Contention Based Opportunistic Spectrum Access in One-Way Highway Vehicular Networks

The spectrum sharing problem is considered under the scenario of a one-way highway vehicular network. We model the locations of the vehicle-to-vehicle (V2V) nodes, the vehicle-to-infrastructure (V2I) nodes, and the road side units (RSUs) as 1D Poisson point processes (PPPs) on a straight line of infinite length. To efficiently reuse the spectrum preoccupied by the V2I nodes, a contention based opportunistic spectrum access (OSA) strategy is proposed for V2V nodes. Particularly, a V2V node is designed to first detect the spatial spectrum holes of the V2I links and then if succeeds, compete with other eligible V2V nodes (in the spatial spectrum holes of the V2I links) for the access permission. Under this setup, the transmission probability of V2V nodes is derived. Further, the coverage performances of the V2V and V2I links are analyzed. It is worth noting that one of the key challenges in the computations of the transmission probability and coverage probabilities stem from the non-homogeneity of the eligible/active V2V nodes. Then, for tractability of the analytical results, we propose a HPPP approximation for the spatial model of the eligible/active V2V nodes and validates the respective effectiveness by means of extensive simulations. We also discuss the key design insights by analyzing the impact of system parameters on the network performance. It is shown through both numerical and simulation results that the proposed contention based OSA strategy can enhance the spectrum efficiency of the one-way highway vehicular network.