Improper Gaussian signaling schemes for interference-limited communications

本提案旨在为限制干扰的移动通信网络开发新的信令方案。目前，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。为了追求高效的干扰管理方案，目前的研究重点是通过利用信道状态信息的联合预编码器设计来进行干扰协调。这些工作中的绝大多数假设传输信号以适当的高斯随机信号分布，当系统不受干扰限制时，已知高斯随机信号是最优的。最近，文献中提出了偏离这些标准假设的替代信号方案。在各种限制干扰的网络中，实部和虚部相关和（或）幂等的非正常高斯信号的传输优于正常高斯信号。本项目将研究不同干扰限制网络的不当信令方案。它有以下目标：-提供关于何时不正确的信令比正确的信令能带来更好的性能的见解。为此，我们将专注于单天线和部分连接的干扰信道，其中的分析是易于处理的，并且允许扩展到更一般的场景的见解。-设计算法，优化一般干扰信道的传输参数。不合适的信令方案不仅包含与合适方案相关的参数，还包含描述信号不合适的附加参数，这使得优化更具挑战性。-将不适当的信号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，使其影响可以是上界的，从而减少对合作的要求。我们将探索考虑不当性的新干扰约束，以及在这些约束下的传输参数优化。-在实际硬件测试平台上评估所设计方案的性能。我们将评估现实世界的缺陷对不适当的信号性能的影响，如信道估计错误、不完美的同步和脏射频效应。

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.