认知频谱共享系统最大比例合并分集的性能分析

研究了一个认知频谱共享系统，该系统是由一个次用户发射机、一个次用户接收机和一对主用户发射机和接收机组成，次用户接收机利用最大比合并策略提高系统性能。首先分析了来自主用户发射机的干扰对频谱共享系统中断概率的影响。经过一些运算得到了中断概率确切的封闭表达式，为评价系统关键参数的联合作用提供了有效手段，如次用户接收机天线的数目、次用户最大的发射功率、干扰温度限制以及主用户发射功率等。另外，还对系统中断概率的渐近性能进行了研究，揭示了次用户系统中断概率具有饱和现象。最后，分析了该系统分集复用增益。仿真结果表明，该中断概率确切封闭表达式与Monte Carlo仿真结果非常吻合，干扰温度约束和主用户的干扰对中断概率具有显著的不利影响，增加次用户接收机的天线数目可提高系统性能。

Performance analysis of cognitive spectrum sharing systems with MRC diversity

This paper considers a cognitive spectrum sharing system which consists of a secondary receiver(SR),a secondary transmitter(ST) and a pair of primary transceivers. Firstly,it investigates the impact of interference from primary transmitters on the outage performance of spectrum sharing systems with maximal ratiocombining(MRC) at the SR. An exact closed-form expression for the outage probability is derived after some operations,which offers an efficient method to assess the joint effects of key system parameters,such as the number of antennas at the SR,the maximum ST power,the interference temperature constraints,and the primary interference power at the SR. Inaddition,the asymptotic behavior of the outage probability is investigated,which reveals that the secondary system exhibits the outage saturation phenomenon. Finally,the diversity gain and multiplexing gain are analyzed. Simulation results demonstrate that the exact closed-form expression for the outage probability is well matched as Monte Carlo simulation results,a stringent interference temperature constraint and the primary interference power have a significant detrimental effect on the outage probability,the system performance can be increased by increasing the number of SR.