中文摘要：

为了有效提高认知网络中次用户的吞吐率性能，提出了一种应用于非理想感知条件下的双门限机会频谱接人策略。该策略能在次用户对信道占用情况感知非理想的条件下，综合考虑次用户的信道质量和非准确的信道占用信息，使次用户在信道感知为空闲和占用时分别以不同的信道质量门限选择接入信道，从而最大程度地利用信道质量较好的传输机会，提高次用户的吞吐率性能。结合本策略，建立了以次用户的有效吞吐率最大化为目标、以对主用户的干扰程度为约束条件的优化问题，并在次用户对信道感知存在误差的条件下给出了最优门限的设计方法。仿真结果表明，所提出的双门限机会频谱接入策略能够在非理想感知条件下显著提高次用户的有效吞吐率。

英文摘要：

To effectively improve the throughput performance of secondary user in cognitive networks, a dual threshold based opportunistic spectrum access policy was proposed, which could be implemented under the condition that secondary user had non-ideal spectrum sensing capability. The proposed policy can take both channel quality information of secondary user and the inaccurate channel occupation information into account, to make secondary user access the channel in sensed idle and busy states with different channel quality thresholds. Based on this, the throughput performance of secondary user can be improved significantly by utilizing the transmission opportunities with good channel quality. With this policy, an optimization problem maximizing the effective throughput of secondary user with interference constraint for protecting primary user was formulated, and the optimal channel quality thresholds were derived under non-ideal spectrum sensing. Simulation results demonstrate the effective throughput performance of secondary user with non-ideal spectrum sensing capability can be improved significantly by implementing the proposed dual threshold based opportunistic spectrum access policy.