多用户大规模MIMO系统中能效的研究

Research on energy efficiency for multi-user massive MIMO system

针对多用户下行大规模多输入多输出(multiple input multiple output,MIMO)无线通信系统,提出一种基于能效的联合优化方案。该方案在采用同时考虑发射功耗和电路功耗的功耗模型以及迫零(zero forcing,ZF)预编码的情况下,推导出天线数、天线子集以及发射功率与系统能效之间的关系式,从而建立联合优化天线数,天线子集和发射功率的能效优化模型,并提出一种新的迭代搜索算法来求解此模型。该迭代算法首先对天线数进行遍历,当天线数确定后,采用基于信道矩阵范数的天线选择算法进行天线子集的选取,随后利用凸优化理论来调整发射功率,不仅提高了系统能效而且降低了算法复杂度。仿真结果表明,与使用全部天线和只考虑天线数的方案相比,所提联合优化方案的能效有明显的提高。

For multi-user downlink massive multi-input and multi-output（ MIMO） wireless communication system,a joint optimization scheme based on energy efficiency is proposed. Adopting the power consumption model which is taking both transmitting power and circuit power into consideration and zero-forcing pre-coding（ ZF） at the same time,the energy efficiency（ EE） with respect to the number of active antennas at Base Station（ BS）,the transmit antenna subset selection and the transmit power is derived in this paper. To maximize the energy efficiency,an energy efficiency optimization model is established by jointly optimizing the number of antennas at BS,antenna subset and transmit power is built in the paper,and a new iterative searching algorithm is proposed to achieve the model,which firstly confirms the antenna number,then adopts the antenna selection algorithm based on the channel matrix norm to select the antenna subset,finally adopts the convex optimization theory to adjust the transmission power. This method could not only improve the system efficiency but also reduce the algorithm complexity. The simulation results demonstrate that comparing with the general algorithm in which all the antennas at BS are used and the general algorithm which only takes the number of antennas into consideration,the scheme the paper proposed can significantly increase the energy efficiency.