The Effect of Hidden Terminal Interference on Safety-Critical Traffic in Vehicular Ad Hoc Networks

In Vehicular Ad hoc NETworks (VANETs) where safety applications rely on broadcast communications, the hidden terminal problem can severely impact the reliability of these applications. Particularly, in forced flow traffic scenarios as the primary case of safety-critical situations, reliability is paramount for inter-vehicle communications to be useful. Not surprising, in these scenarios, the hidden terminal effect is expected to be especially severe, mainly due to the high vehicle density. Accurate characterization of this problem and the extent of its impact on reliability requires that realistic aspects of the traffic system and radio propagation environment are taken into consideration. In this paper, we investigate the hidden terminal problem under realistic conditions with focus on safety-critical traffic scenarios. A state-of-the-art radio propagation model targeted for vehicular environments is employed to characterise the interference power induced by hidden nodes. Our combinations of experiments with various velocities and lane configurations show that, in a road segment operating at full capacity, the hidden terminal interference causes a significant decline in the reachable distance of safety messages, leading to broadcast coverage smaller than safety applications requirements.