Mengjie Zhang

3.375-Gb/s RGB-LED based WDM visible light communication system employing PAM-8 modulation with phase shifted Manchester coding.

Optical background noise and second-order nonlinear distortions are two main challenges faced by indoor high-speed VLC system. In this paper, a novel phase shifted Manchester (PS-Manchester) coding based on PAM-8 is proposed and experimentally demonstrated to mitigate these noise and distortions. With the aid of PS-Manchester coding and WDM, a total data rate of 3.375-Gb/s can be successfully achieved in the RGB-LED based VLC system. The BER is under 7% HD-FEC limit of 3.8x10-3 after 1-m indoor free space transmission. To the best of our knowledge, this is the highest data rate ever achieved in PAM VLC systems.

A novel scalar MCMMA blind equalization utilized in 8-PAM LED based visible light communication system

Inter-symbol interference (ISI) in visible light communication (VLC) systems has been considered as a major problem that seriously deteriorates system performance. A series of equalization algorithms have been widely investigated and utilized to eliminate ISI and improve the system performance. In this paper, we propose a novel algorithm called scalar modified cascaded multi-modulus algorithm (S-MCMMA) used in VLC system with PAM modulation. Furthermore, we experimentally demonstrate a red LED based PAM VLC system employing hardware pre-equalization technology and S-MCMMA equalization. A data rate of 525-Mbit/s for 8-PAM is successfully achieved in 1-m indoor free space transmission with the bit error rate (BER) below the 7 % forward error correction (FEC) limit of 3.8 × 10-3. Compared to the LMS equalization, the performance of S-MCMMA behaves quite similar (with a slight of advantage of S-MCMMA). However, the scheme is blind post-equalization without any training sequence aided thus higher bandwidth efficiency is achieved.

2.32 Gbit/s phosphorescent white LED visible light communication aided by two-staged linear software equalizer

We proposed two-staged linear software equalizer to be applied in high speed visible light communication system. Through the experimental demonstration, we implemented 2.32 Gbit/s VLC transmission based on a phosphorescent white LED with 450MHz bandwidth and 1m transmission distance. The other key technologies are adaptive bit and power loading OFDM, differential amplification PINs and maximum ratio combing algorithm. As far as we know, this is the highest data rate implemented based on a phosphorescent white LED in VLC system.

100-m field trial for 5G wireless backhaul based on circular (7,1) 8-QAM modulated outdoor visible light communication

Visible light communication (VLC) offers a power-efficient, clean alternative to RF technology, which is feasible for future 5G wireless backhaul. We experimentally demonstrate an outdoor WDM-VLC system employing circular (7,1) modulation. An aggregate capacity of 1.74Gb/s is successfully achieved over 100-m outdoor free space transmission.

PAPR reduction of 2.0Gbit/s DFT-S OFDM modulated visible light communication system based on interleaved sub-banding technique

In visible light communication (VLC) system, the Orthogonal Frequency Division Multiplexing (OFDM) technique has been widely used to achieve a high data rate transmission. However, OFDM will cause high peak-to-average power ratio (PAPR) in the VLC system. In this paper, we propose and experimentally demonstrate a new interleaved Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-S OFDM) method. We compare the interleaved DFT-S technique to other PAPR reduction techniques, such as Clipping OFDM and conventional DFT-S. The experimental results show that interleaved DFT-S achieve FEC threshold for an overall 2.0Gb/s 32QAM signal over the 1.05m transmission. In addition, interleaved DFT-S presents significant PAPR reduction, low complexity and optimal BER performance, when compared to other techniques.

Nanopatterned luminescent concentrators for visible light communications

Visible light communication (VLC) is a promising candidate for high-speed wireless communication with numerous unlicensed spectrum. To achieve high-speed data communication, it requires intense light signals concentrated on a tiny fast photodiode. The common way of using focusing optics reduces the field of view (FoV) of the photodiode due to the conservation of étendue. Luminescent solar concentrators (LSC) provide a solution to enhance the signals without affecting the FoV. In this paper we demonstrate nanopatterned LSCs fabricated on flexible plastics that achieve a doubling of optical gain compared to its traditional rectangular counterparts. These LSCs can free VLC detectors from complex active pointing and tracking systems, making them compatible with smart mobile terminals in a simple fashion.

Experiment of audio visual communication system based on white LED and intelligent mobile terminal

With the innovation of mobile digital terminals and the development of visible light communication system, how to combine mobile terminals and existing visible light communication systems will become an important issue. This paper puts forward one kind of visible light communication system, which is used in the room with the earphone jack as the receiving channel of the mobile terminal. The system takes the commercial white light emitting diodes as the transmitter, and the receiver is composed of a high sensitivity PIN and a mobile phone. This system utilize QPSK-OFDM modulation format, and the relationship among bit error rate, transmission rate and distance is investigated. When the transmission rate is lower than 16 kB/s, bit error rate (BER) in this system are under the error threshold within 1 meter.