RNCs via the direct physical connections among them

or connect them through the transport network. RNC is used to allocate and control

the radio resources of the connected or related Node B. However, Node B serves to

convert the data flows between the Iub interface and the Uu interface, and at the

same time, it also participates in part of radio resource management.


19/283


WCDMA Network Version Evolution

3GPP Rel993GPP Rel4

3GPP Rel5

2000 2001 2002

GSM/GPRS CN

WCDMA RTT

IMS

HSDPA 3GPP Rel6

MBMSHSUPA

2005

CS domain change toNGN

WCDMA RTT

z The overall structure of the WCDMA network is defined in 3GPP TS 23.002. Now,

there are the following three versions: R99, R4, R5.

z 3GPP began to formulate 3G specifications at the end of 1998 and beginning of 1999.

As scheduled, the R99 version would be completed at the end of 1999, but in fact it

was not completed until March, 2000. To guarantee the investment benefits of

operators, the CS domain of R99 version do not fundamentally change., so as to

support the smooth transition of GSM/GPRS/3G.

z After R99, the version was no longer named by the year. At the same time, the

functions of R2000 are implemented by the following two phases: R4 and R5. In the

R4 network, MSC as the CS domain of the CN is divided into the MSC Server and the

MGW, at the same time, a SGW is added, and HLR can be replaced by HSS (not

explicitly specified in the specification).

z In the R5 network, the end-to-end VOIP is supported and the core network adopts

plentiful new function entities, which have thus changed the original call procedures.

With IMS (IP Multimedia Subsystem), the network can use HSS instead of HLR. In

the R5 network, HSDPA (High Speed Downlink Packet Access) is also supported, it

can support high speed data service.

z In the R6 network, the HSUPA is supported which can provide UL service rate up to

5.76Mbps. And MBMS (MultiMedia Broadcast Multicast Service) is also supported.


20/283


WCDMA Network Version Evolution

z Features of R6

MBMS is introduced

HSUPA is introduced to achieve the service rate up to 5.76Mbps

z Features of R7

HSPA+ is introduced, which adopts higher order modulation and MIMO

Max DL rate: 28Mbps, Max UL rate:11Mbps

z Features of R8

WCDMA LTE (Long term evolution) is introduced

OFDMA is adopted instead of CDMA

Max DL rate: 50Mbps, Max UL rate: 100Mbps (with 20MHz bandwidth)


21/283


Contents

1. 3G Overview

2. CDMA Principle




22/283


Processing Procedure of WCDMA System

Source

CodingChannel Coding& Interleaving Spreading Modulation

Source

Decoding

Channel Decoding

& Deinterleaving Despreading Demodulation

Transmission

Reception

chipmodulated

signalbi t symbol

Service

Signal

Radio

Channel

Service

Signal

Receiver

z Source coding can increase the transmitting efficiency.

z Channel coding can make the transmission more reliable.

z Spreading can increase the capability of overcoming interference.

z Through the modulation, the signals will transfer to radio signals from digital signals.

z Bit, Symbol, Chip

Bit : data after source coding

Symbol: data after channel coding and interleaving

Chip: data after spreading


23/283


WCDMA Source Coding

z AMR (Adaptive Multi-Rate)

Speech

A integrated speech codec with 8

source rates

The AMR bit rates can be controlled

by the RAN depending on the system

load and quality of the speech

connections

z Video Phone Service

H.324 is used for VP Service in CSdomain

Includes: video codec, speech codec,

data protocols, multiplexing and etc.

5.15AMR_5.15

4.75AMR_4.75

5.9AMR_5.90

6.7 (PDC EFR)AMR_6.70

7.4 (TDMA EFR)AMR_7.40

7.95AMR_7.95

10.2AMR_10.20

12.2 (GSM EFR)AMR_12.20

Bit Rate (kbps)CODEC

z AMR is compatible with current mobile communication system (GSM, IS-95, PDC and

so on), thus, it will make multi-mode terminal design easier.

z The AMR codec offers the possibility to adapt the coding scheme to the radio channel

conditions. The most robust codec mode is selected in bad propagation conditions.

The codec mode providing the highest source rate is selected in good propagation

conditions.

z During an AMR communication, the receiver measures the radio link quality and must

return to the transmitter either the quality measurements or the actual codec mode the

transmitter should use during the next frame. That exchange has to be done as fast

as possible in order to better follow the evolution of the channels quality.


24/283



Transmitter

Source


Source

Decoding

Channel Decoding


Transmission

Reception

chipmodulated

signalbi t symbol

Service

Signal

Radio

Channel

Service

Signal

Receiver




z Scrambling can make transmission in security.


z Bit, Symbol, Chip





25/283


WCDMA Block Coding - CRC

z Block coding is used to detect if there are any uncorrected

errors left after error correction.

z The cyclic redundancy check (CRC) is a common method of

block coding.

z Adding the CRC bits is done before the channel encoding

and they are checked after the channel decoding.

z During the transmission, there are many interferences and fading. To guarantee

reliable transmission, system should overcome these influence through the channel

coding which includes block coding, channel coding and interleaving.

z Block coding: The encoder adds some redundant bits to the block of bits and the

decoder uses them to determine whether an error has occurred during the

transmission. This is used to calculate Block Error Ratio (BLER) used in the outer

loop power control.

z The CRC (Cyclic Redundancy Check) is used for error checking of the transport

blocks at the receiving end. The CRC length that can be inserted has four different

values: 0, 8, 12, 16 and 24 bits. The more bits the CRC contains, the lower is the

probability of an undetected error in the transport block in the receiver.

z Note that certain types of block codes can also be used for error correction, although

these are not used in WCDMA.


