Antennas and propagation for on-body communication systems
TL;DR: Investigations into channel characterization and antenna performance at 2.45 GHz show that for many channels, an antenna polarized normal to the body's surface gives the best path gain.
Abstract: On-body communication channels are of increasing interest for a number of applications, such as medical-sensor networks, emergency-service workers, and personal communications. This paper describes investigations into channel characterization and antenna performance at 2.45 GHz. It is shown that significant channel fading occurs during normal activity, due primarily to the dynamic nature of the human body, but also due to multipath around the body and from scattering by the environment. This fading can be mitigated by the use of antenna diversity, and gains of up to 10 dB are obtained. Separation of the antenna's performance from the channel characteristics is difficult, but results show that for many channels, an antenna polarized normal to the body's surface gives the best path gain. Simulation and modeling present many challenges, particularly in terms of the problem's scale, and the need for accurate modeling of the body and its movement.
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TL;DR: This paper offers a survey of the concept of Wireless Body Area Networks, focusing on some applications with special interest in patient monitoring and the communication in a WBAN and its positioning between the different technologies.
Abstract: The increasing use of wireless networks and the constant miniaturization of electrical devices has empowered the development of Wireless Body Area Networks (WBANs). In these networks various sensors are attached on clothing or on the body or even implanted under the skin. The wireless nature of the network and the wide variety of sensors offer numerous new, practical and innovative applications to improve health care and the Quality of Life. The sensors of a WBAN measure for example the heartbeat, the body temperature or record a prolonged electrocardiogram. Using a WBAN, the patient experiences a greater physical mobility and is no longer compelled to stay in the hospital. This paper offers a survey of the concept of Wireless Body Area Networks. First, we focus on some applications with special interest in patient monitoring. Then the communication in a WBAN and its positioning between the different technologies is discussed. An overview of the current research on the physical layer, existing MAC and network protocols is given. Further, cross layer and quality of service is discussed. As WBANs are placed on the human body and often transport private data, security is also considered. An overview of current and past projects is given. Finally, the open research issues and challenges are pointed out.
1,077 citations
01 Jan 2006
TL;DR: In this article, on-body propagation modeling has been investigated applying various numerical computational techniques, and propagation measurements with body-worn antennas have been carried out at 2.4 GHz inside and outside an anechoic chamber respectively for narrowband communication channel characterisation.
Abstract: In this paper, on-body propagation modelling has been investigated applying various numerical computational techniques. Propagation measurements with body-worn antennas have been carried out at 2.4 GHz inside and outside an anechoic chamber respectively for narrowband communication channel characterisation. Both simulation and measurement results have been also obtained at the UWB (ultra wide-band) band.
652 citations
TL;DR: An overview of WBAN main applications, technologies and standards, issues in WBANs design, and evolutions is reported, with the aim of providing useful insights for WBAN designers and of highlighting the main issues affecting the performance of these kind of networks.
Abstract: Interest in Wireless Body Area Networks (WBANs) has increased significantly in recent years thanks to the advances in microelectronics and wireless communications. Owing to the very stringent application requirements in terms of reliability, energy efficiency, and low device complexity, the design of these networks requires the definition of new protocols with respect to those used in general purpose wireless sensor networks. This motivates the effort in research activities and in standardisation process of the last years. This survey paper aims at reporting an overview of WBAN main applications, technologies and standards, issues in WBANs design, and evolutions. Some case studies are reported, based on both real implementation and experimentation on the field, and on simulations. These results have the aim of providing useful insights for WBAN designers and of highlighting the main issues affecting the performance of these kind of networks.
597 citations
01 Jul 2021
TL;DR: This work rigorously discusses the fundamental changes required in the core networks of the future, such as the redesign or significant reduction of the transport architecture that serves as a major source of latency for time-sensitive applications.
