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Using LMS weighting value as the CSI for soft decision Viterbi decoder. Advisor : Yung-An Kao Student : Chi-Ting Wu 2005.01.28. Outline. Introduction Block diagram Formula computation Simulation results Conclusion. Introduction.
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Using LMS weighting value as the CSI for soft decision Viterbi decoder Advisor : Yung-An Kao Student : Chi-Ting Wu 2005.01.28
Outline • Introduction • Block diagram • Formula computation • Simulation results • Conclusion
Introduction • For Viterbi decoder, we view different sub-carriers in the same channel condition • Actually, different sub-carrier suffers different channel condition • Using the CSI for each sub-carriers • long train symbol? What else? • equalizer weighting values !!
Formula computation • According to the Central Limit Theorem, after we transmit lots of symbols, they all seems like Gaussian distribution • The likelihood function will become
Formula computation And we know that the weighting value is The received signal after phase compensation is
Formula computation We want the same weighting value for Therefore, we use the weighting value : And we take the expected value
Simulation ~ interleaver 500 symbols 100 times average 1:1:15 dB CFO=0.01 No SFO Trms=50ns 4 bit quantization No weighting value
Simulation ~ quantization 100 symbols 100 times average 1:1:15 dB CFO=0.01 No SFO Trms=50ns No weighting value
Simulation ~ weighted CSI 500 symbols 100 times average 1:1:15 dB CFO=0.01 No SFO Trms=50ns 4 bit quantization With interleaver
Simulation ~ weighted CSI 1000 symbols 100 times average 1:1:15 dB CFO=0.01 No SFO Trms=50ns 4 bit quantization With interleaver
Conclusion • Weighting values added should has better performance • Some dimension problems should take notice