Optimal Type-II Concatenated Hybrid ARQ Using Single Parity Check Codes

We consider an incremental redundancy (IR) type-II hybrid ARQ scheme based on multidimensional single parity check (SPC) product codes. Random interleaving is applied between dimensions, resulting in equivalent systematic, parallel or serially concatenated SPC codes. This enables larger interleavers and a larger range of overall code rates. The puncturing pattern used for IR transmissions of the concatenated SPC codes is chosen specifically to reduce decoder complexity for the hybrid ARQ scheme, activating only those constituent decoders for which parity bits have been received. Given the proposed puncturing pattern and a maximum number of allowable transmissions, an approach for determining the optimal number of parity bits per IR transmission in terms of maximizing the overall code rate, is suggested. With this strategy, each data frame is accepted following the transmission of a minimum number of parity bits.