Advances in Body-Centric Wireless Communication: Applications and state-of-the-art
2: Department of Electronics Engineering, University of Bedfordshire, Luton, UK
3: School of Electronic Engineering and Computer Science, Queen Mary, University of London, London, UK
Body centric wireless networking and communications is an emerging 4G technology for short (1-5 m) and very short (below 1 m) range communications systems, used to connect devices worn on (or in) the body, or between two people in close proximity. It has great potential for applications in healthcare delivery, entertainment, surveillance, and emergency services. This book brings together contributions from a multidisciplinary team of researchers in the field of wireless and mobile communications, signal processing and medical measurements to present the underlying theory, implementation challenges and applications of this exciting new technology. Topics covered include: diversity and cooperative communications in body area networks; ultra wideband radio channel characterisation for body-centric wireless communication; sparse characterisation of bodycentric radio channels; antenna / human body interactions in the 60 GHz band; antennas for ingestible capsule telemetry; in vivo wireless channel modelling; diversity and MIMO for efficient front-end design of body-centric wireless communications devices; on-body antennas and radio channels for GPS applications; textile substrate integrated waveguide technology for the next-generation wearable microwave systems; ultra wideband body-centric networks for localisation and motion capture application; down scaling to the nano-scale in body-centric nano-networks; and the road ahead for body-centric wireless communication and networks.
Inspec keywords: cooperative communication; wireless channels; millimetre wave antenna arrays; ultra wideband communication; biomedical telemetry; body area networks; substrate integrated waveguides; biological effects of microwaves; diversity reception; radiotelemetry; next generation networks; MIMO communication
Other keywords: next-generation wearable microwave systems; textile substrate integrated waveguide technology; in vivo wireless channel modeling; body-centric wireless communication devices; frequency 60 GHz; motion capture applications; front-end design; body area networks; ultra wideband body-centric networks; body-centric nano-networks; localisation applications; diversity communications; capsule telemetry; MIMO; ultra wideband radio channel characterisation; antenna-human body interactions; body-centric radio channel sparse characterization; cooperative communications
Subjects: Health Physics; Antenna arrays; Waveguides and microwave transmission lines; Telemetry; Radio links and equipment; General electrical engineering topics; Biomedical communication
- Book DOI: 10.1049/PBTE065E
- Chapter DOI: 10.1049/PBTE065E
- ISBN: 9781849199896
- e-ISBN: 9781849199902
- Format: PDF
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Front Matter
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1 Introduction
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Body-centric wireless networks (BCWNs) have recently gained substantial recognition and interest in both academic and industrial communities due to its direct and beneficial impact both economically and socially in various application domains. Such networks refer to a number of nodes/units scattered across the human body and the surrounding areas to provide communication on the body surface, to access points and wireless devices in the near vicinity and also to provide hieratical networking structure from implants to the main communication hub [1].
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2 Diversity and cooperative communications in body area networks
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In this chapter, we investigate diversity and cooperative communications, and particularly cooperative diversity, for body-centric communications in wireless body area networks (BANs). Cooperative diversity for BANs is vitally important for required communications reliability, as well as increasing network and sensor lifetime by potentially reducing energy consumption, as will be shown here. We describe what is meant by cooperative communications and cooperative diversity, including a brief survey of the state-of-the-art. Description and analysis of the benefits of cooperative diversity in BANs is mainly with respect to the physical layer, but there is also some brief discussion of the MAC layer and network layer. In terms of cooperative receive diversity, feasible in IEEE 802.15.6 Standard compliant BAN, several cooperative receive combining techniques are described, which are all beneficial over single-link communications in terms of firstand second-order statistics. A simple, practical, technique of switch-and-examine combining shows good performance in terms of important metrics, and this can be further enhanced when combined with a simple “sample-and-hold” transmit power control, which can help reduce energy consumption for sensor radios.
