Aravind V. N. Jalajakumari

High-Speed Integrated Visible Light Communication System: Device Constraints and Design Considerations

Visible light communications (VLC) has the potential to play a major part in future smart home and next generation communication networks. There is significant ongoing work to increase the achievable data rates using VLC, to standardize it and integrate it within existing network infrastructures. The future of VLC systems depends on the ability to fabricate low cost transceiver components and to realize the promise of high data rates. This paper reports the design and fabrication of integrated transmitter and receiver components. The transmitter uses a two dimensional individually addressable array of micro light emitting diodes (μLEDs) and the receiver uses an integrated photodiode array fabricated in a CMOS technology. A preliminary result of a MIMO system implementation operating at a data rate of 1 Gbps is demonstrated. This paper also highlights the challenges in achieving highly parallel data communication along with the possible bottlenecks in integrated approaches.

Imaging-MIMO visible light communication system using μLEDs and integrated receiver

Multiple-input multiple-output (MIMO) transmission can be used to increase the throughput of visible light communication (VLC) systems. This approach is highly compatible with the use of arrays of micro light emitting diodes (μLEDs). In this work, we demonstrate an imaging-MIMO VLC system using a two dimensional individually addressable array of μLEDs and an integrated CMOS-based receiver. An aggregate data rate of -920 Mbps is realized using four parallel channels at a link distance of 1 m. Further improvement in the data rates is feasible by optimizing the system components and operating conditions.

Integrated multiple-input multiple-output visible light communications systems: recent progress and results

Solid state lighting systems typically use multiple Light Emitting Diode (LED) die within a single lamp, and multiple lamps within a coverage space. This infrastructure forms the transmitters for Visible Light Communications (VLC), and the availability of low-cost detector arrays offers the possibility of building Multiple Input Multiple Output (MIMO) transmission systems. Different approaches to optical MIMO are being investigated as part of a UK government funded research programme, ‘Ultra-Parallel Visible Light Communications’ (UPVLC). In this paper we present a brief review of the area and report results from systems that use integrated subsystems developed as part of the project. The scalability of these approaches and future directions will also be discussed.

An energy efficient high-speed digital LED driver for visible light communications

In this paper an energy efficient light emitting diode (LED) driver circuit for visible light communications (VLC) and results from the electrical and optical characterization are presented. A current steering digital to analogue converter (DAC) based LED driver circuit supporting 4-channels with an 8-bit resolution is realized in a 0.18 μm complimentary metal oxide semiconductor (CMOS) technology. Each channel delivers a full-scale current of 255 mA and achieves up to 67% electrical efficiency when driving 250 MS/s orthogonal frequency division multiplexing (OFDM) signals. Optical differential drive capability is demonstrated by using two output branches of a single channel to drive two different LEDs with an SNR improvement (>5 dB). The chip is also capable of full digital control of color shift keying (CSK) using multi-color LEDs enabling lighting color-temperature adjustment, dimming and multiple-input and multiple-output (MIMO) optical communications and these aspects will be the subject of future research.

High-Speed Integrated Digital to Light Converter for Short Range Visible Light Communication

Design details and characterization results of an integrated digital to light converter (DLC) for short range visible light communication (VLC) is reported. The integrated DLC can generate 16 light intensity levels at fast switching speeds, up to 500 MHz, thus enabling fast intensity modulated VLC. Data rates up to 365 Mb/s are achieved with bit error rate (BER) × 10-3 at a link distance of 5 cm and an average electrical power efficiency of 70%. Optimization in the micro light emitting diode (μ LED) manufacturing process has resulted in approximately threefold increase in data rate of the system. Spectrally efficient modulation schemes such as orthogonal frequency division multiplexing (OFDM) and pulse amplitude modulation (PAM) are also demonstrated using this integrated system.

60 Mb/s, 2 meters visible light communications in 1 klx ambient using an unlensed CMOS SPAD receiver

We demonstrate an optical link operating in indoor ambient lighting conditions using a CMOS single photon avalanche diode (SPAD) optical receiver and a RGB light emitting diode (LED). The high sensitivity of the SPAD receiver allows the link to operate at 2 m distance at a total 60 Mb/s and bit error rate (BER) of 1×10-3 without lensing. The transmitter implements color shift keying (CSK) using a custom 4-channel current mode CMOS digital to analog converter (DAC). The miniaturized, low cost components employed at transmitter and receiver are suited to integration in portable electronic devices or chip-in-a-bulb respectively.

Multi-Gigabit integrated MIMO visible light communication system: Progress and updates

This paper reports the progress on an integrated multi-Gigabit multiple input multiple output visible light communication system employing an array of micro-light emitting diodes and photodiodes. A system overview and experimental results obtained so far are presented.

A multigigabit per second integrated multiple-input multiple-output VLC demonstrator

In this paper, we report the performance of an imaging multiple-input multiple-output (MIMO) visible light communication (VLC) system. The VLC transmitter consists of a two-dimensional (2-D), individually addressable Gallium Nitride micro light-emitting diode (μLED) array. The receiver uses a 2-D avalanche photodiode array fabricated using complementary metal oxide semiconductor (CMOS). Using integrated CMOS-based LED drivers, a data rate greater than 1 Gb/s was obtained at a link distance of 1 m with the system field of view of 3.45° using four channels. At a reduced link distance of 0.5 m, a data rate of 7.48 Gb/s was obtained using a nine channel MIMO system. This demonstrates the feasibility of compact MIMO systems that offer substantial data rates.

100 Mb/s wavelength division multiplexing visible light communications link using a triple-junction photo-diode

We report the experimental realization of a 100 Mb/s wavelength division multiplexing link using commercial visible LED sources and a triple-junction photo-diode receiver. This is the first demonstration where multiple-junction technology is used for Visible Light Communication, showing its potential as a compact wavelength-selective transceiver.

Design, Fabrication, and Application of GaN-Based Micro-LED Arrays With Individual Addressing by N-Electrodes

We demonstrate the development, performance, and application of a GaN-based micro-light emitting diode ( <inline-formula><tex-math notation=LaTeX>