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Wideband DS-CDMA for Next-Generation Mobile Communications Systems

Wideband DS-CDMA for Next-Generation Mobile Communications Systems. Reference:IEEE Communication Magazine,1998.9. Reporter : Vincent Chen Advisor : Prof. Li-Chun Wang. 2000/8/13. Introduction:. Second-Generation cellular system:. Adopted digital technology Limited basic service

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Wideband DS-CDMA for Next-Generation Mobile Communications Systems

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  1. Wideband DS-CDMA for Next-Generation Mobile Communications Systems Reference:IEEE Communication Magazine,1998.9 Reporter : Vincent Chen Advisor : Prof. Li-Chun Wang 2000/8/13

  2. Introduction: Second-Generation cellular system: • Adopted digital technology • Limited basic service • Low-bit-rate Third-Generation cellular system: • ITU:IMT-2000,2Mb/s • Wideband DS-CDMA • FDD,Air interface standard

  3. The difference between second and third generation • Isolated cell case • Sectored cell: Overcome the interference program The difference between IS95 and WDS-CDMA • IS95: Base on narrowband DS-CDMA • Optimized for basic service

  4. Content: W-CDMA Technology The important concepts: • Intercell asynchronous operation • Pilot channel associated with individual data • channels • 1:Coherent Detection • 2:Interference Cancellation • 3:Adaptive antenna array • (can be viewed as Adaptive cell sectorization)

  5. The technical features: • Fast transmit power control • Coherent spreading code tracking • Coherent rake receiver • Orthogonal multispreading factor forward link • Variable-rate transmission with blind rate detection Field experiment

  6. Enhanced Radio Transmission Techniques Multi-Stage Interference Canceller An Adaptive Antenna Array Combined with A Rake Receiver Matched Filter Rake Receiver Turbo Codes

  7. W-CDMA Technology Design Concept: Transmiter Add Header Channel Coding 10ms Data Modulate QPSK Spread 2GHZ Receiver 10ms Data MF Rake Combiner Subtract Header Viterbi Decoder

  8. Fast Cell Search Under Intercell Asynchronous Operation Cell search algorithm: 1: Detect scramble mask timing of best cell (least sum of propagation path loss plus shadowing) 2: Identify the scramble code group 3: Search for the scramble code

  9. Fast TPC

  10. Coherent spreading code tracking

  11. Coherent Rake Combining

  12. Orthogonal multi-spreading factor forward link

  13. Variable-rate transmission with blind rate detection Discontinuous:Keep same Symbol rate Cyclic Redundancy Check Decoding Continuous:Keep same Chip rate Data rata=M Spreading code=01 Data rata=M/2 Spreading code=0011

  14. Field experiment System set-up for 32kb/s data transmission

  15. Measurement course characterization

  16. The effect of spreading bandwidth

  17. High-speed(1.92 Mb/s) data transmission

  18. Enhanced Radio Transmission Techniques Multi-Stage Interference Canceller COMSIC: COherent Multi-Stage IC CEIGU:Channel Estimation-and-Interference Generation Unit

  19. An Adaptive antenna array combined with a Rake receiver CAAAR Receiver: Coherent Adaptive Antenna Array Rake Receiver

  20. Matched Filter Rake Receiver

  21. Turbo Codes The main difference between Turbo codes and Conventional code • Concatenating two or more recursive systematic codes • Using a pseudo-random interleaver • Iterative decoding algorithm

  22. RSC:Recursive system convolutional encoder

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