Ultra Wideband Wireless Body Area Network Research Articles

User Orientation Detection in Relation to Antenna Geometry in Ultra-Wideband Wireless Body Area Networks Using Deep Learning.

In this paper, the issue of detecting a user's position in relation to the antenna geometry in ultra-wideband (UWB) off-body wireless body area network (WBAN) communication using deep learning methods is presented. To measure the impulse response of the channel, a measurement stand consisting of EVB1000 devices and DW1000 radio modules was developed and indoor static measurement scenarios were performed. It was proven that for the binary classification of user orientation, neural networks achieved accuracy that was more than 9% higher than that for the well-known threshold method. In addition, the classification of user position angles relative to the reference node was analyzed. It was proven that, using the proposed deep learning approach and the channel impulse response, it was possible to estimate the angle of the user's position in relation to the antenna geometry. Absolute user orientation angle errors of about 4-7° for convolutional neural networks and of about 14-15° for multilayer perceptrons were achieved in approximately 85% of the cases in both tested scenarios.

Flexible and Small Textile Antenna for UWB Wireless Body Area Network

In this paper, a miniaturized textile microstrip antenna is proposed for wireless body area networks (WBAN). The ultra-wideband (UWB) antenna used a denim substrate to reduce the surface wave losses. The monopole antenna consists of a modified circular radiation patch and an asymmetric defected ground structure, which expands impedance bandwidth (BW) and improves the radiation patterns of the antenna with a small size of 20 × 30 × 1.4 mm3. An impedance BW of 110% (2.85–9.81 GHz) frequency boundaries was observed. Based on the measured results, a peak gain of 3.28 dBi was analyzed at 6 GHz. The SAR values were calculated to observe the radiation effects, and the SAR values obtained from the simulation at 4/6/8 GHz frequencies followed the FCC guideline. Compared to typical wearable miniaturized antennas, the antenna size is reduced by 62.5%. The proposed antenna has good performance and can be integrated on a peaked cap as a wearable antenna for indoor positioning systems.

Comprehensive Analysis of Wireless Capsule Endoscopy Radio Channel Characteristics Using Anatomically Realistic Gastrointestinal Simulation Model

This paper presents a comprehensive study of radio channels related to capsule endoscopy communications in ultra wideband wireless body area networks (UWB-WBAN) utilizing multiple antenna systems. The research includes 363 channel realizations, obtained through simulations using an anatomically realistic voxel model and a capsule model. A capsule position is modelled in such a way that it moves throughout the entire intestinal tract. The study examines the frequency and time domain characteristics of the channels in various capsule locations, including the most challenging positions deep inside the tissues or far away from most of the antennas. Additionally, the propagation characteristics inside the abdominal tissue are studied by calculating the most obvious propagation paths based on power flow illustrations and reflecting the results with the channel impulse response analysis. The impact of capsule rotation is also studied. It is shown how small changes in capsule location can greatly impact on the channel characteristics if the thickness of the tissues between the capsule and the on-body antenna changes significantly. The paper concludes with statistical analysis of the channel data, including path loss and root mean square (RMS) delay spread. The results provide valuable insight into how the signal propagates inside different parts of the gastrointestinal tract. They show that channel attenuation remains moderate along most of the gastrointestinal tract, and that even the deepest locations in the small intestine area can be resolved with the use of directional on-body antennas and receivers with higher sensitivity.

A Broadband High Gain, Noise-Canceling Balun LNA with 3–5 GHz UWB Receivers for Medical Applications

The Ultra-Wideband Wireless Body Area Network (UWB-WBAN) has been identified to provide an efficient, low-power, and improved wireless communication between sensor nodes worn by the human body to monitor physiological signals. The first part of the UWB receiver is a low noise amplifier (LNA). This article describes an upgrade to a sort of balun LNA that is entirely transistor-based and devoid of inductors for medical worn communication service. The balun LNA uses common gate and a common source configuration which cancels the noise generated by the common gate. This work uses the transistors in place of resistors to minimize the integrated circuit's area, as well as finding the best values for the dimensions of the transistor to minimize energy consumption, achieve a high gain and good linearity. This reduces the noise figure. The designed system utilizes the UWB frequency range of 3-5 GHz and a voltage supply of 1.8V. The designed balun LNA is able to achieve a peak gain of 25.5 dB and noise figure (NF) less than 3.2-3.5 dB using 180µm TSMC CMOS technology. The IIP3 is quite high at 2 dBm, whereas the IIP2 maximum is 21 dBm. The entire power consumption is less than 7.2 mW.

Deep Learning-Based LOS and NLOS Identification in Wireless Body Area Networks.

