1.Wo Bt01 e1 1 Umts Radio Theory-63

UMTS Radio Theory

ZTE University

Content

The Basic Principles of Wireless Communication 3G services Multiple Access Technologies Spectrum Planning Spreading Technology Coding And Interleave Technology Modulation

UMTS Radio mechanism

Radio Transmission Technology Requirements Data ：

144 kbps High speed and driving 384 kbps Modest speed and walking 2 Mbps Low speed and indoor

Voice 4.75Kb/s -- 12.2Kb/s 64kb/s (Video Phone)

Information transmission at variable rate according to bandwidth requirements ；

Delay requirements of different service

3G services

Delay

Bit ErrorDifferent QOS requirements

3G services Categories Actual Service Delay (One-way) Bearer Speed

conversational

Voice <150ms 12.2kbps

Video Call <150ms 64kbps

VoIP <150ms 15.3~39.6kbps

Interaction Game

<250ms N/A

Streaming

Real-time Voice Streaming

<2s 4.7~25kbps

Real-time Video Streaming

<2s 64kbps~2Mbps

Interaction

Web Browsing <4s N/A

WAP Browsing <4s N/A

E-commerce <4s N/A

BackgroundFTP No strict N/A

E-mail No strict N/A

Content



Duplex mode

TDD mode － uplink and downlink has the same frequency Adaptable to any frequency

band Suitable for both asymmetric

and symmetric services FDD mode － uplink and downlink

has the different frequency Paired frequency bands are

needed Suitable for symmetric services

TDD ( Time division duplex,Such as TD-SCDMA)

D D D D U U UU

FDD （ Frequency division duplex, Such as WCDMA and CDMA2000 ）

D D D D D D DD

U U U U U U UU

Why Multiple Access? Increased capacity: serve more users Reduced capital requirements since

fewer media can carry the traffic Decreased per-user expense

Types of Transmission Medium: Twisted pair Coaxial cable Fiber optic cable Air interface (radio signals) Three methods are frequently used: FDMA TDMA CDMA

Each pair of users enjoys a dedicated, private circuit through the transmission medium, unaware that theother users exist.

Transmission

Medium

Multiple access technologies enable various users access public communication line but without interference.

Multiple Access Technologies

Users are using Users are using different frequencydifferent frequency

Time

Frequency

FDMA

FDMA (Frequency Division Multiple Access)

FDMA Traffic channels are assigned to different users at

different frequency band, such as TACS, AMPS.

Time

Frequency

TDMA

Users are using Users are using different time slotdifferent time slot

TDMA (Time Division Multiple Access)

TDMA Traffic channels are assigned to different users at

different time, such as GSM, DAMPS.

Time

Frequency

CDMA

Code

Users are using different Users are using different orthogonal code sequenceorthogonal code sequence

CDMA (Code Division Multiple Access)

CDMA Traffic channels are assigned to users at same time,

same frequency band, but with different code.

Freq. 1

Freq. 1

Code A

Code B

Code

C

BS1

BS2

Code D

Code E

CDMA Application

Users are distinguished by scrambling codes and OVSF codes

Self-interference system CDMA system is restricted to interference (GSM system is

restricted to frequency resources)

Content



GSM900/1800: 3G (W CDM A):

Single Frequency Network

IMT-2000 Spectrum Allocation

1850 1900 1950 2000 2050 2100 2150 2200

ITU

Europe

USA MSSPCS

A D B BC D CE F A FE MSSReserveBroadcast auxiliary

2165 MHz1990 MHz

1850 1900 1950 2000 2050 2100 2150 2200

UMTSGSM 1800 DECT MSS

1885 MHz 2025 MHz

2010 MHz

IMT 2000

MSSUMTS

Japan MSSIMT 2000MSSIMT 2000PHS

IMT 2000

2110 MHz 2170 MHz

MSS MSS

FDD MSSMSSTDD TDD

1980

GSM1800 FDD

1920

China

1880

1865

1870

1885

1890

1910

1930

1945

1965

1970

1975

3G Spectrum Allocation in China

60 MHz30 MHz

FDD TDD

100 MHz15MHz

40 MHz

155MHz

1785 18501755 1880 1920 1980 2010 2025 2110 2170 2200 2400

Satellite Empty Satellite

2300

3G Spectrum Planning in China

Main Operating Frequency Band ： FDD mode ： 1920-1980 MHz / 2110-2170 MHz TDD mode ： 1880-1920MHz 、 2010-2025 MHz

Supplementary Operating Frequency Band ： FDD mode ： 1755-1785 MHz / 1850-1880 MHz TDD mode ： 2300-2400MHz

Frequency Band for Satellite Mobile Communication System ： 1980-2010 MHz / 2170-2200 MHz

The frequency bands, 825 - 835 MHz / 870 - 880 MHz, 885 - 915 MHz / 930 - 960 MHz and 1710 - 1755 MHz / 1805 - 1850 MHz, which are currently allocated to public mobile communication system are also allocated to expanded frequency bands of 3G public communication system, but frequency using mode remains the same for both uplink and downlink.

