关于信道老化的大规模MIMO系统可达速率和能量效率的研究

发布时间：2019-02-26 13:41

【摘要】：大规模MIMO作为5G的关键技术之一,因其具有较高的频谱效率和能量效率而受到了学术界和工业界的广泛关注。在大规模MIMO系统中,信道状态信息(CSI)的准确获取对于分析系统的性能起着关键的作用,而由于用户与基站(BS)之间的相对运动以及BS处理信息的延迟产生的信道老化(channel aging),使得通过导频估计出来的信道和用于波束成形或者检测的信道不一样,对系统的性能造成了损害。因此,研究信道老化现象对大规模MIMO系统的影响非常必要。本文的选题来源于导师承担的国家自然科学基金项目(61372126)。在之前关于信道老化的研究当中,采用MRT预编码技术,推导出了单小区下行链路大规模MIMO系统可达速率的表达式,直观地展示出了系统可达速率和信道老化系数之间的关系。基于此,本文将采用ZF预编码技术来对单小区下行链路大规模MIMO系统的性能进行分析。首先,本文利用ZF预编码技术,推导出了在信道老化环境下,系统可达速率和信道老化系数之间的关系表达式,并证明了在信道老化环境下,功率尺度定律仍然适用,即系统的发送功率至多可以减小为单天线系统发送功率的1/M(M为大规模MIMO系统的天线数)而保持同样的系统性能。仿真结果验证了推导过程的正确性。其次,采用典型的功率消耗模型,将总的电路功率消耗表征为与BS天线数M和用户数K有关的函数,当系统存在信道老化效应时,分别利用MRT预编码技术和ZF预编码技术,推导出了系统能量效率和信道老化系数之间的关系式。仿真结果表明,信道老化的存在会减小大规模MIMO系统的能量效率。最后,为了对抗信道老化这一现象,本文采用FIR维纳线性模型来预测信道,求出在该预测模型下的信道系数,利用MRT预编码技术和ZF预编码技术,对系统的可达速率和能量效率进行了推导分析。仿真结果验证了信道预测模型可以削弱信道老化效应对系统性能的影响。
[Abstract]:As one of the key technologies of 5G, large-scale MIMO has attracted much attention from academia and industry because of its high spectral efficiency and energy efficiency. In large-scale MIMO systems, the accurate acquisition of channel state information (CSI) plays a key role in analyzing the performance of the system. However, due to the relative motion between the user and the base station (BS) and the delay in processing information of the BS, the channel aging (channel aging), makes the channel estimated by pilot different from the channel used for beamforming or detection. Damage to the performance of the system. Therefore, it is necessary to study the effect of channel aging on large-scale MIMO systems. The topic of this paper comes from the project of National Natural Science Foundation (61372126) undertaken by the tutor. In previous studies on channel aging, the expression of reachability rate for large-scale single-cell downlink MIMO system was derived by using MRT precoding technique, and the relationship between system reachability rate and channel aging coefficient was directly demonstrated. Based on this, ZF precoding is used to analyze the performance of single cell downlink large-scale MIMO system. Firstly, by using ZF precoding technology, the relationship between the system reachability rate and the channel aging coefficient in the channel aging environment is derived, and it is proved that the power scaling law is still applicable in the channel aging environment, and the relationship between the system reachability rate and the channel aging coefficient is derived in this paper. That is to say, the transmission power of the system can be reduced to at most 1 M of the transmission power of a single antenna system (M is the number of antennas of a large-scale MIMO system), while maintaining the same system performance. The simulation results verify the correctness of the derivation process. Secondly, using a typical power consumption model, the total power consumption of the circuit is characterized as a function related to the number of BS antennas M and the number of users K. When the channel aging effect exists in the system, the MRT precoding technology and the ZF precoding technique are used respectively. The relationship between system energy efficiency and channel aging coefficient is derived. Simulation results show that the existence of channel aging will reduce the energy efficiency of large-scale MIMO systems. Finally, in order to combat the phenomenon of channel aging, the FIR Wiener linear model is used to predict the channel, and the channel coefficients under the prediction model are calculated. The MRT precoding technique and the ZF precoding technique are used to predict the channel coefficients. The reachability rate and energy efficiency of the system are deduced and analyzed. Simulation results show that the channel prediction model can weaken the effect of channel aging on system performance.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN919.3

【相似文献】