Reduced complexity asynchronous multi-user receivers for spread spectrum multiple access.
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
One of the major problems facing the implementation of multi-user detectors in a mobile radio multiple access environment is the complexity of the receiver structure. This thesis addresses this problem and develops three related receiver structures based on the maximum likelihood multi-user detector. They allow a degradation in performance to be traded for a reduction in the complexity of the receiver. The first family of reduced complexity receivers is derived considering a serial partitioning of the maximum likelihood trellis. A receiver with two degrees of freedom is developed by the application of reduced state sequence estimation (RSSE) techniques to the first receiver. A maximum-ratio combining-like detector with self-noise cancellation is derived for the multi-path fading channel. All three receiver structures allow for significant reductions in complexity with respect to the maximum likelihood detector with only modest performance reductions.