Realization and Application of Full-Duplex Transceivers in Millimeter-Wave Links for Small-Cell Wireless Backhaul Networks

研究和实现应用于无线通信网络的全双工收发信机是本课题的目标。研究的一个主要焦点是致力于回程网络(BHN)，该网络主要用于实现小小区之间的高速数据传输。数据传输通常通过微波频段(6-100 GHz)内的点对点链路以半双工模式执行。随着5G小蜂窝的大规模部署，对更高效、更灵活的BHN的强烈需求即将到来。目前，将点对点链路扩展到更复杂的点到多点链路，扩展到更多中继站的多跳链路，或者扩展到网状结构，需要很高的规划工作，以及提供多个频率通道来减少无线电波之间的干扰。不幸的是，小蜂窝的拥塞不可避免地导致了更复杂的网络架构，进而增加了前面提到的挑战。显然，实际的半双工BHN很快就会达到它们的技术和经济极限。所请求的项目中考虑的全双工技术是解决上述问题的一个值得选择的方案，将显著有助于实现BHN的适应性和效率。由于全双工收发信机能够抑制自身干扰，并工作在同一信道上进行发送和接收，因此无需使用多个频率信道，构建网状网络将是一项简单的任务。此外，众所周知，与通常的半双工系统相比，全双工系统实现了更高的频谱效率。此外，与实际的BHN相比，全双工系统具有更高的抗窃听性，这是一个进一步的优势。在本项目中，我们首先建立了全双工收发机和相关通信网络的数学模型。这些模型将提供一个分析框架来评估和优化具有全双工功能的网状网络。其成果将是在毫米波波段实现BHN的概念。将使用不同的跨学科方法来实现项目目标。一方面，分析方法将被用来描述在实际硬件开发中受约束的自干扰。另一方面，数值和模拟方法将被用来调查和建模在现实约束下的更大的无线电网络。此外，这类网络的性能限制的一般量化应该借助简单的假设从数学上加以阐述。最后，将使用高频(RF)测量仪器和数值场论方法来开发实际的收发信机和天线。整个项目伴随着全双工收发机原型的实验研究。

The research and realization of full-duplex transceivers for the application in wireless communication networks is the goal of the requested project. A main focus of the investigations is dedicated to backhaul networks (BHN) which primary are used to enable high-speed data transmission between small-cells. Data transmission is usually performed in half-duplex mode by point-to-point links within the micro-wave bands (6–100 GHz). Since a massive deployment of small-cells for 5G is discussed, a strong demand for more efficient and flexible BHNs is just around the corner.At the moment, the extension of point-to-point links to the more complicated point-to-multipoint links, to multi-hop links over additional relay stations, or to mesh architectures entails high planning effort as well as the provision of multiple frequency channels to reduce interferences between the radio waves. Unfortunately, the congestion of small-cells inevitably leads to more complicated network architectures and in turn to the mentioned increased challenges. It is obvious that the actual half-duplex BHNs will attain their technical and economical limits soon.The considered full-duplex technology in the requested project is a worthy alternative to tackle the mentioned problematic and will significantly help to achieve adaptivity and efficiency in BHNs. Since full-duplex transceivers are able to suppress their self-interference and to work on the same channel for transmission and reception, building a mesh network will be a simple task without using multiple frequency channels. In addition, it is well-known that full-duplex systems achieve a higher spectral efficiency compared to usual half-duplex systems. Moreover, a full-duplex system is more secure against eavesdropper which is a further advantage in comparison to the actual BHNs.In the present project, we first create mathematical models for both the full-duplex transceiver and the associated communication network. These models will make an analytical framework available to evaluate and optimize mesh networks with full-duplex capability. The outcome will be a concept for realizing BHNs in mm-wave bands.Different interdisciplinary methods will be used to achieve the project goals. On the one hand, analytical methods will be utilized to describe the self-interference subject to constraints in real hardware development. On the other hand, numerical and simulative methods will be applied to investigate and model larger radio networks under realistic constraints on the wave propagation. Furthermore, a general quantification of performance limitations of such networks should be elaborated mathematically with the aid of simple assumptions. At the end, real transceivers and antennas will be developed for which high-frequency (RF) measuring instruments and numerical field theory methods will be used. The entire project is accompanied by experimental investigations with prototype implementations of full-duplex transceivers.