Abstract: Mobile communications have been undergoing a generational change every ten years or so. However, the time difference between the so-called “G’s” is also decreasing. While fifth-generation (5G) systems are becoming a commercial reality, there is already significant interest in systems beyond 5G, which we refer to as the sixth generation (6G) of wireless systems. In contrast to the already published papers on the topic, we take a top-down approach to 6G. More precisely, we present a holistic discussion of 6G systems beginning with lifestyle and societal changes driving the need for next-generation networks. This is followed by a discussion into the technical requirements needed to enable 6G applications, based on which we dissect key challenges and possibilities for practically realizable system solutions across all layers of the Open Systems Interconnection stack (i.e., from applications to the physical layer). Since many of the 6G applications will need access to an order-of-magnitude more spectrum, utilization of frequencies between 100 GHz and 1 THz becomes of paramount importance. As such, the 6G ecosystem will feature a diverse range of frequency bands, ranging from below 6 GHz up to 1 THz. We comprehensively characterize the limitations that must be overcome to realize working systems in these bands and provide a unique perspective on the physical and higher layer challenges relating to the design of next-generation core networks, new modulation and coding methods, novel multiple-access techniques, antenna arrays, wave propagation, radio frequency transceiver design, and real-time signal processing. We rigorously discuss the fundamental changes required in the core networks of the future, such as the redesign or significant reduction of the transport architecture that serves as a major source of latency for time-sensitive applications. This is in sharp contrast to the present hierarchical network architectures that are not suitable to realize many of the anticipated 6G services. While evaluating the strengths and weaknesses of key candidate 6G technologies, we differentiate what may be practically achievable over the next decade, relative to what is possible in theory. Keeping this in mind, we present concrete research challenges for each of the discussed system aspects, providing inspiration for what follows.
529 citations
Cites background from "Antennas and propagation for on-bod..."
...So far, there are no standardized models for body area networks though many studies are reported (see [181] and [182])....
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TL;DR: In this paper, the performance of a compact higher mode microstrip patch antenna (HMMPA) with a profile as low as lambda/20 was investigated by measuring |S 21| path gain between two devices mounted on tissue-equivalent numerical and experimental phantoms, representative of human muscle tissue at 2.45 GHz.
Abstract: In this paper, the on-body performance of a range of wearable antennas was investigated by measuring |S 21| path gain between two devices mounted on tissue-equivalent numerical and experimental phantoms, representative of human muscle tissue at 2.45 GHz. In particular, the study focused on the performance of a compact higher mode microstrip patch antenna (HMMPA) with a profile as low as lambda/20. The 5- and 10-mm-high HMMPA prototypes had an impedance bandwidth of 6.7% and 8.6%, respectively, sufficient for the operating requirements of the 2.45-GHz industrial, scientific, and medical (ISM) band and both antennas offered 11-dB higher path gain compared to a fundamental-mode microstrip patch antenna. It was also demonstrated that a 7-dB improvement in path gain can be obtained for a fundamental-mode patch through the addition of a shortening wall. Notably, on-body HMMPA performance was comparable to a quarter wave monopole antenna on the same size of groundplane, mounted normal to the tissue surface, indicating that the low-profile and physically more robust antenna is a promising solution for bodyworn antenna applications.
318 citations
Cites background from "Antennas and propagation for on-bod..."
...or indeed robust enough for most practical wearable applications, it has been included here for comparison as it is known to give least path loss over-the-body surface [21], as far as omnidirectional antennas are concerned....
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References
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TL;DR: The mutual resistance condition offers a powerful design tool, and examples of new mobile diversity antennas are discussed along with some existing designs.
Abstract: The conditions for antenna diversity action are investigated. In terms of the fields, a condition is shown to be that the incident field and the far field of the diversity antenna should obey (or nearly obey) an orthogonality relationship. The role of mutual coupling is central, and it is different from that in a conventional array antenna. In terms of antenna parameters, a sufficient condition for diversity action for a certain class of high gain antennas at the mobile, which approximates most practical mobile antennas, is shown to be zero (or low) mutual resistance between elements. This is not the case at the base station, where the condition is necessary only. The mutual resistance condition offers a powerful design tool, and examples of new mobile diversity antennas are discussed along with some existing designs.
1,423 citations
01 Nov 2000
TL;DR: A trusted reference for almost 15 years, Fundamentals of Wearable Computers and Augmented Reality goes beyond smart clothing to explore user interface design issues specific to wearable tech and areas in which it can be applied.
