Trellis-coded modulation for code division multiple access communication
Abstract
The performance of direct-sequence spread-spectrum multiple-access (CDMA) communication systems is degraded by the interference from other simultaneous users. Trellis-coded modulation (TCM) techniques have been known to improve the error performance of conventional communication systems without additional bandwidth by expanding the signal constellation and selecting from that constellation. We combine TCM with CDMA to improve the error performance of multiple-access communications. New types of signal sets that exploit the dimensions in an expanded signal set are proposed so that we can improve the error performance of CDMA without additional bandwidth and power. An expression for the output of the coherent correlation receiver is obtained for the case of random sequences. The expression is used to study the density function of the multiple-access interference and to determine arbitrarily tight upper and lower bounds on the average probability of error. We also use the improved Gaussian approximation method to approximate the error performance of TCM/CDMA systems. Analytical and numerical results show the new signal sets can improve the performance of CDMA systems with a coding gain of 6 dB or higher.
Degree
Ph.D.
Advisors
Lehnert, Purdue University.
Subject Area
Electrical engineering
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