Pilot Decontamination in Massive Multiantenna Systems

本研究计划旨在降低无线通信系统的能耗，同时争取更高的数据速率。具有大量天线元件的多天线系统是实现这一目标的一种很有前途的方法。在文献中，这些通常被称为“大规模”多天线系统。大规模的多天线系统允许大幅降低辐射信号功率。目前提出的大多数系统都受到一种称为“先导污染”的不利影响。这种影响是由于相邻单元不可避免地重复使用导频信号造成的，许多研究人员认为这是大规模多天线系统的一个根本缺点。最近，一些申请人概述了一种方法，称为“试点去污”，以克服基于奇异值分解和功率控制的试点污染。对上行信道的初步理论研究表明，该方法非常有效，导频污染不是基本影响，但可以通过非线性信道估计来克服。在本项目中，应更详细地研究中试去污。特别是，应该研究如何将其用于下行传输，以及哪种切换协议是合适的。此外，还应研究多天线系统需要多大的规模才能使导频去污工作可靠。应特别努力寻找在实践中实施试点去污的有效方法。

This research proposal aims to reduce the energy consumption of wireless communication systems while striving for higher data rates. A promising approach to this end are multi-antenna systems with a large number of antenna elements. In literature, these are commonly referred to as "massive" multi-antenna systems.Massive multi-antenna systems allow for a drastic reduction of radiated signal power. Most currently proposed systems suffer from an adverse effect called "pilot contamination". This effect is due to unavoidable reuse of pilot signal is adjacent cells and was believed by many researchers to be a fundamental shortcoming of massive multi-antenna systems. Recently, some of the applicants have outlined a method, referred to as "pilot decontamination" to overcome pilot contamination based on singular value decomposition and power control. Initial theoretical studies on the uplink channel indicate that the method is very powerful and that pilot contamination is not a fundamental effect, but can be overcome by means of nonlinear channel estimation. In this project, pilot decontamination shall be studied in greater detail.In particular, it shall be investigated how it can be utilized for downlink transmission and which handover protocols are suitable.Furthermore, it shall be studied how massive a multi-antenna system needs to be such that pilot decontamination will work reliably.Particular effort shall be devoted to find an efficient way to implement pilot decontamination in practice.