Adaptive Transmission Protocol for Protection of Primary Users in Cognitive Radio

Recently, rapid advance in wireless technologies and development of wireless communication services have enabled a growing demand on wireless spectrum. Many research works also show that traditional fixed spectrum assignment can not use spectrum efficiently. Cognitive Radio, which allows temporary usage for the unlicensed (CR) users, is proposed to cope with the problem. In this work, we propose an adaptive transmission protocol by limiting transmission probability (LTP) of the CR users to guarantee the performance of Primary User under an 802.11 environment. Specifically, our LTP scheme uses 2 analytic models to figure out the relationship between current load of primary users and the optimal transmission parameter setting that can guarantee the throughput of primary users.