Research On Cognitive Radio Network MAC Protocol Which Is Based On IEEE802.22Medium Control

The rapid growth of ubiquitous wireless services has imposed great pressure on the radio spectrum. Given this fact, in1999, Joseph Mitola proposed Cognitive Radio (CR). Cognitive radio technology can effectively uses the idle spectrum resources, and provides a new way to solve the current spectrum shortage. The role of the media access control (MAC) is to realize dynamic spectrum sharing among cognitive users in cognitive radio networks, so the communication resources can be used optimal and the primary users cannot be disturbed.Firstly, this paper describes the characteristics of the definition of cognitive radio and cognitive radio network, and then introduces the key technology of CR networks and the IEEE802.22.We focuses on understanding the MAC layer protocol design of the cognitive radio system.Secondly, the multi-channel MAC protocols of the CR networks are classified and compared. This article points out the difficulty of the multi-channel MAC protocols. For the coexistence of multiple users in the network, a new MAC protocol model in the cognitive radio systems is drawn.Finally, the Carrier Sense Multiple Access with the Collision Avoid (CSMA/CA) protocol is improved to conformity with the IEEE802.22cognitive radio MAC characteristics. Then, this paper proposes a Cognitive MAC Protocol using statistical channel allocation, based on which can improve the system throughout by forecasting the success rate to reduce the channel collision rate. In addition, a distributed multi-channel MAC protocol is proposed. This protocol, based on the dedicated control channel association, can address the exposed terminal and multi-channel hidden terminal problem, while using the power-saving mechanisms to reduce energy consumption.