不同衰落信道下的协作感知性能研究

Performance of Cooperative Spectrum Sensing over Different Fading Channels

认知无线电网络中,协作频谱感知技术可以有效地缓解由于信道衰落、阴影等因素造成感知性能下降的问题。该文对不同衰落信道环境下的本地感知性能进行了系统分析;研究了基于能量检测的协作感知方案在不同K-N决策融合准则以及不同协作用户数量条件下的感知性能;在此基础上,讨论了空间阴影相关性对协作感知性能的影响。数值分析和仿真研究的结果表明,本地感知在衰落信道下的性能较AWGN信道下有较大程度的恶化,其中尤以Suzuki信道下的性能最差,而基于K-N决策融合的协作感知一般在OR准则条件下最优,且随着次用户数量增加而改善。为了克服阴影相关性的不利影响,应尽量使节点间距增大。当协作范围一定时,用户数较少但更为分散的协作具有更好的感知性能。

In cognitive radio network, cooperative spectrum sensing is regarded as an effective scheme to mitigate the degradation of sensing performance, which is brought about by some factors, such as channel fading, shadowing,etc. In this paper,analyze the perform- ance of local spectrum sensing over differenr fading channels in detail, and investigate the performance of cooperative spectrum sensing based on the energy detection and K out of N decision fusion with different numbers of cooperative users. Furthermore,discuss the effect on the sensing performance due to the spatially correlated shadowing. Finally, from the numerical analysis and simulation results, can get a conclusion that the degradation of local performance is more serious over fading channels than that over AWGN channel, in particular, Suzuki channel provides the worst-case scenario under all the listed channels, and the OR rule is usually the best choice for cooperative sensing performance, which is improved with the number of users increasing. In order to mitigate the unfavorable effect of correlated shadowing, the node distance should be increased. In addition, a fewer number of users but more decentralized cooperation maybe has a better sensing performance than that in a dense sensing network in a fixed small area.