认知无线电中的合作频谱感知性能仿真分析

Analysis and Simulation on Cooperative Spectrum Sensing under Power Constraint

在认知无线电网络中,合作频谱感知用来准确地检测主用户的出现。利用了一个新的仿真数字模型研究了在中继用户有发送功率约束的条件下,认知用户间的路径损耗指数(a_2)与主用户和认知用户间的路径损耗指数(a_1)之比a_2/a_1、主用户与两个认知用户间的夹角φ、以及发射功率对合作频谱感知检测性能的影响。数字仿真结果表明:采用合作后检测性能的改善对路径损耗指数之比a_2/a_1非常敏感,并且当a_2/a_1<1时,可以得到较大的合作增益,当a_2/a_1>1时,采用合作后检测性能改善很小。

In cognitive radio network, cooperative spectrum sensing is employed to detect the presence of primary user accurately. The impacts of different parameters on the improvement of sensing performance were discussed by using a new numerical model, while there was power constrain for relay user. The ratio of path loss exponent between the channel from primary user to cognitive user （a2） and the channel from cognitive user to cognitive user （ a1） , angle Ф between the primary user and two cognitive users, and transmit power were considered. Numerical results show that the improvement on sensing performance is very sensitive to the ratio of path loss exponent a2 / a1. Moreover much cooperative gain can be achieved when a2/a1 〈 1, while less gain can be attained as a2 /a1〉 1.