Distributed multi-channel MAC protocol in cognitive radio networks
认知无线电网络分布式多信道MAC协议

The MAC protocols are used for channel sensing, selection and access in cognitive radio(CR) networks. This paper proposed a distributed multi-channel MAC(CR-MMAC) protocol in CR networks based on multi-channel MAC(MMAC) protocol, according to the two-phases sensing mechanisms defined by the IEEE 802.22 standard. The protocol took two-phases sensing mechanisms and distributed negotiation into account, used idle spectrum for communication and adopted reservation mechanism in the stage of channel negotiation of ATIM window of MMAC protocol, which avoided competition collision caused by the CR nodes choosing the same channel for data transmission stage using CSMA/CA. The simulation comparisons show that, CR-MMAC protocol improves network throughput, decreases communication delay, and the comprehensive performance is better than MMAC protocol.