PATRICIAN: New Paradigms for Body Centric Wireless Communications at MM Wavelengths

未来的通信世界有两个尺度。一个是全球性的，互联网提供了普遍的互联互通，并为所有人提供了获取大量信息的途径。另一种是个人的，用户可以在广泛的活动和情况下得到全球的支持。在某种程度上，这种情况已经出现，并反映在诸如城域网、本地网、个人网和体域网（城域网、局域网、PAN、BAN）等术语中。虽然这样的分类澄清了从大到小的通信，反之亦然，但还有另一个挑战，即在通信个性化方面将用户需求与更广泛的网络连接起来，并将全球支持塑造到人类层面。这些也将是认知的，因为个人系统将对用户状态有高度的认识，并将控制连接和数据流以满足个人需求。用户的意识将取决于个人系统的应用，如卫生、商业、娱乐和特殊职业，包括国防和紧急服务。个人感知可能包括安装在身体上的传感器，通过BAN无线连接，并通过PAN连接到外部网络。我们把这两个领域称为以身体为中心的交流。在其最广泛的实施中，将会有大量的以身体为中心的系统，正如人类活动中正常的那样，这些系统有时会聚集在同一个地方，这个地方也会有许多其他的无线通信设备。医院、公共交通、体育和娱乐活动以及购物中心将有高密度的个人系统，在电磁混乱的环境中工作。个人系统必须不受干扰，不干扰其他用户或重要的本地无线系统。在医院环境中，这些问题可能会危及生命。在国防应用中，这一建议特别针对的是，士兵需要佩戴传感器网络，在无线意义上是隐形的。如果来自他的系统的电磁能量被敌方观察员接收到，他就可以被定位和攻击。根据电磁学的规则，低微波频率的体域网络具有不能很好地控制能量传播的大型天线，并且将无法满足许多近距离ban的要求。60千兆赫频段的通信芯片组正变得可用，这些芯片组具有小型天线，具有狭窄的波束，例如将用于在家中分发高清电视。在这个项目中，我们建议研究60ghz及以上频率在体域网络中的使用。挑战是艰巨的。在这些频率上，身体周围的衍射很弱，因此身体的阴影会阻碍通信。解决方案是使用可重构天线。例如，对于身体前部和后部的网络节点之间的通信，可能会选择从地板反弹的路径，而不是试图在身体表面传播的路径。随着身体的运动，这种选择可能需要改变，因为系统试图从阴暗的路径切换到成功的路径。类似的传播路径搜索可用于从本体到本地基站的通信。要实现这种灵活的网络，需要非常了解能量在人体和周围环境中的传播方式，并设计窄波束的可切换天线。基于计算机的未来系统设计需要能量传播和运动体的数字模型，再一次，高频率带来的困难使得这超出了当前的计算能力。伯明翰大学、达勒姆大学和伦敦玛丽女王大学的研究团队在无线电波传播测量、天线设计和数值计算方面有丰富的经验，可以很好地进行这项研究。

The future communications world has two scales. One is global, in which the internet gives universal interconnectivity, and access for all to vast amounts of information. The other is personal, where the user can be supported by the global, in a wide range of activities and situations. To some extent this is already with us and is reflected in terminology such a metropolitan, local, personal and body area networks, (MAN, LAN, PAN, BAN). Whilst such classifications clarify the communications from large to small and vice versa, there is another challenge, that of interfacing the user needs to the wider network, in terms of personalisation of the communications and shaping the global support to the human level. These will also be cognitive, in that the personal system will have high levels of awareness of the user state and will control the connections and data flow to match the personal needs. User awareness will depend on the application of the personal system, such as health, business, entertainment, and special occupations including defence and emergency services. Personal awareness could involve body mounted sensors, wirelessly connected through a BAN and connected to the external network through a PAN. We refer to these two domains as body centric communications.In its widest implementation there will be large numbers of body centric systems, and as is normal in human activity, these will at times congregate in the same place, which will also have many other wireless communications equipment. Hospitals, public transport, sports and entertainment events and shopping malls will have high densities of personal systems, working in an electromagnetically cluttered environment. The personal system must be immune to interference and not interfere with other users or important local wireless systems. In the hospital environment these problems may be life threatening. In defence applications, at which this proposal is especially directed, there is a need for the soldier wearing the sensor network to be invisible in a wireless sense. If electromagnetic energy from his systems is picked up by enemy observers, he can be located and attacked.Body area networks at low microwave frequencies have, by the rules of electromagnetics, large antennas that cannot control the spread of energy well, and will not be able to meet the requirements for many close proximity BANs. Communication chip sets are becoming available at 60 GHz that have small antennas, with narrow beams that will be used, for example, to distribute HD TV around the home. We propose, in this project, to investigate the use of 60 GHz and above for body area networks. The challenges are daunting. At these frequencies, diffraction around the body is weak and so shadowing by the body can prevent communication. The solution is to use reconfigurable antennas. For example, for communications between network nodes on the front and back of the body, a path bouncing off the floor might be chosen over one that attempts to propagate around the body surface. As the body moves, this choice may need to be changed as the systems seeks to switch from shadowed paths to successful ones. Similar propagation path searching can be used for communications from the body to local base stations. To realise this sort of agile networking requires very good knowledge of the way the energy propagates around the body and the surroundings, and the design of switchable antennas with narrow beams. Computer based design of future systems requires digital models of both the energy propagation and the moving body, and again the high frequencies throw up difficulties that make this beyond current computational capabilities. The research teams of the Universities of Birmingham, Durham and Queen Mary University of London are well placed to undertake the study having experience in radiowave propagation measurements, antenna design and numerical computation.