Variable pulse position modulation receivers for visible light communication systems without the knowledge of dimming level

Abstract

The dimming control is one of the most significant issues to provide both illumination and data transmission for visible light communication (VLC) systems. The receivers-such as variable pulse position modulation (VPPM) receiver-must know the dimming level of the received signal for the demodulation process. To provide a complete solution to this problem, we propose two VPPM receivers that can detect data bits without knowledge of dimming level (KDL). The first one, which is referred to as artificial neural network (ANN)-VPPM, includes the ANN technique to achieve a proper step signal instead of traditional mask signals that are generated by using the perfect KDL. The ANN-VPPM gives a successful bit error rate (BER) performance compared to the unsuitable traditional system (U-TS), which is called the traditional system that decodes the VPPM signal using inappropriate mask signals. If the ANN-VPPM is compared to traditional system (TS), which is the traditional system using a perfect mask signal, the TS has better BER performance than the ANN-VPPM. Hence, the other one that is called the proposed estimation method (PEM) is improved to achieve the same BER performance compared to the TS.An estimation performance is given to indicate the 100% estimation rate and to prove that the BER performance of systems is the same at least signal-to-noise ratio of 22 dB. Additionally, the PEM is saving the optical power of the VPPM signal up to 23% at a BER of 10 −3 when compared to U-TS.

Interference mitigation in multiuserWDM VLCsystems using differential receiver

“…One of the main issues in indoor VLC systems is the small coverage area of each cell, which means interference will be very high between transmitters (Txs). In addition, enabling user mobility while keeping the quality of the service at acceptance level is very difficult in indoor VLC systems 1‐3 . Reducing the effect of interference in a multiuser VLC is vital to attain high data rate services for each user.…”

“…In addition, enabling user mobility while keeping the quality of the service at acceptance level is very difficult in indoor VLC systems. [1][2][3] Reducing the effect of interference in a multiuser VLC is vital to attain high data rate services for each user. To realize requirements of lighting in indoor environments, more than one luminaire (light bulb) must be used.…”