Research

FIWIN5G aims to produce the next generation of researchers who will enable Europe to take a leading role in the multidisciplinary area of 5G high-speed wireless internet and beyond, involving devices, systems and networks. To achieve this, the network integrates multidisciplinary scientific expertise, complementary skills, and experience working in academia and industry to empower the researchers to work in interdisciplinary teams, integrate their activities and share expertise.

FIWIN5G comprises 10 leading research institutions across Europe and 11 industrial partners to deliver a comprehensive research and training program. Currently applications for 15 Early Stage Researchers (3 year research fellowships with PhD funding available) are open across the 10 partners. The network is coordinated by Prof John Mitchell in the Department of Electronic and Electrical Engineering and has received €3.9M of funding as a Marie Skłodowska-Curie Action, European Training Network.

Radio over fibre technologies and networks for future mobile communications architechures, fixed wireless access platforms.
Modelling and experimental investigations of optical networks for supporting the delivery of radio signals. The main applications considered are for fixed wireless access systems to provide high-speed access. WIthin this work a few themes have emerged.

- The first considers the impact of the delay incured by optical distribution of wireless signals. The work has shown that although transport of the physical layer is possible over may 10s of km, the MAC layer imposes significant constraints on the possible distance. This was demonstrated with WiFi signals in:
Kalantari-Sabat, B. and Mjeku, M. and Gomes, N.J. and Mitchell, J.E. (2008) Performance impairments in single-mode radio-over-fiber systems due to MAC constraints. Journal of Lightwave Technology , 26 (15) pp. 2540-2548

- More recent work has considered the architectures and advantages of fully integrated radio-over-fibre networks, for example Milosavljevic, M and Thakur, MP and Kourtessis, P and Mitchell, JE and Senior, JM (2012) Demonstration of wireless backhauling over long-reach PONs. Journal of Lightwave Technology , 30 (5) 811 - 817 and Attard, JC and Mitchell, JE (2006) Optical network architectures for dynamic reconfiguration of full duplex, multiwavelength, radio over fiber. OSA Journal of Optical Networking , 5 (6) 435 - 444 This work is being continued in the EU project IPHOBAC-NG which looks to integrate mm-wave reach extension technologies to ultra-dense WDM PONs.

- We are also considering generation and transmission techniques for millimeter (mm) wave bands for a variety of applications including wireless backhaul, for example, Thakur, MP and Medeiros, MCR and Laurencio, P and Mitchell, JE (2011) Optical frequency tripling with improved suppression and sideband selection. Optics Express , 19 (26) B459-B470
High Capacity and Long Reach Optical Access Networks
Research in collaboration with BT investigated the deployment of long reach (100km), high aggregate bit rate (10Gbit/s) and high customer number (1024) optical access networks. These use advanced optical components currently only feasible in core networks to provide highly efficient optical access networks. The demonstrator of this system was reported in Shea, DP and Mitchell, JE (2007) A 10-Gb/s 1024-way-split 100-km long-reach optical-access network. J LIGHTWAVE TECHNOL , 25 (3) 685 - 693

The area of long-reach optical access networks is now gaining a great deal of attention. A review of much of the prior work in this area is available at Shea, DP and Mitchell, JE (2007) Long-reach optical access technologies. IEEE NETWORK , 21 (5) 5 - 11.
We have now extended this idea to consider how multiple short-reach PONs could be consolidated into a multi-wavelength long reach architecture. This was first demonstrated for 2.5Gbit/s PONs using Semiconductor Optical Amplifiers (SOAs) and cross-gain modulation(XGM) in Shea, D.P. and Mitchell, J.E. (2009) Architecture to integrate multiple PONs with long reach DWDM backhaul. IEEE Journal on Selected Areas in Communications , 27 (2) pp. 126-133 and has since been expended to 10Gbit/s PONs using an interferometric structure of SOAs and cross-phase modulation (XPM) in Cao, B and Delgado Mendinueta, JM and Thomsen, B and Mitchell, J (2012) Demonstration of a 10 Gbit/s Long Reach Wavelength Converting Optical Access Network. Journal of Lightwave Technology 2012 (in press).

