A Learning Approach for Robust Carrier Recovery in Heavily Noisy Visible Light Communication

Abstract

Visible Light Communication (VLC) exploits optical frequencies, diffused by usual LED lamps, for adding data communication features to illuminating systems. This paradigm has attracted a growing interest in both scientific and industrial community in the latter decade. Nevertheless, classical wireless communication mechanisms for physical and Medium Access Control (MAC) layers are hardly available for VLC, due to the massive external interference caused by sunlight. A correct signal carrier recover in high noise conditions represent a significant challenge. In this work, it is shown that the synchronization frame length affects the performance of the system in terms of Bit Error Ratio (BER). Since different external conditions require different minimum preamble lengths, we considered an Artificial Intelligence (AI) approach, based on multi-arm bandit formulation, for obtaining a low impact in both BER and goodput of the communication. A low-cost hardware VLC system, implementing a learning algorithm on a Frequency Shift Keying Modulation (FSK), has been designed and tested in different environmental conditions. Experimental results show that a proper choice of preamble length overcomes, in terms of BER and goodput, the classical approach based on fixed preambles.

On the Interference Immunity of Visible Light Communication (VLC)

“…Experimentation have been carried out up to 5GHz, considering three different modulations. Since no significant effects have been observed in the the range [1][2][3][4][5]GHz, results are presented in Figure 3 up to 1 GHz. The most important radiated emissions of the VLC system are at 222, 444 and 666 MHz.…”

“…In [4] the authors propose a signal processing mitigation approach for "mitigating" the impact of external light sources and improving the performance of the VLC in terms of Bit Error Rate (BER). The authors of [5] consider the external interference and propose a learning approach integrated in the VLC system in order to improve its robustness. In particular, the optimal preamble length of the synchronization message is computed by modeling the correct length selection as a multi-arm bandit.…”

A Noise Mitigation Approach for VLC Systems

“…Hence, noise is then mitigated The transmitter stage is implemented by considering a software defined approach. The effectiveness of the software defined concept for visible light communication has been already assessed in [12,13,14,15,16,17,18]. Motivated by the outcome of these works, we have implemented different modulation techniques at the transmitting stage equipped with an USRP-N200.…”