wo bt1001 e01 1 umts radio theory

UMTS Radio TheoryZTE University

ContentThe Basic Principles of Wireless Communication 3G servicesMultiple Access TechnologiesSpectrum PlanningSpreading TechnologyCoding And Interleave TechnologyModulation

UMTS Radio mechanism

Radio Transmission Technology RequirementsData144 kbps High speed and driving384 kbps Modest speed and walking2 Mbps Low speed and indoorVoice4.75Kb/s -- 12.2Kb/s64kb/s (Video Phone)Information transmission at variable rate according to bandwidth requirementsDelay requirements of different service

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3G services

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3G services

CategoriesActual ServiceDelay (One-way)Bearer SpeedconversationalVoice

Duplex modeTDD modeuplink and downlink has the same frequencyAdaptable to any frequency bandSuitable for both asymmetric and symmetric servicesFDD modeuplink and downlink has the different frequencyPaired frequency bands are neededSuitable for symmetric services

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

FDDFrequency division duplex, Such as WCDMA and CDMA2000

Why Multiple Access?Increased capacity: serve more usersReduced capital requirements since fewer media can carry the trafficDecreased per-user expenseTypes of Transmission Medium:Twisted pairCoaxial cableFiber optic cableAir interface (radio signals)

Three methods are frequently used: FDMATDMA CDMA

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

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

FDMA (Frequency Division Multiple Access)FDMATraffic channels are assigned to different users at different frequency band, such as TACS, AMPS.

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TDMA (Time Division Multiple Access)TDMATraffic channels are assigned to different users at different time, such as GSM, DAMPS.

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CDMA (Code Division Multiple Access)CDMATraffic channels are assigned to users at same time, same frequency band, but with different code.

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CDMA ApplicationUsers are distinguished by scrambling codes and OVSF codesSelf-interference system CDMA system is restricted to interference (GSM system is restricted to frequency resources)

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Single Frequency Network

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IMT-2000 Spectrum Allocation

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3G Spectrum Allocation in China

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3G Spectrum Planning in ChinaMain Operating Frequency BandFDD mode1920-1980 MHz / 2110-2170 MHzTDD mode1880-1920MHz2010-2025 MHzSupplementary Operating Frequency BandFDD mode1755-1785 MHz / 1850-1880 MHzTDD mode2300-2400MHzFrequency Band for Satellite Mobile Communication System1980-2010 MHz / 2170-2200 MHzThe 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.

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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.

Conclusion: when c is fixed value,S/N is a reciprocal ratio---constantShanon equationC=Wlog2(1+S/N)W: HzC: bits/swhen C is constant W and S/N can be inter changed.High efficient RTT can increase the real capacity of system which far less the theoretical one.

Spread Spectrum PrinciplesMATHHAMMERMATHHAMMER

Illustrate the procedure lively

radio channel Receiver

TransmitterSpreadingDespreading

Noise

Spread Spectrum PrinciplesUser 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

Spread Spectrum Principles

CDMACDMA WCDMACDMA3CDMACDMACDMA

Spreading ModeDirect sequence spread spectrumDS-SSBase band data is spread by multiplication of pseudo-noise sequence and base-band pulse, the pseudo-noise sequence generated by the pseudo-noise generatorBER subject to Multiple Access Interference and near-far effectPower control can overcome the near-far effect, but it is limited by power detection accuracyWCDMA uses DS-SSFrequency hopping spread spectrumFH-SSData is transmitted in the random channel by the carrier frequency hoppingBefore FH again, data is transmitted using traditional narrowband modulationNo near-far effect

DSSSdirect sequence spread WCDMAFHSS)Bluetooth

3.84MHzSF3.84MHz3.84MHz

DS-SS communication systemA technology of transmission after spreading signal spectrum.

Direct-Sequence Spread spectrum systems mix their input data with a fast spreading sequence and transmit a wideband signalThe spreading sequence is independently regenerated at the receiver and mixed with the incoming wideband signal to recover the original dataUser information bits are spread over a wide bandwidth by multiplying high speed spread code (chip) Spreading signal bandwidth wider than original signal bandwidth.

