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Publications (185)
In this article, we investigate the potential enhancements in signal reliability which can be achieved using a millimeter-wave distributed antenna system (DAS) within an indoor environment. To achieve this, we measured the signal power simultaneously received at nine ceiling-mounted access point (AP) locations likely to be used in future indoor DAS...
Indoor areas, such as offices and shopping malls, are a natural environment for initial millimeter-wave (mmWave) deployments. While we already have the technology that enables us to realize indoor mmWave deployments, there are many remaining challenges associated with system-level design and planning for such. The objective of this article is to br...
Indoor areas, such as offices and shopping malls, are a natural environment for initial millimeter-wave (mmWave) deployments. While we already have the technology that enables us to realize indoor mmWave deployments, there are many remaining challenges associated with system-level design and planning for such. The objective of this article is to br...
A wearable stripline-fed circularly polarized dual patch antenna structure that exhibits enhanced into-body gain is presented. The antenna is designed for body-surface repeater solutions and it addresses the problem of marginal into-body deep tissue communication links, where power consumption is of the utmost importance and system link efficiency...
The use of millimeter wave technologies offer a promising solution for dense small cell networks, despite having to contend with challenging propagation characteristics. In particular, user-induced effects can lead to significant channel variations depending on the user equipment (UE) usage mode which in turn, can impact the quality of service. Est...
Dielectric loss occurring in tissues in close proximity to UHF-implanted antennas is an important factor in the performance of medical implant communication systems. Common practice in numerical analysis and testing is to utilize radiation efficiency (RE) measures external to the tissue phantom employed. This approach means that RE is also dependen...
As wireless connectivity becomes increasingly ubiquitous, a greater emphasis will be placed upon the seamless integration of dissimilar networking technologies. One such example of this will occur in urban environments, where wearable devices and vehicular networks will operate in close proximity to one another. Clearly, a natural extension to both...
Device-to-Device (D2D) communication and wireless small cell networks (SCNs) are two of the most promising paradigms in next generation cellular technologies. However, interference management is a major issue in regard to the use of either or both technologies. In this paper, we propose a D2D pair underlying SCNs using Wireless Power Transfer (WPT)...
Any building with more than one floor will have stairwells of some form, yet this area is often neglected in channel characterisation studies. The authors present fading channel models and examine attainable spatial diversity gains at 90% signal reliability for an off-body multiple-antenna system at frequencies of 3, 4, and 5 GHz in an indoor stair...
We investigate the use of a reverberation chamber for the experimental measurement of deep implant antenna radiation efficiency. The technique was able to measure the extremely low efficiencies associated with deep implant antennas inside a muscle tissue-mimicking liquid phantom. Results were obtained for a range of insulated and un-insulated anten...
Device-to-device (D2D) communications are recognized as a key enabler of future cellular networks which will help to drive improvements in spectral efficiency and assist with the offload of network traffic. Among the transmission modes of D2D communications are single-hop and relay assisted multi-hop transmission. Relay-assisted D2D communications...
This paper investigates the potential improvement in signal reliability for outdoor wearable communications channels operating at 868 MHz using switched combining based macro-diversity. In this study, a number of different macro-diversity configurations consisting of two and four base stations were considered to help mitigate the impact of body sha...
In this paper, a compact printed meandered folded dipole antenna with a volume of 114 mm
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suitable for implantation in a range of different body tissue types with diverse electrical properties is presented for operation in the 2.36-2.4 GHz MBAN and...
This paper investigates the first-order characteristics of dynamic off-body communications channels at 60 GHz. In particular, we have studied signal propagation from a chest worn millimeter wave transmitter as an adult male walked towards and then away from a hypothetical base station. The mobile line of sight (LOS) and non-LOS (NLOS) channel measu...
A study of the intra-body propagation channel between two identical tissue implanted antennas is presented. To investigate the effect of the tissue boundaries, the channel between the two implants is evaluated within a tissue layered numerical phantom with both insulated and un-insulated antenna structures in the MedRadio operating band (2.36–2.40...
This communication investigates the potential improvement in signal reliability for indoor off-body communications channels operating at 5.8 GHz using switched diversity techniques. In particular, we investi-gate the performance of switch-and-stay combining (SSC), switch-and-examine combining (SEC), and (SECps) schemes, which utilize multiple spati...
