The Algorithm Of MAC Protocal Based On Cognitive Radio

With the rapid development of mobile communication technology, the problems ofspectrum resources shortage loom large. Cognitive radio technology is a hot research topicin the field of the radiosphere, it can make use of the idle spectrum resource dynamicallyand save limited spectrum resources greatly. Cognitive radio attracted a lot of attention inengineering and academid field. Scholars at home and abroad study on a series of MACprotocol in cognitive radio and has obtained certain result at the moment. This papermainly studies the MAC protocol based on cognitive radio technology and makeapplication of cognitive radio technology in IEEE802.11protocoland IEEE802.16mprotocol.First of all, we proposed a new mechanism for Opportunistic Spectrum Access (OSA)protocol for signal channel based on IEEE802.11. This mechanism provides that one SU isallowed to occupy all remaining part of all idle channels during the current slot. We modelthe proposed OSA MAC protocol with three-dimensional discrete time Markov chain andobtain the steady state distribution. By simulation we get the diagram which show thataccording to different number of SU, throughput and delay change.The second, we generalized OSA protocol to multi-channel conditions. Bymathematical modeling we get the steady state distribution, throughput and receiving timedelay. By simulation we can get system performance indexes such as maximum of SUwhich is under the QoS condition of the throughput and receiving time delay. Simulationresults show that compared with the double transceiver OSA protocol, OSACC protocolcan get higher throughput.The last, we proposed a distributed multi-channel spectrum access mechanism. Wemodel the proposed mechanism with three-dimensional discrete time Markov chain andobtain the steady state distribution by using censored Markov chain, and access to get totalthroughput and packet loss rate of SUs. By simulation we can get the relationship betweenthroughput, packet loss rate of SUs and system parameters such as initial contentionwindow size and the maximum backoff stage.