Pallab Choudhury

3.4 Gbit/s visible optical wireless transmission based on RGB LED.

In this paper, we experimentally realized a gigabit-class indoor visible light communication system using commercially available RGB White LED and exploiting an optimized DMT modulation. We achieved data rate of 1.5 Gbit/s with single channel and 3.4 Gbit/s by implementing WDM transmission at standard illumination levels. In both experiments, the resulting bit error ratios were below the FEC limit. To the best of our knowledge, these values are the highest ever achieved in VLC systems.

1-Gb/s Transmission Over a Phosphorescent White LED by Using Rate-Adaptive Discrete Multitone Modulation

Light-emitting diodes (LEDs), which will be increasingly used in lighting technology, will also allow for distribution of broadband optical wireless signals. Visible-light communication (VLC) using white LEDs offers several advantages over the RF-based wireless systems, i.e., license-free spectrum, low power consumption, and higher privacy. Mostly, optical wireless can provide much higher data rates. In this paper, we demonstrate a VLC system based on a white LED for indoor broadband wireless access. After investigating the nonlinear effects of the LED and the power amplifier, a data rate of 1 Gb/s has been achieved at the standard illuminance level, by using an optimized discrete multitone modulation technique and adaptive bit- and power-loading algorithms. The bit-error ratio of the received data was

Enhancing Resilience to Rayleigh Crosstalk by Means of Line Coding and Electrical Filtering

1.5\cdot 10^{-3}

A Visible Light localization aided Optical Wireless system

, which is within the limit of common forward error correction (FEC) coding. These results twice the highest capacity that had been previously obtained.

2.1 Gbit/s visible optical wireless transmission

We demonstrate a technique that ameliorates the performance of bidirectional systems impaired by in-band Rayleigh crosstalk, which is common in passive optical access networks based on centralized remote wavelength feeding. The technique is based on the combined use of a suitable line coding and ad hoc postdetection electrical filtering. Therefore, it can be seamless implemented in optical access systems and it is easily scalable with the data rate. We experimentally assess the technique by using a 8B10B coded 1.25-Gb/s signal. We report an increased tolerance to the signal-to-crosstalk ratio by about 5 dB.

25 Gb/s operation of 1-GHz bandwidth R-SOA by using DMT and optical equalization

We report about a Line of Sight Optical Wireless Communication (LoS OWC) system aided by a simplified Visible Light localization algorithm for tracking purposes. We show experimentally that by combining the LoS OWC system with the localization algorithm it is possible to provide a gross data-rate exceeding 300 Mb/s over a 90° illumination angle by using a RGB visible-light LED at 90cm distance.

VLC-signals distribution over GI-POF for in-home wireless networks

We demonstrate gigabit-class indoor visible optical wireless transmission using commercial components and DMT modulation of a common visible RGB LED. We obtained 1 Gbit/s single channel and 2.1 Gbit/s WDM transmission at usual illumination levels.

Symmetric 10 Gb/s WDM-PON based on a cross wavelength-reusing scheme to avoid rayleigh backscattering and maximize band usage

We report the first experimental demonstration of 25Gb/s operation of 1GHz bandwidth-limited Reflective Semiconductor Optical Amplifier based on DMT modulation and optical equalization. This combination is highly resilient to chromatic dispersion.

Flexible radio-over-fibre signal distribution in in-building networks based on modulated ASE noise

We present the proof of concept of a wide-band signals distribution network combining plastic optical fiber (POF) and LED-based visible light communication (VLC). The proposed architecture exploits Frequency Division Multiplexing (FDM) of multiple signals, each of which selected at a specific VLC hot-spot. The multiplexed signals are first distributed via a POF; at the hot-spot a given frequency-band is down-converted to baseband and then transmitted through the optical wireless link. We demonstrated a distribution scenario over 50 m POF/2.5 m VLC link of two hot-spots, each having 200 Mbit/s capacity. We employed optimized discrete multi-tone modulation technique with optimal bit/power loading algorithm, maintaining the bit error ratio within the FEC limit.

Uncooled operation of directly-modulated and polarization insensitive self-seeded Fabry-Peròt laser diodes

We demonstrate a 10 Gb/s symmetrical WDM-PON exploiting a cross seeding scheme to enable wavelength reusing. It avoids reflection-induced penalties, and effectively removes any extinction-ratio constraint by means of DPSK modulation format in the downlink.