26/283


WCDMA Channel Coding

z Effect

Enhance the correlation among symbols so as to recover the signal when

interference occurs

Provides better error correction at receiver, but brings increment of the delay

z Types

No Coding

Convolutional Coding (1/2, 1/3)

Turbo Coding (1/3)

Code Block

of N Bits

No Coding

1/2 Convolutional

Coding

1/3 Convolutional

Coding

1/3 Turbo Codi ng

Uncoded N bits

Coded 2N+16 bits

Coded 3N+24 bits

Coded 3N+12 bits

z UTRAN employs two FEC schemes: convolutional codes and turbo codes. The idea

is to add redundancy to the transmitted bit stream, sO that occasional bit errors can

be corrected in the receiving entity.

z The first is convolution that is used for anti-interference. Through the technology,

many redundant bits will be inserted in original information. When error code is

caused by interference, the redundant bits can be used to recover the original

information. Convolutional codes are typically used when the timing constraints are

tight. The coded data must contain enough redundant information to make it possible

to correct some of the detected errors without asking for repeats.

z Turbo codes are found to be very efficient because they can perform close to the

theoretical limit set by the Shannons Law. Their efficiency is best with high data rate

services, but poor on low rate services. At higher bit rates, turbo coding is more

efficient than convolutional coding.

z In WCDMA network, both Convolution code and Turbo code are used. Convolution

code applies to voice service while Turbo code applies to high rate data service.

z Note that both block codes and channel codes are used in the UTRAN. The idea

behind this arrangement is that the channel decoder (either a convolutional or turbo

decoder) tries to correct as many errors as possible, and then the block decoder

(CRC check) offers its judgment on whether the resulting information is good enough

to be used in the higher layers.


27/283


WCDMA Interleaving

z Effect

Interleaving is used to reduce the probability of consecutive bits error

Longer interleaving periods have better data protection with more delay

1110

1.........

............

...000

0100

0 0 1 0 0 0 0 . . . 1 0 1 1 1

1110

1.........

............

...0000010 0 0 0 1 0 1 0 0 1 0 1 1

Inter-columnpermutation

Output bits

Input bits

Interleaving periods:

20, 40, or 80 ms

z Channel coding works well against random errors, but it is quite vulnerable to bursts

of errors, which are typical in mobile radio systems. The especially fast moving UE in

CDMA systems can cause consecutive errors if the power control is not fast enough

to manage the interference. Most coding schemes perform better on random data

errors than on blocks of errors. This problem can be eased with interleaving, which

spreads the erroneous bits over a longer period of time. By interleaving, no two

adjacent bits are transmitted near to each other, and the data errors are randomized.

z The longer the interleaving period, the better the protection provided by the time

diversity. However, longer interleaving increases transmission delays and a balance

must be found between the error resistance capabilities and the delay introduced.


28/283



Source


Source

Decoding

Channel Decoding


Transmission

Reception

chipmodulated

signalbi t symbol

Service

Signal

Radio

Channel

Service

Signal

Receiver






z Bit, Symbol, Chip





29/283


Correlation

z Correlation measures similarity between any two arbitrary signals.

z Identical and Orthogonal signals:

Correlation = 0

Orthogonal signals

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

1 1 1 1

+1

-1

+1

-1

+1

-1

+1

-1

Correlation = 1

Identical signals

-1 1 -1 11 1 1 1

-1 1 -1 1

C1

C2 +1

+1

C1

C2

z Correlation is used to measure similarity of any two arbitrary signals. It is computed

by multiplying the two signals and then summing (integrating) the result over a

defined time windows. The two signals of figure (a) are identical and therefore their

correlation is 1 or 100 percent. In figure (b) , however, the two signals are

uncorrelated, and therefore knowing one of them does not provide any information on

the other.


30/283


Orthogonal Code Usage - Coding

UE1: 1 1

UE2: 1 1

C1 : 1111 1111C2 : 1111 1111UE1c1 1111 1111UE2c2 1111 1111

UE1c1 UE2c2 2 02 0 2 0 2 0

UE1: 1 1

UE2: 1 1

C1 : 1111 11 11C2 : 1111 1111UE1c1 1111 11 11UE2c2 1111 1111

UE1c1 UE2c2 2 02 0 2 0 2 0

z By spreading, each symbol is multiplied with all the chips in the orthogonal sequence

assigned to the user. The resulting sequence is processed and is then transmitted

over the physical channel along with other spread symbols. In this figure, 4-digit

codes are used. The product of the user symbols and the spreading code is a

sequence of digits that must be transmitted at 4 times the rate of the original encoded

binary signal.


31/283


Orthogonal Code Usage - Decoding

UE1C1 UE2C2: 2 02 0 2 0 2 0

UE1 Dispreading by c1: 1111 1111Dispreading result: 2 02 0 2 0 2 0Integral judgment: 4 (means1) 4 (means1)

UE2 Dispreading by c2: 11 11 11 11

Dispreading result: 2 0 2 0 2 0 2 0Integral judgment: 4 (means1) 4 (means1)

UE1C1 UE2C2: 2 02 0 2 0 2 0

UE1 Dispreading by c1: 111 1 1111Dispreading result: 2 02 0 2 0 2 0Integral judgment: 4 (means1) 4 (means1)

UE2 Dispreading by c2: 11 11 11 11

Dispreading result:

2 0

2 0

2 0

2 0Integral judgment: 4 (means1) 4 (means1)

z The receiver dispreads the chips by using the same code used in the transmitter.

Notice that under no-noise conditions, the symbols or digits are completely recovered

without any error. In reality, the channel is not noise-free, but CDMA system employ

Forward Error Correction techniques to combat the effects of noise and enhance the

performance of the system.

z When the wrong code is used for dispreading, the resulting correlation yields an

average of zero. This is a clear demonstration of the advantage of the orthogonal

property of the codes. Whether the wrong code is mistakenly used by the target user

or other users attempting to decode the received signal, the resulting correlation is

always zero because of the orthogonal property of codes.