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3 Ultra wideband radio channel characterisation for body-centric wireless communication
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This chapter discusses the various experimental investigations undertaken to thoroughly understand the Ultra wideband (UWB) on/off-body radio propagation channels. These characterisation measurement campaigns were performed in both the anechoic chamber and a typical indoor environment (cluttered laboratory). Effect of human body movements on the channel parameters is evaluated. Apart from measurements in an anechoic chamber and in an indoor environment, when body parts were moving, measurements were also taken on a treadmill machine in order to mimic the scenario of UWB body-centric system applied in performance monitoring for sport and exercise medicine. Radio channel parameters are extracted from the measurement data and statistically analysed to provide a preliminary radio propagation model with the inclusion of pseudo-dynamic body movements.
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4 Sparse characterization of body-centric radio channels
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In this chapter, sparse characterization of BWCS is discussed. First of all, a novel sparse non-parametric model is proposed to characterize BWCS channels, it has been demonstrated that it is an important supplement to the existing parametric models; and then, compressive sensing technique is applied to the on-body UWB channel estimation, the impulse response of the channel is perfectly reconstructed; finally, particle swarm optimization based support vector regression technique is used to explore obesity's effect on the on-body narrowband wireless channels. This chapter provides readers a totally new angle of view of looking at the current channel modelling technique in BWCS; thus will be beneficial to the ones who aim to developnew radio channel models for BWCS.
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5 Antenna/human body interactions in the 60 GHz band: state of knowledge and recent advances
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In this chapter, we presented a review of the state-of-the-art, recent advances, and remaining challenges in the field of antenna/human body interactions in the 60 GHz band, with a particular emphasis on the near-field interactions that may occur in emerging body-centric MMW applications. For new near-field exposure scenarios expected to appear in coming years, today there is no any clear regulation in terms of the exposure assessment, and standard methodologies for compliance testing are not available in the 60 GHz band. Most of the exposure guidelines and standards recommend IPD as a dosimetric quantity. It cannot be directly used as a metric for near-field exposures since practically it is very challenging, if not impossible, to determine numerically or experimentally local IPD under near-field conditions. Some reports suggest that temperature rise could be used as an exposure metric at MMW. However, in practice, it is not always possible because of some limitations discussed in this chapter. We suggest to use eIPD as a metric; it can be conveniently retrieved from SAR computations and/or measurements and takes into account the perturbation of the wireless device radiation due to the body proximity.
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6 Antennas for ingestible capsule telemetry
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The electronic implants for biomedical applications came out in mid-50s with the invention of the first pacemakers. This healthcare innovation exposed the potential and revealed the vast opportunities in the field of implantable electronic devices, enabling new ways of diagnostics and treatments maintaining the patient mobility. So, the idea of wireless telemetry was born: it permits to efficiently prevent, monitor and treat a disease timely. In this chapter, we provide an overview of ingestible capsule wireless telemetry with the main focus on specific challenges and difficulties associated to the design of ingestible GI capsule antenna systems.
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7 In vivo wireless channel modeling
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In this chapter, the state of the art of in vivo wireless channel characterization has been presented. Various studies described in the literature are dedicated to the in vivo communication channel, and they consider different parameters in studying various anatomical regions. Furthermore, the location-dependent characteristics of in vivo wireless communication at 915 MHz are analyzed in detail via numerical and experimental investigations. A complete model for the in vivo channel is not available and remains an open research problem. However, considering the expected future growth of implanted technologies and their potential use for the detection and diagnosis of various health-related issues in the human body, the channel modeling studies should be further extended to develop better and more efficient communications systems for future in vivo systems.
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8 Diversity and MIMO for efficient front-end design of body-centric wireless communications devices
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The advancement of intelligent, small sensors, microelectronics, integrated circuit, and low power wireless communication has led us close to the deployment of body area networks (BANs). There is considerable ongoing research on antennas and propagation for BANs. Diversity and Multiple Input Multiple Output (MIMO) are the two well-known multiple antenna techniques to overcome fading and provide channel capacity improvement. In this chapter, we discuss the use of antenna diversity and MIMO for on-body channels to support reliable and high data rate communication. Diversity is also used to cancel the co-channel interference from a nearby BAN device. Probabilistic channel models of diversity and MIMO on-body channels are proposed and validated by measurements.
