Photon-Counting Underwater Wireless Optical Communication by Recovering Clock and Data From Discrete Single Photon Pulses

Abstract

To realize a long-distance underwater communication by using low-cost light emitting diode (LED) and single photon avalanche diode (SPAD), we proposed a method for recovering clock and data directly from discrete random pulse sequences output by SPAD. On this basis, a new communication model is established, taking into account not only fluctuations in photon flux and quantum efficiency of photon detection in a time-slot, but also the phase difference of the recovered clock caused by it. A photon-counting underwater optical wireless communication (UOWC) system was built. The effects of the system setting parameters such as the number of gating signals, synchronous character length and baud rate on the average bit error rate (BER) were verified by experiments. The experimental results show that under condition of only average 10 photons in one time-slot, photoncounting UOWC with a BER of 3.51 × 10 −4 and a baud rate of 1 Mbps can be achieved.

A High-Speed and High-Sensitivity Photon-Counting Communication System Based on Multichannel SPAD Detection

“…Therefore, an accurate slot synchronization method is necessary to determine which pulses belong to each slot. The slot synchronization method we employed here is similar to that cited in a previous study [10], in [10], a series of gated signals which had the same cycle but different offsets were used, and slot synchronization could be achieved by calculating the slot's maximum count value. In this study, the slots were very short and the output pulse width of detector was longer than the slot width, and so we needed to calculate the maximum sum of the four channels' pulse-increasing edges.…”

Security of Underwater and Air-Water Wireless Communication

“…Optical-based underwater WCNs utilize (visible or invisible) light to carry information whereby a laser diode (LD) and/or a light emitting diode (LED) are used as the sources for transmission [46][47][48][49]. The optical underwater WCNs recently received attention due to their favorable characteristics such as high speed, high data rates, and high bandwidth [47][48][49][50][51][52][53][54][55]. The effective communication range of optical-based underwater WCN is greater than its RF-based counterpart but quite lower than acoustic-based counterpart (typically, up to 100m).…”

Real-Time and High-Speed Underwater Photon-Counting Communication Based on SPAD and PPM Symbol Synchronization

“…However, it is difficult to directly apply this method to a photon-counting detector that outputs Poisson discrete digital signals. Yan et al [12] used multiple clocks with the same slot frequency but different phases to count signal pulses in each slot and select an optimum clock. However, this method is only suitable for scenarios with relatively wide slots.…”

“…However, SPAD arrays have a low detection sensitivity and require several hundred to several thousand photons to deliver one bit. The single-pixel digitaloutput-mode SPAD has a communication rate of up to 2 Mbps and a higher sensitivity than the SPAD array by two orders of magnitude [11,12]. On the other hand, only two experimental studies [5,6] have reduced the bit error rate (BER) to a usable level (10 -6 ) through channel coding, and most studies have failed to achieve real-time signal processing or elucidate realtime signal processing methods.…”