32/283


Spectrum Analysis of Spreading & Dispreading

Spreading code

Spreading code

Signal

Combination

Narrowband signal

f

P(f)

Broadband signal

P(f)

f

Noise & Other Signal

P(f)

f

Noise+Broadband signal

P(f)

f

Recovered signal

P(f)

f

z Traditional radio communication systems transmit data using the minimum bandwidth

required to carry it as a narrowband signal. CDMA system mix their input data with a

fast spreading sequence and transmit a wideband signal. The spreading sequence is

independently regenerated at the receiver and mixed with the incoming wideband

signal to recover the original data. The dispreading gives substantial gain proportional

to the bandwidth of the spread-spectrum signal. The gain can be used to increase

system performance and range, or allow multiple coded users, or both. A digital bit

stream sent over a radio link requires a definite bandwidth to be successfully

transmitted and received.


33/283


Spectrum Analysis of Spreading & Dispreading

Max allowed interference

Eb/No

Requiremen

t

Power

Max interference caused

by UE and others

Processing Gain

Ebi t

Interference from

other UE Echip

Eb / No = Ec / NoPG


34/283


Process Gain

z Process Gain

Process gain differs for each service.

If the service bit rate is greater, the process gain is smaller, UE

needs more power for this service, then the coverage of this

service will be smaller, vice versa.

)ratebitratechiplog(10GainocessPr =

z For common services, the bit rate of voice call is 12.2kbps, the bit rate of video phone

is 64kbps, and the highest packet service bit rate is 384kbps(R99). After the

spreading, the chip rate of different service all become 3.84Mcps.


35/283


Spreading Technology

z Spreading consists of 2 steps:

Channelization operation, which transforms data symbols into chips

Scrambling operation is applied to the spreading signal

scramblingchannelization

Data

symbol

Chips after

spreading

z Spreading means increasing the bandwidth of the signal beyond the bandwidth

normally required to accommodate the information. The spreading process in UTRAN

consists of two separate operations: channelization and scrambling.

z The first operation is the channelization operation, which transforms every data

symbol into a number of chips, thus increasing the bandwidth of the signal. The

number of chips per data symbol is called the Spreading Factor (SF). Channelization

codes are orthogonal codes, meaning that in ideal environment they do not interfere

each other.

z The second operation is the scrambling operation. Scrambling is used on top of

spreading, so it does not change the signal bandwidth but only makes the signals

from different sources separable from each other. As the chip rate is already achieved

in channelization by the channelization codes, the chip rate is not affected by the

scrambling.


36/283


WCDMA Channelization Code

z OVSF Code (Orthogonal Variable Spreading Factor) is used as

channelization code

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

Cch,1,0 = (1)

Cch,2,0 = (1,1)

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

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

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

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

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

Cch,8,0 = (1,1,1,1,1,1,1,1)

Cch,8,1 = (1,1,1,1,-1,-1,-1,-1)

Cch,8,2 = (1,1,-1,-1,1,1,-1,-1)

Cch,8,3 = (1,1,-1,-1,-1,-1,1,1)

Cch,8,4 = (1,-1,1,-1,1,-1,1,-1)

Cch,8,5 = (1,-1,1,-1,-1,1,-1,1)

Cch,8,6 = (1,-1,-1,1,1,-1,-1,1)

Cch,8,7 = (1,-1,-1,1,-1,1,1,-1)

z Orthogonal codes are easily generated by starting with a seed of 1, repeating the 1

horizontally and vertically, and then complementing the -1 diagonally. This process is

to be continued with the newly generated block until the desired codes with the proper

length are generated. Sequences created in this way are referred as Walsh code.

z Channelization uses OVSF code, for keeping the orthogonality of different subscriber

physical channels. OVSF can be defined as the code tree illustrated in the following

diagram.

z Channelization code is defined as Cch SF, k,, where, SF is the spreading factor of the

code, and k is the sequence of code, 0kSF-1. Each level definition length of code

tree is SF channelization code, and the left most value of each spreading code

character is corresponding to the chip which is transmitted earliest.


37/283


WCDMA Channelization Code

z SF = chip rate / symbol rate

High data rates low SF code

Low data rates high SF code

16Data 128 kbps DL8Data 128 kbps UL




128Speech 12.2 DL64Speech 12.2 UL

SFRadio bearerSFRadio bearer

z The channelization codes are Orthogonal Variable Spreading Factor (OVSF)

codes. They are used to preserve orthogonality between different physical channels.

They also increase the clock rate to 3.84 Mcps. The OVSF codes are defined using a

code tree.

z In the code tree, the channelization codes are individually described by Cch,SF,k, where

SF is the Spreading Factor of the code and k the code number, 0 k SF-1.

z A channelization sequence modulates one users bit. Because the chip rate is

constant, the different lengths of codes enable to have different user data rates. Low

SFs are reserved for high rate services while high SFs are for low rate services.

z The length of an OVSF code is an even number of chips and the number of codes (for

one SF) is equal to the number of chips and to the SF value.

z

The generated codes within the same layer constitute a set of orthogonal codes.Furthermore, any two codes of different layers are orthogonal except when one of the

two codes is a mother code of the other. For example C4,3 is not orthogonal with C1,0and C2,1, but is orthogonal with C2,0.

z SF in uplink is from 4 to 256.

z SF in downlink is from 4 to 512.


38/283


Purpose of Channelization Code

z Channelization code is used to distinguish different physical

channels of one transmitter

For downlink, channelization code ( OVSF code ) is used to

separate different physical channels of one cell

For uplink, channelization code ( OVSF code ) is used to

separate different physical channels of one UE

z For voice service (AMR), downlink SF is 128, it means there are 128 voice services

maximum can be supported in one WCDMA carrier;

z For Video Phone (64k packet data) service, downlink SF is 32, it means there are 32

voice services maximum can be supported in one WCDMA carrier.


39/283


Purpose of Scrambling Code

z Scrambling code is used to distinguish different transmitters

For downlink, scrambling code is used to separate different

cells in one carrier

For uplink, scrambling code is used to separate different UEs

in one carrier

z In addition to spreading, part of the process in the transmitter is the scrambling

operation. This is needed to separate terminals or base stations from each other.


40/283


Scrambling Code

z Scrambling code: GOLD sequence.

z There are 224 long uplink scrambling codes which are used for

scrambling of the uplink signals. Uplink scrambling codes are

assigned by RNC.

z For downlink, 512 primary scrambling codes are used.

z Different scrambling codes will be planned to different cells in downlink.

z Different scrambling codes will be allocated to different UEs in uplink.

z The scrambling code is always applied to one 10 ms frame.

z In UMTS, Gold codes are chosen for their very low peak cross-correlation.


