Abstract: The key of cognitive radio spectrum access technique is to instruct cognitive users how to choose the appropriate
unoccupied channel and how to share the spectrum. In the case of rare common control channel, spectrum prediction algorithm which based on the Partially Observable Markov Decision Processes（POMDP） can significantly improve the system’s throughput. If the cognitive system undistinguished uses the licensed spectrum, the spectrum holes selected can’t meet the user’s needs. For the cognitive user’s different demands about channel capacity, the dynamic spectrum access process of cognitive radio networks is researched by introducing the appropriate selection principle and the fusion access strategy. In addition, the throughput of cognitive users and the system collision rate are analyzed by using abundant simulation. Results show that the fusion access strategy can effectively improve the system throughput and collision rate.

Key words: dynamic spectrum access, channel capacity, appropriate selection principle

摘要： 认知无线电频谱接入技术的关键是指导认知用户如何选择合适的空闲信道以及如何在认知用户间实现频谱共享。在公共控制信道较难获得的情况下，基于部分可观测 Markov 决策过程（POMDP）的频谱预测算法，可以显著地提高系统的吞吐量。认知系统如果不加区分地使用授权频谱将可能导致所选择的频谱空洞不能满足认知用户需求。针对认知用户对不同信道容量的需求，引用适量选择原则，并运用融合接入策略，研究认知无线网络动态频谱接入过程。另外，通过大量仿真对认知用户的吞吐量和系统碰撞率进行分析，结果表明融合接入策略可以有效地提高系统的吞吐量及系统碰撞率。

关键词: 动态频谱接入, 信道容量, 适量选择原则