Vehicle-to-roadside-unit-to-vehicle communication system under different amplify-and-forward relaying schemes

Abstract

A vehicular Rayleigh fading communication system in which a vehicular transmitter (VT) is communicating with a vehicular receiver (VR) only through a dedicated stationary amplify-and-forward (AF) relaying roadside unit (RSU) is proposed in this paper (i.e., V2RSU2V system). To capture the effect of VT and VR motion, system's fading channels from VT to RSU and from RSU to VR are modeled to be time-varying in accordance with the first order autoregressive model. For the sake of performance comparison, the three common AF relaying sub-schemes are adopted at the RSU relay in separate scenarios; namely, the optimal channel-state-information-and-noise-assisted variable-gain (CSIN-VG) sub-scheme, the blind fixed-gain (B-FG) sub-scheme, and the semi-blind fixed-gain (SB-FG) sub-scheme. Under these AF relaying sub-schemes, closed-form expressions for outage probabilities are derived. The derived expressions are given in terms of variant vehicular system and channel parameters and can be directly considered for the special scenario of stationary VT and VR. Numerical and simulation results are reported to validate the analytical work and to reveal new insightful guidelines into vehicular systems outage performance. For example, results reveal that, for low average signal-to-noise-ratio (SNR) per symbol values, the SB-FG sub-scheme is superior in terms of outage performance for all vehicular scenarios and all threshold SNR values. As well, at high per-symbol average SNR values, results illustrate that the CSIN-VG sub-scheme is superior for high threshold SNR values, while the SB-FG is superior for low threshold SNR values. The study in this paper is timely due to the rapid advancements towards autonomous vehicles and smart transportation networks.