Multifunctional Polymer Light-Emitting Diodes with Visible Light Communications (MARVEL)

Lead Research Organisation: University College London
Department Name: Electronic and Electrical Engineering

Abstract

With the dramatic increase in traffic carried by telecommunication networks, the demand for wireless resources (spectrum) is quickly outstripping its limited supply. Serious deterioration of service quality due to spectral congestion is becoming evident in high-density user scenarios, where users demand leads to a limited access. This problem is even worse in indoor applications where a lack of spectrum and a large number of users causes significant network slowdown. It is estimated that more than 70% of wireless traffic takes place in an indoor environment (home/office etc.). Thus, there is the need for reliable low-cost, high-capacity wireless technologies to ensure seamless indoor wireless connectivity at all times. Visible light communications (VLC) offers wireless connectivity using the visible band (~400 THz), which is a license free spectrum with high security and where its sources are used to provide lighting. VLC utilises semiconductor light emitting diodes (LED), which can be modulated at high speeds while providing a constant level of illumination. Traditionally, VLCs use inorganic LEDs as their transmitters' light sources. Such devices introduce significant drawbacks that have yet to be addressed, such as the inability to produce large panels due to the brittle and complex epitaxial processing methods that are expensive. Furthermore, to provide proper illumination, matrices of devices are required, thus introducing a significant circuit complexity. Other drawbacks include the inability to use flexible substrates that are attractive for mobile devices and the difficulties in producing devices with inherent different wavelengths. All of these disadvantages can be dealt with by replacing the commonly used inorganic metals by organic polymers as the semiconductor material of the LEDs. Polymer LEDs (PLEDs) can be manufactured using inexpensive wet processing methods at room temperature (such as inkjet printing) to produce single panel devices with large photoactive areas, at extremely low cost. Further, PLEDs can be deposited on a wide variety of substrate materials and with different shapes, allowing the development of a new generation of devices. Using a simple manufacturing process (one step deposition of different organic polymers) PLEDs may be designed to produce red, green and blue (RGB) light and then combined to allow the dual function of lighting and signal transmission.

Over the past decade, the teams applying for this grant have collectively demonstrated major successes in using organic (polymer) LEDs in VLC systems, with manufacturing, cost and operational advantages. Our previous work has led to several "world firsts" in terms of transmitted signal quality and bit rates, and our results were published at leading international journals and conferences.

In this proposal we will build on the existing strengths and varied expertise of our three team consortium. Specifically our research in inorganic semiconductors, optical component design and fabrication, electronic circuit design and communication systems integration, will be used to construct and demonstrate a new PLED based VLC proof of concept system, which includes novel device, circuit and system designs. We expect to achieve unprecedented VLC transmission speeds in realistic indoor environments. The project will study new methods of designing PLEDs and new optical techniques to maximise their light efficiency. New circuits and communication engineering techniques will be investigated to allow optimised coupling of electronic circuitry to PLEDs, overcoming some of PLEDs inherent data carrying limitations. We aim to assemble a complete system and test in in a specially designed test chambers of VLC.

In summary, we believe this work to be highly timely as it addresses the two key challenges; the design of systems operating in license free spectral bands and the provision of easy to manufacture and low cost organic optoelectronic devices.

Planned Impact

We hope that the leading work on inorganic devices in the UK will be strongly complemented by this work, to the benefit of the UK's leading standing in this fast developing area.

the scope and impact of MARVEL is broad. The research will not only develop the required technologies to reach its multiple goals but also it will look into creating new business opportunities based on VLC in an important number of practical scenarios. In fact, home, office and public places, are basic scenarios where the technology developed in MARVEL can be applied. As people spend most of their time in such places, the impact of this work on users is potentially high. The impact of of this research on operators, equipment manufacturers (mobile devices and infrastructure), standardization bodies and regulators is expected to be high.

Academically, the knowledge attained in modelling, design, simulations, implementation and processing of PLED based VLC networks will be invaluable in extending the interdisciplinary expertise of the research associates. The EPSRC and UK government has listed conductive polymer technologies as an area for significant growth and this proposal directly supports these claims and enables improved UK competitiveness in the display technology sector with a unique interdisciplinary project. Furthermore the European Union Horizon 2020 programme has identified organic technologies as an area for growth, and allocated at least 30m Euros for research funding.

