Throughput of Arq Protocols over Rician, Nakagami and Mimo Block Fading Channels†

Block fading is a popular channel model that approximates the behavior of different wireless communication systems. Automatic-repeat request (ARQ) protocols are used to provide reliable communication in wireless networks. In this paper the throughput of the basic selective-repeat (SR) ARQ in block fading environments is derived. Single-antenna ARQ systems employing both coherent BPSK and QPSK and noncoherent orthogonal BFSK are analyzed over block fading channels characterized by Rician and Nakagami fading distributions. Moreover, the performance of multi-input multi-output (MIMO) ARQ systems employing space-time block codes (STBCs) is derived. The effect of antenna correlation in MIMO ARQ systems is investigated analytically. Results show that longer block lengths improve the performance of basic ARQ protocols. Furthermore, the throughput gain obtained by increasing the block length is a decreasing function of the block length. As the fading severity of the channel increases, the performance improvement resulting from increasing the block length increases.