认知星地混合网络中基于干扰约束的最优功率控制方法

Optimal power control based on interference power constraint in cognitive satellite terrestrial networks

在认知星地混合网络中,当卫星用户作为次级用户时,为了不影响地面主用户系统的正常工作,在上行链路中要对卫星用户进行必要的功率控制。针对衰落信道场景,选择最大化卫星用户的遍历容量(EC)作为优化的目标函数,分别提出了基于峰值干扰功率约束(PIC)和平均干扰功率约束(AIC)的功率控制方法,并给出了最优发射功率的闭合表达式。仿真结果表明,卫星信道条件越好、地面干扰链路衰减越大,卫星用户的性能越好;除此之外,基于AIC的功率控制方法要优于基于PIC的功率控制方法。

In cognitive satellite terrestrial networks, when the satellite users are secondary users, power control is necessary to guarantee the communication quality of terrestrial primary user in the uplink case. In the context of fading channels, maximizing the Ergodic Capacity（ EC） of the satellite user was selected as the objective function, then two optimal power control schemes were proposed based on Peak Interference power Constraint（ PIC） and Average Interference power Constraint（ AIC）, respectively. Meanwhile, the closed expression of the optimal transmit power was given. Simulation results show that the ergodic capacity of satellite user can be increased when the satellite link experiences the weaker shadowing conditions; moreover, under the the specific satellite link condition, the performance of satellite user becomes better with the increasing of the terrestrial interference link fading parameters. In addition, power control method based on AIC is superior to that based on PIC.