Cooperative MIMO Relaying with Orthogonal Space-Time Block Codes in Wireless Channels with and without Keyholes

Cooperative multiple-input multiple-output (MIMO) relaying is investigated in the paper. We introduce DFAF selection MIMO relaying, where the relay equipped with multiple antennas can adaptively switch between decode-and-forward (DF) and amplify-and-forward (AF) according to its decoding state of the sourcemessage. We consider two wireless environment scenarios: 1)The scenario with traditional channels are considered firstly. We analyze the outage performance of DF-AF selection MIMO relaying, and a closed-form expression is derived. In addition, the diversity order is obtained based on the expression. For comparison purpose, we also obtain the closed-form outage probability and the diversity order for the AF MIMO relaying and the DF MIMO relaying. 2)We investigate the cooperative MIMO relaying in the presnece of keyholes secondly. We present performance analysis of orthogonal space-time block coded transmission for a cooperative MIMO relaying system with keyholes. For DF MIMO relaying, exact outage probability and symbol error probability (SEP) are obtained. Regarding AF MIMO relaying and DF-AF selection MIMO relaying, the lower and upper bounds are derived. In both traditional and keyhole scenarios, theoretical analysis which has been further verified through Monte-Carlo simulations demonstrate that the DF-AF selection MIMO relaying has better performance than the AF MIMO relaying and the DF MIMO relaying. Received on 09 October 2013; accepted on 09 December 2013; published on 14 July 2014