Adaptive channel access protocol for asynchronous inter-vehicle communication network using spread spectrum

Inter-vehicle communication (IVC) systems, where vehicles exchange information with each other, can decrease traffic accidents and promote smoother driving. To realize such systems, decentralized (i.e., base-station-less) network management is required because of the independent movement of vehicles. However, it is very difficult to achieve decentralized synchronization among unspecified vehicles. Therefore we propose an adaptive channel access protocol for an asynchronous communication using spread spectrum (SS), so synchronization is not required. Moreover by using the SS boomerang method, we can realize an IVC system which is adaptable to vehicle density. Such a system is very important for IVC because without an adaptable communication system, when there is high vehicle density some vehicles can not access the channel and transmit their packets reliably. From computer simulations, it was confirmed that the proposed protocol is effective in realizing adaptive communication and all vehicles can transmit their packets reliably