A compact implantable printed meandered folded dipole antenna with a volume of 101.8 mm3 and robust performance is presented for operation in the 2.4 GHz medical ISM bands. The implant antenna is shown to maintain its return loss performance in the 2360–2400 MHz, 2400–2483.5 MHz and 2483.5–2500 MHz frequency bands, simulated in eleven different bod...
A wearable silver nano particle inkjet printed antenna suitable for wireless biomedical sensing is presented. The performance is evaluated on a synthetic variable layered phantom test-bed, representative of human tissue for operation in the 868/915 MHz, and 2400 MHz industrial, scientific and medical frequency bands. Antenna radiation efficiency me...
In this paper we compare a number of the classical models used to characterize fading in body area networks (BANs) with the recently proposed shadowed κ-μ fading model. In particular, we focus on BAN channels which are considered to be susceptible to shadowing by the human body. The measurements considered in this study were conducted at 2.45 GHz f...
This special issue provides the latest research and development on wireless mobile wearable communications. According to a report by Juniper Research, the market value of connected wearable devices is expected to reach $1.5 billion by 2014, and the shipment of wearable devices may reach 70 million by 2017. Good examples of wearable devices are the...
The use of biosensors attached to the body for health monitoring is now readily accepted, and the merits of such systems and their potential impact on healthcare receive much attention. Wearable medical systems used in clinical applications to monitor vital signs must be comfortable to wear, yet have robust performance to ensure reliable communicat...
This paper contributes to and expands on the Nakagami-m phase model. It derives exact, closed-form expressions for both the phase cumulative distribution function and its inverse. In addition, empirical first- and second-order statistics obtained from measurements conducted in a body-area network scenario were used to fit the phase probability dens...
Passive person detection and localization is an emerging area in UWB localization systems, whereby people are not required to carry any UWB ranging device. Based on experimental data, we propose a novel method to detect static persons in the absence of template waveforms, and to compute distances to these persons. Our method makes very little assum...
This paper investigates the characteristics of the complex received signal in body area networks for two environments at the opposite ends of the multipath spectrum at 2.45 GHz. Important attributes of the complex channel such as the Gaussianity of the quadrature components and power imbalance, which form the basis of many popular fading models, ar...
Wearable antenna performance measurements were used to characterize a synthetic variable layered phantom testbed, representative of human tissue for operation in the 868/915 MHz, and 2400 MHz industrial, scientific and medical frequency bands. Antenna radiation efficiency measurements on the phantom were compared with measurements on the thorax reg...
In this paper we investigate the received signal characteristics of a mobile chest-worn transmitter at 5.8 GHz within a high multipath indoor environment. The off-body channel measurements considered both the co- and cross-polarized received signal for both line-of-sight (LOS) and non-LOS (NLOS) conditions. A straightforward channel model based upo...
We present a novel device-free stationary person detection and ranging
method, that is applicable to ultra-wide bandwidth (UWB) networks. The method
utilizes a fixed UWB infrastructure and does not require a training database of
template waveforms. Instead, the method capitalizes on the fact that a human
presence induces small low-frequency variati...
This study presents the findings of an empirical channel characterisation for an ultra-wideband off-body optic fibre-fed multiple-antenna array within an office and corridor environment. The results show that for received power experiments, the office and corridor were best modelled by lognormal and Rician distributions, respectively [for both line...
Body to body links are the most scenario dependent form of body centric communications with performance highly dependent on the users' movements, relative positioning and the local operating environment. This paper focuses on line of sight cases which although they should be the most dependent, still have considerable variability depending on local...
The range of potential applications for indoor and campus based personnel localisation has led researchers to create a wide spectrum of different algorithmic approaches and systems. However, the majority of the proposed systems overlook the unique radio environment presented by the human body leading to systematic errors and inaccuracies when deplo...
In this paper, we first provide a theoretical validation for a low-complexity transmit diversity algorithm which employs only one RF chain and a low-complexity switch for transmission. Our theoretical analysis is compared to the simulation results and proved to be accurate. We then apply the transmit diversity scheme to multiple-input and multiple-...
