大规模MIMO系统中基于天线分组技术的能效分析

发布时间：2018-03-31 18:46

本文选题：大规模MIMO系统　切入点：能效优化　出处：《郑州大学》2017年硕士论文

【摘要】：大规模MIMO系统在基站端部署大规模的天线阵元,利用空间复用、传输分集和波束赋形等挖掘空间增益,有效提升谱效和能效,是5G的关键技术之一。但由于基站天线数量可达上百支,密集的天线部署会导致相关性高的天线子集和相关性低的天线子集并存。天线之间的相关性会影响系统容量,如果不根据射频链路的特性充分挖掘天线的利用效率,系统将难以获得预期的增益。天线分组技术利用天线之间的相关性将基站端天线分成若干组,相关性高的天线组通过波束赋形和预编码的设计,消除终端用户间的干扰;相关性低的天线组进行空间复用,满足最大化数据速率的要求,最终使得系统在获得较高谱效的同时得到较好的误比特率性能。但绿色通信的愿景要求未来无线网络不仅具有高谱效,还应具有高能效,所以,对于无线网络来说,能效变得至关重要。因此,针对大规模天线阵列的相关特性,本文基于天线分组技术,研究大规模MIMO系统中的能效优化问题。论文的主要工作和创新点如下:1)针对大规模MIMO系统中的能效优化问题,构建基于天线分组的单用户大规模MIMO系统模型,研究天线分组技术对能效的影响。首先建立大规模MIMO系统中基于能效的天线分组系统模型;以最大化系统能效为优化目标,分析天线分组过程中,每组天线数对大规模MIMO下行链路系统容量、功耗以及能效的影响;提出了基于二分法的组内天线数最优值求解算法。仿真结果表明当信道相关系数变大,即信道相关性变强时,使用天线分组技术可以有效提高系统能效;存在使系统能效达到最优的每组天线数唯一解,使用所提基于二分法的最优天线数求解算法能够快速收敛至该唯一解。当发送功率为10dBm时,与使用所有天线相比,采用本文提议的天线分组及组内天线数优化策略可使系统能效大约提升28%。2)为进一步提升基于天线分组的大规模MIMO多用户系统的能效,本文提出了一种天线分组和功率分配联合优化方案。该方案以最大化能效为目标,优化组间功率分配和组内最优天线数。基于所提方案,构建了能效优化问题的数学模型,证明了组间最优功率分配解的存在性。优化问题的求解采用了标准迭代优化算法,结合经典的注水功率分配算法,联合迭代组内天线数和组间功率分配值直至系统能效最大化,此时对应的解即为组间功率分配和组内天线数的最优解。数值仿真结果表明,在相关信道中,天线分组技术可以提高大规模MIMO系统的能效,而将天线分组和功率分配技术结合起来,可以进一步提升系统能效。
[Abstract]:Large scale MIMO system deploys large scale antenna array elements at the base station end, mining spatial gain by using spatial multiplexing, transmission diversity and beamforming, which can effectively improve spectral efficiency and energy efficiency. It is one of the key technologies of 5G, but because the number of base station antennas can reach hundreds, dense antenna deployment will lead to the coexistence of high correlation antenna subset and low correlation antenna subset. The correlation between antennas will affect the system capacity. If the efficiency of antenna utilization is not fully exploited according to the characteristics of RF link, it will be difficult for the system to obtain the expected gain. Antenna grouping technology uses the correlation between antennas to divide the base station antenna into several groups. The antenna group with high correlation eliminates the interference between the end users by the design of beamforming and precoding, and the antenna group with low correlation is multiplexed in space to meet the requirements of maximizing the data rate. In the end, the system can obtain higher spectral effect and better bit error rate performance. However, the vision of green communication requires that wireless networks not only have high spectral efficiency, but also have high energy efficiency in the future, so, for wireless networks, Energy efficiency has become critical. Therefore, in view of the characteristics of large antenna arrays, this paper is based on antenna grouping technology. The main work and innovation of this paper are as follows: 1) aiming at the problem of energy efficiency optimization in large-scale MIMO systems, a single-user large-scale MIMO system model based on antenna grouping is constructed. The effects of antenna packet technology on energy efficiency are studied. Firstly, an energy efficiency based antenna packet system model in large-scale MIMO system is established, and the optimization goal is to maximize system energy efficiency, and the process of antenna grouping is analyzed. The effect of the number of antennas per group on the capacity, power consumption and energy efficiency of large-scale MIMO downlink system is discussed. An algorithm based on dichotomy is proposed to solve the optimal number of antennas in the group. The simulation results show that when the channel correlation coefficient increases, that is, the channel correlation becomes stronger. The use of antenna grouping technology can effectively improve system energy efficiency; there is a unique solution for each group of antennas that make the system energy efficient. The proposed optimal antenna number solution based on dichotomy can quickly converge to this unique solution. When the transmission power is 10dBm, compared with all antennas, Using the antenna packet and antenna number optimization strategy proposed in this paper can improve the system energy efficiency about 28.2) to further improve the energy efficiency of large-scale MIMO multiuser system based on antenna packet. In this paper, a joint optimization scheme of antenna grouping and power allocation is proposed, which aims at maximizing energy efficiency, and optimizes the power allocation among groups and the optimal number of antennas within the group. Based on the proposed scheme, a mathematical model of the energy efficiency optimization problem is constructed. The existence of optimal power allocation solution between groups is proved. The standard iterative optimization algorithm is used to solve the optimization problem. Combined with the classical water injection power allocation algorithm, the number of antennas in the iterative group and the inter-group power allocation value are combined until the system energy efficiency is maximized. The corresponding solution is the optimal solution of the power allocation between groups and the number of antennas within the group. The numerical simulation results show that the antenna grouping technique can improve the energy efficiency of large-scale MIMO systems in the correlated channels. The combination of antenna grouping and power allocation technology can further improve system energy efficiency.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN919.3

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