Soft Input Decoding of Reed Solomon Codes with Miscorrection Detection and Avoidance

In this paper a novel scheme is introduced to perform the soft input decoding of Reed Solomon Codes using iterative bit flipped decoding based on the LLRs of the received bits. MAP is used as the inner decoder to obtain the LLRs for the decoded bits at the receiver. In case of decoding failure or a decoding error by the outer RS decoder, a combination of bits from the received word are flipped based on their LLRs. This bit flipped word is then considered in the next iteration. CRC code is used for detecting and avoiding the decoding errors of the RS codes. Simulations are performed for different code rates and it is shown that this additional error detection and correction capability of the concatenated codes results in a coding gain for each of the code rate presented. An upper bound is derived on the decoder error probability of the scheme presented in this work. It is shown that this bound is far lower than the bound on the decoder error probability for the RS codes.