In this article, the usage of deep learning (DL) in ultra-wideband (UWB) Wireless Body Area Networks (WBANs) is presented. The developed approach, using channel impulse response, allows higher efficiency in identifying the direct visibility conditions between nodes in off-body communication with comparison to the methods described in the literature. The effectiveness of the proposed deep feedforward neural network was checked on the basis of the measurement data for dynamic scenarios in an indoor environment. The obtained results clearly prove the validity of the proposed DL approach in the UWB WBANs and high (over 98.6% for most cases) efficiency for LOS and NLOS conditions classification.

High-speed adaptive wireless body area networks

Adaptive ultra-wideband wireless body area network (WBAN) is proposed in this paper as a feasible mobile health platform, offering a high-speed and robust service. It employs a space-time-frequency-coded (STFC) multiband orthogonal frequency division multiplexing ultra-wideband technology. It is designed to improve the average bit error performance for high data rate applications while maintaining a reasonably high throughput in body-to-external links of a WBAN. The proposed adaptive WBAN comprises two novel components, namely, the frame transmission model and the bit error rate (BER) estimation-based adaptive algorithm. In addition, the optimization of adaptive parameters is conducted to obtain an extra improvement, hence enhancing the performance further. Simulation results show that the proposed optimized adaptive system achieves up to a 2-dB gain over the adaptive WBAN, thus providing up to a 6-dB gain over the non-adaptive WBAN system. This improvement is equivalent to a reduction of the power consumption by up to 37% compared to the non-optimized adaptive WBAN and up to 75% compared to the non-adaptive WBAN system, thus extending the battery life and enhancing the reliability of WBAN services significantly.

Routing over multi-hop fading wireless body area networks with reliability considerations.

Optimal reliable routing is studied in the context of fading wireless body area networks (WBANs). A non-cooperative game is proposed to model and analyze the strategic interactions among body-worn health-care devices when each seeks to find the most reliable path to the hub. A distributed algorithm based on the proposed game is provided and proved to converge to a multi-hop Pareto-dominant Nash topology. The game-theoretic framework is evaluated through numerical simulations in conditions approximating actual deployment of a moving ultra wideband WBAN. The framework shows remarkable promise in improving the reliability of transmission, compared to the IEEE 802.15.6 two-hop topology extension with a best channel selection algorithm and the star topology benchmark schemes.

Path loss variation of on-body UWB channel in the frequency bands of IEEE 802.15.6 standard.

The wireless body area network (WBAN) has gaining tremendous attention among researchers and academicians for its envisioned applications in healthcare service. Ultra wideband (UWB) radio technology is considered as excellent air interface for communication among body area network devices. Characterisation and modelling of channel parameters are utmost prerequisite for the development of reliable communication system. The path loss of on-body UWB channel for each frequency band defined in IEEE 802.15.6 standard is experimentally determined. The parameters of path loss model are statistically determined by analysing measurement data. Both the line-of-sight and non-line-of-sight channel conditions are considered in the measurement. Variations of parameter values with the size of human body are analysed along with the variation of parameter values with the surrounding environments. It is observed that the parameters of the path loss model vary with the frequency band as well as with the body size and surrounding environment. The derived parameter values are specific to the particular frequency bands of IEEE 802.15.6 standard, which will be useful for the development of efficient UWB WBAN system.

On-body measurements of SS-UWB patch antenna for WBAN applications

In this paper, performance of a Swastika slot-ultra-wideband (SS-UWB) patch antenna for an on-body application is investigated. This antenna is intended for the use in UWB wireless body area network (WBAN) applications, between 3.1 and 10.6GHz. The proposed antenna is a SS-UWB patch antenna of dimension 27mm×27mm×1.6mm. It is fabricated and tested in free space scenario instead in anechoic chamber to obtain more realistic on-body measurement results. This SS-UWB patch antenna covers the ultra-wide frequency spectrum in the range 4.25–12.5GHz [8.25GHz] with a quasi-omni directional gain from 1.77 to 5.6dB. This antenna's efficiency is from 81.3% to 90.67% (−1.8 to −0.85dB) over free space. The antenna is characterized in free space as well as on body model with and without antenna body gap. Measured results obtained from the antenna like S11, radiation pattern, antenna efficiency, and gain are matched with the simulated results.

Demonstration of a fully differential VGA chip with small THD for ECG acquisition system**Project supported by the National Natural Science Foundation of China (Nos. 61264001, 61465004, 61161003, 61166004), the Guangxi Natural Science Foundation (Nos. 2013GXNSFAA019333, 2013GXNSFAA019338), the Science and Technology Research Key Project of Guangxi Department of Education (No. 2013ZD026), and the Innovation Project of GUET Graduate Education (No. GDYCSZ201457).

