Research On Beacon Broadcast Algorithm In Vehicular Ad Hoc Networks Based On Network Coding

Although the growing number of cars facilitates people’s daily travel and life largely, the frequency of traffic jams and accidents also increases. In order to solve this problem, especially to ensure road traffic safety, people are turning their attention to the vehicular ad hoc networks(VANETs). Vehicular applications in VANETs can be divided into two categories:safety applications and value-added applications. The safety applications are used to improve road traffic safety. Vehicles need to exchange some vehicle safety related information in real time in safety applications. Such information is divided into two categories:one is the status information of vehicle, called the beacon. Beacon is sent with the broadcast periodically, and it has very high demands about reception rates, timeliness and fairness. the other is event-driven emergency alarm message.In order to improve the reception rates and coverage of the beacon, we propose a direction-based network coding repetition(DNCR) algorithm. Using DNCR, a vehicle node can estimate the beacon reception rates of neighboring vehicles by sampling, and it will maintain the two-direction candidate node weight table with the encoding candidate collection mechanism. The vehicle node will select two beacons whose weight is the largest from these weight table respectively, then it will XOR coding these selected beacons and broadcast the encoding packet. By this way, the selected candidate beacons belong to different traveling directions, and the encoding packet can be decoded with the biggest possibility.Finally, the proposed DNCR algorithm is simulated and analyzed by NS-2.35network simulator and VanetMobiSim traffic simulator. The simulation results show that DNCR can effectively improve broadcast reception rates under low vehicle density, and its network load is less than that of NCR.