An adaptive hybrid ARQ scheme using shortened codes

In this paper we propose a sub-block retransmission scheme for ARQ and hybrid ARQ schemes. When the channel is quiet the sub-block retransmission scheme behaves like a conventional ARQ or hybrid ARQ scheme. As the channel becomes noisy, the data block is divided into small sub-blocks for transmission. Each sub-block is encoded for error control by an appropriate shortened code and the code length of the shortened code is adaptive to the corresponding channel BER. The received block is checked for errors sub-block by sub-block. The proposed sub-block retransmission scheme provides improved throughput over conventional ARQ schemes by retransmitting only the naked sub-blocks in the occurrence of errors. An example of transferring ATM cells is considered for simulation.