基于空间调制的光通信理论与技术

发布时间：2018-08-22 17:47

【摘要】：光通信(OWC)结合了照明和通信两大功能,采用发光二极管(LED)进行数据交换,具有频谱资源丰富、保密性好、节能环保等优点,逐渐成为广泛关注的新型无线通信技术。本文以理论研究和分析为主,针对基于空间调制(SM)技术的OWC系统的信道容量展开研究,分别给出了信道容量的上下界,同时研究了自适应调制技术在OWC系统的应用。通过本文研究,可以进一步丰富OWC的理论。由于OWC中光信号采用强度调制,和传统无线射频通信存在本质差异,OWC信号是单极性的信号,所以传统射频通信中的很多理论对OWC都不适用,因此研究OWC的相关问题变得十分必要。对于信道容量问题和自适应调制技术而言,明确针对基于SM技术的OWC系统的结论尚没有在公开发表的论文上出现。本论文分析对比了 OWC系统中常用的几种空间调制技术:空间位移键控调制(SSK),广义空间位移键控调制(GSSK),空间调制(SM),广义空间调制(GSM)。空间调制技术将待传输比特调制到信号域和空间域同时传输。信号域上将信息比特进行脉冲幅度调制(PAM),调制符号对应星座图上的星座点,空间域上将信息比特调制到激活LED的序号,通过空间域符号提高了频谱利用率。采用空间调制的通信系统不会受信道间干扰(ICI)的影响,也不需要对发射端的LED进行同步,系统复杂度大大降低。本论文研究了基于SM技术的OWC系统的信道模型,推导了 OWC的信道容量。首先对OWC系统进行分类,分为多输入单输出系统(MISO)和多输入多输出(MIMO)系统两类,分别对信道容量进行研究。接着利用信息处理不等式推导了下界信道容量;然后基于接收端准确判决激活LED序号的假设推导了上界信道容量。本论文研究了自适应调制技术在OWC系统中的应用,并提出了最优和次优两种方案。
[Abstract]:Optical communication (OWC), which combines the functions of lighting and communication, uses light-emitting diode (LED) to exchange data, has the advantages of rich spectrum resources, good confidentiality, energy saving and environmental protection, and has gradually become a new wireless communication technology which has been paid more and more attention. Based on the theoretical research and analysis, this paper studies the channel capacity of OWC system based on spatial modulation (SM) technology, gives the upper and lower bounds of channel capacity, and studies the application of adaptive modulation technology in OWC system. Through the research in this paper, the theory of OWC can be further enriched. Because the intensity modulation is used in the optical signal of OWC, and there is essential difference between the optical signal and the traditional radio frequency communication, the signal is unipolar, so many theories in the traditional radio frequency communication are not applicable to the OWC. Therefore, it is necessary to study the related problems of OWC. For channel capacity problem and adaptive modulation technology, the conclusion of OWC system based on SM technology has not appeared in the published papers. In this paper, several spatial modulation techniques commonly used in OWC system are analyzed and compared: spatial displacement keying modulation, (SSK), generalized spatial displacement keying modulation, (GSSK), spatial modulation, (SM), generalized spatial modulation (GSM). Spatial modulation technology modulates the bits to be transmitted to the signal domain and the spatial domain simultaneously. In the signal domain, the information bits are modulated by pulse amplitude modulation (PAM),) to correspond to the constellation points on the constellation map, and the information bits are modulated to the sequence number of the active LED in the spatial domain. The spectral efficiency is improved by the spatial symbol. The spatially modulated communication system is not affected by the interchannel interference (ICI), nor does it need to synchronize the LED of the transmitter, so the complexity of the system is greatly reduced. In this paper, the channel model of OWC system based on SM technology is studied, and the channel capacity of OWC is deduced. Firstly, the OWC system is classified into two categories: multiple input single output system (MISO) and multi-input and multi-output (MIMO) system. The channel capacity is studied respectively. Then the lower bound channel capacity is derived by using the information processing inequality, and the upper bound channel capacity is derived based on the assumption that the receiver can accurately determine the activation of the LED sequence number. In this paper, the application of adaptive modulation technology in OWC system is studied, and two schemes are proposed: optimal and suboptimal.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

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