41/283


Primary Scrambling Code Group

Primary

scrambling

codes for

downlink

physical

channels

Group 0

Primaryscrambling code 0

Primaryscrambling code

8*63

Primaryscrambling code

8*63 +7512 primary

scrambling

codes

Group 1

Group 63



64 primary

scrambling code

groups

Each group consists of 8

primary scrambling codes

z There are totally 512 primary scrambling codes defined by 3GPP. They are further

divided into 64 primary scrambling code groups. There are 8 primary scrambling

codes in every group. Each cell is allocated with only one primary scrambling code.


42/283


Code Multiplexing

z Downlink Transmission on a Cell Level

Scrambling code

Channelization code 1



User 1 signal

User 2 signal

User 3 signal

NodeB


43/283


Code Multiplexing

z Uplink Transmission on a Cell Level

NodeB

Scrambling code 3

User 3 signal

Channelization code

Scrambling code 2

User 2 signal

Channelization code

Scrambling code 1

User 1 signal

Channelization code


44/283



Source


Source

Decoding

Channel Decoding


Transmission

Reception

chipmodulated

signalbi t symbol

Service

Signal

Radio

Channel

Service

Signal

Receiver






z Bit, Symbol, Chip





45/283


Modulation Overview

1 00 1

time

Basic steady radio

wave:

carrier = A.cos(2Ft+)Ampl itude Shif t

Keying:

A.cos(2Ft+)Frequency Shift

Keying:

A.cos(2Ft+)Phase Shift Keying:

A.cos(2Ft+)

Data to be transmitted:

Digital Input

z A data-modulation scheme defines how the data bits are mixed with the carrier signal,

which is always a sine wave. There are three basic ways to modulate a carrier signal

in a digital sense: amplitude shift keying (ASK), frequency shift keying (FSK), and

phase shift keying (PSK).

z In ASK the amplitude of the carrier signal is modified by the digital signal.

z In FSK the frequency of the carrier signal is modified by the digital signal.

z The PSK family is the most widely used modulation scheme in modern cellular

systems. There are many variants in this family, and only a few of them are

mentioned here.


46/283


Modulation Overview

z Digital Modulation - BPSK

1

t

1 10

1

t-1

NRZ coding

fo

BPSK

Modulated

BPSKsignal

Carrier

Informationsignal

=0 = =0

1 102 3 4 9875 6

1 102 3 4 9875 6

Digital Input

High Frequency

Carrier

BPSK Waveform

z In binary phase shift keying (BPSK) modulation, each data bit is transformed into a

separate data symbol. The mapping rule is 1 > + 1 and 0 > 1. There are only

two possible phase shifts in BPSK, 0 and radians.

z NRZ means none return zero.


47/283


Modulation Overview

z Digital Modulation - QPSK

-1 -1

1 102 3 4 9875 6

1 102 3 4 9875 6

NRZ Input

I di-Bit Stream

Q di-Bit Stream

I

Component

Q

Component

QPSK Waveform

1

1

-1

1

-1

1

1

-1

-1

-1

1 1 -1 1 -1 1 1 -1

z The quadrature phase shift keying (QPSK) modulation has four phases: 0, /2, , and

3/2 radians. Two data bits are transformed into one complex data symbol; A symbol

is any change (keying) of the carrier.


48/283


Modulation Overview

NRZcoding

90o

NRZcoding

QPSK

Q(t)

I(t)

fo

A

A Acos(ot)

Acos(ot + /2)

1 1 /41 -1 7/4-1 1 3/4-1 -1 5/4

)cos(2: +oAQPSK


49/283


Demodulation

z QPSK Constellation Diagram

1 102 3 4 9875 6

QPSK Waveform

1,1

-1,-1

-1,1

1,-1

1 -11 -1 1 -1-11-1 1

-1,1

NRZ Output


50/283


WCDMA Modulation

z Different modulation methods corresponding to different

transmitting abilities in air interface

HSDPA: QPSK or 16QAMR99/R4: QPSK

z The UTRAN air interface uses QPSK modulation in the downlink, although HSDPA

may also employ 16 Quadrature Amplitude Modulation (16QAM). 16QAM requires

good radio conditions to work well. As seen, with 16QAM also the amplitude of the

signal matters.

z As explained, in QPSK one symbol carries two data bits; in 16QAM each symbol

includes four bits. Thus, a QPSK system with a chip rate of 3.84Mcps could

theoretically transfer 2 3.84 = 7.68 Mbps, and a 16QAM system could transfer 4

3.84 Mbps = 15.36 Mbps. In 3GPP also the usage of 64QAM with HSDPA has been

studied.


51/283



Source

CodingChannelCoding Spreading Modulation

Source

Decoding

Channel

Decoding Despreading Demodulation

Transmission

Reception

chipmodulated

signalbi t symbol

Service

Signal

Radio

Channel

Service

Signal

Transmitter

Receiver






z Bit, Symbol, Chip





52/283


Wireless Propagation

ReceivedSignal

Transmitted

Signal

Transmission Loss:

Path Loss + Multi-path Fading

Time

Amp li tude

z A mobile communication channel is a multi-path fading channel and any transmitted

signal reaches a receive end by means of multiple transmission paths, such as direct

transmission, reflection, scatter, etc.


53/283


Propagation of Radio SignalSignal at Transmitter

Signal at Receiver

-40

-35

-30

-25

-20

-15

-10

-5

dB

0

0dBm

-20

-15

-10

-5

5

10

15

20

Fading


54/283


Fading Categories

z Fading Categories

Slow Fading Fast Fading

z Furthermore, with the moving of a mobile station, the signal amplitude, delay and

phase on various transmission paths vary with time and place. Therefore, the levels of

received signals are fluctuating and unstable and these multi-path signals, if overlaid,

will lead to fast fading. Fast fading conforms to Rayleigh distribution. The mid-value

field strength of fast fading has relatively gentle change and is called slow fading.

