Outage Probability and SER of Multi-Antenna Fixed Gain Relaying in Cooperative MIMO Networks

This paper proposes multiple-input multiple-output (MIMO) transmission in fixed gain amplify-and-forward relaying to allow for high data rate coverage in wireless distributed networks. We consider a hierarchical network architecture in which the relay is a multiple antenna static node assisting single antenna mobile nodes. We derive new exact closed-form expressions for the outage probability and the symbol error rate (SER) valid for arbitrary N antennas at the relay under independent but not necessarily identically distributed (i.n.d.) Rayleigh fading. Our solutions apply to general operating scenarios with distinct average received signal-to-noise ratios (SNRs) throughout the network. Based on these, we derive new concise asymptotic expressions which accurately characterizes the outage probability and the SER in the high SNR regime. In our asymptotic solutions, we present an exact expression for the array gain in terms of the average received SNRs and the number of antennas N. We further show that the maximum achievable diversity order is N+1.