Efficient Partial Retransmission ARQ Strategy with Verification-based Decoding for Nonbinary Block Codes

Abstract

In previous work, a verification-based decoding was used to indicate an approximate beginning of uncorrectable error patterns for nonbinary convolutional codes. Sender then retransmitted a partial frame, which included some unnecessary symbols. This paper proposes a more efficient ARQ with minimum retransmitted symbols thanks to the fact that the selected decoder can pinpoint exact error symbol positions. Preferred feedback frame structure is also proposed. Simulation results show that for a (60, 30) LDPC codes in a 2-state fading channel, the feedback frame with the subgroup format is preferred over the fixed size or the binary coded format. For this code, the shortest feedback frame uses 15 subgroups with 4 members for the whole range of the transition probability of non-fade to fade state of 0.05-0.25. It is better than the 3, 6, 10 and 12 members per subgroup because “15” is close to a power of 2 and “4” is small enough since the only subgroups with wrong symbols will be included in the feedback frame.