中文摘要：

为了提高认知用户的响应性能,并降低传输中断的概率,通过限制进入系统的认知用户数据包数量,并令授权用户以超时隙为单位优先使用信道,提出一种带有接入阈值和超时隙的集中式认知无线网络频谱分配策略。结合时隙序号及系统中认知用户数据包的数量建立2维离散时间Markov链模型,给出认知用户数据包的平均延迟、吞吐量及信道切换率等性能指标的表达式。建立系统收益函数,针对不同的超时隙大小给出接入阈值的优化设置方案,并利用优化结果,进行系统实验。实验结果显示：合理的接入阈值和超时隙大小可以有效提高认知用户的传输质量。

英文摘要：

In order to improve the response performance and decrease the transmission interruption probability, a centralized spectrum allocation strategy with an access threshold and super-slot for cognitive radio networks is proposed by limiting the number of data packets in the system and allowing the primary users access spectrum with a pre-emptive priority based on a super-slot. Through combining the sequence number of the specified slot in a super-slot and the number of data packets for the cognitive users in the system, a two-dimensional discrete-time Markov chain model is established presenting the formulas for the performance measures in terms of the average latency, the throughput and the channel switching ratio as well. A profit function is created; the access threshold is optimized for different super-slot sizes and the system experiments are conducted via the use of the optimization results. The experiment results show that a reasonable access threshold and a proper super-slot size can improve the transmission quality for the cognitive users.