As part of this work, collaborations with the UCL optical networks group considered the impact on the burst mode receiver requirement of such technologies Mendinueta, JMD and Mitchell, JE and Bayvel, P and Thomsen, BC (2011) Digital dual-rate burst-mode receiver for 10G and 1G coexistence in optical access networks. Optics Express , 19 (15) 14060 - 14066 and Mendinueta, JMD and Cao, B and Thomsen, BC and Mitchell, JE (2011) Performance of an optical equalizer in a 10 G wavelength converting optical access network. OPTICS EXPRESS , 19 (26) 229 - 234
Wireless Sensor Networks

Early work in this area mainly focused on the development of hardware platforms to demonstrate network capabilities, included collaborations with the National Orthopaedic Hospital, a company developing compressor valve monitoring systems and colleagues in Civil Engineering.
More recently the work has developed to consider techniques to improve the throughput and energy consumption in wireless sensor network, considering physical layer techniques such as adaptive spreading codes and network techniques such as situational awareness. For example we have considered as part of a recently completed project (EPSRC/TSB funded) with Rolls-Royce and SELEX/GALILEO, the development of an experimentally validated model of the deployment of wireless sensors within gas turbine engines, "Wireless Communication Networks for Gas Turbine Engine Testing”, X Dai,et.al., International Journal of Distributed Sensor Networks, Article ID 212876, 2012.
Work in the area of situational awareness has being funded by SELEX GALILEO to consider sensor systems that adapt based on knowledge of the information they are gaining and carrying. For example"Networking and Application Interface Technology for Wireless Sensor Network Surveillance and Monitoring" D.S. Ghataoura, G.E. Matich, and J.E. Mitchell, IEEE Communications Magazine , 49 (10) 90 - 97. 2011, and "VIGILANT+: mission objective interest groups for wireless sensor network surveillance applications" D.S. Ghataoura, G.E. Matich, and J.E. Mitchell, IET Wireless Sensor Systems, 1 (4) 229 - 240, 2011

Impairments in WDM optical networks.
The original subject of my PhD thesis, has since been extended to look at implication of imperfect wavelength isolation when the interfering terms are not all equal, Attard, JC and Mitchell, JE and Rasmussen, CJ (2005) Performance analysis of interferometric noise due to unequally powered interferers in optical networks. J LIGHTWAVE TECHNOL , 23 (4) 1692 - 1703.
Further work has considered how RF techniques can be applied to measure the impairments witnessed in burst-mode WDM networks where high-speed determination is critical. Impairment considered include Chromatic Dispersion (CD), polarisation mode dispersion (PMD) and noise (OSNR). This has led to both a theoretical study - Baker-Meflah, L and Thomsen, BC and Mitchell, JE and Bayvel, P (2010) Multi-Impairment WDM Optical Performance Monitoring for Burst Switched Networks. Journal of Lightwave Technology , 28 (23) 3417 - 3426 and an experimental study - Baker-Meflah, L and Thomsen, B and Mitchell, JE and Bayvel, P (2008) Simultaneous chromatic dispersion, polarization-mode-dispersion and OSNR monitoring at 40Gbit/s. OPT EXPRESS , 16 (20) 15999 - 16004.

Some Recent Projects I've Been Involved In:

  • EP/K033166/1 Efficient Energy Management In Energy Harvesting Wireless Sensor Networks: An Approach Based On Distributed Compressive Sensing
  • TS/G002614/1 Widagate: Wireless Data Acquisition In Gas Turbine Engine Testing
  • EP/D077362/1 Bandwidth Efficient Multi-carrier System for Wireless Channels
  • EP/D037026/1 Photonic Enabled Data Transport from Millimetric to Megametric Scales
  • GR/S44655/01 Feasibility Study of Spectrum Slices Radio-Over-Fibre Communications Networks
  • EU FP6 NoE - ISIS, Infrastructures for broadband access in wireless/photonics and Integration of Strengths in Europe
  • EU FP6 NoE - e-Photon/ONe, Optical Networks: Towards Bandwidth Manageability and Cost Efficiency
  • EU FP6 IP - NOBEL, Next Generation Optical Networks for Broadband European Leadership
  • EU FP7 NoE - BONE, Building the Future Optical Network in Europe
  • EU FP7 STREP - IPHOBAC-NG Integrated Photonic Broadband Radio Access Units for Next Generation Optical Access Networks

Graduated PhD/EngD Students:

  • Dr Neil Geary (EngD with Lucent Technologies)
  • Dr Joe Attard (PhD)
  • Dr Darren Shea (EngD with BT)
  • Dr Adrian Tregunna (EngD with BT)
  • Dr Saad Sari (PhD)
  • Dr Bahman Kalentari-Sabet (PhD)
  • Dr Lamia Meflah (PhD)
  • Dr Ibiso Wokoma (PhD)
  • Dr LamLing (Venus) Shum (PhD)
  • Dr Beverley Cook (EngD with Siemens)
  • Dr Darminder Ghataoura (EngD with SELEX GALILEO)
  • Dr Bowen Cao (PhD)
  • Dr Fei Qin (PhD, EPSRC/BT Dorothy Hodgekins Award)
  • Dr Oluyemi Omomukuyo  (PhD)
  • Dr George Konstantinou (PhD, EPSRC funded)
  • Dr John Atkinson (PhD, SELEX ES)