Abstract: Data will not help you if you cant see it where you need it. Or cant collect it where you need it. Upon these principles, wearable technology was born. And although smart watches and fitness trackers have become almost ubiquitous, with in-body sensors on the horizon, the future applications of wearable computers hold so much more. A trusted reference for almost 15 years, Fundamentals of Wearable Computers and Augmented Reality goes beyond smart clothing to explore user interface design issues specific to wearable tech and areas in which it can be applied. Upon its initial publication, the first edition almost instantly became a trusted reference, setting the stage for the coming decade, in which the explosion in research and applications of wearable computers and augmented reality occurred. Written by expert researchers and teachers, each chapter in the second edition has been revised and updated to reflect advances in the field and provide fundamental knowledge on each topic, solidifying the books reputation as a valuable technical resource as well as a textbook for augmented reality and ubiquitous computing courses. New Chapters in the Second Edition Explore: Haptics Visual displays Use of augmented reality for surgery and manufacturing Technical issues of image registration and tracking Augmenting the environment with wearable audio interfaces Use of augmented reality in preserving cultural heritage Human-computer interaction and augmented reality technology Spatialized sound and augmented reality Augmented reality and robotics Computational clothing From a technology perspective, much of what is happening now with wearables and augmented reality would not have been possible even five years ago. In the fourteen years since the first edition burst on the scene, the capabilities and applications of both technologies are orders of magnitude faster, smaller, and cheaper. Yet the books overarching mission remains the same: to supply the fundamental information and basic knowledge about the design and use of wearable computers and augmented reality with the goal of enhancing peoples lives.
394 citations
"Antennas and propagation for on-bod..." refers background in this paper
...A number of applications exploiting such devices have been in development recently and are widely known by a common name 'wearable' or 'ubiquitous' computing [ 1 ]....
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TL;DR: The exposure of a subject in the far field of radiofrequency sources operating in the 10-900-MHz range has been studied and the thermal model used, which takes into account the thermoregulatory system of the human body, has been validated through a comparison with experimental data.
Abstract: The exposure of a subject in the far field of radiofrequency sources operating in the 10-900-MHz range has been studied. The electromagnetic field inside an anatomical heterogeneous model of the human body has been computed by using the finite-difference time-domain method; the corresponding temperature increase has been evaluated through an explicit finite-difference formulation of the bio-heat equation. The thermal model used, which takes into account the thermoregulatory system of the human body, has been validated through a comparison with experimental data. The results show that the peak specific absorption rate (SAR) as averaged over 10 g has about a 25-fold increase in the trunk and a 50-fold increase in the limbs with respect to the whole body averaged SAR (SAR/sub WB/). The peak SAR as averaged over 1 g, instead, has a 30- to 60-fold increase in the trunk, and up to 135-fold increase in the ankles, with respect to SAR/sub WB/. With reference to temperature increases, at the body resonance frequency of 40 MHz, for the ICNIRP incident power density maximum permissible value, a temperature increase of about 0.7/spl deg/C is obtained in the ankles muscle. The presence of the thermoregulatory system strongly limits temperature elevations, particularly in the body core.
279 citations
"Antennas and propagation for on-bod..." refers background in this paper
...There are many publications on the effect of the human body on the operation of antennas located in close proximity [2-4]; on the absorption of energy within the body and, in particular, specific absorption rate (SAR) for proximate antennas [ 5-7 ]; and on the propagation on and off the body for use in cell-phone and pager systems [8, 9]. Therefore, many of the tools needed for the study of...
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TL;DR: In this paper, a channel model for a wireless body area network at 400 MHz, 900 MHz and 2.4 GHz was derived and the electromagnetic wave propagation around the body was simulated with a finite-difference time-domain simulator.
Abstract: A channel model for a wireless body area network at 400 MHz, 900 MHz and 2.4 GHz is derived. The electromagnetic wave propagation around the body is simulated with a finite-difference time-domain simulator. Creeping waves were identified as the propagation path around the body. Its impact on the delay spread in an indoor environment is discussed.
269 citations
16 Nov 2003
TL;DR: In this paper, the authors presented UWB channel measurements from 3 to 6 GHz for a body area network (BAN) in an anechoic chamber and an office room.
Abstract: The paper presents UWB channel measurements from 3 to 6 GHz for a body area network (BAN) in an anechoic chamber and an office room. Both, transmit and receive antenna were placed directly on the body. Channel parameters as delay spread and path loss are extracted from the measurements and the influence of the body is highlighted. We show that in some situations there are significant echoes from the body (e.g. from the arms) and we observed deterministic echoes from the floor that could help to simplify a RAKE receiver structure. Finally, we consider the overall energy consumption of the BAN and give decision regions for singlehop and multihop links in relation to signal processing energy.
268 citations
"Antennas and propagation for on-bod..." refers result in this paper
...Curve fitting to these data shows that the variation of the path gain with separation is best approximated by the inverse power law with the exponent 3.2 which is in line with the results reported in [ 3 ]....
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