可见光通信的脉冲调制和调光方法研究

发布时间：2018-09-11 10:59

【摘要】：LED灯具有寿命长、节能环保的特点，是下一代的主要照明光源。而用其进行通信的可见光通信也受到越来越多人的关注。本文主要是围绕可见光通信的调光和数据调制来展开研究的。首先，简要介绍了可见光通信系统的组成及特点。分析了可见光通信中发射端到接收端的链路模型，即可概括为直射视距链路和漫反射链路。并详细叙述了这两个信道链路的数学模型及系统的信噪比。其次，本文详细分析了可见光通信中的调光和数据传输方案。最常做的是用脉冲宽度调制来调光，再与其他的数据调制方案结合，从而满足人们用LED灯同时来照明和通信的要求。因为这种方案需额外的PWM来调光，所以大大增加了系统的复杂度。另一种方法是用子载波脉冲位置调制，改变调制深度来调光，但其需要高频子载波来来传输数据。最后是有别于以上两种方法的速率可变的多脉冲位置调制，它用一种调制方案就能同时实现调光和传输数据。可以说，多脉冲位置调制在可见光通信中有天然的优势。最后，基于多脉冲位置调制在可见光通信中的独有的优势，重点研究其误码率、带宽功率需求。由于仿真发现MPPM的误码率相对于PPM较高，于是，接下来提出了减小MPPM误码率，提高其可靠性的改进方案，即间隔多脉冲位置调制方案。并设计出间隔多脉冲位置调制的两种添加保护间隔的方法，即最小时隙法和最小BER法。经过分析并仿真两种方法下系统的误码率、带宽功率需求，结果表明，两种方法较MPPM误码率都降低了许多，相对PPM也都有较好的抑制码间干扰的能力。只是最小时隙法更适合用于信源比特较小的情况，而最小BER法更为灵活，，应用范围更广。
[Abstract]:LED lamps have the characteristics of long life, energy saving and environmental protection, and are the main lighting source of the next generation. More and more people pay attention to the visible light communication. This paper focuses on the dimming and data modulation of visible light communication. Firstly, the composition and characteristics of visible light communication system are introduced briefly. The link model from transmitter to receiver in visible light communication is analyzed, which can be summarized as direct line-of-sight link and diffuse reflection link. The mathematical model of the two channel links and the signal-to-noise ratio of the system are described in detail. Secondly, the scheme of dimming and data transmission in visible light communication is analyzed in detail. The most common thing to do is to use pulse width modulation to dimming light and then combine it with other data modulation schemes to meet the requirements of both lighting and communication using LED lights at the same time. The complexity of the system is greatly increased because the additional PWM is required for this scheme. Another method is to modulate the position of the subcarrier pulse to change the modulation depth, but it needs the high frequency subcarrier to transmit the data. Finally, the multi-pulse position modulation, which is different from the above two methods, can realize dimming and transmitting data simultaneously with one modulation scheme. It can be said that multi-pulse position modulation has a natural advantage in visible light communication. Finally, based on the unique advantages of multi-pulse position modulation in visible light communication, the BER and bandwidth power requirements are studied. Because the simulation results show that the bit error rate (BER) of MPPM is higher than that of PPM, an improved scheme to reduce the BER and improve the reliability of MPPM is proposed. Two methods of adding protection interval to multi-pulse position modulation are designed, that is, the minimum slot method and the minimum BER method. The BER and bandwidth power requirements of the two methods are analyzed and simulated. The results show that the BER of the two methods is much lower than that of MPPM, and that the BER of the two methods is better than that of PPM. However, the minimum time slot method is more suitable for small source bits, while the minimum BER method is more flexible and more widely used.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.1

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