Economic and societal: VLC in networking is well suited for a number of applications including a replacement for standard Wi-Fi deployment in local area networks in indoor environments; in areas where Wi-Fi networks are not practical or may cause harm due to electromagnetic interference from the Wi-Fi system or it causing issues with in-room equipment, such as a hospital setting; in home area networks to communicate with appliances and automatic home systems; car-to-car communications; underwater communications systems between various manned and unmanned platforms; for communication between handheld devices; as an enabler for local positioning systems. This introduces a huge market opportunity for the VLC in addition to posing a technical challenge, since the current RF based mobile systems cannot support all these requirements. Therefore, the adoption of VLC technologies can give rise to new business ecosystems, characterised by new actors and value chains. This research will assist in making this to become a reality, since our results would demonstrate white LED cab be used in a wide scale allowing communications as well as illumination with minimum energy usage, high performance and high data rates. Therefore, this research will provide economic and societal benefits within a few years in the UK as well as worldwide,

Knowledge and training: We plan to disseminate our findings to a much wider community including the lighting industries, telecommunication network service provider, in the UK and the rest of the world.
The proposed research will offer personal development for the research team. researchers will be mentored by the PIs and CoIs, who between them have proven track records in of nurturing close 50 early-career researchers to reach their full potential. Furthermore, RAs will be able to draw upon the investigators considerable technical expertise and experience. Furthermore, PhD students (funded by the universities) will work in this area and related areas and will be trained in optoelectronic and VLC systems design as well as in practical techniques. We believe such training will provide the necessary skills for furthering the UK's standing in this area in industry and academia.

Publications

10 25 50
 
Description 1- New methods of modulating (superimposing) data on devices used for lighting (red, green and blue LEDs) have been developed and tested in the laboratory. We have also been developing circuits for visible light transmitters and receivers that are optimised for the specialist types of devices to be developed in this project, which are organic based devices.
2- Adjustments to modulation formats have been proposed that introduce substantially lower computational complexity in VLC systems. This is important because it saves hardware resources and battery life, based on simple-yet-elegant tweaks to well known systems.
3- A new modulation format called super-Nyquist carrier-less amplitude and phase modulation was developed that saves bandwidth by compressing sub-bands. This has shown spectral efficiency improvements of over 40% and has been published in the prestigious Optics Express journal.
4- work has been developed that investigates the performance of organic LEDs in the context of high speed VLC systems and tests the performance of different operating points and materials to obtain optimal performance.
5- the optoelectronic characteristics of organic LEDs have been investigated from a communications systems point of view for the first time, and published in several articles. a model has been developed that is expected to be adopted by the research community.
6- a real time system has been developed based on field programmable gate arrays that transmits high data rates over visible wavelengths using organic LEDs. this has developed into a demonstration at the prestigious IEEE flagship event, INFOCOM, one of the most important conferences in the field of communications.
7- a new method of doubling the data rate (to be published) has been developed through this project, leveraging on wavelength division multiplexing and the natural non-linear response of photodetectors. Diversity between signals carried on different wavelengths is introduced and exploited to recover the original data. This means, the same frequency spectrum can be used to send 2 (or more) parallel data streams and decoded using simple subtractions. to be published.
8- new photodetector circuits have been developed that tolerate large equivalent capacitances. this means that large area devices can be utilised, thus increasing link distances; this has been a significant challenge in the research community for the proposal of visible light communications, and as such, this work was accepted at the most prestigious electronics and circuits conference in the world, IEEE ISCAS.
9- circuits have also been proposed that show the effective LED capacitance being absorbed into artificial transmission lines, improving the bandwidth through simple circuit techniques.
10- results have been proved through transmission over other relevant wavelengths including several radio-based applications, showing the generality of the work, which is important, because 5G access will be made up of many technologies.
Exploitation Route we anticipate that the adoption of circuit models and equivalent circuits proposed in this project will result in significant recognition both by academic contemporaries and industrialists, alike. we will also lobby that modulation techniques and digital signal processing methods developed through this project will directly be adopted in the next set of standards for visible light communications systems (IEEE802.15.7), which are under development. our work has been adopted by large industrial companies (i.e. National Instruments) and developed in conjunction with others (i.e. Huawei and Siemens AG).
Sectors Digital/Communication/Information Technologies (including Software),Electronics,Healthcare