Research into localization has produced a wealth of algorithms and techniques to estimate the location of wireless network nodes, however the majority of these schemes do not explicitly account for non-line of sight conditions. Disregarding this common situation reduces their accuracy and their potential for exploitation in real world applications....
A unique property of body area networks (BANs) is the mobility of the network as the user moves freely around. This mobility represents a significant challenge for BANs, since, in order to operate efficiently, they need to be able to adapt to the changing propagation environment. A method is presented that allows BAN nodes to classify the current o...
Because of its superior time resolution, ultra-wide bandwidth (UWB) transmission can be a highly accurate technique for ranging in indoor localization systems. Nevertheless, the presence of obstructions may deteriorate the ranging performance of the system. Indoor environments are often densely populated with people. However, th e effect of the hum...
It has previously been shown that human body shadowing can have a considerable impact on body-to-body communications channels in low multipath environments. Signal degradation directly attributable to shadowing when one user's body obstructs the main line of sight can be as great as 40 dB. When both people's bodies obstruct the direct line of sight...
Because of its superior time resolution, ultra-wide bandwidth (UWB) transmission can be a highly accurate technique for ranging in indoor localization systems. Nevertheless, the presence of obstructions may deteriorate the ranging performance of the system. Indoor environments are often densely populated with people. However, th e effect of the hum...
Technologies and applications based on short range radio communication links have pervaded almost all aspects of modern life. From wireless doorbells through Bluetooth headsets and WiFi browsing to streaming high definition multimedia, we have never been so dependent on short range links. This paper outlines some of the physical layer requirements...
The characterization and understanding of body to body communication channels is a pivotal step in the development of emerging wireless applications such as ad-hoc personnel localisation and context aware body area networks (CABAN). The latter is a recent innovation where the inherent mobility of body area networks can be used to improve the coexis...
The concept of a body-to-body network, where smart communicating devices carried or worn by a person are used to form a wireless network with devices situated on other nearby persons. New innovations in this area will see the form factor of smart devices being modified, so that they may be worn on the human body or integrated into clothing, in the...
The authors consider a point percolation lattice representation of a large-scale wireless relay sensor network (WRSN) deployed in a cluttered environment. Each relay sensor corresponds to a grid point in the random lattice and the signal sent by the source is modelled as an ensemble of photons that spread in the space, which may 'hit' other sensors...
Active radio-frequency identification systems that are used for the localisation and tracking of people will be subject to the same body centric processes that impact other forms of wearable communications. To achieve the goal of creating body worn tags with multiyear life spans, it will be necessary to gain an understanding of the channel conditio...
In this paper we conduct a number of experiments to assess the impact of typical human body movements on the signal characteristics of outdoor body-to-body communications channels using flexible patch antennas. A modified log-distance path loss model which accounts for body shadowing and signal fading due to small movements is used to model the mea...
In ultra-low data rate wireless sensor networks (WSNs) waking up just to listen to a beacon every superframe can be a major waste of energy. This study introduces MedMAC, a medium access protocol for ultra-low data rate WSNs that achieves significant energy efficiency through a novel synchronisation mechanism. The new draft IEEE 802.15.6 standard f...
Indoor personnel localization research has generated a range of potential techniques and algorithms. However, these typically do not account for the influence of the user's body upon the radio channel. In this paper an active RFID based patient tracking system is demonstrated and three localization algorithms are used to estimate the location of a...
Medical implant communication service (MICS) devices are active radio frequency (RF) transmitters operating in the 402 MHz region. The MICS service is conceived as a point to point communication link between a body implanted medical device and a nearby (up to around 3 m) base station, with a typical usage scenario of a bed side or home unit or phys...
This paper presents the results of an investigation into the effect of using co-axial cables in ultra-wideband off-body radio channel characterisation and performance evaluation for wearable antennas. Experiments were carefully designed to faithfully compare the use of a co-axial feed cable for a wearable antenna versus an optic fibre feed, and thu...
Human body shadowing in off-body channels occurs when the body partially or completely obstructs the direct signal path between a bodyworn wireless device and nearby transceiver. In this paper a statistical approach is taken to analyse and model the impact of path loss, body shadowing and small scale fading caused by movements of a human at 2.45 GH...