Content



SHANON Formula

C = Blog2(1+S/N)

Spread Spectrum Principles

Where, C is capacity of channel, b/s B is signal bandwidth, Hz S is average power for signal, W N is average power for noise, W It is the basic principle and theory for spread spectrum

communications.


5 MHz12 KHz

Power is “Spread” Over a Larger BandwidthMATHHAMMER

MATHHAMMER

radio channel

ReceiverTransmitter

SpreadingDespreading

Noise


User information bits are spread over a wide bandwidth by multiplying high speed spread code(chip)

Spread signal bandwidth W wider than original signal bandwidth Rb

f

S （ f ）

f0Before spreading

signal

S （ f ）

ff0After spreading

signal

S （ f ）

ff0After despreading

signalWhite noise

f

S （ f ）

f0Before despreading

signalWhite noise

signal interference White noise


Spreading Mode

Direct sequence spread spectrum （ DS-SS ） Base band data is spread by multiplication of pseudo-noise

sequence and base-band pulse, the pseudo-noise sequence generated by the pseudo-noise generator

BER subject to Multiple Access Interference and near-far effect Power control can overcome the near-far effect, but it is limited

by power detection accuracy WCDMA uses DS-SS

Frequency hopping spread spectrum （ FH-SS ） Data is transmitted in the random channel by the carrier

frequency hopping Before FH again, data is transmitted using traditional

narrowband modulation No near-far effect

DS-SS communication system

A technology of transmission after spreading signal spectrum.

FastSpreadingSequence

SlowInformation

Sent

TX

SlowInformationRecovered

RX

FastSpreadingSequence

WidebandSignal


Many code channels are individually“spread” and then added together tocreate a “composite signal”

Unwanted Power from Other Resoures


Any Code Channel can be extracted from the received composite signal by using the “right” orthogonal code

Energy for transmitting signal can be lower than interference and noise

Processing Gain

Broadband Interference

Concept of orthogonal code

Orthogonal—the result of multiplying and sum is 0

Code1 +1 -1 +1 +1 -1 +1 -1 -1

Code2 -1 +1 +1 -1 -1 +1 +1 -1

Mul -1 -1 +1 -1 +1 +1 -1 +1

Sum 0Orthogonal

Code1 +1 -1 +1 -1 -1 +1 -1 -1Code2 +1 +1 -1 +1 -1 -1 +1 -

1Mul +1 -1 -1 -1 +1 -1 -1 +1Sum -2

Non-orthogonal

-1 1 -11-1 -11 1 -1 -1 11-1 1-1 1MUL-1 1 -11-1 -11 1

1 -1 1 -1

-4 40 0

Judge -1 1

1 -1 1 -1

-1 1 MUL

Integral

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

Example of orthogonal code

S1S1

S2S2

S1xC1S1xC1

S2XC2S2XC2

WW Spreading

Despreading(S1xC1)+(S2xC2)(S1xC1)+(S2xC2)

Air InterfaceAir Interface

[S1xC1+S2xC2]x[S1xC1+S2xC2]xC2C2

==S2S2

[S1xC1+S2xC2]xC[S1xC1+S2xC2]xC11

==S1S1 NN SS

C1xC2=0,C1,C2,orthogonal

Direct spread technique

Spreading code =1 -1 -1 1 -1 1 1 -1 ( SF = 8 )

Symbol

Spreading

Despreading

1-1

1-1

1

-1

1-1

1-1

Data=010010

Spreading code

Spread signal= Data × code

Data =Spread signal ×Spreading code

Chip

Sketch map of Spreading and Despreading

Characteristics of Spreading Communication

High anti-multi-path- interference capability Anti-sudden-pulse High security Lower transmitting power Easy to implement large-capacity Multiple Access

Communication Occupy band wide Complex realization

Content



Purpose of Channel Coding

By adding redundant information in the original data stream, receivers can detect and correct the error signal, and improve data transmission rates.

