Research And Application Of Iterative Signal Processing Techniques

The trend of future wireless communication system is to have higherdate rate and better transmission quality, thus advanced signal processingtechnologies are demanded to combat wireless channel impairments.Iterative signal processing techniques improve system performancesignificantly, thus suitable for next generation communication systems. Inthis dissertation, iterative signal processing techniques are investigated inchannel equalization and signal collision recovery field.Compared with traditional channel equalization methods which do notremove channel influence efficiently, either not effective or too expensivefor implementation, iterative equalization method as an iterative jointequalizing and decoding algorithm shows remarkable ability againstsystem degradations due to ISI. Iterative equalization technique takes theadvantage of information passing between equalizer and channel decoder,enjoys iterative gains, approaches optimum receiver and improves thesystem overall performance.In this paper, traditional equalization techniques are firstly summarizedand simulated. After that, principles of iterative equalization are illustratedin details. Common iterative equalization algorithms are investigated inmathematical ways and their performances are compared throughsimulation. Within that, an iterative equalization method for single carriersystem is chosen and implemented in hardware based on performance andcost evaluation criteria.The essence of channel equalization is removing the influence of asignal introduced by itself. From this point of view, an extendedequalization method is proposed in this paper to remove the influence introduced by signals from other users. WLAN signal collision problem isinvestigated in which terminals send signals at the same time and theirsending signals influence each other. In this paper, a novel method isintroduced to remove such influences. The proposed method takesadvantage of WLAN’s feature of retransmission and random jitter, decodesdata in an algebraic calculation way and increases overall systemthroughput. Iterative techniques are also introduced in this paper toimprove the performance of the proposed method where the iterativeprocess is performed between channel decoder and signal splitter.