The characterization and understanding of body to body communication channels is a pivotal step in the development of emerging wireless applications such as ad-hoc personnel localisation and context aware body area networks (CABAN). The latter is a recent innovation where the inherent mobility of body area networks can be used to improve the coexis...
In this paper we conduct a number of experiments to assess the impact of typical human body movements on the signal characteristics of outdoor body-to-body communications channels using flexible patch antennas. A modified log-distance path loss model which accounts for body shadowing and signal fading due to small movements is used to model the mea...
Active radio-frequency identification systems that are used for the localisation and tracking of people will be subject to the same body centric processes that impact other forms of wearable communications. To achieve the goal of creating body worn tags with multiyear life spans, it will be necessary to gain an understanding of the channel conditio...
Body Area Networks are unique in that the large-scale mobility of users allows the network itself to travel across a diverse range of operating domains. This presents the possibility of creating interactive smart environments where Context Aware Body Area Networks can sense and co-operate with nearby wireless networks. This paper describes an inves...
Ultra-wideband (UWB) technology offers a promising solution for future indoor high-speed, low-power wireless body centric communications. Development and design of such systems requires detailed understanding of the indoor off-body UWB channel, which to date has been scarcely investigated. This paper presents results for a series of controlled expe...
The increasing popularity of portable and wearable technology will mean that further demands will be placed on an already overwhelmed radio spectrum, particularly within the unlicensed industrial, scientific and medical bands. Because of this, future short-range body centric technologies may benefit from operation at underutilised frequency allocat...
An analytical model for across the body surface communication systems is presented. The paper is focused on the calculation of the approximate path gain, both along and around planar and cylindrical geometries, representative of the human body for antennas polarized normal to the body surface. The model is validated at 2.45 GHz using finite-differe...
Body Area Networks are unique in that the large-scale mobility of users allows the network itself to travel across a diverse range of operating domains or even to enter new and unknown environments. This network mobility is unlike node mobility in that sensed changes in inter-network interference level may be used to identify opportunities for inte...
For Special Operations Forces, an important attribute of any future radio will be the ability to conceal transmissions from the enemy while transmitting large amounts of data for situational awareness and communications. These requirements will mean that military wireless systems designers will need to consider operating frequencies in the mm-wave...
In this letter, we investigate the distribution of the phase component of the complex received signal observed in practical experiments using body area networks. Two phase distributions, the recently proposed κ-µ and η-µ probability densities, which together encompass the most widely used fading models, namely Semi-Gaussian, Rayleigh, Hoyt, Rice, a...
Received signal strength measurements and delay statistics are presented for both a stationary and mobile user equipped with a wearable UWB radio transmitter (TX) within a hospital environment. The measurements were made for both waist and chest mounted antennas using RF-over-fibre technology to eliminate any spurious electromagnetic scattering eff...
Operating short-range body centric communications at millimetre-wave frequencies will offer a number of key benefits, most notably high data rates potentially in excess of 2 Gb/s. However, development of compact, portable, bodyworn channel sounding equipment presents significant challenges at these frequencies. As an alternative method to character...
Dual-band operation is highly desirable for wearable devices that need to connect with a range of wireless systems. We present a series of microstrip-line fed, dual-band compact patch antennas designed to operate in the common 2.45 GHz and 5.8 GHz bands for body-centric communications. All of the designs are low-profile and, with further study, may...
This study presents a co-design approach to wireless network control systems (WNCS). Experimental studies are carried out to identify and analyse the delays inherent in WNCS, with a new inverse Gaussian model for their statistical distribution proposed. Two different packet-based predictive control schemes are presented. One uses dynamic matrix con...
A body area network (BAN) is a network of bodyworn or implanted electronic devices, including wireless sensors which can monitor body parameters or to detect movements. One of the big challenges in BANs is the propagation channel modeling. Channel models can be used to understand wave propagation in and around the human body and they are essential...
An analytical model for across the body surface communication systems is presented. The paper is focused on the calculation of the approximate path gain, both along and around planar and cylindrical geometries, representative of the human body for antennas polarized normal to the body surface. The model is validated at 2.45 GHz using finite-differe...
