A cooperative relay selection scheme in V2V communications under interference and outdated CSI

Vehicle-to-vehicle communication systems are characterized by a highly time varying channel. For this reason, many relay selection schemes demand the continuous monitoring of all available channel links, resulting to an unnecessary increase of the system overhead processing. In this paper, an alternative (lower complexity) cooperative relaying selection scheme is adopted. For this new scheme, the influence of interference as well as the existence of outdated channel state information in a decode-and-forward relaying scenario is investigated. To this aim the bivariate double-Nakagami probability density function is introduced and used to model the correlation between the channel states during the selection and the data transmission instances. The performance is analysed using the criteria of outage probability and the average symbol error probability. It is shown that with the proposed approach a significant reduction in feedback load processing is achieved, with only a slight loss in performance.