Visible light communication with efficient far-red/near-infrared polymer light-emitting diodes

Visible light communication (VLC) is a wireless technology that relies on optical intensity modulation and is potentially a game changer for internet-of-things (IoT) connectivity. However, VLC is hindered by the low penetration depth of visible light in non-transparent media. One solution is to extend operation into the “nearly (in)visible” near-infrared (NIR, 700–1000 nm) region, thus also enabling VLC in photonic bio-applications, considering the biological tissue NIR semitransparency, while conveniently retaining vestigial red emission to help check the link operativity by simple eye inspection. Here, we report new far-red/NIR organic light-emitting diodes (OLEDs) with a 650–800 nm emission range and external quantum efficiencies among the highest reported in this spectral range (>2.7%, with maximum radiance and luminance of 3.5 mW/cm2 and 260 cd/m2, respectively). With these OLEDs, we then demonstrate a “real-time” VLC setup achieving a data rate of 2.2 Mb/s, which satisfies the requirements for IoT and biosensing applications. These are the highest rates ever reported for an online unequalised VLC link based on solution-processed OLEDs

Optical wireless communications

The phenomenal global demand for wireless communication links with greater bandwidths is motivating engineers world over to come up with alternatives communication links. One of such system that has received a great deal of attention and has shown evidence of a promising future is infrared optical communications.This project explores the fundamental aspects involved in designing and building a transmitter and a receiver as part of an infrared optical wireless link for indoor use. It is mainly concerned with extracting as much bandwidth as possible from the circuit designed. The system built in this project is capable of data transmission of over 20Mbits/second but this is however nowhere near the limit of the systems as will be discussed in the dissertation. Optical communication links have been developed which are capable of data transfer rates of 1.25Gbits/second (Jeganthan, 2001).The work done in this project and that which have been done by others present a compelling argument as to why infrared optical wireless communications is a formidable form of wireless communications and as a matter of fact a worthy alternative to the well known radio frequency (RF) systems

Hybrid Free-Space Optical and Visible Light Communication Link

V součastnosti bezdrátové optické komunikace (optical wireless communication, OWC) získávají širokou pozornost jako vhodný doplněk ke komunikačním přenosům v rádiovém pásmu. OWC nabízejí několik výhod včetně větší šířky přenosového pásma, neregulovaného frekvenčního pásma či odolnosti vůči elektromagnetickému rušení. Tato práce se zabývá návrhem OWC systémů pro připojení koncových uživatelů. Samotná realizace spojení může být provedena za pomoci různých variant bezdrátových technologií, například pomocí OWC, kombinací různých OWC technologií nebo hybridním rádio-optickým spojem. Za účelem propojení tzv. poslední míle je analyzován optický bezvláknový spoj (free space optics, FSO). Tato práce se dále zabývá analýzou přenosových vlastností celo-optického více skokového spoje s důrazem na vliv atmosférických podmínek. V dnešní době mnoho uživatelů tráví čas ve vnitřních prostorech kanceláří či doma, kde komunikace ve viditelném spektru (visible light communication, VLC) poskytuje lepší přenosové parametry pokrytí než úzce směrové FSO. V rámci této práce byla odvozena a experimentálně ověřena závislost pro bitovou chybovost přesměrovaného (relaying) spoje ve VLC. Pro propojení poskytovatele datavých služeb s koncovým uživatelem může být výhodné zkombinovat více přenosových technologií. Proto je navržen a analyzovám systém pro překonání tzv. problému poslední míle a posledního metru kombinující hybridní FSO a VLC technologie.The field of optical wireless communications (OWC) has recently attracted significant attention as a complementary technology to radio frequency (RF). OWC systems offer several advantages including higher bandwidth, an unregulated spectrum, resistance to electromagnetic interference and a high order of reusability. The thesis focuses on the deployment and analyses of end-user interconnections using the OWC systems. Interconnection can be established by many wireless technologies, for instance, by a single OWC technology, a combination of OWC technologies, or by hybrid OWC/RF links. In order to establish last mile outdoor interconnection, a free-space optical (FSO) has to be investigated. In this thesis, the performance of all-optical multi-hop scenarios is analyzed under atmospheric conditions. However, nowadays, many end users spend much time in indoor environments where visible light communication (VLC) technology can provide better transmission parameters and, significantly, better coverage. An analytical description of bit error rate for relaying VLC schemes is derived and experimentally verified. Nonetheless, for the last mile, interconnection of a provider and end users (joint outdoor and indoor connection) can be advantageous when combining multiple technologies. Therefore, a hybrid FSO/VLC system is proposed and analyzed for the interconnection of the last mile and last meter bottleneck

Hologram selection in realistic indoor optical wireless systems with angle diversity receivers

