Cognitive Radio and Machine-to-Machine Communications
Cognitive Radio: from Antennas to Intelligent Networking
The development of reconfigurable antennas is considered to be very promising in modern and future communication systems. Reconfigurable antennas have made use of many reconfiguration techniques, including many that are centred upon switching mechanisms, such as PIN diodes or MEMS, and others that embed electronic devices (e.g., varactors) to achieve tunable behaviour. Other techniques, such as optical switches, mechanical structure changing or the ability to change the permeability or permittivity of smart substrate materials, have also been used. Reconfigurable antennas have created new horizons for many types of applications, especially in Cognitive Radio, Multiple-Input-Multiple-Output (MIMO) Systems, personal communication systems, satellites and many other applications.
Cognitive Radio is one of the potential wireless applications that may place severe demands on RF system designers and particularly antenna designers, when it comes to providing flexible radio front-ends capable of achieving the set objectives of the technology. The aim of this work is to investigate possible roles that different categories of reconfigurable antenna can play in Cognitive and smart Radio. Hence, our research focuses on investigating some novel methods to frequency-reconfigure compact ultra-wideband antennas to work in different bands; this will offer additional filtering to the radio front-end. In the ultra-wideband mode, the antenna senses the spectrum for available bands with less congestion and interference and, hence, decides on the most suitable part to use at that point, initiating the necessary reconfiguration, allowing reliable and efficient communication links between the radio devices. An ultra-wideband antenna with reconfigurable integrated notch capability is also demonstrated to provide further enhancement to interference rejection and improve the overall communication link. Furthermore, the design of novel pattern and polarisation reconfigurable antennas is also investigated to assist Cognitive Radio through spatial, rather than frequency, means.
An ultimate target for this research is to combine different degrees of reconfiguration into one compact, state-of-the-art antenna design that meets the growing demand of cognitive and smart radio devices for more intelligent and multi-functional wireless devices within the personal area network domains and beyond.
Machine-to-Machine (M2M) communications: from Antennas to Intelligent Spectrum Sensing
The M2M and Internet of Things (IoT) sector has had the potential for massive growth for a number of years. The most recent forecasts are for 50 billion connected devices by 2020. An enormous range of applications, such as cars, sensors, traffic lights, healthcare and many others, have been suggested as target markets.
Our group has been actively working on M2M communications, from antennas to intelligent spectrum sensing algorithms. to fully unleash the potential benefits M2M can bring. Various compact and high-gain antennas, operating in the TV white space spectrum, have been developed for M2M communications, such as car park sensors and smart meters. To enhance spectrum availability for M2M communications, we have developed a number of spectrum-sensing algorithms, including a TV white space geo-location model, Welch’s, Wavelet, compressive spectrum sensing and hybrid sensing for single and multiple sensors nodes, and validated by the live spectrum monitoring system, as described in the next section. Our group are also actively involved with the Weightless SIG, ETSI oneM2M, smart M2M, and other standard bodies.
Commercial Spectrum Sensing Node
As a tool for this research theme, a commercial system for monitoring the spectrum between 10 MHz and 6 GHz has been installed in the School of Electronic Engineering and Computer Science. The RFeye Node from CRFS can be connected to an Ethernet network and includes a GPS unit for precise location and time-stamping. It can support multiple antenna operation and perform angle-of-arrival and time-difference-of-arrival calculations. The short video below is a recording of the spectrum plot at QMUL between 470 MHz and 3 GHz, with frequency on the horizontal axis in MHz and signal strength in dBm on the vertical axis. Strong signals can be observed at the cellular network frequencies (800 MHz, 900 MHz, 1800 MHz and 2100 MHz) and the 2.45 GHz ISM band commonly used for Wi-Fi networks.
Whitespace Machine Communication Lab
Much of the research in this theme is organised under the Whitespace Machine Communication (WMC) Lab led by Dr Yue Gao. The lab focuses on developing theoretical research into practice in the interdisciplinary area among antennas, signal processing and white space spectrum for Cyber Physical System (CPS), Machine-to-Machine (M2M) and Internet-of-Things (IoT) applications. Areas of research include:
- UHF, UWB antennas, Characteristic Modes Analysis
- Sub-Nyquist sampling, compressive sensing, s-FFT, multi-coset
- Smart wireless system design and integration
- MIMO, Massive MIMO, mm-wave antennas, OAM
Check out the lab for up-to-date news, publications and research opportunities, and follow the lab on Twitter.
Highlights and Research Outcomes
Selected Research Grants and Projects
- 2014.3 – 2014.7: Industry secondment with Weightless M2M standard body, £17k, EPSRC
- 2014.1 – 2016.7: UHF Antenna design for RF Sensors, £7k, WSN Tech Ltd
- 2013.7 – 2014.1: Novel Antenna Structures for Low Frequencies, £60k, Selex ES
- 2013.10: Research equipment support, £17k, CRFS Ltd
- 2010.10 – 2014.8: Reconfigurable Antennas and Radio Front–ends for Cognitive Radio, £60k, EPSRC-funded PhD studentship
Selected Recent Publications
- T. Aboufoul, C. G. Parini, X. Chen and A. Alomainy, "Pattern-Reconfigurable Planar Circular Ultra-Wideband Monopole Antenna", IEEE Transactions on Antennas and Propagation, Vol. 61, Issue 10, pp 4973-4980.
- T Aboufoul, A Alomainy, C Parini, "Polarization reconfigurable ultrawideband antenna for cognitive radio applications", Microwave and Optical Technology Letters 55 (3), 2013, pp.501–506.
- T Aboufoul, A Alomainy, C Parini,"Reconfigured and notched tapered slot UWB antenna for cognitive radio applications", International Journal of Antennas and Propagation, Volume 2012 (2012), Article ID 160219.
- T. Aboufoul, A. Alomainy, "Reconfigurable UWB Antenna for Cognitive Radio Applications Using GaAs FET Switches", IEEE Antennas and Wireless Propagation Letters, Vol. 11:392–394 2012.
- N. Wang, Y. Gao and X. Zhang, "adaptive spectrum sensing algorithm under different primary user utilizations,” IEEE Communications Letters, vol.17, no.9, pp.1838-1841, September 2013.
- X. Zhang, Z. Yan, Y. Gao, and W. Wang, “On the Study of Outage Performance for Cognitive Relay Networks (CRN) with the Nth Best-Relay Selection in Rayleigh-fading Channels,” IEEE Wireless Communications Letters, vol.2, no.1, pp.110-113, February 2013.
- X. Zhang, J. Xing, Z. Yan, Y. Gao, and W. Wang, "Outage Performance Study of Cognitive Relay Networks with Imperfect Channel Knowledge,” IEEE Communications Letters, vol. 17, no. 1, January 2013