Physical Layer Reliability Vs ARQ in MIMO Block-Fading Channels

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In today's wireless communication systems, Automatic Repeat reQuest (ARQ) is implemented at the MAC layer in order to retransmit packets that have been erroneously transmitted at the PHYsical (PHY) layer. Following a joint PHYMAC design, information provided by the ARQ scheme can be exploited at the PHY layer in order to improve the system's performance. This paper extends the work presented in the context of SISO channels to the context of MIMO blockfading channels. Based on statistical channel knowledge at the transmitter, it provides an analysis of the natural tradeoff that exists between the PHY layer transmission rate and the number of ARQ retransmissions.