WCDMA Radio Theory

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Presentation Transcript

WCDMA Radio Theory : 

WCDMA Radio Theory ZTE University TD&W&PCS BSS Course Team

Course Objectives : 

Course Objectives At the end of this course, you will be able to: Master channel encoding of WCDMA Master spread spectrum principle of WCDMA Master modulation of WCDMA

Content : 

Content The basic principles of wireless communication Radio Propagation Characteristics Multi Access Spread spectrum Technology Channel Coding Interleave Technology WCDMA wireless technology

Characteristic of Radio Propagation : 

Characteristic of Radio Propagation Electromagnetic propagation: direct radiation?reflection?diffraction and scattering Signal attenuation: Path loss: Loss of electromagnetic waves in large scope of the spread reflects the trend of the received signal in the spreading? Slow fading:Loss because of being blocked by the building and hill in the propagation path Fast fading:Electromagnetic signals rapidly decline in a few dozens wavelength ranges Description of Fast fading distribution Rayleigh distribution:non line-of –sight transmission Rice distribution:line-of –sight transmission Radio propagation charactistics

Characteristics of Radio Propagation : 

Frequency off-set caused by the movement of mobile ,that is Doppler effect Characteristics of Radio Propagation Radio propagation charactistics

Multi-Path Effects : 

Multi-Path Effects sending signal Radio propagation charactistics

Content : 

Content The basic principles of wireless communication Radio Propagation Characteristics Multi Access Spread spectrum Technology Channel Coding Interleave Technology WCDMA wireless technology

Multiple Access : 

Frequency division multiple access technology Channels in different frequency are allocated to different users, e.g. TACS?AMPS? Time division multiple access technologychannels in different time are allocated to different users, e.g. GSM?DAMPS? Code division multiple access technology Users distinguished by scramble code, e.g. CDMA Multiple Access Multiple access

Content : 

Content The basic principles of wireless communication Radio Propagation Characteristics Multi Access Spread spectrum Technology Channel Coding Interleave Technology WCDMA wireless technology

Principle of Spreading spectrum : 

Principle of Spreading spectrum A technology of transmission technology after spreading frequency of signal. Theoretical Basis: Shannon theory C=Wlog2(1+S/N) Spreading technology

Sketch Map of Spreading : 

Sketch Map of Spreading Spreading technology

Spreading Mode : 

Spreading Mode Direct sequence spread(DS-SS) Base band data is spreaded 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(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 Spreading technology

Characteristics of Spreading Communication : 

Characteristics of Spreading Communication High anti-multi-path- interference capability High security Lower transmitting power Easy to implement large-capacity Multiple Access Communication Occupy band wide Complex realization Spreading technology

Content : 

Content The basic principles of wireless communication Radio Propagation Characteristics Multi Access Spread spectrum Technology Channel Coding Interleave Technology WCDMA wireless technology

Purpose of Channel Coding : 

Purpose of Channel Coding purpose: By adding redundant information in the original data stream, receivers can detect and correct the error signal, and improve data transmission rates. Error-correcting ability obtains by adding redundancy in the original data Channel coding

Principle of Channel Coding : 

Principle of Channel Coding Channel coding Convolutional coding and Turbo coding (1/2,1/3) are widely applied. Increase redundancy and transmission time Suitable to correct few non-continuous errors Channel coding

Content : 

Content The basic principles of wireless communication Radio Propagation Characteristics Multi Access Spread spectrum Technology Channel Coding Interleave Technology WCDMA wireless technology

Principle of Interleave Technology : 

Principle of Interleave Technology advantage Interleave is to change the sequence of data to discretize the burst continuous errors Advance the correcting validity disadvantage: Increase the processing delay Especially, Several independent random errors may intertwined for the unexpected error . Interleaving technology

Encoding and Interleaving : 

Encoding and Interleaving W C D M A T U R B O S P E A K W W C C D D M M A A T T U U R R B B O O S S P P E E A A K K W T S W T S C U P C U P D R E D R E M B A M B A A O K A O K W ? ? C D D M M A A T ? ? U R R B B O O S ? ? P E E A A K K Encoding Interleaving W T S ? ? ? ? ? ? C U P D R E D R E M B A M B A A O K A O K Deinterleaving Decoding Interleaving technology

Content : 

Content The basic principles of wireless communication WCDMA wireless technology

Data transmission Procedure : 

UE Data Encoding & Interleaving Spreading&Scrambling RF Transmission RF Receiving Demodulation Despreading&Descrambling Data transmission Procedure Modulation Baseband demodulation WCDMA wireless technology

Convolutional Code : 

Convolutional Code Mainly used in the voice channel and control signal channel Coding rate is ½ and 1/3? WCDMA wireless technology

Characteristics of Convolutional code : 

Characteristics of 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. WCDMA wireless technology