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9 On-body antennas and radio channels for GPS applications
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This chapter has presented the characterisation of the GPS antennas operating in different on-body scenarios. Performance of these antennas is severely affected by the multipath arrival of the GPS signal in realistic operational conditions. These effects have been investigated using a statistical model replicating the multipath GPS environment. It has been shown that the linear polarised antennas can work better for on-body GPS links in multipath environment as compared to the conventional choice of CP antennas. It has also been shown that the antenna performance depends hugely on the body posture and on-body antenna position. The model also reduces the antenna design and testing durations by removing the need of detailed, uncontrolled and lengthy open field test procedures and providing efficient and accurate predictions of GPS antenna performance in cluttered environment.
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10 Textile substrate integrated waveguide technology for the next-generation wearable microwave systems
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Ever since the transistor replaced the vacuum tube by the end of the 1950s and, thereafter, the invention of the integrated circuits (ICs), the influence of computers on society has increased hand over fist. Whereas, in the 1990s, we used to rely on keyboard and mouse to browse our first web pages and send our first emails, most people nowadays carry around, in their pocket, a device that lets them contact anyone, anywhere in the world, or access any piece of information from a data source more vast than all of the world's libraries combined. And all of this by simply swiping a screen or by using voice commands. But what does the future have in store for us? Where will this evolution bring us in the next 5-10 years?
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11 Ultra wideband body-centric networks for localisation and motion capture applications
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Localisation and motion tracking using body-worn antennas are emerging as an important research area based on ultra wideband (UWB) technology. Motion tracking itself is motivated by a variety of applications such as training of athletes, patient monitoring in health care domain, localisation of people in home or office environment, and the human body is an integral part of such applications. Hence, it is important to study the effect of human body on UWB localisation and the accuracy achieved while localizing the antennas present on the body. The choice of sensors, such as compact, efficient and low-cost UWB antennas, makes human localisation and activity monitoring a promising new application made possible by advances in UWB technology. In this chapter, UWB three-dimensional (3D) human body localisation is studied using body-worn antennas placed on different locations on the human body through numerical and experimental investigations. Detailed analysis is performed based on the measurement data in terms of propagation phenomenon for each antenna location and how the presence of human body affects ranging and localisation accuracy. The objective of the work is to achieve high-accuracy localisation of the human body using time of arrival positioning techniques and also evaluate the results with the optical motion capture system which is used as a standard reference.
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12 Down scaling to the nano-scale in body-centric nano-networks
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As Metin Sitti said, small-scale network has a quite bright future, especially in healthcare and bioengineering scenario because the corresponding devices in the network are “unrivalled for accessing into small, highly confined and delicate body sites, where conventional medical devices fall short without an invasive intervention” [1]. Nano-technology has gained a great attention since it was put forward in 1959 [2]. The most fundamental elements to materialize nano-technology are the development of battery-free nano-devices, which can be used to accomplish simple tasks such as computation, sensing, and communication [3]. Furthermore, by combining these basic units, the capacity of these nano-devices could be substantially expanded and much more complex tasks can be targeted, which highlights the concept of nanonetworks. The latter opens the door to an immense range of applications ranging from medical technologies to flexible electronics [4]. On the other hand, researches on body area networks (BAN) at microwave frequencies have obtained great achievements, and it is pointed out by Prof. Metin Sitti that the entire network systems would be shrunk into nano-scale with the nano-robots and molecular machine as the elements in the near future [1]. Additionally, combined with the concept of internet of things, the internet of multi-media nano-things has been introduced and detailed in Reference 5, which indicates the significance of the study of nano-communication. As the name indicates, nano-communication encapsulates the communication between devices at the nano-scale applying novel and modified communication and radio propagation principles in comparison to conventional and existing solutions as further explained in this manuscript [3]. Among three scenarios of body-centric communications, namely: in-body, on-body, and off-body [6], where the in-body application related to medical healthcare is the most promising and of great interest.
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13 The road ahead for body-centric wireless communication and networks
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Wireless interaction of the human user with the computing devices has seen a profound growth in the past decade. Wearable technology has successfully moved past the adoption stage and now stands at the brink of massive diversification with an explosion in popularity and applicability. The estimated market value of the wearable technology is expected to hit $32 billion mark by 2020 [1, 2]. It would cause the global wearable devices market it to grow from 20 million device shipments in 2015 to 187.2 million units annually by 2020 [3].
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Back Matter
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