Concatenated Reed-Solomon Inner and Convolutional Outer Codes for Mobile Channels with Soft Core Processor Implementation

Abstract

The use of Reed-Solomon inner code in the Forney’s concatenated code structure was proposed to correct longer burst errors in high speed mobile communications without interleaving. Vector Symbol Decoding (VSD) was selected as the outer code decoding of the large sized outer symbols (greater than 100 bits per symbol). The complete concatenated coding system with VSD was analyzed for both BoseChaudhuri-Hocquenghem (BCH) and Reed-Solomon (RS) inner codes. The inner decoder for BCH was a combined list and soft Viterbi algorithm (VA) or a soft VA, while the inner decoder for RS was an algebraic decoder. Results were shown for the BCH inner only, the VSD only and for the complete system. In a Rician channel with a carrier frequency of 2.1 GHz at 80 km.hr-1 and a signal to noise ratio of 11 dB, the probability of decoding failure for the system with RS and hard decision was three magnitudes lower than the one with BCH and soft VA. For VSD only with no inner code, the larger sized symbols provided better performance in a burst error channel, while a smaller size was better in a random error channel. In addition, all the coding processes were implemented on a soft processor TSK 3000A and field programmable gate array boards to show that it was practical in terms of complexity.