Symbol-Based Turbo Codes for Wireless Communications

This thesis studies a new method of combining Turbo Codes with various modulation techniques to take advantage of inherent trade-o s between BER performance, code rate, spectral e ciency and decoder complexity. Our new method, which we call Symbol-Based Turbo Codes, parses the parallel data streams of the Turbo Code encoder into n-bit symbols and maps each symbol to a point in a 2n-ary signal set. In the case of Symbol-Based Turbo Codes with BPSK modulation, the BER performance can be improved while at the same time decreasing the decoder complexity as compared with the traditional Turbo Code. Symbol-Based Turbo Codes are good candidates for spread spectrum communication systems such as CDMA. Speci cally, the Symbol-Based Turbo Code with orthogonal modulation can be used for a non-coherent up-link, or bi-orthogonal modulation for a coherent up-link. Furthermore, Symbol-Based Turbo Codes with either M-ary PSK modulation or BPSK modulation can be used for a coherent down-link. iv Acknowledgements I would like to acknowledge my supervisor Dr. A. K. Khandani for his guidance throughout my research. Thank-you for sharing your insight and enthusiasm about the use of Turbo Codes in PCS applications. I would like to thank NSERC, ICR and the University of Waterloo for their nancial support. I would also like to thank all my friends at the University of Waterloo InterVarsity Christian Fellowship. Your friendship and encouragement has meant a lot to me throughout my years at university. v