Turbo Code : 

Turbo 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 WCDMA wireless technology

Characteristics of Turbo Codes : 

Characteristics of Turbo Codes 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 . WCDMA wireless technology

Interleaving Technology of WCDMA : 

Interleaving Technology of WCDMA Intra-frame interleave Bits transform in the internal frame Inter-frame interleave Data transform among the frames Intra-Turbo codes interleave Complex nesting of intra-frame and inter-frame interleave WCDMA wireless technology

Data transmission Procedure : 

UE Data Encoding & Interleaving Spreading&Scrambling Modulation RF Transmission RF Receiving Demodulation Despreading&Descrambling Decoding & Deinteleaving UE Data Data transmission Procedure WCDMA wireless technology

Spreading of WCDMA : 

Symbol rate × SF = 3.84Mcps WCDMA,SF of uplink channelized code:4~256 SF of downlink channelized code:4~512 OVSF: Orthogonal Variable Spreading Factor OVSF Code Scramble Code Data bit Chip after Spreading Spreading of WCDMA WCDMA wireless technology

Despreading of WCDMA : 

Despreading of WCDMA Method of despreading WCDMA wireless technology

Spreading and Despreading : 

Symbol Spreading Despreading 1 -1 1 -1 1 -1 1 -1 1 -1 Data = 010010 Spreading code Spread signal = Data × code Spreading code = 1 -1 -1 1 -1 1 1 -1 ( SF = 8 ) Data = Spread signal × Spread code Chip Spreading and Despreading WCDMA wireless technology

Concept of orthogonal code : 

Concept of orthogonal code Orthogonal— the result of multiplying and sum is 0 WCDMA wireless technology

Code Resource Allocation : 

Code Resource Allocation Channelization code: Channelization codes are based on the orthogonal variable spreading factor (OVSF) technology. Transmission from a single source are separated by channelization codes. Scrambling code: Scrambling codes are used after spreading, which will not change the signal bandwidth. They are only used to differentiate different UEs or Node Bs. In WCDMA, code resources are mainly divided into channelization codes and scrambling codes. WCDMA wireless technology

Channelization Code : 

Channelization Code Adopt OVSF code C ch,SF,k:describe channelization code, SF:spread factor, k:code number, 0 < k<SF-1 WCDMA wireless technology

Characteristic of channelization code : 

Characteristic of channelization code Premise of code allocation: ensure not occupied for the code in the root direction and downwards subtree Result of code allocation: block all low rate SC in subtree and high rate in upwards root direction WCDMA wireless technology

Example : 

Example WCDMA wireless technology

Scrambling code : 

OVSF Code Scramble Code Data bit Chip after Spreading Scrambling code 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. 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. WCDMA wireless technology

Scrambling code of WCDMA : 

Scrambling code of WCDMA WCDMA scrambling code is generated from Gold sequence Gold has excellent self_correlation, Mutual_correlation is very small between subsection serial. It is used to identify cell and user for multiple address. WCDMA Scrambling code is pseudo random binary sequence (PN code) It has similar noise array character , is that one kind is seemingly random but cyclicity binary system array. Can make the user data a further randomization , strengthened by scrambling a code to keep secret the function, at the same time easy to carry out multiple access communication. WCDMA wireless technology

Characteristic of Scrambling code : 

Characteristic of Scrambling code There are 224 Uplink Scrambling Codes, they are used to distinguish different users in one cell. Uplink Scrambling codes include long scrambling codes and short scrambling codes. The Short Scrambling codes are used for multi-user detecting There are 218-1 Downlink Scrambling Codes, used to distinguish different cells Scrambling codes in common use are 0,1,……,8191,they are divided into 512 aggregations,each aggregation has 1primary scrambling code and 15 secondary scrambling codes. 512 primary scrambling codes can be divided into 64 scrambling code groups ,there is 8 primary scrambling in each group. WCDMA wireless technology

Data transmission Procedure : 

UE Data Encoding & Interleaving Spreading&Scrambling Modulation RF Transmission RF Receiving Demodulation Despreading&Descrambling Decoding & Deinteleaving UE Data Data transmission Procedure WCDMA wireless technology

WCDMA Modulation : 

WCDMA Modulation UL: BPSK DL:QPSK(HSDPA introduce 16QAM) WCDMA wireless technology

Exercise : 

Exercise multiple access technolog include ? pls describe the channel coding purpose and interleaving technology purpose. WCDMA adopts( ) and( )channel coding technology. the coding rate is( ) ( ) the spreading code of WCDMA is ( ), the sf of ul channelize code is ( ), and the dl is ( ) There are ( ) Uplink Scrambling Codes, they are used to distinguish different( ) in one cell. There are ( ) Downlink Scrambling Codes, used to distinguish( ) WCDMA modulation technology include ( ) and ( )

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