Yang Xiaolong, Tan Xuezhi, Ye Liang, Ma Lin
Communication Research Center, Harbin Institute of Technology, Harbin 150080, China.
Sensors (Basel). 2016 Jul 20;16(7):1127. doi: 10.3390/s16071127.
Cognitive radio can significantly improve the spectrum efficiency, and spectrum handoff is considered as an important functionality to guarantee the quality of service (QoS) of primary users (PUs) and the continuity of data transmission of secondary users (SUs). In this paper, we propose an analytical framework based on a preemptive repeat identical (PRI) M/G/1 queuing network model to characterize spectrum handoff behaviors with general service time distribution of both primary and secondary connections, multiple interruptions and transmission delay resulting from the appearance of primary connections. Then, we derive the close-expression of the extended data delivery and the system sojourn time in both staying and changing scenarios. In addition, based on analysis of spectrum handoff behaviors resulting from multiple interruptions caused by the appearance of the primary connections, we investigate the traffic-adaptive policy, by which the considered SU will optimally adjust its handoff spectrum policy. Moreover, we investigate the admissible region and provide the reference for designing the admission control rule for the arriving secondary connection requests. Finally, simulation results verify that our proposed analytical framework is reasonable and can provide the reference for executing the optimal spectrum handoff strategy and designing the admission control rule for the SU in cognitive radio networks.
认知无线电能够显著提高频谱效率，频谱切换被视为保障主用户（PU）服务质量（QoS）以及次用户（SU）数据传输连续性的一项重要功能。在本文中，我们提出了一个基于抢占式重复相同（PRI）M/G/1排队网络模型的分析框架，以刻画频谱切换行为，该行为涉及主连接和次连接的一般服务时间分布、主连接出现导致的多次中断以及传输延迟。然后，我们推导出了在驻留和切换场景下扩展数据交付和系统逗留时间的闭式表达式。此外，基于对主连接出现导致的多次中断所引发的频谱切换行为的分析，我们研究了流量自适应策略，通过该策略，所考虑的次用户将最优地调整其切换频谱策略。而且，我们研究了许可区域，并为设计到达的次连接请求的准入控制规则提供参考。最后，仿真结果验证了我们所提出的分析框架是合理的，并且能够为认知无线电网络中执行最优频谱切换策略以及设计次用户的准入控制规则提供参考。
