Medium access control method based on broadcast preamble sampling for cognitive sensor network

The present invention relates to cognitive wireless sensor network technologies, and in particular to a medium access control method for a cognitive sensor network based on broadcast preamble sampling. A cognitive node in the cognitive sensor network adopts a periodical dormancy-awakening mechanism. Firstly, a state of a primary user is judged by using a spectrum sensing technology. If the primary user is not active, a data sending node establishes a communication link by using a broadcast preamble code. Each neighbor node simultaneously considers information of hops from a gateway according to an awakening order, and independently determines to serve as a relay node for forwarding data. Furthermore, a transmission conflict between the cognitive node and the primary user may be caused due to return or missed alarm of the primary user. The present invention adopts a retransmission mechanism based on confirmation to ensure transmission reliability of data packets. The present invention is independent of a common control channel, and can realize reliable access of the cognitive sensor network for an authorized frequency band at low overhead.