Improper Gaussian signaling schemes for interference-limited communications

该方案旨在为干扰受限的移动通信网络开发新的信令方案。如今，多用户干扰已经成为无线通信端到端性能的主要限制因素。为了寻求有效的干扰管理方案，目前的研究集中在利用信道状态信息的联合预编码器设计的干扰协调上，其中绝大多数工作假设传输的信号以适当的高斯随机信号的形式分布，当系统不受干扰限制时，已知这些信号是最优的。最近，文献中已经提出了偏离这些标准假设的替代信令方案。研究表明，在不同的干扰受限网络中，实部和虚部相关和/或功率不等的非正态高斯信号的传输性能优于正态高斯信号。它有以下目标：-提供关于何时不适当的信令能够比适当的信令实现更好的性能的见解。为此，我们将重点关注单天线和部分连接的干扰信道，这些信道的分析很容易处理，并允许深入了解更一般的情况。-设计优化一般干扰信道的传输参数的算法。不适当的信令方案不仅包含与适当方案相关联的参数，而且还包含描述信号不适当的附加参数，这使得优化更具挑战性。-将不适当的信令应用于底层认知无线电场景，这可以被视为低协作多用户网络的范例。在这些场景中，通过设置干扰约束来管理干扰，以便其影响可以是上界的，从而需要更少的合作。我们将在考虑不适当的情况下探索新的干扰约束，以及受这些约束约束的传输参数的优化。-在真实的硬件试验台上评估所设计方案的性能。我们将评估真实世界的损伤对不正确信令性能的影响，例如信道估计错误、不完美的同步和肮脏的无线电频率效应。

This proposal aims at developing novel signaling schemes for interference-limited mobile communication networks. Already today, multiuser interference presents the major limiting factor of the end-to-end performance in wireless communications. In pursuit of efficient interference management schemes, current research focuses on interference coordination by means of a joint precoder design that exploits the channel state information.The vast majority of these works assumes that the transmitted signals are distributed as proper Gaussian random signals, which are known to be optimal when the system is not interference-limited. Recently, alternative signaling schemes that deviate from these standard assumptions have been proposed in the literature. It has been shown that the transmission of improper Gaussian signals, whose real and imaginary parts are correlated and/or have unequal power, outperform proper Gaussian signals in various interference-limited networks.This project will study improper signaling schemes for different interference-limited networks. It has the following objectives:- To provide insights on when improper signaling enables better performance than its proper counterpart. To this end, we will focus on single-antenna and partially connected interference channels, where the analysis is tractable and permits insights that can be extended to more general scenarios. - To design algorithms that optimize the transmission parameters for general interference channels. An improper signaling scheme contains not only the parameters associated with a proper scheme, but also additional ones that describe the impropriety of the signal, which makes the optimization more challenging.- To apply improper signaling to underlay cognitive radio scenarios, which can be regarded as a paradigm for low-cooperative multiuser networks. In these scenarios, the interference is managed by setting interference constraints, so that its effect can be upper-bounded and thereby require less cooperation. We will explore new interference constraints taking impropriety into account, as well as the optimization of the transmission parameters subject to these constraints.- To evaluate the performance of the devised schemes on a real hardware testbed. We will assess the impact of real-world impairments on the performance of improper signaling, such as channel estimation errors, imperfect synchronization, and dirty radio-frequency effects.