大规模MIMO中继系统预编码设计及性能分析

发布时间：2018-01-22 00:50

本文关键词： 大规模MIMO中继全数字预编码有限射频链路混合预编码 ADC量化　出处：《东南大学》2017年硕士论文　论文类型：学位论文

【摘要】：大规模多输入多输出(Multiple-Input Mu1tiple-Output,MIMO)技术能够显著提升无线通信频谱和能量效率,是支撑5G移动通信的关键技术之一。随着基站天线数目不断增加,原系统中的热噪声效应和多用户干扰将可以忽略不计,并且简单的线性波束赋形变得渐近最优。另一方面,中继技术具有增强无线覆盖,降低发送功率,以及提升系统可靠性等诸多优点。基于上述考虑,配备大规模天线阵列的中继系统得到广泛关注。然而,大规模MIMO系统在而向实际部署时遇到一些关键挑战,例如大量射频链路导致功耗过高、高精度模数转换器(ADC,Analog-to-Digital Converter)成本昂贵等。因此,研究如何以较低成本实现高效大规模MIMO无线传输非常必要。本文主要考虑在实际射频链路数目受限,以及采用混合精度ADC架构进行接收这两种场景下,分别对大规模MIMO中继系统的预编码性能进行一系列研究。首先考虑传统全射频链路架构的大规模MIMO中继系统,本论文研究了全数字预编码方案下的系统性能。针对全双工中继,研究了基于大规模天线阵列以及低发送功率的自干扰(LI,Loop Interference)消除方案。然后,在非理想信道状态信息(CSI,Channel State Information)的场景下,对于全双工以及半双工这两种中继模式,分别给出了系统可达和速率的近似表达式并进行了仿真验证。进一步,提出了一种混合双工方案,针对信道大尺度衰落条件自适应选择全双工/半双工模式,该混合模式相较于单一的双工模式具有显著的性能增益。然后,论文对大规模MIMO中继系统的模拟/数字混合预编码展开了研究。在实际射频链路少于中继天线数的约束下,提出大规模MIMO中继系统的上、下行混合接收/预编码设计方法。该方法通过提取信道相位信息来设计模拟预编码,以获取阵列增益,而对基带等效信道采用迫零(ZF,Zero-Forcing)预编码来消除多用户干扰(MUI,Multiuser Interference)。在非理想想CS场景下,论导了基于该混合预编码方案的可达和速率近似表达式,并给出了射频链路数目与天线数之间关系的显式表达式。特别地,推导出两种典型功率缩放场景下的系统渐近性能。针对实际模拟移相器(APS,Analog Phase Shifter)精度有限的问题,研究了相位量化对混合预编码性能的影响。理论与仿真结果均表明,当天线规模较大时,该混合预编码方案性能将趋近于传统的全数字预编码。通过对总功率消耗进行合理建模,论文进一步研究了系统的能量效率(EE,Energy Efficiency),证明了EE关于发送功率和射频链路数是拟凹函数,从而可通过迭代求解获得最优的系统参数配置。论文最后为解决大量高精度ADC导致功耗与成本过高的问题,研究了基于混合精度ADC架构进行接收的大规模MIMO中继系统。通过引入加性量化噪声模型(AQNM,Additive Quantization Noise Model),论文在理想CSI和最大比合并(MRC,Maximal Ratio Combining)接收设计下,推导了混合精度ADC架构下可达速率的近似表达式。进一步,研究了天线数目、用户和中继的发送功率,以及高精度ADC所占比例等系统参数对可达速率的影响。此外,针对几种典型的场景,论文分别给出了可达速率的渐近表达式,揭示出系统渐近性能可以很好地由所有ADC的"等效"(平均)精度来刻画。仿真表明,混合ADC架构能够在功耗和性能之间取得很好的折衷,为大规模MIMO进行实际部署提供了有效的技术支持。
[Abstract]:Large scale multi input multi output (Multiple-Input Mu1tiple-Output MIMO) technology can significantly improve the wireless communication spectrum and energy efficiency, is one of the key supporting technologies of 5G mobile communication. With the increasing number of base station antenna, the thermal noise effect of the original system and multi-user interference will be negligible, and the linear beam shape becomes simple asymptotically optimal. On the other hand, relay technology has enhanced wireless coverage, reducing the transmission power, and improve the system reliability and other advantages. Based on the above considerations, the relay system is equipped with a large antenna array has been widespread concern. However, the large scale MIMO system to meet some key challenges in the actual deployment, such as a large number of RF link leads to high power consumption high precision analog-to-digital converter (ADC, Analog-to-Digital, Converter) high cost. Therefore, study how to achieve in order to lower the cost of Efficient large-scale MIMO wireless transmission is very necessary. This paper considers the limitation in the actual RF link number and the mixed precision ADC architecture to receive the two scenarios, respectively on the scale of MIMO relay system precoding performance through a series of research. First consider the large-scale MIMO relay system the traditional full RF link architecture, this paper studies the performance of the system of digital pre encoding schemes. For full duplex relay on the self interference of large-scale antenna array and low transmit power based on (LI, Loop, Interference) cancellation scheme. Then, in a non ideal channel state information (CSI Channel, State Information) scene, for full duplex, half duplex the two relay mode are presented and the approximate expression rate up to the system and simulation. Further, the paper puts forward a hybrid duplex scheme, needle On the large scale fading conditions of adaptive selection of full duplex / half duplex mode, the mixed mode compared to the single duplex mode has a significant performance gain. Then, simulation of large-scale / MIMO relay system in digital pre encoding is studied. In the actual radio relay antenna number less than link constraints, proposed large-scale MIMO relay system, downlink hybrid receiver / pre encoding design method. By this method to design the analog pre encoding channel phase information extraction, in order to obtain the array gain, while the baseband equivalent channel using zero forcing (ZF, Zero-Forcing) precoding to eliminate the multi-user interference (MUI, Multiuser, Interference) in the non ideal. The CS scenario, the approximate expression of the hybrid theory guide pre encoding scheme based on rate and up to, and give the relationship between the RF link number and the number of antennas explicitly in particular. System, asymptotic performance is derived for two kinds of typical power zoom scenarios. In view of the actual analog phase shifter (APS Analog, Phase Shifter) problem of finite precision, studied the effect of phase quantization on pre mixed encoding performance. Theoretical analysis and simulation results show that when the antenna is in large scale, full digital pre encoding the pre mixing the performance will be close to the traditional encoding scheme. Through reasonable modeling on power consumption, the paper further studies the energy efficiency of the system (EE, Energy, Efficiency), proved that EE about the transmission power and the number of RF chains is quasi concave function, which can obtain the optimal parameters of the system configuration through the iterative algorithm. Finally, in order to solve a large number of high precision ADC lead to the problem of high cost and power consumption, of large-scale MIMO relay system received mixed precision based on ADC architecture. Through the introduction of additive quantization noise model (AQN M, Additive Quantization Noise Model), the ideal CSI and maximum ratio combination (MRC Maximal, Ratio Combining) receiver design, the approximate expression rate of up to ADC under the framework of the mixed precision is derived. Further, the number of antennas, users and relay transmit power, and the proportion of high precision ADC system influence of parameters on the achievable rate. In addition, according to several typical scenarios, the paper respectively gives the asymptotic expression of the achievable rate, reflects the system asymptotic performance can be well by all of ADC's "equivalent" (on average) to characterize the accuracy. Simulation results show that the hybrid ADC architecture can achieve good tradeoff between power consumption and the performance, provide effective technical support for the actual deployment of large-scale MIMO.

【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN919.3

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