Slow fading conforms to lognormal distribution.


55/283


Diversity Technique

z Diversity technique is used to obtain uncorrelated signals for

combining

Reduce the effects of fading

Fast fading caused by multi-path

Slow fading caused by shadowing

Improve the reliability of communication

Increase the coverage and capacity

z Diversity technology means that after receiving two or more input signals with

mutually uncorrelated fading at the same time, the system demodulates these signals

and adds them up. Thus, the system can receive more useful signals and overcome

fading.


56/283


Diversity

z Time diversity

Channel coding, Block interleaving

z Frequency diversity

The user signal is distributed on the whole bandwidth

frequency spectrum

z Space diversity

z

Polarization diversity

z Diversity technology is an effective way to overcome overlaid fading. Because it can

be selected in terms of frequency, time and space, diversity technology includes

frequency diversity, time diversity and space diversity.

z Time diversity: Channel coding

z Frequency diversity: WCDMA is a kind of frequency diversity. The signal energy is

distributed on the whole bandwidth.

z Space diversity: using two antennas


57/283


Principle of RAKE Receiver

Receive set

Correlator 1

Correlator 2

Correlator 3

Searcher correlator Calculate the

time delay and

signal strength

CombinerThe

combined

signal

tt

s(t) s(t)

RAKE receiver help to overcome on the multi-path fading and enhance the receive

performance of the system

z The RAKE receiver is a technique which uses several baseband correlators to

individually process multipath signal components. The outputs from the different

correlators are combined to achieve improved reliability and performance.

z When WCDMA system is designed for cellular system, the inherent wide-bandwidth

signals with their orthogonal Walsh functions were natural for implementing a RAKE

receiver. In WCDMA system, the bandwidth is wider than the coherence bandwidth of

the cellular. Thus, when the multi-path components are resolved in the receiver, the

signals from different paths are uncorrelated with each other. The receiver can then

combine them using some combining schemes. So with RAKE receiver WCDMA

system can use the multi-path characteristics of the channel to get signal with better

quality.


58/283


Summary

z In this course, we have discussed basic concepts of WCDMA:

Spreading / Despreading principle

UTRAN Voice Coding

UTRAN Channel Coding

UTRAN Spreading Code

UTRAN Scrambling Code

UTRAN Modulation

UTRAN Transmission/Receiving


59/283

Thank youwww.huawei.com


61/283


Foreword

z The physical layer offers data transport services to higher layers.

z The physical layer is expected to perform the following functions inorder to provide the data transport service, for example: spreading,

modulation and demodulation, despreading, Inner-loop power

control and etc.


62/283


Objectives

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

Outline radio interface protocol Architecture

Describe structure and functions of different physical channels

Describe UMTS physical layer procedures


63/283


Contents

1. Physical Layer Overview

2. Physical Channels

3. Physical Layer Procedure


64/283


Contents





65/283


UTRAN Network Structure

RNS

RNC

RNS

RNC

Core Network

NodeB NodeB NodeB NodeB

Iu-CS Iu-PS

Iur

Iub IubIub Iub

CN

UTRAN

UEUu

CS PS

Iu-CSIu-PS

CSPS

z UTRAN: UMTS Terrestrial Radio Access Network.

z The UTRAN consists of a set of Radio Network Subsystems connected to the Core

Network through the Iu interface.

z A RNS consists of a Radio Network Controller and one or more NodeBs. A NodeB is

connected to the RNC through the Iub interface.

z Inside the UTRAN, the RNCs of the RNS can be interconnected together through the

Iur. Iu(s) and Iur are logical interfaces. Iur can be conveyed over direct physical

connection between RNCs or virtual networks using any suitable transport network.


66/283


Uu Interface Protocol Structure

L3

control

control

control

control

C-plane signaling U-plane information

PHY

L2/MAC

L1

RLC

DCNtGC

L2/RLC

MAC

RLCRLC

RLC

Duplication avoidance

UuS boundary

L2/BMC

control

PDCPPDCP L2/PDCP

DCNtGC

RRC

RLCRLC

RLCRLC

BMC

radio bearer

logical channel

transport channel

z The layer 1 supports all functions required for the transmissionof bit streams on the

physical medium. It is also in charge of measurements function consisting in indicating

to higher layers, for example, Frame Error Rate (FER), Signal to Interference Ratio(SIR), interference power, transmit power, It is basically composed of a layer 1

managemententity, a transport channelentity, and a physical channelentity.

z The layer 2 protocol is responsible for providing functions suchas mapping, ciphering,

retransmission and segmentation. It is made of four sub-layers: MAC (Medium

Access Control), RLC (Radio Link Control), PDCP (Packet Data Convergence

Protocol) and BMC (Broadcast/Multicast Control).

z The layer 3 is split into 2 parts: the access stratum and the non access stratum. The

access stratum part is made of RRC (Radio Resource Control)entity and

duplication avoidanceentity. duplication avoidance terminates in the CN but is part

of the Access Stratum. The higher layer signalling such as Mobility Management (MM)

and Call Control (CC) is assumed to belong to the non-access stratum, and therefore

not in the scope of 3GPP TSG RAN. In the C-plane, the interface between 'Duplication

avoidance' and higher L3 sub-layers (CC, MM) is defined by the General Control (GC),

Notification (Nt) and Dedicated Control (DC) SAPs.

z Not shown on the figure are connections between RRC and all the other protocol

layers (RLC, MAC, PDCP, BMC and L1), which provide local inter-layer control

services.

z The protocol layers are located in the UE and the peer entities are in the NodeB or the

RNC.


67/283

z Many functions are managed by the RRC layer. Here is the list of the most important:

Establishment, re-establishment, maintenance and release of an RRC

connection between the UE and UTRAN: it includes an optional cell re-

selection, an admission control, and a layer 2 signaling link establishment.

When a RNC is in charge of a specific connection towards a UE, it acts as theServing RNC.