No correct coding: BER<10-1 ~ 10-2Can not satisfy

the communication

Convolutional coding ： BER<10-3Can satisfy the

speech communication

Turbo coding ： BER<10-6Can satisfy the

data communication

Principle of Channel Coding

Channel coding Error-correcting ability obtains by adding redundancy in the

original data Convolutional coding and Turbo coding （ 1/2 ， 1/3 ） are

widely applied. Increase noneffective load and transmission time Suitable to correct few non-continuous errors

W C D M AT U R B OS P E A K

W W C C D D M M A AT T U U R R B B O OS S P P E E A A K K

W ? C C D D M M A A

T T ? U R R B B O O

S S P P E E A ? K K

Decoding

Encoding

Principle of Interleave Technology

advantage Interleave is to change the sequence of data to random the

unexpected errors Advance the correcting validity

disadvantage Increase the processing delay Especially, Several independent random errors may intertwined for

the unexpected error.

x1 x6 x11 x16 x21x2 x7 … x22x3 x8 … x23x4 x9 … x24x5 x10 … x25

Data input A = (x1 x2 x3 x4 x5 … x25)

Data output A’= (x1 x6 x11 x16… x25)

e.g.

Encoding and Interleaving

W C D M AT U R B OS P E A K

W W C C D D M M A AT T U U R R B B O OS S P P E E A A K K

W T S W T SC U P C U PD R E D R EM B A M B AA O K A O K

W ? ? C D D M M A ?T ? ? U R ? ? B O OS ? ? P ? E A A K K

Encoding Interleaving

W T S ? ? ?? ? ? C U PD R ? D ? EM ? A M B AA O K ? O K

DeinterleavingDecoding

Encoding + Interleaving can correct both continuous and non-continuous errors

Content



Principle of Modulation

Definition Modulation is the process where the amplitude,

frequency, or phase of an electronic or optical signal carrier is changed in order to transmit information.

Using symbol stand for one or more bits to improve communication effectiveness

Classification Analog Modulation Digital Modulation

Symbolbit Modulation

Analog Modulation

The purpose of analog modulation is to impress an information-bearing analog waveform onto a carrier for transmission. Common analog modulation methods include:

Amplitude modulation (AM) Frequency modulation (FM) Phase modulation (PM)

Digital Modulation

The purpose of digital modulation is to convert an information-bearing discrete-time symbol sequence into a continuous-time waveform (perhaps impressed on a carrier). Basic analog modulation methods include

Amplitude shift Keying (ASK) Frequency shift Keying (FSK) Phase shift Keying (PSK)

Content

The Basic Principles of Wireless Communication UMTS Radio mechanism

UMTS Data transmission Procedure Channel Coding of UMTS Spreading Technology of UMTS Modulation of UMTS

WCDMA Data transmission Procedure

RF ReceivingDemodulationDespreading

Decoding & De-inteleaving

UE Data

UE Data Spreading

RF Transmitting

Modulation

Baseband demodulation

Baseband modulation

Encoding & Interleaving

Content



Mainly used in the voice channel and control signal channel

Coding rate is ½ and 1/3.

Output 0 G0 = 557 (octal)

Input D D D D D D D D



Rate 1/3 convolutional coder

Convolutional Code

Easy decode Short delay Generally use the Viterbi Algorithm Channel bit error rate is 10 － 3 magnitude Suitable to realtime service

e.g. speech and video service.

Characteristics of Convolutional code

Used in Data service channel Code Rate is 1/3 Can be implemented in the transmission for large block and long

delay services Turbo coding structure is based on two or more weak error

control code combinations. The information bits are interleaved in the two Encoder, and generate two information flow. At last, this information can be multiplexed and punctured

Decoding needs cycle iterative calculation

InterleaverEncoder 1

Encoder 2

Mul

tiple

x

inputoutput

Turbo Code

Complex decoding Use the LOG-MAP arithmetic Channel bit error rate is 10 － 6 magnitude Very suitable to non-realtime package service

which is BER sensitive & delay insensitive, e.g. WWW, FTP, E_mail, multimedia transmission.

Characteristics of Turbo Codes

Content



Symbol rate × SF = Chip rate=3.84McpsFor UMTS ， SF of uplink channelization code ： 4~256

SF of downlink channelization code: 4~512

OVSF: Orthogonal Variable Spreading Factor

OVSF Code Scrambling Code

Data Spread Data

Spreading Process of UMTS

Symbol Chip

3.84Mcps

3.84Mcps

Channelization Code

Adopt OVSF code Definition: Cch,SF,k, describe channelization code, where

SF : spread factor ， k : code number, 0 < k<SF-1

SF = 1 SF = 2 SF = 4

C ch,1,0 = (1)

C ch,2,0 = (1,1)

C ch,2,1 = (1,-1)

C ch,4,0 =(1,1,1,1)

C ch,4,1 = (1,1, -1, -1)

C ch,4,2 = (1, -1 ,1, -1)

C ch,4,3 = (1, -1, -1, 1)

Scrambling Code

UMTS Scrambling code is pseudo random binary sequence It has similar noise array character, seemingly random

but with regularity. Can make the user data further random , strengthened

by scrambling a code to keep secret the user data, at the same time easy to carry out multiple access communication.

