CAREER: Near-Optimum Low-Complexity Soft Decision Decoding of Linear Codes

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Error control coding has become an integral part of almost every digital communication system . The objective of this proposal is to investigate several important problems in coding and to establish teaching plans to develop competent engineers and scientists for the fast changing area of digital communications. The proposed research includes three inter-related areas: (1) soft-decision decoding of linear codes; (2) turbo decoding; and (3) coded modulation for unequal error protection (UEP) applications. The first research area is composed of two parts. In the first part, a new unified analytical approach which lets us tightly bound the error performance of many reliability-based algorithms at practical SNR is to be investigated. Although numerous such algorithms have been proposed for more than 30 years, no such bound exists yet. In the second part of (1),it is proposed to devise efficient soft decision decoding schemes for long powerful block codes with reduced decoding complexity. No existing algorithm can decode such codes without a tremendous computational effort. In area (2), it is proposed to reduce the delay associated with turbo decoding. This long decoding delay prevents the use of turbo-codes in real time communication systems despite their astonishing error performance at very low SNR values. Finally, it is proposed to devise coded modulation schemes with UEP applications based on conventional signal constellations. Very few such schemes have been proposed despite the increasing demand of coding schemes able to adapt to different channel conditions, such as satellite broadcasting for HDTV. The second part of this proposal concerns the teaching plans of the PI. Based on the principle that students are the primary reason most electrical engineering programs exist in universities, the PI's teaching main goal is to develop students into engineers and scientists who will be able to make significant contributions to the development of data communicatio n systems. Also, the particular geographical and cultural situations of the University of Hawaii with respect to other US-mainland universities are considered.