The MAC Protocol Research Of Cognitive Multi-channel Network

Ad hoc network is a temporary network formed by some mobile devices, it can existwithout depending on traditional infrastructure and each mobile terminal in network hasrouting functions. With its self-organizing and independence, Ad hoc network is widelyused in military field and civilian field. As one key technology of Ad hoc network, MACprotocols became a hot issue of the present study.This paper introduces the basic network structure and network characteristics of Adhoc network, network MAC protocols are analyzed and based on different network scale,the contract rate on the performance of the single channel and multi-channel networks aresimulated, compared and analysised, the results show that the performance of themulti-channel network is superior to the single channel network, which lies the foundationfor futher study about congnitive Ad hoc network.The algorithm of binary backoff about MAC protocol in multi-user communication,which can not resolve the data collision and exposed terminal hidden terminal problem,put forward an adaptive backoff algorithm with Cognitive functions of CR-BOA(Cognitive Rodio Network-Back Off Algorithm). Based on the characteristics of cognitivenetwork to improve the backoff algorithm. CR-BOA algorithm is according to theregulation of the throughout to reduce the delay of the network and improve theperformance of the network. This algorithm can predict the congestion degree of thechannel which quickly determine the best value of the moved window. The closed-loopfeedback control model conforms to the characteristics of cognitive network: it can sensethe current situation of the network and can affect the performance of the network. Finally,on the OPNET network simulation platform, according to the two kinds of algorithm tobuild the network and comparing their performance of network, verify the CR-BOAsuperiority of the algorithm.