基于信道获益和业务实时性的频谱切换策略

为了尽可能地降低认知无线电频谱切换的次数，更加全面地考虑通信环境里的因素，引入模糊控制技术，提出一个可行的频谱切换策略。首先，认知用户接收方根据信噪比和主用户活动性估计信道获益，再通过信道反馈机制将结果值告知认知用户发送方；最后，认知用户发送方将业务分成两类：实时业务与非实时业务，并将信道获益与业务实时性作为两个新参数纳入频谱切换策略。仿真结果显示，与随机选择策略相比，根据信道获益选择信道可以明显降低认知用户的切换率。另外，将业务进行分类，非实时用户与实时用户相比有更低的切换可能性，这种差距可以达到32%。

A Spectrum Handoff Strategy Based on Channel Benefit and Real-time Characteristic of Traffic

To reduce the number of spectrum handoff in cognitive radio as far as possible, and consider the factor in communication environment more fully, a feasible spectrum handoff strategy based on fuzzy control is proposed. Firstly, the channel benefit is estimated by the secondary user receiver based on signal to noise ratio and primary user activity, then the result is sent to the secondary user sender by channel feedback mechanism. Finally, the traffic is classified by the secondary user sender to two categories: real-time traffic and non-real-time traffic, and two new antecedents are introduced to spectrum handoff strategy such as channel benefit, real-time characteristic of traffic. Simulated results show that, there is considerable reduction in handoff rate of secondary user compared with the random selection strategy. Besides, the non-real-time users have lower handoff probability than the real-time users when classifying the traffic, and the gap can reach 32%.