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

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.

The use of mm wave systems for BANs is disruptive, in that it will provide high levels of signal security at the RF level, by lowering interference and enabling many BANs to operate in the same area. It will have high levels of impact, initially, in the defence sector, where communications emanating from the dismounted soldier leads to detection, location and vulnerability to enemy attack. The high attenuation will lead to much higher levels of security against detection, interception and jamming. MM wave BANs will also benefit civilian sectors such as healthcare, personal entertainment, sports training, and emergency services. In hospital, clinics, entertainment venues, and public transport, there is a need to relay personalised data to and from individuals, in confined areas, or in crowds, and the high frequency and highly directive beams from small mm antennas will reduce interference between users and between users and other communications equipment. Programs such as the Future Infantry Soldier Technology (FIST) in the UK and Land Warrior and Future Force Warrior (FFW) in the USA aim to increase user performance by a variety of body worn systems. For example, FIST contains a sighting system linked to a helmet-mounted sight and FFW will contain an on-board physiological and medical sensor suit that would collect and monitor information regarding vital signs of the warrior. The communications in future systems will be wirelessly supported and must be small size and have low weight, power, interference and signature. The SEAS Defence Technology Centre and Roke Manor Research have written support letters that indicate the high significance of this work and have emphasised the importance of low observable BANs. In terms of healthcare, medical sensor networks, are becoming important are in hospitals and clinics. Up to 40 % of critical-care time is spent manually recording patient data and sensor networks could reduce this dramatically. However the increasing density of patients and wireless supported equipment using the ISM band (2.45 and 5.8 GHz) mean that mutual interference is a major concern, as is eavesdropping and denial of service attacks. As the world's population ages, in-home body centric networks may assist residents by providing memory enhancement, control of home appliances, medical data lookup, and emergency communication. Whilst interference is less of an issue, sensor size is crucial both in terms of patient comfort and convenience, and encouraging them not to remove them. MM wavelength based communications will lead to smaller equipment.