UMTS scrambling code is generated from Gold sequence Gold sequence has excellent self-correlation. Cross-correlation is very week between two codes. It is used to identify cell and user for multiple access.

Characteristic of Scrambling code

There are 224 Uplink Scrambling Codes, they are used to distinguish different users in one cell.

There are 218-1 Downlink Scrambling Codes, used to distinguish different cells Scrambling codes usually used are the first 8192 codes,

which are code 0 ， 1 ，……， 8191. They are divided into 512 aggregations ， each aggregation has 1 primary scrambling code (PSC) and 15 secondary scrambling codes (SSC).

The 512 primary scrambling codes are divided further into 64 primary scrambling code groups , with 8 primary scrambling codes in each group.

Numbering rule for Downlink Scrambling Codes

…

218-1 Downlink Scrambling Codes in all(0..262142)

No. 511 Scrambling Code Group

81768177

8191

8176 ： PSC8177 ： SSC…8191 ： SSC


81608161

8175

8160 ：主扰码8161 ：辅扰码…8175 ：辅扰码


80648065

8079

8064 ：主扰码8065 ：辅扰码…8079 ：辅扰码

…


112113

127

8176 ： PSC8177 ：辅扰码…8191 ：辅扰码


1617

31

16 ： PSC17 ： SSC…31 ： SSC


01

15

0 ： PSC1 ： SSC…15 ： SSC

No.63 Primary Scrambling Code Group … …

No.0 Primary Scrambling Code Group

Code Functions

Channelization code ---- for separation of physical channels in the uplink and separation of users in the downlink

Scrambling code ---- for separation of users/terminals in the uplink and cells/sectors in the downlink.

Air Interface

2chc

3chc

1chc

scramblingc Modulation

Spreading code & scrambling code

Cch ： spread code Relative to service rate ， extended to 3.84Mchips/s A kind of orthogonal code

Cscrambling ： scrambling code Have no effect on signal bandwidth Downlink for identifier cell ， uplink identifier terminal A pseudo-random sequence

f

P

W

Processing Gain

Rb

Despreading

Processing Gain

PG=Wc/Rb (Wc : Chip rate , Rb : Service bit rate) Transmitter/receiver can obtain gain after

spread/despread The narrower original signal bandwidth, the larger Pg ,

the betterThe higher PG, the more anti-interference capability system has.

b

c

RWGain Processing

Eb =Signal Power

Bit Rate = SR

E / tB / t

= N0 =Noise PowerBandwidth = N

W

Eb

N0

=

SR

NW

=SR X

WN =

SN X W

R

Signal to Noise

Processing Gain

The more the expansion multiples, the higher the processing gain, the stronger the anti-jamming capability

Relation between Eb/N0 and PG

Despreading procedure

Method of despreading

Input signal

Local PN code

When T=Ts, judge

Output after despreading

integral

0

Ts(*)dt

Content



Modulation Methods in UMTS

BPSK (Binary Phase Shift Keying) in Uplink channles QPSK (Quadrature Phase Shift Keying) in Downlink channels 16QAM (16-state Quadrature Amplitude Modulation) in HSDPA

Physical Channel Spread-Spectrum Modulation Process-Downlink

∑ ∑

Separationof realPartsAnd

Imaginaryparts

PulseForming

PulseForming

SerialParallelSwitch

SerialParallelSwitch

……

……

Downlink physical channel 1

Cch,SF,m

j

I+jQSdl,n

G1

Cch,SF,m

j

I+jQSdl,n

G2Downlink

physical channel 2

Gp

Gp

P-SCH

S-SCH

cos(wt)

-sin(wt)

Re(T)

Im(T)

Physical Channel Spread-Spectrum Modulation Process-Uplink

Separationof realPartsAnd

Imaginaryparts

PulseForming

Pulse Forming

cos(wt)

-sin(wt)

Sdpch,n

Re(S)

Im(S)

∑

Cd,1 βd

I

cc

Q

j

I+jQ

∑

∑

DPDCH1Cd,3 βd

DPDCH3 Cd,5 βdDPDCH5

Cd,2 βdDPDCH2Cd,4 βd

DPDCH4 Cd,6 βdDPDCH6

ccCc βc

DPCCH

Q

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1.Wo Bt01 e1 1 Umts Radio Theory-63