Simple hybrid type II ARQ technique using soft output information

The authors present a simple automatic repeat request (ARQ) scheme for turb o codes which uses the soft output information, available as a by-product o f the decoding process, to indicate the need for retransmission of a partic ular data block. The technique utilises the punctured data, not normally se nt in recursive systematic convolutional (RSC) turbo code systems, to impro ve the operation of the decoder rather than the retransmission of the whole block, thus maximising the throughput. Furthermore, as no cyclic redundanc y check (CRC) is included there is no overhead on transmission rate. The sc heme is capable of correctly identifying a large proportion of all errors a cross a range of Ed N-0 whilst minimising incorrect retransmission requests .