Single and joint iterative decoding for higher order modulation schemes

The research project described in this thesis concentrates on the study, and application of specific channel coding techniques, in particular, low-density parity-check (LDPC) codes, iterative decoding on Tanner graphs, and their application on joint iterative receivers based on the turbo principle, previously proposed. The construction of random LDPC codes that fulfil certain desirable characteristics, such as large girth, specific p and -y values, and acceptable BER and FER performance for short code lengths, traditionally requires a high degree of processing power (i. e. CPU cycles) to run stochastic routines that firstly search within all the possible combinations for those ones that match the desired characteristics of the LDPC matrix, and secondly determines the bit-error rate (BER) and frame-error rate (FER) performance. The construction of well structured LDPC codes by means of algebraic methods has provided LDPC codes that achieve excellent performance, with desirable structure on their LDPC matrices. However, from the universe of LDPC matrices, those ones created through well structured procedures are a small group. Multiple procedures to modify their characteristics such as length and rate have assisted to increase the pool of LDPC codes based on