Effect of Line-of-Sight on Dual-Hop Nonregenerative Relay Wireless Communications

In this paper, we analyze the effect of the line-of-sight (LOS) on the symbol error probability (SEP) of nonregenerative cooperation in multiple-input multiple-output (MIMO) dual-hop relay channels with n_S source antennas, n_R relay antennas, and no destination antennas-referred to as a (n_S,n_R,n_D)-MIMO dual-hop nonregenerative relay channel. In particular, we consider the channels of the source-to-relay (S-to-R) and the relay-to-destination (R-to-D) links are Rayleigh and Rician fading distribution, respectively. To be specific, we derive the exact SEP for maximum likelihood (ML) decoding of orthogonal space-time block codes (OSTBCs) over such channels and validate the analytical results by comparing with Monte-Carlo simulation. It is shown that for a fixed channel gain a strong LOS component degrades the error performance, e.g. SEP, of MIMO cooperative communications due to the lack of scattering.