Engineering and Innovation Studentship project proposal– 2017 entry

Project Highlights:

  • Research at the leading edge of antenna design for wireless communications
  • High-impact project bringing broadband connectivity to passengers throughout their journeys, building on work funded by HM Government and the Department for Transport.
  • Collaborate with Network Rail, the University of Oxford and QinetiQ.

Project Description:

This project tackles the last remaining challenge that must be overcome before it is possible to offer broadband connectivity to all rail passengers, everywhere in the rail network. This will bring significant quality-of-life benefits to the over 4.5 million rail passengers who travel every day in the UK, allowing them to communicate over video links, work in the cloud, and consume media with the same service level as a home broad band connection. There is also significant economic benefit. Rail travel contributes over £9 Billion to the UK economy [1] and broadband connectivity will contribute over £6 Billion by 2024[2]. This project will contribute a step-change to the spectral efficiency of wireless links, enhance the provision of 5G services across the transport sector, and have knock-on benefits in other domains, such as reducing network cabling in data centres.

In more detail, the challenge is that a high capacity wireless link is needed to bridge the gap between the fixed telecommunications network, and the trackside stations that will communicate to the passing trains. Existing electromagnetic spectrum allocations are not sufficient to provide the required 40 Gbps link capacity, and so a high-spectral efficiency approach is required. Conventional 5G mobile communications approaches achieve high spectral efficiency by using multiple input and multiple output antennas (MIMO) but can only perform well if there is a cluttered environment with multiple paths for the radio beams to travel between the two stations. Alongside a rail track, the environment is uncluttered, and so alternative approaches are needed. One promising approach is to use spatial modes, such as orbital angular momentum modes [3]. First explored in depth in optics, then brought to radio, orbital angular momentum modes have been experimentally shown to be useful for high-spectral efficiency links, producing 32 Gbps link capacity in the 60 GHz band [3]. Adaptations are required to make such systems practical for use alongside transport infrastructure, such as reducing the size of the receiver antenna, and improving the transmit antenna properties by using surface-wave approaches. We have theoretically explored these approaches with promising results [4], and recentlyproduced experimental validation. An example of the fields produced our current surface-wave antenna design for orbital angular momentum modes is shown in Fig.1(a,b), along with a schematic illustration of the phase profiles of some examples OAM modes in Fig. 1(c).

Figure 1: Surface-wave antenna generating orbital angular momentum (OAM) modes (a) magnitude of the radiation in 3D (b) phase of the radiation in a 2D plane in the far field, and (c) schematic representation of the phase profile of a subset of the possible OAM modes.

The primary topic of your research will be to explore new antenna designs that improve the performance both for transmit and receive tasks. Initially, you will explore the optimisation of transmit-only antennas comprising an array of dipole or patch elements, focusing on establishing a practical limit on the performance improvement that can be expected through the addition of multiple radiating elements beyond a conventional circular ring design. The primary means of achieving the optimisation will be evolutionary optimisation techniques. Then you will adapt the designs for implementation using meta-material surface-wave antennas, which allow an additional degree of freedom via manipulating the waves as they travel across the surface of the antenna. The ultimate goal is to create thin antennas that can transmit or receive multiple orbital angular momentum modes at once, and split the signal into separate receivers (one for each mode).

Drs Drysdale and Marino will oversee your training, but the project will also benefit from the close involvement of our collaborators from Network Rail, the University of Oxford and QinetiQ; and in particular Prof. Ben Allen (also University of Oxford).

Methodology:

The performance improvement comes from using spatial modes that have the property of allowing multiple independent channels of data to be transmitted in the same time, space and frequency band, yet still be independently received. The key advance that we are pioneering is the use of small, flat antennas to receive these modes, which have the benefit of being more practical in real-world outdoor environments. The challenge comes in ensuring the data channels remain independent (which sometimes is not the case if the antenna is made too small).

The antenna design process begins with quasi-analytical design equations, and then moves onto full-wave numerical electromagnetic simulations using tools such as CST Microwave Studio, and our own in-house FDTD codes [5] running on the University’s high-performance computer cluster. You will develop implementations of optimisation algorithms in python that will integrate with our in-house codes and/or our post-processing routines.

Experimental validation is an essential part of the methodology, and will rely on our own in-house capability (Vector Network Analysis to 26 GHz), with a primary focus on our 4 - 6GHz multiple-antenna line-of-sight test bed (MALTS), which has been funded by the Department for Transport, The Open University and HM Government. Additional facilities are available through the network of collaborators and will depend on project needs as they develop.

Indication of project timeline:

Year 1:Introduction to spatial modes for communications systems. Learn to model conventional antenna elements using CST Microwave Studio, and calculate array properties using our in-house post-processing codes; Conduct literature search for suitable candidate optimisation methods, such as evolutionary methods, and implement a selection of three. Compare the performance of transmit arrays generated using these methods. Implement test arrays using our 5 GHz test bed, and test indoors and outdoors using our vector network analyser-based setup.

Year 2:After having gained familiarity with spatial modes in Year 1, you will move on to learn about surface-wave antennas, and the role of meta-materials in enhancing their performance. Adapt the antenna designs from Year 1 to use surface-wave techniques, and in particular, explore the role of patterned surfaces (meta-materials) for manipulating the fields. Explore candidate designs that can separate the signals from different mode numbers. Fabricate test structures and conduct experimental tests.

Year 3:Refine the surface-wave meta-material antenna designs. Fabricate the full designs for in-depth testing. Available techniques may include channel sounding in radio frequency anechoic chambers and field scanning using coaxial probes. Integrate your antennas with software-defined radios to demonstrate the simultaneous transmission of multiple data channels. Publications will have been submitted in each of the three years; complete thesis write-up.

References

[1] “What is the value of rail to the UK economy?,” Oxera, for Rail Delivery Group, 2014

[2] “UK Broadband Impact Study,” SQW, for Dept. Culture, Media & Sport 2013

[3] Y. Yan, G. Xie, M. P. J. Lavery, et al. Nat. Comms., 5, 4876, March 2014

[4] C. J. Vourch, B. Allen, T. D. Drysdale, “Planar millimetre-wave antenna simultaneously producing four orbital angular momentum modes and associated multi-element receiver array,” IET Microwave Antennas and Propagation, vol.10, no. 14, pp. 1492-1499,201

[5] T. Stefański and T. D. Drysdale, “Parallel implementation of the ADI-FDTD method,” Microwave and Optical Technology Letters, vol. 51, no. 5, 2009

Candidate Applications:

  • 1000 word cover letter outlining how you are equipped in educational background and expertise to conduct the research project,
  • a CV including contact details of three academic references
  • An Open University application form, downloadable from: (Note: This is an Advertised studentship and you do not need to submit a proposal).
  • IELTs English Language test scores.

Applications should be submitted to by 4pm 8th March 2017.

Interviews will be held during w/c 27th March 2017.