A sector-based backward direction detection technique for vehicular ad hoc networks

In vehicular ad hoc networks, a witness vehicle which becomes aware of an accident generates an emergency message and propagates it backwards in multihop manner in order to notify following vehicles of the accident. In this case, the vehicles receiving the message should detect whether or not they are in the backward direction from the witness vehicle. A typical direction detection technique requires floating-point calculations because it depends on the Trigonometrical Function. However, since the floating-point calculation is not supported in Kernel layer of Linux OS. This paper proposes a sector-based backward direction detection technique which utilizes integer calculation. We implemented our proposed technique on an embedded Linux OS, called SnapGear, and showed that it has a negligible detection error.