C=Wlog2(1+S/N)WCS/N

(Shannon Theroy)>> >xDSL(Hz)(b/S)AT&T(Claude Elwood Shannon)>> >1948(Mathematical Theory of Communication)>> >SNW(Hz)CC=Wlog2(1+S/N)(bps)>> >(1)W(S/N)>> >(1)SN>> >(2)N0C>> >(3)CWS/N>> >(4)W()>> >n0,n0=N/W>> >3S/NdBC/Wb/S/HzC/W>> >FDMATDMACDMASDMAOFDMxDSLDMTCAP

Spread Spectrum Principles

Unwanted Power from Other Resoures

Spread Spectrum PrinciplesAny Code Channel can be extracted from the received composite signal by using the right orthogonal codeEnergy for transmitting signal can be lower than interference and noise

Processing GainBroadband Interference

Process Gain

Concept of orthogonal codeOrthogonal

the result of multiplying and sum is 0

Code1+1 -1 +1 +1 -1 +1 -1 -1Code2-1 +1 +1 -1 -1 +1 +1 -1Mul-1 -1 +1 -1 +1 +1 -1 +1Sum0Orthogonal

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-2Non-orthogonal

0

-11-11-1-111-1-111-11-11

MUL1-11-1-1111-11-1-4400Judge-111-11-1-11MULIntegralExample of orthogonal code

Spreading

Despreading

C1xC2=0,C1,C2,orthogonal

Direct spread technique

SpreadingStotal(t)=A1S1(t)PN1PR1+ A2S2(t)PN2PR2+ A3S3(t)PN3PR3+De-spreadingS(t) PN1PR1 =A1S1(t)PN1PR1 PN1PR1 + A2S2(t)PN2PR2 PN1PR1 + A3S3(t)PN3PR3 PN1PR1 +=A1S1(t)+0Multiple Address InterferenceS(t) PN1PR1 =A1S1(t)PN1PR1 PN1PR1 + A2S2(t)PN2PR2 PN1PR1 + A3S3(t)PN3PR3 PN1PR1 +=A1S1(t)+IAMI(t)

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

1-1 1-1

1-1

1-1Data=010010Spreading codeSpread signal= Data codeData =Spread signal Spreading codeChipSketch map of Spreading and Despreading

Characteristics of Spreading CommunicationHigh anti-multi-path- interference capabilityAnti-sudden-pulseHigh securityLower transmitting powerEasy to implement large-capacity Multiple Access Communication Occupy band wideComplex realization

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

WCDMA1/21/310exp(-3)Turbo WCDMA1/35114TURBOLOGMAP10exp(-6)WWWFTPEMAIL

Principle of Channel CodingChannel codingError-correcting ability obtains by adding redundancy in the original dataConvolutional coding and Turbo coding 1/21/3 are widely applied.Increase noneffective load and transmission timeSuitable to correct few non-continuous errors

Principle of Interleave TechnologyadvantageInterleave is to change the sequence of data to random the unexpected errorsAdvance the correcting validitydisadvantageIncrease the processing delayEspecially, Several independent random errors may intertwined for the unexpected error.

Encoding and InterleavingW C D M AT U R B OS P E A KW 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 KW T S W T SC U P C U PD R E D R EM B A M B AA O K A O KW ? ? C D D M M A ?T ? ? U R ? ? B O OS ? ? P ? E A A K KEncodingInterleavingW T S ? ? ?? ? ? C U PD R ? D ? EM ? A M B AA O K ? O KDeinterleavingDecodingEncoding + Interleaving can correct both continuous and non-continuous errors

Principle of ModulationDefinitionModulation 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 effectivenessClassificationAnalog ModulationDigital Modulation

Analog ModulationThe 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 ModulationThe 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 includeAmplitude shift Keying (ASK)Frequency shift Keying (FSK)Phase shift Keying (PSK)

ContentThe Basic Principles of Wireless Communication UMTS Radio mechanismUMTS Data transmission ProcedureChannel Coding of UMTSSpreading Technology of UMTSModulation of UMTS

WCDMA Data transmission Procedure

Demodulation

Despreading

Decoding & De-inteleaving

UE Data

UE Data

Spreading

RF Transmitting

Modulation

Baseband demodulation

Encoding & Interleaving

1514.4M14.4M/15() / 44bitsymbol *1616=3.84M 3840k/16()15()416QAM3/4() 10.8M

Mainly used in the voice channel and control signal channelCoding rate is and 1/3.