We present both a theoretical and experimental demonstration of a fully differential variable gain amplifier (VGA) with small total harmonic distortion (THD) for an electrocardiogram (ECG) acquisition system. Capacitive feedback technology is adopted to reduce the nonlinearity of VGA. The fully differential VGA has been fabricated in SMIC 0.18-μm CMOS process, and it only occupies 0.11 mm2. The measurements are in good agreement with simulation results. Experimental results show that the gain of VGA changes from 6.17 to 43.75 dB with a gain step of 3 dB. The high-pass corner frequency and low-pass corner frequency are around 0.22 Hz and 7.9 kHz, respectively. For each gain configuration, a maximal THD of 0.13% is obtained. The fully differential VGA has a low THD and its key performance parameters are well satisfied with the demands of ECG acquisition system application in the UWB wireless body area network.

System fidelity factor evaluation of wearable ultra‐wideband antennas for on‐body communications

This study reports an experimental study of the system fidelity factor (SFF) of ultra-wideband wireless body area network antennas in an on-body environment. This study also investigates the influence in the SFF because of the antenna polarisation with respect to the body. For this purpose, two antennas having different polarisations are compared: a mono-cone antenna with the polarisation perpendicular to the wearer and a printed monopole with the polarisation either parallel or perpendicular to the wearer. A phantom made of pork meat was considered as a model for the wearer's body, and five different communication scenarios involving each pair of antennas were considered. On-body experimental results show that the time-domain behaviour of the transmission is better for two different antenna types having the same polarisation, but, more importantly, that the SFF (and thus the time-domain fidelity of the signal) is better for a link having a polarisation perpendicular to the body.

An OTA-C filter for ECG acquisition systems with highly linear range and less passband attenuation**Project supported by the National Natural Science Foundation of China (Nos. 61161003, 61264001, 61166004) and the Guangxi Natural Science Foundation (No. 2013GXNSFAA019333).

A fifth order operational transconductance amplifier-C (OTA-C) Butterworth type low-pass filter with highly linear range and less passband attenuation is presented for wearable bio-telemetry monitoring applications in a UWB wireless body area network. The source degeneration structure applied in typical small transconductance circuit is improved to provide a highly linear range for the OTA-C filter. Moreover, to reduce the passband attenuation of the filter, a cascode structure is employed as the output stage of the OTA. The OTA-based circuit is operated in weak inversion due to strict power limitation in the biomedical chip. The filter is fabricated in a SMIC 0.18-μm CMOS process. The measured results for the filter have shown a passband gain of −6.2 dB, while the −3-dB frequency is around 276 Hz. For the 0.8 VPP sinusoidal input at 100 Hz, a total harmonic distortion (THD) of −56.8 dB is obtained. An electrocardiogram signal with noise interference is fed into this chip to validate the function of the designed filter.

Investigation of a Compact Ultrawide Band Antenna for Wearable Applications

The on-body performance parameters of a compact quasi-self-complementary ultra wideband (UWB) antenna for wearable applications are investigated in this paper. The antenna is intended to be applied in various applications in healthcare and sport performance monitoring. The on-body return loss response, impedance, radiation pattern, gain and radiation efficiency of the proposed antenna are studied. The antenna is very compact in size and it shows very good performance when it is placed on the body, therefore it will be suitable candidate for on-body applications in UWB wireless body area networks (WBANs).

Ultra wideband loop antenna on contact with human body tissues

Human body tissues have a strong effect on the antenna operation in wireless body area networks (WBANs). In this study, the authors present the deep investigations of the effect of body tissue thicknesses on the performance of an ultra wideband (UWB) loop antenna by simulations when the antenna is operated on contact with tissues. The planar UWB loop antenna is designed for the examinations, which is targeted to be used in UWB WBAN applications. The effect of tissue thicknesses on the antenna performance is analysed and characterised in the terms of reflection coefficient S 11 , gain and total antenna efficiency, group delay, radiation patterns and specific absorption rate by simulations. A parametric layered human body tissue model with the frequency-dependent behaviour is exploited in the investigations. Further, the reflection coefficient of the presented antenna is measured in the different locations of the author's body. The main aim of these investigations is to demonstrate how the thickness of outermost body tissues affects the antenna performance.

An ultra-wideband wireless body area network: Evaluation in static and dynamic channel conditions

Wireless body area network is a collection of wearable wireless sensors placed around or in a human body that are used to monitor important information from a human body. A receiver (i.e. control unit) is required to connect these sensors to remote locations (i.e. hospital database and call centres). In this work an ultra-wideband (UWB) body sensor node has been designed and tested to analyze the realistic performance of a UWB-based wireless body area network. The results indicate that the locations of sensors and the control unit on a human body play an important role on the performance of the wireless body area network system. The work herein also investigates optimal receiver positions for different sensor configurations. The results are evaluated in both static and dynamic channel conditions based on data transmission from the UWB sensor node developed for wireless body area network applications. Four common sensor positions, namely the chest, head, wrist and waist and three receiver positions-chest, waist and arm are considered. The experiment is conducted in an Anechoic chamber to minimize the effects of the environment. In the static experiment, the subject under test remains motionless for the entire test duration. Under static channel conditions, it was seen that the transmission power can be reduced by 26dB, when the receiver is positioned at the optimum point on the body. The evaluation of the dynamic channel condition is also performed by allowing the test subject to move the body as in a walking motion. Due to the body movements, the transmission power should be increased by 7dB to maintain the same bit error rate as that of the static experiment.

