| Summary: | In this thesis receiver architectures for an unknown, time-varying Rayleigh fading channel are investigated. This includes fast fading scenarios, where the channel impulse response (CIR) can change significantly between two adjacent samples. Channel estimation based on the minimum mean squared error criterion (MMSE) applied to smoothing and linear prediction is considered. One of the key objectives in this thesis is the analysis of error propagation effects due to decision feedback. The studied receiver architectures are divided into two main parts: one-shot receivers which detect the received symbol on a symbol-by-symbol basis, and sequence detectors which jointly estimate and detect the entire received signal sequence. Considering one-shot receivers, a decision directed receiver is studied using differential modulation (DPSK). The receiver can significantly improve the fast fading performance of conventional DPSK, through linear predictive channel estimation. It is demonstrated through simulation that the performance of the decision directed receiver is better than that of an idealised reference receiver where channel estimation is not corrupted by decision feedback errors (e.g. by means of employing a pilot signal). Furthermore, a receiver employing coherent modulation is considered. The necessary phase reference is provided by time multiplexed pilot symbols. A receiver which exclusively uses these pilot symbols for channel estimation is the pilot aided receiver. The performance for slow fading is excellent, whereas the performance degrades as the Doppler frequency increases. The degradation is proportional to the spacing of the pilots. The performance of both the decision directed and the pilot aided receiver can be significantly improved by employing a second stage channel estimation filter, using a smoothing type estimation filter.
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