Block coded modulation based ARQ schemes with blocks combining

In this paper, we present a new type-II hybrid ARQ scheme. This scheme employs block coded modulation (BCM) for error-correction and a linear block code for error-detection. This scheme is referred to as the BCM-ARQ scheme. Rate 1/2 block code with QPSK as error-correction code is considered. Computer simulation is used to evaluate the throughput of the proposed scheme. In comparison with the classical ARQ schemes, the proposed ARQ scheme provides enhanced throughput under high probability of error conditions without any increase in the bandwidth. A BCM-ARQ scheme with combining of successive received blocks is also introduced. In this scheme, the decoder for error correction operates on combination of all received sequences for a block, rather than only on the most recent received one. It is shown that blocks combining further improves the throughput of the BCM-ARQ scheme for higher channel error rate.