Body-Centric Wireless Communications
The development of wearable computer systems has been growing rapidly. These are becoming smaller and more lightweight; no one wants to wear a bulky and heavy computer all day! We will soon see a wide range of unobtrusive wearable and ubiquitous computing equipment integrated to into our everyday clothes. In a possible wearable computer, the monitor/display would be on a pair of glasses, the keyboard worn on the wrist, and the motherboard worn on the waist. It is undesirable to use bulky cables to connect these devices, so communication will be wireless, using an antenna.
The human body is an uninviting and often hostile environment for a wireless signal. Compact yet efficient antennas need to be fully characterized and integrated with the RF transceiver. Some of these are conformability and immunity to frequency and polarization detuning. It is important to understand material properties of fabrics and potential use of microwave metamaterials to minimize the specific absorption rate (SAR).
We are working on the important issue of the design of such an antenna. We are particularly considering the following issues:
- The antenna itself must be small and lightweight, since it is part of a lightweight device;
- The small size of the antenna must not reduce its performance;
- The antenna structure must be designed to have limited radiation power in the direction of the wearer, to minimize possible health problems;
- The transmission power must be low, to prolong battery life and hence operating time.
- Textile conformal antennas to provide user-friendly solutions
- Surface guided wave antenna to improve on-body communications
- Radio propagation in complex environments and considering dispersive human tissues
- System-level modelling for potential narrowband and ultra wideband communication systems.
Wearable Sensor Antennas have to be compact and easily integrated. They should be immuned from de-tuning and performance degradation due to surrounding components and when placed on the body. They should have high efficiency to achieve maximum radiated power to enlarge coverage area specifically for communication between body mounted devices and base units/access points. It is also needed in the wireless sensor antenna design to overcome shadowing problems caused by the human body and the dynamic environment.
Numerical Modeling of On-body Antennas and Propagation
Since radio propagation on human body is quite a complex electromagnetic problem, numerical simulation tools will provide physical insight into the propagation mechanisms present and enable its prediction in far more complex environment. Accurate and fast theoretical modeling by Finite-Difference Time-Domain (FDTD) method on large size conformal human bodies mounted with antennas is seen as the most valuable method; however it is constrained by computational power and memory resorting to inefficient staircase orthogonal meshes on curved surfaces. Local distorted nonorthogonal FDTD (LN-FDTD) method was developed such that only those cells close to the curved boundary are distorted and processed with the nonorthogonal FDTD (NFDTD) algorithm; others remain as Cartesian cells. The in-house conformal FDTD modelling software was used to evaluate on-body propagation channels.
Antennas and Propagation for Wireless Implants
Wireless Implants provide flexibility to the patience and the surgeon in terms of replacement and long lifetime. They have advantages of maintaining constant availability and ease of operation, which are required for future patient monitoring and diagnosis systems. Applications include but not limited to:
- Accurate drug delivery.
- Non-Invasive Endoscopy.
- Patient diagnosis and locator.
- Muscle stimulator.
- Brain signals analysis and control.
UWB Antennas and Their Applications in the Home Environment
UWB provides High capacity, Multipath robustness, Fine time resolution for accurate delay estimate, Low transmission power, Inexpensive systems and Multi-access. Dispersion of human tissues across the frequency band needs to be considered in on-body antenna and propagation characterisation. Usually, non-dispersive antennas are required for optimum performance with radiation that minimises path loss across UWB band. Since UWB is Impulse Radio technology, received pulse shape and property is of great importance.
Highlights and Research Outcomes
- The group has published two book, more than 8 book chapters and more than 150 substantial journal and refereed conference papers on Body-Centric Wireless Communications.
- This work is in collaboration with many academic partners (Imperial College London, University of Birmingham, etc.) and industrial collaborators (DSTL, Philips Research, GE Global Research, Toumaz Technologies Ltd., etc.)
- The group has organised/co-organised 3 workshops related to body-centric wireless networks sponsored by the European School of Antennas, more than 5 focused seminars and also Prof. Yang Hao guest edited the IEEE Transactions on Antennas and Propagation special issue on Body-Centric Communications.
- Academics in the Antennas Group involved in body-centric research have been invited to deliver special talks and keynotes in many international conferences organized by the IEEE and IET
- Prof. Yang Hao was elected as IEEE Fellow in 2013 in recognition of his contributions to body-centric wireless communications.
- Various media appearances and international exposure related to wearable electronics.
