We demonstrate a high-speed light fidelity (LiFi) communication system deploying ultra-high brightness laser-based white light illumination sources in a surface mount device (SMD) packaging platform. The LiFi transmitter SMD source provides 450 lumens of white light output with a brightness of 1000 cd/mm2 in a dual wavelength configuration comprising blue and infrared (IR) emitting laser diodes within the SMD. First, we present high-speed data transmission beyond 25 Gbit/s over a 3 meter channel distance with the combined data rates from the blue and IR lasers in the single SMD. Next, we present a 2.8 Gbit/s data rate with the dual wavelength laser SMD light source using a side-emissive fiber as the transmitter. This work proves the viability of LiFi systems deploying laser-based white light sources operating at very high data rates with the visible light and communication signal delivered in conventional free-space transmission architectures along with novel configurations using side-emitting fibers.

In this work, we have designed, developed and deployed the world’s first optical wireless communication (OWC) system using off-the-shelf lasers and solar photovoltaics. Four bidirectional OWC prototypes have been installed on the Orkney Islands of Scotland at a 30 m link distance for the provision of high-speed internet access to two residential properties. The silicon-made solar panels can harvest power up to 5 W from sunlight and they offer data rates as high as 8 Mb/s. Using additional analogue processing, data rates higher than the existing landline broadband connection are achieved. This breakthrough opens the development path to low cost, self-powered and plug-and-play free-space optical (FSO) systems.

The need for more throughput in wireless cellular networks has been increasing in recent years. It has led to an increase in operational costs due to higher energy use as operators deploy more cell sites or increase transmission power at existing ones to satisfy demand. Energy costs are a major expense, and reducing them is a priority. This article presents a scheduler which aims to solve the problem of energy efficient resource allocation in orthogonal frequency division multiple access (OFDMA) cellular systems. The suggested approach is to make the resource scheduling process also consider energy costs as well as allow it to manipulate these by exploiting time/frequency vs energy efficiency trade-offs that are present in the system. The energy efficient score-based scheduler (EESBS) is a novel scheduler which takes energy costs into account when allocating resource blocks (RBs) to users. This allows it to promote energy efficiency in the system alongside throughput and fairness maximization. One of the means it has to manipulate users' expended energy is the bandwidth expanded mode (BEM). BEM is a technique that allows the scheduler to decrease a user's energy consumption by allocating it more RBs and maintaining a constant data rate. This is possible when the energy consumption is dominated by the energy used for data communication as opposed to control channel overhead transmission. Time compression mode (TCoM) is a technique that is complementary to BEM. It allows for energy savings through a reduction of the number of allocated RBs to a user when the energy consumption is dominated by the transmission of signaling traffic. Both BEM and TCoM need to be employed by an energy-aware scheduler like EESBS in order to extract the maximum performance gains. A realistic framework modeling future cellular systems is established to test the performance of the proposed techniques. Within this framework, EESBS generates an average energy saving of 29% over a frequency selective proportional fair (FsPF) benchmark. EESBS coupled with BEM or TCoM achieves a saving of 38% over the same benchmark. These savings are achieved with no detriment to user satisfaction in terms of achieved data rate.

Color converting films of colloidal quantum dots (CQDs) encapsulated with flexible glass are integrated with microsize GaN LEDs (μLEDs) in order to form optical sources for high-speed visible light communications (VLC). VLC is an emerging technology that uses white and/or colored light from LEDs to combine illumination and display functions with the transmission of data. The flexible glass/CQD format addresses the issue of limited modulation speed of typical phosphor-converted LEDs while enhancing the photostability of the color converters and facilitating their integration with the μLEDs. These structures are less than 70 μm in total thickness and are directly placed in contact with the polished sapphire substrate of 450-nm-emitting μLEDs. Blue-to-green, blue-to-orange and blue-to-red conversion with respective forward optical power conversion efficiencies of 13%, 12% and 5.5% are reported. In turn, free-space optical communications up to 1.4 Gb/s VLC is demonstrated. Results show that CQD-converted LEDs pave the way for practical digital lighting/displays with multi- Gb/s capability.

An onboard mobile communication system can be operated when the height of an aircraft is above 3000 m and the maximum equivalent isotropic radiated power (EIRP) outside an aircraft is below -13 dBm for 200 kHz bandwidth in a 1800 MHz system based on the Electronic Communications Committee (ECC) reports. However, in order to provide seamless connectivity for aircraft passengers, the onboard communication system should be in operation in every phase of the flight. Therefore, in this paper, the compatibility of an in-cabin Long Term Evolution (LTE) 1800 MHz femto cellular system with the current terrestrial LTE 1800 systems are investigated when an aircraft is stationary on the ground. Edinburgh Airport in Scotland and the existing LTE cells that provide network coverage at the airport are modeled through a simulation platform. Three Airbus A321 aircraft are modeled, while stationary, in the parked position on the apron and an in-cabin LTE femto cellular system is deployed within each aircraft. Signal-to-noise plus-interference ratio (SINR) and power leakage from the in-cabin evolved NodeBs (eNBs) in the downlink direction are considered as performance metrics to investigate the coexistence of the terrestrial and in-cabin systems. The simulation results show that the in-cabin LTE 1800 MHz femto cellular system can be operated without causing any significant interference to the existing terrestrial LTE 1800 MHz system while the aircraft is parked on the apron. However, it may be advisable to only operate the system when the aircraft doors are closed, in order to mitigate any possible interference effect on the users who are boarding the aircraft through the passenger boarding bridge. According to the results shown for a linear apron concept, the legislation governing the onboard mobile communication systems should be revised, in order to pave the way to the goal of seamless mobile connectivity in the next generation of communication systems.