Simple hybrid type II ARQ technique using soft output information

The authors present a simple automatic repeat request (ARQ) scheme for turbo codes which uses the soft output information, available as a by-product of the decoding process. To indicate the need for retransmission of a particular data block. The technique utilises the punctured data, not normally sent in recursive systematic convolutional (RSC) turbo code systems, to improve the operation of the decoder rather than the retransmission of the whole block, thus maximising the throughput. Furthermore, as no cyclic redundancy check (CRC) is included there is no overhead on transmission rate. The scheme is capable of correctly identifying a large proportion of all errors across a range of E_b/N_o whilst minimising incorrect retransmission requests