MIMO-OFDM应用于室内可见光通信的技术研究

发布时间：2018-08-07 14:23

【摘要】：利用白光LED光源进行无线信息传输已成为当前国内外无线通信领域的研究热点,可见光通信(VLC)技术将LED照明和无线通信相结合,利用白光LED响应时间短、可被高速调制的特性,以光线作为载体,通过高速调节白光LED明亮强度来进行信息传输。VLC技术由于具有辐射安全性、超宽的频带及LED的普遍性,将成为室内无线高速通信的解决方案。MIMO-OFDM技术将OFDM和空时编码技术有机的结合起来,能够有效地抵抗多径效应,抑制干扰和噪声,能够大幅度的提高无线通信系统的传输速率和信道容量,实现数据高速可靠的传输。本文研究了OFDM系统子载波之间的正交性,调制解调以及传输误码率等性能,并将之与单载波传输系统在大尺度衰落下进行了详细的仿真比较,得出OFDM系统即使在大尺度衰落下也能够具有理想的低传输误码率。分析了MIMO应用于室内可见光通信的信道模型,一种是非成像式无线光MIMO通信,另一种是成像式MIMO通信,而且得出成像式无线光MIMO通信更适于实际应用。通过分析白光LED的驱动特性和室内可见光传输的信道模型,提出了利用MIMO-OFDM技术应用于室内可见光通信系统中,来实现高速可靠地信息传输。本文通过仿真对比了MIMO-OFDM技术、PPM调制技术和MIMO调制技术在不同的信噪比下误码率的情况,在相同的传输速率的情况下,MIMO-OFDM应用在可见光通信的调制技术表现出更低的误码率,在相同的码元周期进行信息传输时,信息传输速率更快而且误码率很低。在MIMO信号检测端,仿真对比分析了ML检测算法、ZF检测算法和MMSE检测算法在不同的信噪比情况下误码率情况,最大似然检测方法显示出更小的误码率,其次最小均方误差检测算法。但是最大似然检测算法随着发射天线个数和调制阶数的增加,算法复杂度会急剧的增加。
[Abstract]:White light LED light source for wireless information transmission has become a hot research topic in the field of wireless communication at home and abroad. Visible light communication (VLC) technology combines LED lighting with wireless communication, and the white light LED has short response time and can be modulated at high speed. With light as carrier, the technology of transmitting information by adjusting the bright intensity of white LED at high speed has the advantages of radiation safety, wide frequency band and the universality of LED. MIMO-OFDM will be the solution of indoor wireless high-speed communication. MIMO-OFDM can effectively resist multipath effect and suppress interference and noise by combining OFDM with space-time coding technology. It can greatly improve the transmission rate and channel capacity of wireless communication system, and achieve high-speed and reliable data transmission. In this paper, the orthogonality, modulation and demodulation between subcarriers of OFDM system, transmission error rate and so on are studied, and compared with single carrier transmission system in large scale fading. It is concluded that OFDM system can have ideal low bit error rate even in large scale fading. This paper analyzes the channel model of MIMO applied to indoor visible light communication, one is non-imaging wireless optical MIMO communication, the other is imaging MIMO communication, and it is concluded that imaging wireless optical MIMO communication is more suitable for practical application. Based on the analysis of the driving characteristics of white LED and the channel model of indoor visible light transmission, the application of MIMO-OFDM technology in indoor visible light communication system is proposed to realize high-speed and reliable information transmission. In this paper, the error rate of MIMO-OFDM modulation technology and MIMO modulation technology in different SNR is compared by simulation. In the case of the same transmission rate, the modulation technology of MIMO-OFDM in visible light communication shows a lower bit error rate. In the same symbol period, the information transmission rate is faster and the bit error rate is very low. At the detection end of MIMO signal, the error rate of ML detection algorithm, ZF detection algorithm and MMSE detection algorithm are compared and analyzed in different SNR cases. The maximum likelihood detection method shows a smaller bit error rate. Secondly, the minimum mean square error detection algorithm. However, the complexity of the maximum likelihood detection algorithm increases sharply with the increase of the number of transmit antennas and modulation order.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.1

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