Measurement and analysis of fading characteristics of V2V propagation channel in two tunnels

In order to fulfill the requirement of vehicle-to-vehicle communication system for wireless channel fading characteristics and corresponding models, vehicle to vehicle(V2V) wireless channel measurement activities are carried out at the frequency bands of 5.9 GHz and 5.2 GHz in two kinds of tunnel scenes. And small-scale fading characteristics are analyzed for outside the tunnel, inside the tunnel and their junction part. Based on the close-in(CI) log-distance model and ABG (α-β-γ) model, the distance dependent received power models are established. The received power inside and outside the tunnel in the two scenarios are evaluated and compared, and the path loss index is 1.83 and 1.9, respectively. The results show that the CI model with a reference distance of 1 m has higher fitting degree. In addition, the fading distribution of measured data amplitude is compared with five typical theoretical fading distributions, and it is found that its characteristic is closer to the Rice distribution with the minimum goodness of fit value, and the Rice K-factor in the tunnel is smaller than that outside the tunnel. Further, distance-based K-factor models for the tunnel and the junction part are presented. We find that the K-factor at the conjunction area are independent of the distance, while the K-factor inside the tunnel decreases with the increase of the distance.