Joint data detection for punctured ARQ diversity systems

We investigate a bandwidth efficient ARQ scheme in which the medium access control (MAC) only requests a partial retransmission after packet reception error. To reduce channel usage, the original packet is punctured prior to retransmission(s), thereby forming a modified ARQ scheme which we name punctured automatic repeat request (PARQ). The puncturing in the system can be viewed as a form of "diversity" to blindly estimate the channel. We focus on the detection of the original data sequence by presenting a maximum likelihood (ML) algorithm and a simpler multirate linear equalizer. We also investigate the BER performance based on estimated channel responses from both the blind and the semiblind channel estimation algorithms.