In this paper, we introduce a new adaptive optical wireless system that employs a finite vocabulary of stored holograms. We propose a fast delay, angle, and power adaptive holograms (FDAPA-Holograms) approach based on a divide and conquer (DandC) methodology and evaluate it with angle diversity receivers in a mobile optical wireless system. The ultimate goal is to increase the signal-to-noise ratio (SNR), reduce the effect of intersymbol interference, and eliminate the need to calculate the hologram at each transmitter and receiver location. A significant improvement is achieved in the presence of demanding background illumination noise, receiver noise, multipath propagation, mobility, and shadowing typical in a realistic indoor environment. The combination of beam delay, angle, and power adaptation offers additional degrees of freedom in the link design, resulting in a system that is able to achieve higher data rates (5 Gb/s). At a higher data rate of 5 Gb/s and under eye safety regulations, the proposed FDAPA-Holograms system offers around 13 dB SNR with full mobility in a realistic environment where shadowing exists. The fast search algorithm introduced that is based on a D&C algorithm reduces the computation time required to identify the optimum hologram. Simulation results show that the proposed system, FDAPA-Holograms, can reduce the time required to identify the optimum hologram position from 64 ms taken by a classic adaptive hologram to about 14 ms

Optical wireless communications

The phenomenal global demand for wireless communication links with greater bandwidths is motivating engineers world over to come up with alternatives communication links. One of such system that has received a great deal of attention and has shown evidence of a promising future is infrared optical communications.This project explores the fundamental aspects involved in designing and building a transmitter and a receiver as part of an infrared optical wireless link for indoor use. It is mainly concerned with extracting as much bandwidth as possible from the circuit designed. The system built in this project is capable of data transmission of over 20Mbits/second but this is however nowhere near the limit of the systems as will be discussed in the dissertation. Optical communication links have been developed which are capable of data transfer rates of 1.25Gbits/second (Jeganthan, 2001).The work done in this project and that which have been done by others present a compelling argument as to why infrared optical wireless communications is a formidable form of wireless communications and as a matter of fact a worthy alternative to the well known radio frequency (RF) systems

Contextually and identity aware 5G services

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University LondonThe fifth generation (5G) mobile networks aim to be ten times faster than the existing 4G connection, whilst providing low latency, and flexibility. Hence, various alterations are planned to the existing network infrastructure to be able to reach the 5G expected performance levels. The main technologies that were used, to ensure high performance, flexible network, and efficient resource allocation, are Software Defined Network and Network Function Virtualization. As these technologies are replacing the device-based architecture with, a service-based architecture. This thesis provides a design of location database interactive web interface and interactive mobile application. The implementation of real time video streaming location server, the streaming system's performance parameters demonstrated a high level of QoS (0.07ms jitter and 9.53ms delay). In regard to experimental examination, it measured the localisation coverage, accuracy measurements and a highly scalable security solution. The localisation coverage and accuracy measurements were achieved through the mmWave and VLC link transmitters. The proposed simulated annealing algorithm aimed at data optimisation for location measurements accuracy showed results of the average location error of x and y which showed significant improvement from x= 22.5 and y=21.6 to x=11.09 and y= 11.63. The proposed indoor location security solution showed significant results, as it provides a high scalability solution using the VNF. The solution showed that it was not 100% effective, as some of the fake discover packets still reached the DHCP server. This was due to the high load of traffic passing through the network. Nonetheless, 90% of the fake DHCP discover packets never reached the DHCP server because the scripts began blocking all fake discover packets after realising it was an attack. This conveys that the proposed system was able to run successfully without crashing or overloading the controller. Overall, the main challenges facing 5G have been addressed with their proposed solutions, which showed promising results. Conclusively showing that there is a lot more space for technological advancements to support the future of mobile networks.European Union’s Horizon 2020 research program - the Internet of Radio-Light (IoRL) project H2020-ICT 761992

A Global Human Settlement Layer from optical high resolution imagery - Concept and first results

A general framework for processing of high and very-high resolution imagery for creating a Global Human Settlement Layer (GHSL) is presented together with a discussion on the results of the first operational test of the production workflow. The test involved the mapping of 24.3 millions of square kilometres of the Earth surface spread over four continents, corresponding to an estimated population of 1.3 billion of people in 2010. The resolution of the input image data ranges from 0.5 to 10 meters, collected by a heterogeneous set of platforms including satellite SPOT (2 and 5), CBERS-2B, RapidEye (2 and 4), WorldView (1 and 2), GeoEye-1, QuickBird-2, Ikonos-2, and airborne sensors. Several imaging modes were tested including panchromatic, multispectral and pan-sharpened images. A new fully automatic image information extraction, generalization and mosaic workflow is presented that is based on multiscale textural and morphological image features extraction. New image feature compression and optimization are introduced, together with new learning and classification techniques allowing for the processing of HR/VHR image data using low-resolution thematic layers as reference. A new systematic approach for quality control and validation allowing global spatial and thematic consistency checking is proposed and applied. The quality of the results are discussed by sensor, by band, by resolution, and eco-regions. Critical points, lessons learned and next steps are highlighted.JRC.G.2-Global security and crisis managemen

