A Noise Mitigation Approach for VLC Systems

Abstract

Visible Light Communication (VLC) is based on the dual use of the illumination infrastructure for wireless data communication. The major interest on this communication technology lies on its specific features to be a secure, costeffective wireless technology. Recently, this technology has gained an important role as potential candidate for complementing traditional RF communication systems. Anyway a major issue for the VLC development is a deep comprehension of the noise and its impact on the received signal at the receiver. In this work, we present a simple but effective approach to analyze the noise and drastically reduce it through a signal processing method. In order to validate the effectiveness of this analytical approach, we have developed an USRP-based testbed. Experimental results have been carried out by evaluating the symbol error rate (SER) and show the effectiveness of the noise mitigation approach in different interference conditions and at different distance between the transmitter and the receiver.

Adaptive Modulation Control for Visible Light Communication Systems

“…However, since optical signals are modulated as square waves, filtering process is not sufficient to achieve a clean output. In [10] spectral line interference is theoretically analysed and approximately mitigated by adopting a set of improved waveform samples; in [11] noise effects on synchronization are reduced using a learning technique based on multi-armed bandit; an effective noise mitigation approach, based on the noise listening and successive noise mitigation to limit the effects of external lights on Symbol Error Rate (SER) has been introduced in [12].…”

“…Differently, in the case of ceiling-to-floor communication it is important to pay attention for the uplink channel due to light coming from floor-to-ceiling. • We apply a noise mitigation approach as defined in [12], with the main difference that we integrate this approach to work in real-time. In practice, the variations of external conditions directly impact on the performance of the system evaluated in terms of SNR and thanks to a fine-coarse synchronized uplink channel, the communication system is able to adapt with the most appropriate modulation scheme.…”

“…From this point of view, the opportunity of hearing interference without any information signal is fundamental to acquire information about the disturbing elements. However, the simple measure of interference level, that is power, is not sufficient to provide statistical elements for interference mitigation [12]. In order to do so, we resort to linear prediction for the interference term so as to have the auto-correlation properties.…”

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.…”

“…The authors prove the importance of including this interference in the optical wireless indoor channel model in order to enhance the performance of the communication system above all for systems operating at high rate of several Mbit/s. 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.…”