Interference Management in MIMO Wireless Networks

随着对支持更高比特率的无线通信服务的需求不断增长，存在通过同时多个传输来重用相同频谱来增加通信系统的带宽效率的日益迫切的需求。为了解决这个问题和许多其他问题，最成功和最有效的解决方案之一是部署多输入多输出（MIMO）技术。 然而，多用户（MU）MIMO系统通常被设计为使用非优化方法来处理限制网络容量的干扰。因此，该提议寻求设计管理MU MIMO系统中的干扰以实现最高网络吞吐量的信号处理策略和无线网络协议。 处理干扰的传统方法是（i）通过时域或频域中的非重叠传输来避免干扰，（ii）将其他发射机的信号作为噪声合并并通过功率控制来减轻噪声，或者（iii）部署多用户解码。在MU-MIMO系统中，其中空间信令维度被用于并行地服务于许多用户，存在通过在终端处的线性预编码和功率控制来整形干扰以最小化目的地处的组合干扰的影响的机会。 在这个建议中，我们寻求开发策略，以处理在MU MIMO系统中的干扰，通过整合信号对齐几个强发射机和干扰消除非协调传输。具体地说，通过精心设计的预处理向量和传输调度，我们期望具有相关信息的信号将根据所选择的编码策略被对齐到适当的空间维度。传输方案也将被优化以降低计算复杂度并提高时频利用率。 这项工作的范围将涵盖单跳，多跳和多路网络。在多跳系统中，源和目的地通过一个或多个其他节点作为中继通信，我们计划利用物理层网络编码的概念，以帮助无线网络的操作与节点分布在空间中根据泊松点过程。 我们在这里的重点是媒体接入（用户选择）的机会，功率分配，重点是中继间干扰消除的拓扑控制和路由级别的问题。我们希望在这里部署的工具，从随机几何计算宏观性能的无线网络的分析，平均在所有潜在的几何图案的终端。这项工作的挑战将是评估从部署的信号对准技术，其中所有终端可能不同步或完全合作的增益。

With the growing demands for wireless communication services to support higher bit rates, there is an ever-pressing need to increase bandwidth efficiency of communication systems through the reuse of the same spectrum by simultaneous multiple transmissions. To address this and many other issues, one of the most successful and efficient solutions is the deployment of Multiple-Input Multiple-Output (MIMO) technology. However, the multi-user (MU) MIMO systems are often designed to use non-optimized methods to deal with the interference limiting the network capacity. As a result, this proposal seeks to design signal processing strategies and wireless network protocols that manage interference in MU MIMO systems to achieve the highest network throughput. Conventional approaches to deal with interference are (i) to avoid interference by non-overlapping transmissions in time or frequency domains, (ii) lump other transmitters' signals as noise and mitigate it through power control, or (iii) deploy multi-user decoding. In MU-MIMO systems, where the spatial signaling dimension is utilized to serve many users in parallel, there are opportunities for shaping the interference through linear pre-coding at the terminals and power control to minimize the effects of the combined interference at the destinations. In this proposal, we seek to develop strategies to deal with interference in MU MIMO systems by integrating signal alignment for few strong transmitters and interference cancellation for non-coordinated transmissions. Specifically, by a thoughtful design of pre-processing vectors and scheduling of transmissions, we expect that the signals with relevant information will be aligned into proper spatial dimensions according to the selected coding strategies. The transmission schemes will be also optimized to reduce computational complexity and to improve time-frequency utilization. The scope of this work will cover single-hop, multi-hop, and multi-way networks. In multi-hop systems, where a source and destination communicate through one or more other nodes that act as a relay, we plan to exploit the concept of physical layer network coding to aid the operation of the wireless network with the nodes distributed in space according to the Poisson-point process. Our focus here is on medium access (user selection) opportunities for power allocation, with emphasis on the topology control and routing-level issues for inter-relay interference cancellation. We expect here to deploy for analysis the tools from stochastic geometry which computes macroscopic properties of wireless networks, by averaging over all potential geometrical patterns for the terminals. The challenge in this work will be to evaluate the gains from the deployed signal alignment techniques where all terminals may not be synchronized or fully cooperating.