Tackling the looming spectrum crisis in Wireless Communication

20世纪80年代第一批移动电话的问世标志着用于商业目的的移动通信的开始。30年后的今天，无线连接已成为我们日常生活的基本组成部分，并越来越被视为与电力、天然气和水一样的必需品。这种无与伦比的成功意味着我们今天面临着无线电频率(RF)频谱的迫在眉睫的短缺：据预测，在未来五年内，通过无线网络发送的数据量将增加10倍。此外，来自高通的数据表明，频谱效率(每赫兹带宽传输的比特数)是饱和的。因此，美国联邦通信委员会警告说，一场“频谱危机”正在迫在眉睫。EPSRC联谊会的拟议工作旨在为这一根本和深远的挑战提供激进的新解决方案。拟议工作的一个关键支柱是将射频光谱扩展到包括红外光谱和可见光光谱。发光二极管(LED)器件技术的最新进展似乎使用光进行高速无线通信的愿景成为现实。与射频相比，用光具有许多关键优势。可用频谱广阔，可见光频谱比射频频谱大一万倍；不受政府监管，免费；比无线频谱更安全，其信号可以在前提外被拦截；它可以实现单位面积三个数量级的数据密度。与红外光谱相比，可见光光谱具有额外的优势。首先，出于眼睛安全的考虑，它不受功率限制。其次，它可以同时用于两个目的：照明和高速数据传输，从而更好地利用能源。然而，虽然已经使用现成的白色LED演示了单个链路的几百兆比特每秒(Mbps)，但1千兆比特每秒(Gbps)和房间覆盖仍然是一个悬而未决的问题。此外，针对多用户网络化OWC系统的研究也很少。此外，调光对可实现的数据速率的影响也没有得到很好的了解。此外，在一些环境和场景中，光的使用是困难或不可能的，例如当发射器和接收器之间存在严重阻塞时，或者当终端高速移动时。在这些情况下，使用射频频谱仍然是更合适的。综上所述，当无线系统能够以动态和自组织的方式自主地选择它们的传输介质时，潜在的整体性能有很大的改进。拟议研究的第二个重要支柱是克服当前蜂窝系统的射频频谱效率饱和，同时降低能量消耗。解决这个问题的一个关键是成功地解决无线网络中的干扰，这种干扰是当邻近的多个通信链路使用(或重复使用)相同的带宽或频率时发生的。一方面，频率重用是有益的，因为单位面积使用的传输资源越频繁，频谱效率就越高。另一方面，密集的频率重用导致了上述干扰问题。将采用全新的方法，其中包括在设计新的无线空中接口时已经存在的干扰。在过去，无线空中接口针对单个传输链路进行优化，随后由于系统部署中的干扰而导致的性能降级被修复，但现有的解决方案要么不切实际，要么不是最优的。我们将研究一种新的空中接口，该接口基于最近对空间调制概念的成功演示和世界范围的研究，该概念最初由申请人提出。

The advent of the first mobile phones in the 1980s marked the beginning of mobile communications for commercial purposes. Now, thirty years later, wireless connectivity has become a fundamental part of our everyday lives and is increasingly being regarded as an essential commodity like electricity, gas and water. This unparalleled success means that we are today facing the imminent shortage of radio frequency (RF) spectrum: It is predicted that the amount of data sent through wireless networks will increase by a factor of 10 during the next five years. Moreover, data from Qualcomm demonstrates that the spectrum efficiency (number of bits transmitted per Hertz bandwidth) is saturating. Therefore, the US Federal Communications Commission has warned that a "spectrum crisis" is looming.The proposed work in this EPSRC Fellowship is aimed at providing radical new solutions to this fundamental and far reaching challenge. A key pillar of the proposed work is the extension of the RF spectrum to include the infrared as well as the visible light spectra. The recent advancements in light emitting diode (LED) device technology now seems to let the vision of using light for high speed wireless communications become a reality.Using light has many key advantages as compared with RF. The available spectrum is vast, the visible light spectrum is 10,000 times larger than the RF spectrum; it is free as it is not subject to government regulations; it is more secure than the radio frequency spectrum the signals of which can be intercepted outside a premise; it can achieve three orders of magnitude higher data density per unit area. Compared to the infrared spectrum, the visible light spectrum has additional advantages. First, it is not power-limited due to eye-safety concerns. Second, it can serve two purposes at the same time: illumination and high speed data transmission, resulting in a better use of energy. However, while several hundred megabit per second (Mbps) have been demonstrated for a single link using an off-the-shelf white LED, 1 gigabit per second (Gbps) and room coverage is still an open issue. In addition, there is little research for multi-user networked OWC systems. Also, the effects of dimming on the achievable data rates are not well understood. In addition, there are environments and scenarios where the use of light is difficult or not possible such as when there is heavy blockage between transmitters and receivers, or when terminals move with high speeds. In those situations, it will still be more appropriate to use the RF spectrum. To sum up, there are potential large overall performance improvements when wireless systems can select their transmission medium autonomously and in a dynamic as well as self-organising fashion. A second essential pillar of the proposed research is to overcome the RF spectrum efficiency saturation of current cellular systems while at the same time reducing the energy consumption. A key to solving this issue is to successfully tackle interference in wireless networks which occurs when multiple communication links in close vicinity use (or reuse) the same bandwidth or frequency. On the one hand frequency reuse is beneficial since the more often transmission resources are used per unit area, the higher the spectrum efficiency. On the other hand, intensive frequency reuse results in the aforementioned interference issues. Radically new approaches will be followed that include interference already in the design of a new wireless air-interface. In the past, wireless air-interfaces were optimised for single transmission links, and performance degradations due to interference in a system deployment were mended subsequently, but existing solutions are either impractical or sub-optimum. We will investigate a new air-interface that is based on the recent successful demonstrations of and world-wide research on the concept of spatial modulation which was originally proposed by the applicant.