Split-Turbo Codes for Nonuniform Sequences

Non-systematic channel encoding can be superior to systematic encoding in the presence of redundancy in the transmitted data. The advantage becomes more significant the higher the channel coding rate is. However, known turbo like codes for this purpose only perform well at low channel coding rates. Furthermore, typical non-systematic codes designed for this problem usually suffer from lack of robustness across various forms of non-uniformity over the transmitted data. We consider a class of non-systematic turbo codes based on splitting redundant data bits into coded bits. Splitting is achieved by cascading an inverse of a sparse matrix with a turbo code. We show encoding and decoding procedures for these codes, and empirically demonstrate their performance with simulation results. The proposed codes exhibit excellent performance in the presence of redundancy, superior to that of systematic codes and many other non-systematic codes. Unlike other non-systematic turbo like codes, they also demonstrate robustness to the non-uniformity of the transmitted data, and excellent performance for various non-uniformities at high channel coding rates.