Convolutional Code

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Easy decodeShort delayGenerally use the Viterbi AlgorithmChannel bit error rate is 103 magnitude Suitable to realtime servicee.g. speech and video service.

Characteristics of Convolutional code

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Used in Data service channelCode Rate is 1/3Can be implemented in the transmission for large block and long delay servicesTurbo 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 puncturedDecoding needs cycle iterative calculation

Turbo Code

*WCDMATurbo1/3Eb/No5dB34.78dBTurboRTTraker50%10%10dBTurbo10%10-6ARQTurbo+ARQ50dBTurbo

Complex decodingUse the LOG-MAP arithmeticChannel bit error rate is 106 magnitudeVery suitable to non-realtime package service which is BER sensitive & delay insensitive, e.g. WWW, FTP, E_mail, multimedia transmission.

Characteristics of Turbo Codes

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Symbol rate SF = Chip rate=3.84McpsFor UMTSSF of uplink channelization code4~256 SF of downlink channelization code: 4~512OVSF: Orthogonal Variable Spreading Factor OVSF CodeScrambling CodeDataSpread DataSpreading Process of UMTSSymbolChip3.84Mcps3.84Mcps

The actual process of spreading is done over two phases, channelization and scrambling. Either a 38400 chip scrambling code, or a shorter 256 chip scrambling code can be to used to scramble the data. The difference between these two approaches is that with the use of shorter codes, multi-user detection schemes can be used at the base station

Channelization CodeAdopt OVSF codeDefinition: Cch,SF,k, describe channelization code, where

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

Scrambling CodeUMTS Scrambling code is pseudo random binary sequenceIt 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 sequenceGold 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 codeThere 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 cellsScrambling codes usually used are the first 8192 codes, which are code 018191. They are divided into 512 aggregationseach 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.

224---?? 24th power based on 2.?

Numbering rule for Downlink Scrambling Codes218-1 Downlink Scrambling Codes in all(0..262142)No.63 Primary Scrambling Code Group No.0 Primary Scrambling Code Group

No. 511 Scrambling Code Group81768177

81918176PSC8177SSC8191SSC


8175816081618175


8079806480658079


1278176PSC81778191


3116PSC17SSC31SSC


150PSC1SSC15SSC

218-1 downlink SCs (scrambling codes) are available.213 = 8192, numbered by 0 .. 8191 are used for primary and secondaryscrambling purposes.Those 213 codes are divided into 29 = 512 groups, each containing a 24= 16 SCs. The first of that set of 16 SCs is always used as the primaryscrambling code SC ( n = 16i with i = 0..511) for that group and theresidual 15 SCs are available as secondary scrambling codes.The number of 512 primary scrambling codes are organised again in64 scrambling code groups, each containing 8 scrambling codes, ofcourse.The following relation with respect to the code numbering applies:SC number = 16 8 j + 16 kwithj = 0..63 (code group number) andk = 0..7 (primary SC number within the code group j).

Code FunctionsChannelization 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 InterfaceSpreading code & scrambling code Cchspread codeRelative to service rateextended to 3.84Mchips/sA kind of orthogonal codeCscramblingscrambling codeHave no effect on signal bandwidthDownlink for identifier celluplink identifier terminalA pseudo-random sequence

Pseudo----/Psju:deu/

fP

WProcessing GainRbDespreading

Processing GainPG=Wc/Rb (Wc : Chip rate , Rb : Service bit rate)Transmitter/receiver can obtain gain after spread/despreadThe narrower original signal bandwidth, the larger Pg , the better

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

-Pg = [chip rate] / [bit rate of service] S (after de-spread)= S (before de-spread) + Pg( spread gain)Safterdespreading/N > Eb/Notarget (ensure Qos for different service)S Signal from User A(after despreading)Total Interference+Noise LevelS Signal from User A (before despreading,part of noise floor)

The more the expansion multiples, the higher the processing gain, the stronger the anti-jamming capabilityRelation between Eb/N0 and PG

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Despreading procedureMethod of despreading

Judge when T=Ts------integral---means calculate area.Actually, we use high voltage---positive denote 1, we use negative voltage denote 1,

Modulation Methods in UMTSBPSK (Binary Phase Shift Keying) in Uplink channlesQPSK (Quadrature Phase Shift Keying) in Downlink channels16QAM (16-state Quadrature Amplitude Modulation) in HSDPA

Physical Channel Spread-Spectrum Modulation Process-Downlink

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Physical Channel Spread-Spectrum Modulation Process-Uplink

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Conclusion: when c is fixed value,S/N is a reciprocal ratio---constantShanon equationC=Wlog2(1+S/N)W: HzC: bits/swhen C is constant W and S/N can be inter changed.High efficient RTT can increase the real capacity of system which far less the theoretical one.