Technical Design Report for the PANDA Micro Vertex Detector

This document illustrates the technical layout and the expected performance of the Micro Vertex Detector (MVD) of the PANDA experiment. The MVD will detect charged particles as close as possible to the interaction zone. Design criteria and the optimisation process as well as the technical solutions chosen are discussed and the results of this process are subjected to extensive Monte Carlo physics studies. The route towards realisation of the detector is outlined

Optimising the NAOMI adaptive optics real-time control system

This thesis describes the author's research in the field of Real-Time Control (RTC) for Adaptive Optics (AO) instrumentation. The research encompasses experiences and knowledge gained working in the area of RTC on astronomical instrumentation projects whilst at the Optical Science Laboratories (OSL), University College London (UCL), the Isaac Newton Groups of Telescopes (ING) and the Centre for Advanced Instrumentation (СfAI), Durham University. It begins by providing an extensive introduction to the field of Astronomical Adaptive Optics covering Image Correction Theory, Atmospheric Theory, Control Theory and Adaptive Optics Component Theory. The following chapter contains a review of the current state of world wide AO instruments and facilities. The Nasmyth Adaptive Optics Multi-purpose Instrument (NAOMI), the common user AO facility at the 4.2 William Herschel Telescope (WHT), is subsequently described. Results of NAOMI component characterisation experiments are detailed to provide a system understanding of the improvement optimisation could offer. The final chapter investigates how upgrading the RTCS could increase NAOMI'S spatial and temporal performance and examines the RTCS in the context of Extremely Large Telescope (ELT) class telescopes

Performance modelling and enhancement of wireless communication protocols

In recent years, Wireless Local Area Networks(WLANs) play a key role in the data communications and networking areas, having witnessed significant research and development. WLANs are extremely popular being almost everywhere including business,office and home deployments.In order to deal with the modem Wireless connectivity needs,the Institute of Electrical and Electronics Engineers(IEEE) has developed the 802.11 standard family utilizing mainly radio transmission techniques, whereas the Infrared Data Association (IrDA) addressed the requirement for multipoint connectivity with the development of the Advanced Infrared(Alr) protocol stack. This work studies the collision avoidance procedures of the IEEE 802.11 Distributed Coordination Function (DCF) protocol and suggests certain protocol enhancements aiming at maximising performance. A new, elegant and accurate analysis based on Markov chain modelling is developed for the idealistic assumption of unlimited packet retransmissions as well as for the case of finite packet retry limits. Simple equations are derived for the through put efficiency, the average packet delay, the probability of a packet being discarded when it reaches the maximum retransmission limit, the average time to drop such a packet and the packet inter-arrival time for both basic access and RTS/CTS medium access schemes.The accuracy of the mathematical model is validated by comparing analytical with OPNET simulation results. An extensive and detailed study is carried out on the influence of performance of physical layer, data rate, packet payload size and several backoff parameters for both medium access mechanisms. The previous mathematical model is extended to take into account transmission errors that can occur either independently with fixed Bit Error Rate(BER) or in bursts. The dependency of the protocol performance on BER and other factors related to independent and burst transmission errors is explored. Furthermore, a simple-implement appropriate tuning of the back off algorithm for maximizing IEEE 802-11 protocol performance is proposed depending on the specific communication requirements. The effectiveness of the RTS/CTS scheme in reducing collision duration at high data rates is studied and an all-purpose expression for the optimal use of the RTS/CTS reservation scheme is derived. Moreover, an easy-to-implement backoff algorithm that significantly enhances performance is introduced and an alternative derivation is developed based on elementary conditional probability arguments rather than bi-dimensional Markov chains. Finally, an additional performance improvement scheme is proposed by employing packet bursting in order to reduce overhead costs such as contention time and RTS/CTSex changes. Fairness is explored in short-time and long-time scales for both the legacy DCF and packet bursting cases. AIr protocol employs the RTS/CTS medium reservation scheme to cope with hidden stations and CSMA/CA techniques with linear contention window (CW) adjustment for medium access. A 1-dimensional Markov chain model is constructed instead of the bi-dimensional model in order to obtain simple mathematical equations of the average packet delay.This new approach greatly simplifies previous analyses and can be applied to any CSMA/CA protocol.The derived mathematical model is validated by comparing analytical with simulation results and an extensive Alr packet delay evaluation is carried out by taking into account all the factors and parameters that affect protocol performance. Finally, suitable values for both backoff and protocol parameters are proposed that reduce average packet delay and, thus, maximize performance