中文摘要：

为探讨认知无线中,认知用户SU以某一访问流程共享主用户PU的频谱资源以及SU有效传输时间优化的问题,假定PU信道的状态变化为泊松分布,SU在物理层使用OFDM调制技术。分析了SU使用PU信道通信时占用的信道数n和传输期长度Tt对数据有效传输时间的影响,并用MATLAB作出了仿真图,找到了各自的最优值。作图仿真和理论分析基本吻合。在此基础上,进一步仿真了PU干扰时间率ITR这一重要限定条件的约束效果,得出了ITR的限定在减轻SU对PU干扰程度的同时,也造成SU有效传输时间下降的结论。

英文摘要：

In order to investigate how Secondary User shares Primary User＇s free spectrum and how SU＇s valid transmission time in cognitive radio is optimized, according to the flow chart, the PU＇s channel state was assumed to conform to Poisson distribution, and OFDM modulation was used in SU＇s physical layer. Both the influence of the number of channels SU occupied and＇the duration of the transmission period on the total valid transmission time were analysed and the optimal values were found respectively. MATLAB simulation was devised to verify the analysis and the result accorded with the theoretical analysis. Based on this, an important constraining condition Interference Time Ratio was studied. It＇s concluded that ITR mitigates the SU＇s interference to the PU, while decreases the SU＇s valid transmisson time.