Multislot Antenna with a Screening Backplane for UWB WBAN Applications

A novel multislot antenna with a conducting backplane reflector (MSA-BP) designed for ultrawideband wireless body area networks (WBANs) applications is presented. The objective is to achieve a desensitization of the antenna behavior regarding the proximity effects of the human body, thanks to the field screening operated by the backplane. Partly because of the latter, the antenna is fed with a tapered CPW. The influence of antenna parameters and human body proximity on the radiation characteristics of the MSA-BP is analyzed. Simulated results of the antenna close to a three-layer arm phantom are presented. Impedance and radiation measurements of the isolated antenna as well as propagation characteristics along the human body demonstrating the desensitization effect are also presented. The characteristics of the MSA-BP, in terms of the on-body total radiation efficiency, are significantly improved compared to any (quasi-) omnidirectional counterpart.

Electrically coupled tapered slot ultra wideband antenna with tunable notch

A band notch characteristic using a unequi-arm H-shaped conductor element is used for designing a Tapered-Slot ultra wideband (UWB) antenna that can be useful in rejection of the higher band assigned for wireless local area network, with a targeted application in UWB wireless body area network. Based on the simulation and measurement results, a band notched tapered slot UWB antenna using a unequi-arm H-shaped conductor proves to be effective in rejecting unwanted frequency in terms of its selectivity and small real estate. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26075

Cooperative Communications in Ultra-Wideband Wireless Body Area Networks: Channel Modeling and System Diversity Analysis

In this paper, we explore the application of cooperative communications in ultra-wideband (UWB) wireless body area networks (BANs), where a group of on-body devices may collaborate together to communicate with other groups of on-body equipment. Firstly, time-domain UWB channel measurements are presented to characterize the body-centric multipath channel and to facilitate the diversity analysis in a cooperative BAN (CoBAN). We focus on the system deployment scenario when the human subject is in the sitting posture. Important channel parameters such as the pathloss, power variation, power delay profile (PDP), and effective received power (ERP) crosscorrelation are investigated and statistically analyzed. Provided with the model preliminaries, a detailed analysis on the diversity level in a CoBAN is provided. Specifically, an intuitive measure is proposed to quantify the diversity gains in a single-hop cooperative network, which is defined as the number of independent multipaths that can be averaged over to detect symbols. As this measure provides the largest number of redundant copies of transmitted information through the body-centric channel, it can be used as a benchmark to access the performance bound of various diversity-based cooperative schemes in futuristic body sensor systems.

Performance of UWB Impulse Radio With Planar Monopoles Over On-Human-Body Propagation Channel for Wireless Body Area Networks

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <?Pub Dtl=""?>Ultrawideband (UWB) is a promising technology for wireless body area networks (WBANs). This paper studied the impacts of 3.1–10.6 GHz on-human-body UWB channel on the impulse radio WBAN system. A performance evaluation method is presented for the realistic UWB WBAN systems, which observes the waveform distortion along the signal path. The measurement and characterization of the 3.1–10.6 GHz on-human-body UWB channel are devised to generate the radiographs of path loss and delay spread for the first time. The performance of the UWB impulse radio WBAN transceiver in terms of bit error rate (BER) is evaluated based on the waveform distortion and on-human-body channel measurement, which shows the human body effect is more significant than the environment effect, especially when the propagation channel contains no line-of-sight path. Various candidate pulse shapes and modulation schemes for UWB WBAN are studied and their performances with the measured WBAN channel are evaluated and compared. </para>

Textile UWB Antennas for Wireless Body Area Networks

A new ultrawideband (UWB) textile antenna designed for UWB wireless body area network (WBAN) applications is presented. Unlike previous textile antennas, these antennas offer a direct integration into clothing due to a very small thickness (0.5 mm) and flexibility. We have realized two different designs of textile antennas: coplanar waveguide fed printed UWB disc monopole and UWB annular slot antenna. To our knowledge, these are the first textile UWB antennas reported in the open literature. Measured return loss and radiation pattern characteristics of textile UWB antennas agree well with simulations. Moreover, measured transfer functions show that these textile antennas possess excellent transient characteristics, when operating in free space as well as on the human body. They can operate in the entire UWB band approved by the Federal Communications Commission (3.1-10.6 GHz)