Indoor gigabit optical wireless communications: challenges and possibilities

Indoor Gigabit optical wireless communication systems have the potential to offer multiple high-speed data services that can be delivered to homes via an optical fibre cable in the near future. In this paper we will discuss the challenges involved in the design of such systems and future possible advances. Results from a recent cellular Gigabit prototype link will also be presented and discussed

Prolog to the section on wireless communications technology

The authors take a look at the existing 3G systems in service and investigate the capabilities of 4G, and while the theoretical throughput of these cellular systems is expected to be high, the future promises to offer more technological improvements and innovations.<br/

A guide to wireless networking by light

The lack of wireless spectrum in the radio frequency bands has led to a rapid growth in research in wireless networking using light, known as LiFi (light fidelity). In this paper an overview of the subsystems, challenges and techniques required to achieve this is presented

A comparison of APD and SPAD based receivers for visible light communications

Visible light communications (VLC) is an alternative method of indoor wireless communications that requires sensitive receivers. Ideally, single photon avalanche detectors (SPADs) could be used to create more sensitive receivers. However, the dead-time, finite output pulse width and photon detection efficiency of existing SPAD arrays limits their sensitivity and bandwidth. In this paper an accurate equation for the impact of dead-time on the sensitivity of a SPAD array is presented. In addition the impact of the width of the output pulses on the on-off keying (OOK) data rate is investigated. Finally, a comparison between receivers containing an APD and a large array of SPADs shows that although the receiver containing the SPAD is more sensitive in the dark the APD-based receiver is more sensitive in normal operating condition. However, the models that predict the performance of both receivers suggest that newer SPAD arrays will enable significant improvements in receiver sensitivity

Efficient depletion of host DNA contamination in malaria clinical sequencing.

The cost of whole-genome sequencing (WGS) is decreasing rapidly as next-generation sequencing technology continues to advance, and the prospect of making WGS available for public health applications is becoming a reality. So far, a number of studies have demonstrated the use of WGS as an epidemiological tool for typing and controlling outbreaks of microbial pathogens. Success of these applications is hugely dependent on efficient generation of clean genetic material that is free from host DNA contamination for rapid preparation of sequencing libraries. The presence of large amounts of host DNA severely affects the efficiency of characterizing pathogens using WGS and is therefore a serious impediment to clinical and epidemiological sequencing for health care and public health applications. We have developed a simple enzymatic treatment method that takes advantage of the methylation of human DNA to selectively deplete host contamination from clinical samples prior to sequencing. Using malaria clinical samples with over 80% human host DNA contamination, we show that the enzymatic treatment enriches Plasmodium falciparum DNA up to ∼9-fold and generates high-quality, nonbiased sequence reads covering >98% of 86,158 catalogued typeable single-nucleotide polymorphism loci

Ultra-sensitive UV solar-blind optical wireless communications with an SiPM

In this Letter, an SiPM with a dedicated cooling system suitable for receiving ultra-low-power solar-blind wavelengths is reported. This is designed to decrease the temperature of the detector from 21°C to –10°C, and the corresponding dark count rate (DCR) is reduced by approximately 10 dB. A 275 nm optical wireless communication (OWC) system is established using on–off-keying (OOK) modulation. Transmission rates ranging from 100 kbit/s to 2 Mbit/s are demonstrated with this cooled SiPM. The received power is as low as 30 pW (corresponding to 41.5 photons per bit) at a data rate of 1 Mbit/s and a bit error rate of 2.4 × 10–3

Derivation of an analytical expression for the power coupling coefficient for offset launch into multimode fiber

The demand for higher bandwidth in local area networks (LANs) has fuelled considerable research in techniques for mitigating modal dispersion in multimode fiber (MMF).These techniques include selective mode excitation, offset launching, angular multiplexing and electronic dispersion compensation, all of which strive to optimize the channel impulse response of a MMF.To obtain the optimal bandwidth-enhancement results from these techniques, knowledge of the distribution of power coupling coefficients given an arbitrary offset launch in a MMF is important.In this paper, an analytical expression for the power coupling coefficient for an incident Gaussian beam launched with a radial offset into a MMF having an infinite parabolic refractive index profile is derived.This expression is useful in understanding the parameters which may affect the power coupling coefficient and how they may enhance the MMF bandwidth. The power coupling coefficients obtained from the derived analytical expression are compared with numerical results and are in excellent agreement.The analytical expression may be extended to manufactured MMF

European H2020 Project WORTECS Wireless Mixed Reality Prototyping

This paper presents European collaborative project WORTECS objectives and reports on the development of several radio and optical wireless prototypes and a demonstrator targeting mixed reality (MR) application. The aim is to achieve a net throughput of up to Tbps in an indoor heterogeneous network for the MR use case, which seems to be a high throughput "killer application" beyond 5G. A special routing device is associated with the demonstrator to select the most suitable wireless access technology. Post introduction to the project, an overview of the demonstrator is presented with details of the current progress of the prototypes

Evaluation of the ACE employment programme: helping employers to make tailored adjustments for their autistic employees

Purpose The purpose of this study was to explore the views of autistic people, carers and practitioners regarding the barriers autistic employees face at work (Study 1) and to use these views to inform the design of an employment programme for autistic employees without learning disabilities (Study 2). Design/methodology/approach In Study 1, 16 (20%) carers, 17 (21%) practitioners and 47 (59%) autistic adults who had been or were currently employed, answered a survey regarding barriers at work. Study 2 evaluates the efficacy of a set of profiling assessment tools (PA) developed to help employers make individually-tailored adjustments for their autistic employees by delivering an employment programme consisting of 15, 8-week work placements. Findings In Study 1, only 25% of autistic adults reported having had adjustments in the workplace and all groups reported this as the main barrier – alongside employers’ lack of understanding. Two sets of results demonstrate the efficacy of the PA tools in addressing this barrier. First, a comparative cost simulation revealed a cost-saving in terms of on-job support of £6.67 per participant per hour worked relative to published data from another programme. Second, 83% of autistic employees reported having had the right adjustments at work. Research limitations/implications This is an exploratory study that did not include a comparison group. Hence, it was not possible to evaluate the efficacy of the PA tools relative to a standard employment programme intervention, nor to assess cost reduction, which currently is only estimated from already available published data. Practical implications Overall the findings from these studies demonstrate that the time invested in the high-quality assessment of the profile of autistic employees results in saving costs over time and better outcomes. Originality/value The originality of the Autism Centre for Employment programme resides in that, unlike other programmes, it shifts the focus from helping autistic employees to helping their employers