 
Description Results developed through this project have been used by a major industrial company, namely National Instruments (with revenues over $1.2B), who have used a case study based on new modulation schemes and signal processing techniques as a demonstrator for 5G (http://sine.ni.com/cs/app/doc/p/id/cs-17492#). Two of the project investigators are the senior authors of the case study. These results have been directly extrapolated from work developed in this project.
First Year Of Impact 2018
Sector Digital/Communication/Information Technologies (including Software),Electronics
Impact Types Economic,Policy & public services

 
Description Academic collaboration with Czech Technical University 
Organisation Czech Technical University in Prague
Department Department of Electromagnetic Field
PI Contribution Exchange of intellectual input and dissemination of information. Training of staff including visits and free-of-charge access to state-of-the-art laboratories at UCL. Knowledge and expertise exchange in the areas of advanced modulation formats and signal processing, directly corresponding to input required for work packages 2 and 3, whilst enabling the Czech Technical University to increase their knowledge and begin their own research into polymer based visible light communications systems.
Collaborator Contribution Same as previous, including visits to CTU and free-of-charge access to their laboratories and facilities. Access to expertise and development of ideas that correspond directly to the tasks and work packages of this project.
Impact Several papers have been produced and published (10.1109/ICCW.2017.7962624, 10.1109/JPHOT.2017.2749203), refer to dissemination section of the submission. A number of successive papers are in preparation for submission based on collaborations between our laboratories.
Start Year 2017
 
Description Collaboration with Newcastle University 
Organisation Newcastle University
Country United Kingdom 
Sector Academic/University 
PI Contribution Dr Paul Anthony Haigh has been appointed as lecturer at Newcastle University through activities based on this project. He will continue to collaborate with UCL and Northumbria University on this project.
Collaborator Contribution Paul has directly contributed to many of the papers published in this project, and will continue to do so after he moves to Newcastle University.
Impact see papers
Start Year 2019
 
Description Industrial collaboration with Huawei 
Organisation Huawei Technologies
Country China 
Sector Private 
PI Contribution UCL experts have provided intellectual input and expertise into demonstrating mobile-to-mobile visible light communications using the in-built features of mobile phones, and also high speed optical fibre access based on advanced modulation formats developed at UCL.
Collaborator Contribution Provided mobile devices and optical fibre topologies and performed the experimental testing, resulting in several upcoming publications.
Impact Two papers published (https://doi.org/10.1364/ACPC.2017.M2G.4, https://doi.org/10.1364/ACPC.2017.S4B.6) and several papers under submission and in preparation in the area of mobile visible light communications specifically relating to WP2 and WP3.
Start Year 2017
 
Description Industrial collaboration with Siemens Healthineers 
Organisation Siemens Healthcare
Country Germany 
Sector Private 
PI Contribution Knowledge exchange with UCL experts from various fields, new applications for devices and new areas for innovation for Siemens Healthineers devices.
Collaborator Contribution Provisioning of bespoke-in-the-world organic polymer photodetectors, specifically adapted from their original purpose as X-ray detectors for use in this project.
Impact Cash-in-kind transfer of organic polymer photodetectors. Bespoke devices adapted specifically for our use based on our specifications and requests. multi-disciplinary covering materials science, organic electronics, circuit design, information theory and communications systems. Papers in preparation for submission specifically related to WP1.
Start Year 2017
 
Description IET e-academy lecture series 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Study participants or study members
Results and Impact A lecture series was developed and delivered for the IET e-academy for their career professional development (CPD) courses. It is expected that thousands of participants based in the UK and beyond will use the course towards gaining their chartered engineering status. The course was developed in 2017 and made accessible to users in early 2018.
Year(s) Of Engagement Activity 2017,2018
URL https://ietacademy.eu.crossknowledge.com/site/path/328#tab/path/activity/28954