In a communication system it results undoubtedly of great interest to compress the information generated by the data sources to its most elementary representation, so that the amount of power necessary for rel iable communication can be reduced. it is often the case that the redundancy shown by a variety of data sources can be modelled by taking into account the probabilistic dependance among consecutively source symbols rather than the probabilistic distribution of a single symbol. These sources are commonly referred to as single or multiterminal sources with memory being the memory, in this latter case, the existing temporal correlation among the consecutive symbol vectors generated by the multiterminal source. when the source has memory, the average amount of information per source symbol is given by the entropy rate, which is lower than its entropy per single letter. in this context, given a coded or uncoded communication system, one can decrease the power requi red to achieve a certain probability of error by taking into account this memory in the detection process, i.e. by exploiting the entropy rate rather than the entropy per single letter of the source. This Thesis investigates the design of iterative encoding and decoding schemes for the transmission of single and multiterminal sources with memory through noisy point to point and Múltiple input Múltiple Output channels. To that end, the dissertation is divided in two different (but closely related) parts: - The first part concentrates on the point to point transmission of single sources with memory. The classical way to tackle this problem is based on the Separation Theorem, by first implementing source compression and then channel coding. Assuming infinite complexity, no loss in performance is incurred when compared to joint source-channel coding techniques. However, when the complexity is an issue this separation is no longer optimal. To alleviate this lost in performance, classical joint source channel coding schemes exploit the memory of the source by attaching its statistical structure to the decoding process, Thus, the complexity of the decoder depends strongly on the source characteristics in order to relax the complexity of the decoder, we show that preprocessing the source before the encoder by a data sorting algorithm is a universal method to exploit the correlation without relying on the source parameters. We investígate the application of the Burrows Wheeler Transform to both source and channel coding. For this latter case, we present a novel source controlled binary modulation scheme that adapts the allocated energy according to the distribution of the binary symbols at the bwt output - The second part focuses on the transmission of multiterminal sources with memory through multiuser communication networks. we first deal with the gaussian broadcast channel, where each component of the multiterminal source output vector is sent to the corresponding receiver by using a single transmit signal. To that purpose, severa! encoding strategies are studied, and a practical superposition scheme for correlated multiterminal sources is proposed. The exploitation of the memory in correlated multiterminal sources when being sent through múltiple access channels is also covered, with emphasis on designing iterative receivers by means of factor qraphs. we consider frequency selective channels and propose joint source-channel coding schemes that iteratively perform equalization, decoding and memory exploitation. Two different equalizers and a correlation estimation method are also proposed. Simulation results show that the performance of the derived schemes is close to the Separation-based limits. Summarizing these contributions, the goal of this dissertation is to design communication schemes that take into account the memory of single or multiterminal sources to reduce the transmit power requi red for a certain level of performance and...
Date of Award | 2006 |
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Original language | English |
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Awarding Institution | - Universidad de Navarra-TECNUN
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Iterative Joint Source-Channel Coding Techniques for Single and Multiterminal Sources in Communication Networks
Del Ser Lorente, J. (Author). 2006
Doctoral thesis: Doctoral Thesis