Single-channel slotted contention in cognitive radio vehicular networks

Abstract

Cognitive radio vehicular ad-hoc networks (CR-VANETs) allow the vehicles to exploit the unused channels in their vicinity to fulfil the bandwidth demands of infotainment applications. Existing CR-VANET approaches aim at incorporating spectrum sensing and reporting to the widely used IEEE 802.11p standard developed for VANETs. However, all such approaches were developed for CR-VANETs with low vehicular traffic densities. Applying such approaches at high traffic densities results in long sensing periods, long contention periods with frequent collisions and unnecessary transmissions of sensing information, and variable delays that depend on the vehicular density. In this study, the authors present the single-channel slotted contention ((SC)2) protocol designed for highways with highly dense vehicular traffic. The (SC)2 protocol counters the deficiencies of typical CR-VANETs in high-density networks using three components: random single-channel sensing, slotted contention, and implicit-OR aggregation. The proposed protocol can be easily incorporated with the IEEE 802.11p. Analytic and simulation results show that the proposed protocol increases the CR-VANET throughput and the overall spectrum utilisation while significantly decreasing the radio environment map time in high densities when compared to the conventional IEEE 802.11p protocols.