차량 Ad-hoc 네트워크에서의 전송률 적응 MAC 알고리즘 설계

Abstract

VANET(Vehicular Ad-hoc Network), standard of IEEE 802.11p specification is based on 802.11 MAC protocol. It grants all nodes make equal opportunity to get channel, making it possible lower bit-rate nodes to get communication channel for a proper amount of time so keeping the nodes of higher bit-rate from acquiring connected channel that downward-equalize the entire network performance. Also the probability of collision occurring increases as the number of nodes grow. The proposed algorithm ensures that nodes with acquired channels for a fixed amount of time until the 'packet burst' according to the current transmission rate have a firm priority over other nodes. This algorithm not only allows us to build a wireless network that improves network throughput and reduces the probability of collisions, but also gives each node a fair chance to gain connectivity based on channel conditions. The algorithm improves the overall performance of the network by setting the CW (contention window) width wider than the standard and modulating the continuous transmission threshold according to the channel acquisition time.