非完美CSI情况下大规模MIMO系统的下行链路能效优化

Downlink energy efficiency optimization for massive MIMO systems with imperfect CSI

为了满足密集的用户需求,正在发展的蜂窝网络增加了移动系统下的能量消耗,但更广的网络覆盖范围和功耗更低的无线通信系统也给无线通信系统带来了更多的挑战。针对这些持续增长的需求,本文设计了一种能实现能量效率最大化的多小区大规模多输入多输出(multiple input multiple output,MIMO)系统下行链路的实现方法,提出了在非完美信道状态信息(channel state information,CSI)情况下包含基站天线数、导频复用因子以及用户数量等参数的信干噪比最佳闭式表达,通过最大比合并(maximal ratio combining,MRC)接收技术推导出大规模MIMO系统的下行链路频谱效率,再根据功耗模型得到系统的整体能量效率,利用交替迭代的优化算法进行优化求解,得出最大能效时的相关参数数值。由仿真结果可知,本文所提的多小区大规模MIMO系统的下行链路的实现方法与现有多小区方法相比,能量效率有12.2%的提升,并且对于环境的变化有更好的鲁棒性,对于多小区大规模MIMO系统具有一定参考意义。

In order to meet the intensive needs of users,the developing cellular network has increased the energy consumption of the mobile system,but wider network coverage and lower power consumption of wireless communication system also bring more challenges to the wireless communication system.In view of these growing demands,this paper designs a multicell massive multiple input multiple output(MIMO)system downlink implementation method which can maximize energy efficiency.In this paper,an optimal closed-form expression of signal to interference plus noise ratio(SINR)is proposed in the case of imperfect channel state information(CSI),which includes the number of base station antennas,pilot multiplexing factor and the number of users.The downlink spectral efficiency of massive MIMO system is derived by the maximal ratio comlining(MRC)receiving technique,and then the overall energy efficiency of the system is obtained according to the power consumption model.The alternating iteration optimization algorithm is used to optimize the solution and obtain the relevant parameters when the energy effciency is the maximum.According to the simulation results,compared with the existing multicell methods,the proposed downlink implementation method of the multicell massive MIMO system can improve the energy efficiency by 12.2%,and it is more robust to the changes of the environment.Therefore,it has certain reference significance for the multicell massive MIMO system.