Robust Timing Synchronization for AC-OFDM Based Optical Wireless Communications

TL;DR

This paper introduces a robust, efficient timing synchronization method for AC-OFDM optical wireless systems, improving accuracy and compatibility across various modulation schemes in visible light communication environments.

Contribution

It presents a novel synchronization scheme that outperforms existing methods in AC-OFDM optical wireless systems, applicable to multiple modulation techniques.

Findings

Method achieves higher synchronization accuracy.

Applicable to ACO-OFDM, PAM-DMT, DHT schemes.

Validated through numerical and experimental results.

Abstract

Visible light communications (VLC) have recently attracted a growing interest and can be a potential solution to realize indoor wireless communication with high bandwidth capacity for RF-restricted environments such as airplanes and hospitals. Optical based orthogonal frequency division multiplexing (OFDM) systems have been proposed in the literature to combat multipath distortion and intersymbol interference (ISI) caused by multipath signal propagation. In this paper, we present a robust timing synchronization scheme suitable for asymmetrically clipped (AC) OFDM based optical intensity modulated direct detection (IM/DD) wireless systems. Our proposed method works perfectly for ACO-OFDM, Pulse amplitude modulated discrete multitone (PAM-DMT) and discrete Hartley transform (DHT) based optical OFDM systems. In contrast to existing OFDM timing synchronization methods which are either not suitable for AC OFDM techniques due to unipolar nature of output signal or perform poorly, our proposed method is suitable for AC OFDM schemes and outperforms all other available techniques. Both numerical and experimental results confirm the accuracy of the proposed method. Our technique is also computationally efficient as it requires very few computations as compared to conventional methods in order to achieve good accuracy.