Operating short-range body centric communications at millimetre-wave frequencies will offer a number of key benefits, most notably high data rates potentially in excess of 2 Gb/s. However, development of compact, portable, bodyworn channel sounding equipment presents significant challenges at these frequencies. As an alternative method to character...
This paper presents both stationary and mobile signal strength measurements for a wearable UWB radio channel in a hospital environment. The measurements were made using RF-over-fibre technology to eliminate unwanted electromagnetic effects associated with the use of co-axial cables. The results show that received signal strength values depended on...
This paper introduces a compact, low profile shorted patch antenna designed for on-body communication at 2.45 GHz. The proposed antenna operates with a small (~¿/5 dimension) groundplane yet maintains a reasonable radiation efficiency of 50.9 % when in close proximity to a muscle tissue phantom. The antenna has more than sufficient impedance bandw...
Human activity in the vicinity of body-centric wireless communications systems often affects received signal characteristics. In particular, pedestrian movements may induce temporal fading and cause shadowing events in situations where an individual or group obstructs the dominant signal path. In this paper, we report results from a series of caref...
In this paper, a single layer split ring resonant (SRR) antenna with a lumped capacitor based on CPW (coplanar waveguide) excitation is studied to offer a low profile and compact ground plane structure. The effects of basic structural parameters are investigated to give a practical insight. A double layer SRR is examined for comparison. The human b...
This paper presents a systematic measurement campaign of diversity reception techniques for use in multiple antenna wearable systems operating at 868 MHz. The experiments were performed using six time-synchronized bodyworn receivers and considered mobile off-body communications in an anechoic chamber, open office area and a hallway. The cross-corre...
A frequency offset modulation scheme using wideband noise carriers is considered. The main advantage of such a scheme is that it enables fast receiver synchronization without channel adaptation, while providing robustness to multipath fading and in-band interference. This is important for low-power wireless systems with bursty traffic, such as sens...
Mobile ad hoc networking of dismounted combat personnel is expected to play an important role in the future of network-centric operations. High-speed, short-range, soldier-to-soldier wireless communications will be required to relay information on situational awareness, tactical instructions, and covert surveillance related data during special oper...
This paper presents a robust, dynamic cross-layer wireless communication architecture for wireless networked control systems. Each layer in the proposed protocol architecture contributes to the overall goal of reliable, energy efficient communication. The protocol stack also features a broadcast-based link-layer that determines and recovers from ro...
Medical body area networks will employ both implantable and bodyworn devices to support a diverse range of applications with throughputs ranging from several bits per hour up to 10 Mbps. The challenge is to accommodate this range of applications within a single wireless network based on a suitably flexible and power efficient medium access control...
The autocorrelation of signal fading in wireless body area networks will be dependent upon a number of factors including wearable node positioning, user state and local environment. In this paper, we present some of the preliminary work undertaken to model the correlation function of the complex envelope for various on-body propagation channels.
Modeling of on-body propagation channels is of paramount importance to those wishing to evaluate radio channel performance for wearable devices in body area networks (BANs). Difficulties in modeling arise due to the highly variable channel conditions related to changes in the user's state and local environment. This study characterizes these influe...
In this paper, an analysis of radio channel characteristics for single- and multiple-antenna bodyworn systems for use in body-to-body communications is presented. The work was based on an extensive measurement campaign conducted at 2.45 GHz representative of an indoor sweep and search scenario for fire and rescue personnel. Using maximum-likelihood...
A characterization of the fading observed in an 8-node wireless body area network in an outdoor environment is presented. When the user was stationary the degree of fading for on-body links was found to be low, with estimated Nakagami m parameters Gt 1. However, when the user was mobile, depending on the body dynamics in the vicinity of the node lo...
The ability to switch between propagating modes is important for body-centric applications such as medical body area networks where a single node may need to be able to optimise communications for either on-body sensor links or off-body links to the wider network. Therefore, we present a compact 2.45 GHz active mode-switching wearable antenna for b...
The ability to electronically switch between off-body and on-body communications is a useful feature for wearable antenna applications. Therefore, we present a novel stacked-patch antenna with a switched propagation mode for body-centric communications at 2.45 GHz. Mounted 2 mm above a muscle-tissue phantom and in the on-body mode, the proposed sin...