基于阵列单光子检测的水下LED无线光通信收发关键技术研究

The light-emitting diode (LED)-based wireless optical communication with single photon device is one of the potential technologies for underwater long-distance communication. Unfortunately, the system performance is seriously limited by the following factors: 1) The channel delay model of underwater long-distance optical communication is imperfect; 2) The dynamic range of the traditional single-point single photon avalanche diode (SPAD) detector is narrow and the dead-time effect restricts the transmission rate. 3) The output characteristic of the single photon device follows Poisson/ quasi-Poisson model. Hence, the traditional Gaussian transceiver theroy cannot be directly applied. According to the research ideas of arrayed design of transceiver and photonic design of detector, we propose the underwater LED-based wireless optical communication transceiver technology based on array multi-pixel photon counter (MPPC). Correspondingly, the main task of this project consists of the following three aspects: 1) Based on large-scale photonic monte-carlo numerical simulation , a long underwater delay channel model is established. 2)Duo to the natural characteristic of multi-wick in one LED bulb, we research the signal design and detection scheme of multi-wick cooperative superposed transmission based on array MPPC. 3) Starting with the efficient union detection under the Poisson cascade Gaussian mixture complex channel model, we study the actual output mathematical model of array MPPC. Then we design the signal synchronization, union detection and low-complexity detection schemes. Through the research of this project, we aim to provide theoretical foundation for long distance array single photon underwater wireless optical communication and advance the application of underwater integrated information network.

基于单光子检测的LED无线光通信是水下长距离通信的优选技术之一，然而系统性能受限于以下几个因素：1）水下长距离光通信时延信道模型不完善；2）传统单点单光子探测器动态范围小，死时间效应约束传输速率；3）单光子器件输出为泊松/准泊松的复杂模型，传统高斯信道收发机理论不能直接应用。依据“收发设计阵列化、探测器件光子化”的研究思路，本项目开展基于阵列多像素光子计数器MPPC的水下LED无线光通信技术研究，主要内容包含三部分：1)基于大规模光子级蒙特卡洛数值仿真，建立长距离水下时延信道模型；2）依据LED灯泡多灯芯的天然特性，研究基于阵列MPPC的多灯芯协同叠加传输信号设计和检测方案；3）以泊松级联高斯复杂信道模型的联合检测为出发点，研究阵列MPPC的实际准泊松信号输出特性、信号同步、联合检测和低复杂度检测方案。本项目力求为阵列单光子水下LED无线光通信奠定理论依据，推进水下综合信息网实用化进程。

本项目面向拓展距离的水下LED无线光通信典型应用需求，提出“收发器件阵列化，探测单元光子化”的研究思路，着力解决发送端信号设计、接收端联合高效检测的关键技术难题。具体而言，本项目的主要研究成果为：（1）建立典型情景下可见光通信系统不同光电探测器接收器的评价准则，分析了PIN、APD和SPAD接收机的噪声特性；建立了信噪比模型，总结了影响APD和SPAD接收机性能的主要因素。（2）设计非理想离散光子计数信号波形，降低了接收端检测复杂度，利用该波形的光通信系统，无需跟踪水下信道时变性。（3）提出水下单光子广播可见光通信时域联合多层多速率编码调制，该方案使得所有用户能够免于互相干扰的恢复自身数据，并且可以证明由于采用了联合设计方案整体星座的能量效率优于目前可用的分时复用方案。（4）提出面向高速通信的阵列探测器关联接收方法，关联选通接收机在高信号功率下具有更好的背景光耐受性和更好的误码率性能。（5）设计阵列多像素光子计数器的可见光通信实验系统，验证了所提方案的有效性。在此过程中，发表学术论文15 篇，其中SCI 检索7篇，EI检索5篇；出版学术专著1部；申请国家专利5项；累计具体指导和协助指导培养博士/硕士研究生9人，已提交学位论文9篇；获得河南省自然科学三等奖1项。