Selected Research Grants and Projects
- PATRICIAN: New Paradigms for Body Centric Wireless Communications at MM Wavelengths, in total, £1.2M EPSRC, with University of Birmingham and Durham (2011.1 – 2014. 12)
- Reduction of Energy Demand in Buildings through Optimal Use of Wireless Behaviour Information (Wi-be) Systems”, in total £600K, EPSRC, with University of Nottingham, Reading (2010.8 – 2013.7)
- Electrically Small Antennas loaded with Metamaterials for Body-centric Wireless Communications, Royal Society International Newton Fellowship support for Dr Rui Yang, £66K, (2009. 10 – 2011.9)
- Post Doctoral Support for Research Students, EPSRC ImpactQM funded post–doctoral training for research students (£10k, 2012)
- Industry Secondment – Enhancement and optimisation of antenna performance for personal health devices, EPSRC ImpactQM funded secondment with Acute Technology Ltd. (£12k, 2012)
- Smart Antenna Systems for Cooperative Low–Power Wireless Personal and Body Area Networks, EPSRC funded project (£122k, 2010 – 2011)
- iRFSim for BSNs: Imaging based subject-specific RF simulation environment for wearable and implantable wireless Body Sensor Networks (BSNs), EPSRC, with Prof. GZ Yang, Imperial College (2007. 11- 2010.10)
- Wireless Implantable Biosensors with Advanced On-Body Data processing, NEAT, Department of Health, with Prof. Pankaj Vadgama, QMUL (2007. 11- 2008.10)
- Wearable Antennas for Body-Centric Wireless Network, EPSRC, with Prof. Peter Hall, University of Birmingham (2007.4 -2010. 3)
- Wearable Antenna Modelling, DSTL (2006. 4 -2008. 3)
- Characterisation of On-Body Communication Channels, EPSRC, with Prof. Peter Hall, University of Brimingham (2003.7- 2006.6)
- Advance Traceable Measurements for Wearable Antennas, Royal Academy of Engineering Industrial Secondment Scheme (£75k, April 2014–November 2014)
- Novel Composite Radiator – Main investigator – Funded by Defence Science and Technology Laboratory (£40k, 2011–2012)
Selected Recent Publications
- A Pellegrini, A Brizzi, L Zhang, K Ali, Y Hao, et al, Antennas and Propagation for Body-Centric Wireless Communications at Millimeter-Wave Frequencies: A Review [Wireless Corner], Antennas and Propagation Magazine, IEEE 55 (4), 262-287.
- Pellegrini A, Brizzi A, Zhang L, Hao Y. (2013) . Path Loss Characterization in a Body-Centric Scenario at 94 GHz. IEICE TRANSACTIONS ON COMMUNICATIONS. vol. E96B, 2448-2454.10.1587/transcom.E96.B.2448
- Q. H. Abbasi, A. Sani, A. Alomainy and Y. Hao, "Numerical Characterisation and Modelling of Subject–Specific Ultra Wideband Body–Centric Radio Channels and Systems for Healthcare Applications", IEEE Transaction on Information and Technology in Biomedicine, 16(2):221–227 05 Mar 2012.
- Q. H. Abbasi, A. Sani, A. Alomainy and Y. Hao, "Experimental Characterisation and Statistical Analysis of the Pseudo–Dynamic Ultra Wideband On–Body Radio Channel", IEEE Antenna and Wireless Propagation letter, Volume 10, pp. 748–751, August 2011.
- X. D. Yang, Q. H. Abbasi, A. Alomainy and Y. Hao, "Spatial Correlation Analysis of On–Body Radio Channels Considering Statistical Significance ", IEEE Antenna and Wireless Propagation letter, Volume 10, pp. 780–783, August 2011.
- Q. H. Abbasi, A. Alomainy, Y. Hao, "Characterisation of MB–OFDM based Ultra Wideband Systems for Body–Centric Wireless Communications ", IEEE Antenna and Wireless Propagation letter, Volume 9, pp. 324–327, Dec. 2011
- Q. Abbasi, A. Sani, A. Alomainy and Y. Hao, "Ultra Wideband On–Body Radio Channel Characterisation and System–Level Modelling for Multiband OFDM Body–Centric Wireless Network",IEEE Transactions on Microwave Theory and Techniques, Vol. 58, no. 12, pp. 3485–3492, December 2010.
- Andrea Sani, Akram Alomainy and Yang Hao, "Numerical Characterization and Link Budget Evaluation of Wireless Implants Considering Different Digital Human Phantoms", IEEE Transactions on Microwave Techniques and Theory, Biomedical Special Issue, Vol. 57, Issue 10 (Part 2), pp. 2605–2613.
- A. Sani, A. Alomainy, G. Palikaras, Y. Nechayev, Y. Hao, C. G. Parini, P. S. Hall, "Experimental Characterization of UWB On–Body Radio Channel in Indoor Environment Considering Different Antennas", IEEE Transactions on Antennas and Propagation, Vol. 57, Issue 10 (Part 2).
- A. Sani, Y. Zhao, A. Alomainy, Y. Hao and C. G. Parini, "An Efficient FDTD Algorithm Based on Equivalence Principle for Analyzing On–Body Antenna Performance", IEEE Transactions on Antennas and Propagation, Special Issue on Body–Centric Wireless Networks, Vol. 57, Issue 4, Part 1, April 2009, pp. 1006–1014.
- A. Alomainy and Y. Hao, "Modelling and Characterisation of Biotelemetric Radio Channel from Ingested Implants Considering Organ Contents", IEEE Transactions on Antennas and Propagation, Special Issue on Body–Centric Wireless Networks, 2009, Vol. 57, Issue 4, Part 1, April 2009, pp. 999–1005.
- A. Alomainy, A. Sani, A. Rahman, J. Santas and Y. Hao, “Transient Characteristics of Wearable Antennas and Radio Propagation Channels for Ultra Wideband Body–Centric Wireless Communications”, IEEE Transactions on Antennas and Propagation, Special Issue on Body–Centric Wireless Networks, Vol. 57, Issue 4, Part 1, April 2009, pp. 875–884.