Establishment, reconfiguration and release of Radio Bearers: a number of

Radio Bearers can be established fora UE at the same time. These bearers are

configured depending on the requested QoS. The RNC is also in charge of

ensuring that the requested QoS can be met.

Assignment, reconf iguration and release of radio resources for the RRC

connection: it handles the assignment of radio resources (e.g. codes, shared

channels). RRC communicates with the UE to indicate new resources allocation

when handovers are managed.

Paging/Notification: it broadcasts paging information from network to UEs.

Broadcasting of i nformation provided by the non-access stratum (Core

Network) or access Stratum. This corresponds to system informationregularly

repeated.

UE measurement reporting and cont rol of the reporting: RRC indicates

what to measure, when and how to report.

Outer loop power control: controls setting of the target values.

Control of ciphering: provides procedures for setting of ciphering.

z The RRC layer is defined in the 25.331 specification from 3GPP.


68/283

z The RLCs main function is the transfer of data from either the user or the control

plane over the Radio interface. Two different transfer modes are used: transparent

and non-transparent. In non-transparent mode, 2 sub-modes are used:

acknowledged orunacknowledged.

z

RLC provides services to upper layers: data transfer(transparent, acknowledged and unacknowledged modes).

QoS setting: the retransmission protocol (for AM only) shall be configurable by

layer 3 to provide different QoS.

notification of unrecoverable errors: RLC notifies the upper layers of errors

that cannot be resolved by RLC.

z The RLC functions are:

mapping between higher layer PDUs and logical channels.

ciphering: prevents unauthorized acquisition of data; performed in RLC layer

for non-transparent RLC mode.

segmentation/reassembly: this function performs segmentation/reassembly of

variable-length higher layer PDUs into/from smaller RLC Payload Units. The

RLC size is adjustable to the actual set of transport formats (decided when

service is established). Concatenation and padding may also be used.

error correction: done by retransmission (acknowledged data transfer mode

only).

flow control: allows the RLC receiver to control the rate at which the peer RLC

transmitting entity may send information.


69/283

z MAC services include:

Data transfer: service providing unacknowledged transfer of MAC SDUs

between peer MAC entities.

Reallocation of radio resources and MAC parameters: reconfiguration of

MAC functions such as change of identity of UE. Requested by the RRC layer.

Reporting of measurements: local measurements such as traffic volume and

quality indication are reported to the RRC layer.

z The functions accomplished by the MAC sub-layer are listed above. Heres a quick

explanation for some of them:

Priority handling between the data flows of one UE: since UMTS is

multimedia, a user may activate several services at the same time, having

possibly different profiles (priority, QoS parameters...). Priority handling

consists in setting the right transport format for a high bit rate service and for alow bit rate service.

Priority handl ing between UEs: use for efficient spectrum resources utilization

for bursty transfers on common and shared channels.

Ciphering: to prevent unauthorized acquisition of data. Performed in the MAC

layer for transparent RLC mode.

Access Service Class (ACS) select ion for RACH transmission: the RACH

resources are divided between different ACSs in order to provide different

priorities on a random access procedure.


70/283

z PDCP

UMTS supports several network layer protocols providing protocol transparency

for the users of the service.

Using these protocols (and new ones) shall be possible without any changes to

UTRAN protocols. In order to perform this requirement, the PDCP layer hasbeen introduced. Then, functions related to transfer of packets from higher

layers shall be carried out in a transparent way by the UTRAN network entities.

PDCP shall also be responsible for implementing different kinds of optimization

methods. The currently known methods are standardized IETF (Internet

Engineering Task Force) header compression algorithms.

Algorithm types and their parameters are negotiated by RRC and indicated to

PDCP.

Header compression and decompression are specific for each network layerprotocol type.

In order to know which compression method is used, an identifier (PID: Packet

Identifier) is inserted. Compression algorithms exist for TCP/IP, RTP/UDP/IP,

Another function of PDCP is to provide numbering of PDUs. This is done if

lossless SRNS relocation is required.

To accomplish this function, each PDCP-SDUs (UL and DL) is buffered and

numbered. Numbering is done after header compression. SDUs are kept until

information of successful transmission of PDCP-PDU has been received from

RLC. PDCP sequence number ranges from 0 to 65,535.


71/283

z BMC (broadcast/multicast control protocol)

The main function of BMC protocol are:

Storage of cell broadcast message. the BMC in RNC stores the cell

broadcast message received over the CBC-RNC interface for scheduled

transmission.

Traffic vo lume monitoring and radio resource request for CBS. On the

UTRAN side, the BMC calculates the required transmission rate for the cell

broadcast service based on the messages received over the CBC-RNC

interface, and requests appropriate .CTCH/FACH resources from fromRRC

Scheduling of BMC message.The BMC receives scheduling information

together with each cell broadcast message over the CBC-RNC interface. Based

on this scheduling information, on the UTRAN side the BMC generates schedule

message and schedules BMC message sequences accordingly. On the UE

side ,the BMC evaluates the schedule messages and indicates scheduling

parameters to RRC, which are used by RRC to configure the lower layers for

CBS discontinuous reception.

Transmission of BMC message to UE.The function transmits the BMC

messages according to the schedule

Delivery of cell broadcast messages to the upper layer.This UE function

delivers the received non-corrupted cell broadcast messages to the upper layer


72/283

z The layer 1 (physical layer) is used to transmit information under the form of

electrical signals corresponding to bits, between the network and the mobile user.

This information can be voice, circuit or packet data, and network signaling.

z The UMTS layer 1 offers data transport services to higher layers. The access to these

services is through the use of transport channels via the MAC sub-layer.z These services are provided by radio links which are established by signaling

procedures. These links are managed by the layer 1 management entity. One radio

link is made of one or several transport channels, and one physical channel.

z The UMTS layer 1 is divided into two sub-layers: the transport and the physical sub-

layers. All the processing (channel coding, interleaving, etc.) is done by the transport

sub-layer in order to provide different services and their associated QoS. The physical

sub-layer is responsible for the modulation, which corresponds to the association of

bits (coming from the transport sub-layer) to electrical signals that can be carried over

the air interface. The spreading operation is also done by the physical sub-layer.

z These two parts of layer 1 are controlled by the layer 1 management (L1M) entity. It is

made of several units located in each equipment, which exchange information through

the use of control channels.


