Speed-dependent autonomous beamwidth variation for VANET safety applications

In this paper, a novel autonomous antenna-beamwidth control is proposed for safety applications operating in vehicular ad hoc networks that typically rely on periodical single-hop broadcast transmissions. Specifically, in our proposed scheme, the antenna beamwidth is varied according to the vehicular speed. Varying the beamwidth allows us to attain a higher quality of service, because the effective transmission area specific to a safety application depends on the speed of the transmit vehicle. The proposed protocol has the additional benefit in terms of implementation, since it does not need additional negotiation overheads with other vehicles, hence allowing us to dispense with any change in the current standard. Our simulation results demonstrate that the proposed scheme is capable of achieving a lower packet error ratio as well as lower communication latency than is the conventional system using omnidirectional antennas.