Illustrate the procedure lively

CDMACDMA WCDMACDMA3CDMACDMACDMA

DSSSdirect sequence spread WCDMAFHSS)Bluetooth

3.84MHzSF3.84MHz3.84MHzDirect-Sequence Spread spectrum systems mix their input data with a fast spreading sequence and transmit a wideband signalThe spreading sequence is independently regenerated at the receiver and mixed with the incoming wideband signal to recover the original dataUser information bits are spread over a wide bandwidth by multiplying high speed spread code (chip) Spreading signal bandwidth wider than original signal bandwidth.

C=Wlog2(1+S/N)WCS/N

(Shannon Theroy)>> >xDSL(Hz)(b/S)AT&T(Claude Elwood Shannon)>> >1948(Mathematical Theory of Communication)>> >SNW(Hz)CC=Wlog2(1+S/N)(bps)>> >(1)W(S/N)>> >(1)SN>> >(2)N0C>> >(3)CWS/N>> >(4)W()>> >n0,n0=N/W>> >3S/NdBC/Wb/S/HzC/W>> >FDMATDMACDMASDMAOFDMxDSLDMTCAP

Process Gain0

SpreadingStotal(t)=A1S1(t)PN1PR1+ A2S2(t)PN2PR2+ A3S3(t)PN3PR3+De-spreadingS(t) PN1PR1 =A1S1(t)PN1PR1 PN1PR1 + A2S2(t)PN2PR2 PN1PR1 + A3S3(t)PN3PR3 PN1PR1 +=A1S1(t)+0Multiple Address InterferenceS(t) PN1PR1 =A1S1(t)PN1PR1 PN1PR1 + A2S2(t)PN2PR2 PN1PR1 + A3S3(t)PN3PR3 PN1PR1 +=A1S1(t)+IAMI(t) WCDMA1/21/310exp(-3)Turbo WCDMA1/35114TURBOLOGMAP10exp(-6)WWWFTPEMAIL

1514.4M14.4M/15() / 44bitsymbol *1616=3.84M 3840k/16()15()416QAM3/4() 10.8M* *

*WCDMATurbo1/3Eb/No5dB34.78dBTurboRTTraker50%10%10dBTurbo10%10-6ARQTurbo+ARQ50dBTurbo*

The actual process of spreading is done over two phases, channelization and scrambling. Either a 38400 chip scrambling code, or a shorter 256 chip scrambling code can be to used to scramble the data. The difference between these two approaches is that with the use of shorter codes, multi-user detection schemes can be used at the base station Walsh funtionbintreeancestor: direct children224---?? 24th power based on 2.?218-1 downlink SCs (scrambling codes) are available.213 = 8192, numbered by 0 .. 8191 are used for primary and secondaryscrambling purposes.Those 213 codes are divided into 29 = 512 groups, each containing a 24= 16 SCs. The first of that set of 16 SCs is always used as the primaryscrambling code SC ( n = 16i with i = 0..511) for that group and theresidual 15 SCs are available as secondary scrambling codes.The number of 512 primary scrambling codes are organised again in64 scrambling code groups, each containing 8 scrambling codes, ofcourse.The following relation with respect to the code numbering applies:SC number = 16 8 j + 16 kwithj = 0..63 (code group number) andk = 0..7 (primary SC number within the code group j).Pseudo----/Psju:deu/-Pg = [chip rate] / [bit rate of service] S (after de-spread)= S (before de-spread) + Pg( spread gain)Safterdespreading/N > Eb/Notarget (ensure Qos for different service)S Signal from User A(after despreading)Total Interference+Noise LevelS Signal from User A (before despreading,part of noise floor)*

Judge when T=Ts------integral---means calculate area.Actually, we use high voltage---positive denote 1, we use negative voltage denote 1,

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wo bt1001 e01 1 umts radio theory

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different frequency

different users

frequency resources

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frequency bandfdd mode1920