73/283


RAB, RB and RL

RAB

RB

RLNodeB

RNC CNUE

UTRAN

z RAB: The service that the access stratum provides to the non-access stratum for

transfer of user data between User Equipment and CN.

z RB: The service provided by the layer 2 for transfer of user data between UserEquipment and Serving RNC.

z RL: A "radio link" is a logical association between single User Equipment and a single

UTRAN access point. Its physical realization comprises one or more radio bearer

transmissions.


74/283


Contents





75/283


Contents


2.1 Physical Channel Structure and Functions

2.2 Channel Mapping


76/283


WCDMA Radio Interface Channel Definition

z Logical Channel = information container

Defined by is transferred

z Transport Channel = characteristics of transmission

Described by and with data

is transmitted over the radio interface

z Physical Channel = specification of the information global

content

providing the real transmission resource, maybe a frequency ,

a specific set of codes and phase

z In terms of protocol layer, the WCDMA radio interface has three types of channels:

physical channel, transport channel and logical channel.

z Logical channel: Carrying user services directly. According to the types of the carried

services, it is divided into two types: control channel and service channel.

z Transport channel: It is the interface between radio interface layer 2 and layer 1, and it

is the service provided for MAC layer by the physical layer. According to whether the

information transported is dedicated information for a user or common information for

all users, it is divided into dedicated channel and common channel.

z Physical channel: It is the ultimate embodiment of all kinds of information when they

are transmitted on radio interface. Each channel which uses dedicated carrier

frequency, code (spreading code and scramble) and carrier phase (I or Q) can beregarded as a physical channel.


77/283


Logical Channel

Control channel

Traffic channel

Dedicated traffic channel (DTCH)

Common traffic channel (CTCH)

Broadcast control channel (BCCH)

Paging control channel (PCCH)

Dedicate control channel (DCCH)

Common control channel (CCCH)

z As in GSM, UMTS uses the concept of logical channels.

z A logical channel is characterized by the type of information that is transferred.

z As in GSM, logical channels can be divided into two groups: control channels forcontrol plane information and traffic channel for user plane information.

z The traffic channels are:

Dedicated Traff ic Channel (DTCH): a point-to-point bi-directional channel,

that transmits dedicated user information between a UE and the network. That

information can be speech, circuit switched data or packet switched data. The

payload bits on this channel come from a higher layer application (the AMR

codec for example). Control bits can be added by the RLC (protocol information)

in case of a non transparent transfer. The MAC sub-layer will also add a header

to the RLC PDU.

Common Traffic Channel (CTCH): a point-to-multipoint downlink channelfor transfer of dedicated user information for all or a group of specified UEs.

This channel is used to broadcast BMC messages. These messages can either

be cell broadcast data from higher layers or schedule messages for support of

Discontinuous Reception (DRX) of cell broadcast data at the UE. Cell broadcast

messages are services offered by the operator, like indication of weather, traffic,

location or rate information.


78/283


Logical Channel

Control channel

Traffic channel

Dedicated traffic channel (DTCH)

Common traffic channel (CTCH)

Broadcast control channel (BCCH)

Paging control channel (PCCH)

Dedicate control channel (DCCH)

Common control channel (CCCH)

z The control channels are:

Broadcast Contro l Channel (BCCH): a downlink channel that broadcasts all system

information types (except type 14 that is only used in TDD). For example, systeminformation type 3 gives the cell identity. UEs decode system information on the BCH

except when in Cell_DCH mode. In that case, they can decode system information type

10 on the FACH and other important signaling is sent on a DCCH.

Paging Cont rol Channel (PCCH): a downlink channel that transfers paging

information. It is used to reach a UE (or several UEs) in idle mode or in connected mode

(Cell_PCH or URA_PCH state). The paging type 1 message is sent on the PCCH.

When a UE receives a page on the PCCH in connected mode, it shall enter Cell_FACH

state and make a cell update procedure.

Dedicated Control Channel (DCCH): a point-to-point bi-directional channel that

transmits dedicated control information between a UE and the network. This channel isused for dedicated signaling after a RRC connection has been done. For example, it is

used for inter-frequency handover procedure, for dedicated paging, for the active set

update procedure and for the control and report of measurements.

Common Control Channel (CCCH): a bi-directional channel for transmitting control

information between network and UEs. It is used to send messages related to RRC

connection, cell update and URA update. This channel is a bit like the DCCH, but will be

used when the UE has not yet been identified by the network (or by the new cell). For

example, it is used to send the RRC connection request message, which is the first

message sent by the UE to get into connected mode. The network will respond on the

same channel, and will send him its temporary identities (cell and UTRAN identities).After these initial messages, the DCCH will be used.


79/283


Transport Channel

Dedicated Channel (DCH)

Broadcast channel (BCH)

Forward access channel (FACH)

Paging channel (PCH)

Random access channel (RACH)

High-speed downlink shared channel

(HS-DSCH)

Common transport

channel

Dedicated transpor tchannel

z In order to carry logical channels, several transport channels are defined. They are:

Broadcast Channel (BCH): a downlink channel used for broadcast of system

information into the entire cell.

Paging Channel (PCH): a downlink channel used for broadcast of control

information into the entire cell, such as paging.

Random Access Channel (RACH): a contention based uplink channel used

for initial access or for transmission of relatively small amounts of data (non

real-time dedicated control or traffic data).

Forward Access Channel (FACH): a common downlink channel used for

dedicated signaling (answer to a RACH typically), or for transmission of

relatively small amounts of data.

Dedicated Channel (DCH): a channel dedicated to one UE used in uplink or

downlink.


