Wearable Antennas for Body-Centric Wireless Networks

人体上的通信对于个人和移动的通信社区来说是相对未开发的商品。到目前为止，移动的电话技术已经允许用户随时随地通话。但在发达国家，这一市场正趋于饱和，并已投入大量资金为第三代手机提供多媒体服务。相机和低容量MP3播放器现在是标准配置。未来会怎样？大的愿景是人们穿着大量的传感器，处理器，数据存储器，用于健康或职业或娱乐原因，所有这些都通过无线或有线连接在特殊的衣服上。这些单元甚至可以在身体内部以提供医疗解决方案，例如自动药物计量和膀胱控制等。具有蓝牙耳机的公知的移动的电话是无线体上链路的示例。著名的白色iPod耳机也许是有线系统需要被无线取代的一个例子。苹果公司，iPod的制造商，和耐克最近同意合作设计一种特殊的鞋子，允许穿着者使用iPod来监控时间，燃烧的卡路里和步伐，并在iPod和鞋子之间使用无线通信链接。这些例子显示了技术在大众市场中的发展方式。此外，一段时间以来，军队和特种服务（例如消防员）都一直在使用身体上系统来支持各种危险环境中的用户，并且使用无线来移除或减少线束是重要的。什么是实现大愿景的必要条件？制造商总是简单地将现有系统用于新应用。将蓝牙用于移动的电话耳机就是一个例子。它是一个无线系统开发的另一种用途，即连接外围设备到计算机。但是，为了优化操作，即提高可靠性并降低电池消耗，需要更深入地了解身体上的无线电波传播通道以及如何设计天线。在以前的EPSRC授予伯明翰大学和伦敦的玛丽皇后大学，开始了解无线电信道和确定天线设计中的重要因素的这项开创性工作。通过对当身体移动时信道以及因此接收到的信号衰落的方式进行广泛的测量，已经发现了很多，并且确定了潜在的统计数据。然而，该研究计划仅在蓝牙频率2.45GHz下工作，并且主要是表征窄带信道，而不是实时视频通信所需的数据速率。拟议的研究是必要的，以向前推进的立场，包括更多的工作，为这个频率和其他优化天线的设计。例如，最佳辐射模式将使用统计方法针对一系列身体类型和身体姿势以及各种频率（包括比迄今为止检查的频率高得多的频率）来确定。例如，在40或60GHz下的操作将给出非常高的数据速率的可能性以及彼此靠近的身体网络之间的非常低的干扰，但是将遭受衰落问题。天线分集是一种用于减少衰落的公知技术。将在各种频率下研究其在身体上的使用。由FCC发布的从3到10 GHz的频谱使得超宽带系统成为真实的可能性，并且其高容量潜力、低功率和良好的抗衰落特性使其成为未来身体上系统的理想选择。然而，迄今为止制造的所有天线对于实际的身体使用来说都太大了。将研究小型可穿戴类型的设计。最后，用于身体通信的天线对计算方法提出了巨大的挑战，并将研究改进的技术以支持整个研究计划。

Communications on the human body is a relatively unexplored commodity for the personal and mobile communications community. Up to now mobile phone technologies have allowed the user to talk anytime anywhere. But in the developed world this market is becoming saturated and so much has been invested into providing third generation phones with multimedia services. Cameras and low capacity MP3 players are now standard. What does the future hold? The big vision is of people wearing a multitude of sensors, processors, data storage for health or occupational or entertainment reasons and all of these being connected either by wireless or by wires in special clothing. These units may even be inside the body to provide medical solutions such as automatic drug metering and bladder control etc. The well known mobile phone with Bluetooth headset is an example of a wireless on-body link. The famous white iPod headset is perhaps an example of a wired system that needs to be replaced by wireless. Apple, the makers of the iPod, and Nike have recently agreed to collaborate on specially designed footwear that would allow the wearer to use their iPod to monitor time, calories burned and pace, and which uses a wireless communication link, between the iPod and the shoe. These examples show the way that technology is moving in the mass market. In addition, for some time now both the military and the special services, such as firefighters, have been using on-body systems to support their users in various hazardous environments and the use of wireless to remove or reduce the wiring harness is important. What is needed to make the big vision happen? Manufacturers will always simply use existing systems for new applications. The use of Bluetooth for the mobile phone headset is an example of this. It is a wireless system developed for another use, namely connection of peripherals to computers. But to optimise the operation, that is to improve the reliability and reduce battery consumption, requires a deeper understanding of both the radiowave propagation channel on the body and how to design the antennas. In a previous EPSRC grant the University of Birmingham and Queen Mary University of London, began this pioneering work of understanding the radio channel and identifying the factors important in antenna design. Much has been uncovered via extensive measurements of the way in which the channel and hence the received signal fades when the body moves have been made and the underlying statistics determined. However the research programme has only been working at the Bluetooth frequency, 2.45GHz, and mainly been characterising narrowband channels, but not the kinds of data rates needed in communications of live video. The proposed research is necessary to move the position forward to include more work on the design of optimised antennas both for this frequency and for others. For example, the best radiation pattern will be determined using statistical methods for a range of body types and body postures, and various frequencies, including much higher ones than examined so far. For example, operation at 40 or 60GHz would give the possibility of very high data rates and also very low interference between body networks close to each other, but will suffer from fading problems. Antenna diversity is a well known technique for fading reduction. Its use on the body will be investigated at various frequencies. The release of the spectrum from 3 to 10 GHz by the FCC has made ultra wideband systems a real possibility and its high capacity potential, low power and good anti-fading properties make it ideal for future on-body systems. However all of the antennas so far made are too big for realistic on-body use. Design of small wearable types will be investigated. Finally antennas for on body communications throw up immense challenges for computational methods and improved techniques will be investigated to support the whole research programme.