A comparison of two novel channel coding techniques for CDMA
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In Code Division Multiple Access (CDMA) systems forward error correction (FEC) is an important factor in improving system perfonnance. Because of the multiple access interference observed in asynchronous CDMA, FEC is required to improve system capacity. Several alternative coding techniques are available, including "trellis codes" specifically designed for CDMA, very low rate convolutional codes and conventional convolutional codes.
An analytic approach is developed to compare the perfonnance of different coding techniques for CDMA on the same basis by extending several improved analysis techniques which were developed for uncoded CDMA. Analytic results are presented for additive white Gaussian noise (AWGN) channels and frequency non-selective Rician Fading (FNRF) channels. The perfonnance of coded CDMA systems in frequency selective Rayleigh fading channels is also analyzed using simulation techniques.
Both analytic and simulation results show that by using trellis codes or very low rate convolutional codes significant perfonnance improvement is achieved over conventional convolutional codes. Trellis codes outperfonn very low rate convolutional codes in AWGN and FNRF channels while both codes show similar perfonnance in frequency selective Rayleigh fading channels.
- Masters Theses