80/283


Physical Channel

z A physical channel is defined by a specific carrier frequency, code

(scrambling code, spreading code) and relative phase.

z In UMTS system, the different code (scrambling code or spreading

code) can distinguish the channels.

z Most channels consist of radio frames and time slots, and each

radio frame consists of 15 time slots.

z Two types of physical channel: UL and DL

Physical Channel

Frequency, Code, Phase

z Now we will begin to discuss the physical channel. Physical channel is the most

important and complex channel, and a physical channel is defined by a specific carrier

frequency, code and relative phase. In CDMA system, the different code (scramblingcode or spreading code) can distinguish the channel. Most channels consist of radio

frames and time slots, and each radio frame consists of 15 time slots. There are two

types of physical channel: UL and DL.


81/283


Downlink Physical Channel

z Downlink Dedicated Physical Channel (DL DPCH)

z Downlink Common Physical Channel

Primary Common Control Physical Channel (P-CCPCH)

Secondary Common Control Physical Channel (S-CCPCH)

Synchronization Channel (SCH)

Paging Indicator Channel (PICH)

Acquisition Indicator Channel (AICH)

Common Pilot Channel (CPICH)

High-Speed Physical Downlink Shared Channel (HS-PDSCH)

High-Speed Shared Control Channel (HS-SCCH)

z The different physical channels are:

Synchronization Channel (SCH): used for cell search procedure. There is theprimary and the secondary SCHs.

Common Control Physical Channel (CCPCH): used to carry common controlinformation such as the scrambling code used in DL (there is a primary CCPCHand additional secondary CCPCH).

Common Pilot Channels (P-CPICH and S-CPICH): used for coherentdetection of common channels. They indicate the phase reference.

Dedicated Physical Data Channel (DPDCH): used to carry dedicated datacoming from layer 2 and above (coming from DCH).

Dedicated Physical Control Channel (DPCCH): used to carry dedicatedcontrol information generated in layer 1 (such as pilot, TPC and TFCI bits).

Page Indicator Channel (PICH): carries indication to inform the UE that paginginformation is available on the S-CCPCH.

Acquis it ion Indicator Channel (AICH): it is used to inform a UE that thenetwork has received its access request.

High Speed Physical Downlink Shared Channel (HS-PDSCH): it is used tocarry subscribers BE service data (mapping on HSDPA) coming from layer 2.

High Speed Shared Control Channel (HS-SCCH): it is used to carry controlmessage to HS-PDSCH such as modulation scheme, UE ID etc.


82/283


Uplink Physical Channel

z Uplink Dedicated Physical Channel

Uplink Dedicated Physical Data Channel (Uplink DPDCH)

Uplink Dedicated Physical Control Channel (Uplink DPCCH)

High-Speed Dedicated Physical Channel (HS-DPCCH)

z Uplink Common Physical Channel

Physical Random Access Channel (PRACH)

z The different physical channels are:

Dedicated Physical Data Channel (DPDCH): used to carry dedicated data

coming from layer 2 and above (coming from DCH).

Dedicated Physical Control Channel (DPCCH): used to carry dedicated

control information generated in layer 1 (such as pilot, TPC and TFCI bits).

Physical Random Access Channel (PRACH): used to carry random access

information when a UE wants to access the network.

High Speed Dedicated Physical Control Channel (HS-DPCCH): it is used to

carry feedback message to HS-PDSCH such CQI,ACK/NACK.


83/283


Function of Physical Channel

NodeB UE

P-CCPCH-Primary Common Control Physical ChannelP-CCPCH-Primary Common Control Physical Channel

P-CPICH--Primary Common Pilot ChannelSCH--Synchronisation Channel

P-CPICH--Primary Common Pilot ChannelSCH--Synchronisation Channel

Cell Search Channels

DPDCH--Dedicated Physical Data ChannelDPDCH--Dedicated Physical Data Channel

DPCCH--Dedicated Physical Control ChannelDPCCH--Dedicated Physical Control Channel

Dedicated Channels

Paging ChannelsPICH--Paging Indicator ChannelPICH--Paging Indicator Channel

SCCPCH--Secondary Common Control Physical ChannelSCCPCH--Secondary Common Control Physical Channel

PRACH--Physical Random Access ChannelPRACH--Physical Random Access Channel

AICH--Acquisition Indicator ChannelAICH--Acquisition Indicator Channel

Random Access Channels

HS-DPCCH--High Speed Dedicated Physical Control ChannelHS-DPCCH--High Speed Dedicated Physical Control Channel

HS-SCCH--High Speed Share Control ChannelHS-SCCH--High Speed Share Control Channel

HS-PDSCH--High Speed Physical Downlink Share ChannelHS-PDSCH--High Speed Physical Downlink Share Channel

High Speed Downlink Share Channels


84/283


Synchronization Channels (P-SCH & S-SCH)z Used for cell search

z Two sub channels: P-SCH and S-SCH

z SCH is transmitted at the first 256

chips of every time slot

z Primary synchronization code is

transmitted repeatedly in each time slot

z Secondary synchronization code

specifies the scrambling code groups of

the cell

Primary

SCH

Secondary

SCH

Slot #0 Slot #1 Slot #14

acsi,0

pac pac pac

acsi,1 acs

i,14

256 chips2560 chips

One 10 ms SCH radio frame

z When a UE is turned on, the first thing it does is to scan the UMTS spectrum and find

a UMTS cell. After that, it has to find the primary scrambling code used by that cell in

order to be able to decode the BCCH (for system information). This is done with the

help of the Synchronization Channel.

z Each cell of a NodeB has its own SCH timing, so that there is no overlapping.

z The SCH is a pure downlink physical channel broadcasted over the entire cell. It is

transmitted unscrambled during the first 256 chips of each time slot, in time multiplex

with the P-CCPCH. It is the only channel that is not spread over the entire radio

frame. The SCH provides the primary scrambling code group (one out of 64 groups),

as well as the radio frame and time slot synchronization.

z The SCH consists of

36255366 wcdma ran planning and optimization book1 wrnpo basics

Documents

wcdma ranfundamental7162019

wcdma network architecture

huawei technologies

analog systems

fundamentals of ran

theamps system

thecellular network

system capacity