Performance of hybrid ARQ for IP packet transmission on fading channel

This paper proposes and analyzes the performance of a hybrid selective repeat (SR)/multicopy (MC) automatic repeat request (ARQ) scheme to transmit fragmented internet protocol (IP) packets. The ARQ scheme works in SR mode until the last IP packet fragment is transmitted. If a fragment is negatively acknowledged after the last fragment is transmitted, then the system goes in MC mode. In MC mode, multiple copies of the erroneous fragment are transmitted. After all IP fragments are received without error, the system goes back to SR mode. Performance of the proposed scheme is evaluated in terms of bit error rate (BER), IP packet size, and fragmentation size with and without Bose Chaudhuri Hocquenghem (BCH) error correction codes. Both the results are obtained under additive white Gaussian noise (AWGN) as well as fiat Rayleigh fading channels. The proposed scheme gives a throughput of 0.9, even at high BER conditions, for any IP packet size under AWGN channel while, an 8-dB improvement is achieved, when using BCH(63, 51, 2) for throughput of 0.9, over selective repeat + stutter scheme 2 (SR+ST 2) under a fiat Rayleigh fading channel. Index Terms - Fading channel, IP packet transmission, multicopy retransmission, selective-repeat ARQ, spread spectrum, wireless communication.