Cooperative vehicular ad-hoc transmission for LTE-A MIMO-downlink using Amplify-and-Forward relaying

Cooperative communication has been recently applied to vehicular networks to enable coverage extension and enhance link reliability through distributed spatial diversity. In this paper, we investigate the performance of cooperative vehicular relaying over a doubly-selective (i.e., frequency-selective and time-selective) fading channel for an LTE-Advanced downlink session. Using Amplify-and-Forward (AF) relaying with orthogonal cooperation protocol and Multiple-Input Multiple-Output (MIMO) deployment at the source and destination, we derive a pairwise error probability (PEP) expression and demonstrate the achievable diversity gains. Space-Time Block Coding (STBC) is used to ensure the orthogonality of the transmitted-received signals. Our results demonstrate that, via proper linear precoding constellation, the proposed cooperative-MIMO vehicular relaying is capable of extracting the maximum available diversity in frequency (through multipath diversity), time (through Doppler diversity) and space (through cooperative diversity as well as the MIMO deployment) dimensions. We further conduct numerical simulations to confirm the analytical derivations and present the error rate performance of the cooperative relaying vehicular scheme under consideration.