Research On Recursive Overlapped Time Division Multiplexing Technique

The thesis focuses on a recursive overlapped time division multiplexing (ROvTDM) technique. The bit error rate (BER) performances of three structures of ROvTDM system are analyzed, which include the single-path ROvTDM system, the parallel concatenated scheme for ROvTDM system and the product structure of ROvTDM system. Moreover, the comparation of ROvTDM and nonrecursive overlapped time division multiplexing system is carried out.The organization of this thesis and contributions is presented below.1. The basic ROvTDM technique is studied. First, OvTDM is introduced, which is a high-speed transmission technology in time domain, utilizing the ISI formed by the high-speed symbols. Inspired by the recursive structure in convolutional code, a recursive structure is introduced to the OvTDM system so that the ROvTDM system is constructed. Thanks to the recursive structure, the equivalent coding constraint length is enlarged and the ROvTDM encoder output is further randomized.2. A parallel concatenated scheme which is similar with the original turbo code is proposed for ROvTDM. Like the structure of the turbo encoder, the parallel concatenated scheme consists of two same ROvTDM encoders linked together by interleaving. At the receiver, decoding calls on iterative processing in which two component decoders operate cooperatively and iteratively under the maximum a posterior (MAP) criterion. The performance of the system is improved greatly.3. The coded ROvTDM scheme is developed in order to further improve the performance of the system. Turbo product code is used. The performance of the coded ROvTDM is superior to the coded nonrecursive OvTDM.4. The product structure of ROvTDM system is proposed at last. Two-dimension product code changes the data sequence into a Nc×N1 matrix. The data in each row is encoded in ROvTDM encoder first while the data in each column is encoded second.