Novel advanced broadcast scheme for efficient safety message collision alleviation in vehicular networks

Safety message broadcasting may cause a broadcast storm in vehicular ad-hoc network without an effective feedback mechanism. In particular, with increasing number of vehicles, serious collisions and incurred long delays are not acceptable for emergency safety messages. In this paper, we proposed an advanced broadcast scheme by the functionality of distributed coordination function and multi-channel operation in dedicated short range communication to decrease collision probability and increase received ratio of safety messages. The proposed scheme can increases safety message transmission efficiency and reduce the latency by delicately designing a rebroadcast probability, choosing the channel and selecting the backoff timer. After broadcasting in the control channel, transmitters return to their original service channel. Then, the vehicles receiving the safety message should inform the others in the same service channel to switch to the control channel for the safety message. Afterwards, the vehicles broadcast the safety message once and go back to the original service channel. This method can inform the other vehicles in different channels to increase the broadcast penetration. The proposed scheme can work without global positioning system (GPS). However, GPS can adapt the rebroadcast probability on hot spots to enhance the efficiency of the proposed scheme. Through detailed simulations, the proposed scheme is shown to be more efficient compared to the existing ones.