基于MIMO的可见光通信中的信道均衡

针对基于多输入多输出(MIMO)的室内可见光通信(Visible-Light Communication,VLC)系统中存在的码间串扰(ISI)问题进行了分析,并提出了适用于MIMO可见光通信系统的信道均衡方案及实现方法.仿真实验结果表明,该方法可以有效降低MIMO可见光通信系统中的码间串扰的影响.     

基于MPPM调光控制的混合可见光通信系统研究

在本文中,为适应照明的调光需求,提出了一种具 有高频谱效率的调光控制方案,这是也是可见光 通信(VLC)的关键需求。提出的方案将正交频分复用(OFDM)与多脉冲位置调制(MPPM) 相结合, 不仅支持高速可见光通信,同时满足了用户对照明源的亮度调节的需求。这种混合调制方法确保系统具有MPPM的调光功能,且引入的OFDM传输可以有效地提高频谱效率。更重要的是,MPPM跟OFDM的传输不会互相干扰,而且接收端对两种信号的检测互不干扰,实现简单。仿真结果表明,该 方案可以支持较宽的亮度范围,并支持高频谱无线光通信。     

基于张量模式噪声补偿的室内可见光通信系统的信道估计

针对现有中继转发式室内可见光通信系统中信道估计算法存在的导频数量过大、估计效率和精度低的问题,提出基于张量模式噪声补偿的信道估计方法。首先,充分利用可见光通信系统发射数据的特点设计了一种适合在接收数据中进行噪声补偿的导频结构。然后,在PARATUCK2张量分解框架下,构造了这种导频模式的含噪通信系统模型。最后,结合张量分解方法,设计了一种以导频所得噪声补偿对实际噪声进行估计的方法,完成所有信道参数的计算。仿真实验结果表明,将基于张量模式噪声补偿的估计算法应用在中继转发式室内可见光通信系统中,可以在加快寻优迭代速度的同时提高估计精确度,充分验证该算法的有效性和可行性。     

基于LED阵列的可视信道室内可见光通信系统设计

随着固态光源的发展,大功率LED已被广泛应用到照明中。将照明功能与通信功能结合的室内可见光通信系统将有广泛的应用前景。为了满足室内照明和通信要求,通过使用大功率LED构成阵列,设计发射端、接收端,接口模块,构建了基于强度调制及直接检测方法的全双工可见光通信系统。并对系统信道模型进行分析,对单向链路实际光强分布及其可靠通信范围进行实际测量。实验证明该系统的可行性和可靠性。     

基于自适应OFDM的室内可见光通信系统性能研究

为了提高室内可见光通信(VLC)系统性能并充分利用信道带宽资源,将OFDM与自适应技术结合应用于VLC系统中.讨论了系统反馈途径的实现方法,在室内空间环境建模的基础上,对自适应OFDM通信系统的吞吐量和误码率进行了Matlab仿真和分析.     

色/频/空三维资源复用的室内可见光非直流偏置OFDM系统性能研究

提出一种新的室内可见光非直流偏置正交频分（Non-DC-Biased Orthogonal Frequency Division Multiplexing, NDC-OFDM）复用系统,该系统采用多个颜色LEDs作为光源,在保证高传输可靠性的同时可以维持环境光的稳定。将空间调制和同色异谱调制结合并应用到室内可见光OFDM通信系统中得到一种新的适用于室内可见光通信系统的NDC-OFDM传输方案,该方案具有OFDM、空间调制和同色异谱调制的优势,适用于高速室内白光通信系统。仿真结果表明所提出的NDC-OFDM室内可见光传输系统与传统的直流偏置光OFDM （DC-biased Optical OFDM）和非对称限幅光OFDM （Asymmetrically Clipped Optical OFDM）相比具有更好的优势,并且与其它NDC-OFDM室内可见光传输方案相比,对于OFDM信号高峰均功率比引起的光信号非线性畸变问题,本文提出的多色LEDs NDC-OFDM室内可见光传输方案除了具有更好的鲁棒性外,还不会产生光强度波动。     

白光LED室内可见光通信的关键技术

可见光通信是一项新兴基于白光LED的无线光通信技术,具有发射功率高、不占用无线电频谱、无电磁干扰、无电磁辐射和节约能源等优点,能够同时实现照明和通信的双重功能。阐述了可见光通信技术的发展动态,介绍基于白光LED的室内可见光通信系统,并对提高系统整体性能的若干关键技术进行了研究讨论,为白光LED室内可见光通信系统进一步研究提供依据。     

基于U-OFDM的室内可见光通信系统调光控制方法

作为未来短距离无线通信有效可选方案的可见光通信,照明控制是其面临的主要挑战之一.在分析了采用连续电流调节(CCR)和脉冲宽度调制(PWM)两种调光控制技术的OFDM系统工作原理的基础上,提出了一种新的室内可见光高速通信调光控制系统设计方案.该方案将照明应用中的两种调光技术引入到功率效率高、误码性能好的单极性光OFDM(Unipolar OFDM)系统中,在提供良好传输性能的同时实现了照明信号的连续调节和线性调节功能.仿真实验表明,提出的方案调光控制性能与非对称消波光OFDM (ACO-OFDM)系统接近,而误码性能则优于后者,即U-OFDM调光控制系统可在不牺牲照明质量的同时获得更好的误码性能.     

白光LED室内可见光通信的关键技术

可见光通信是一项新兴基于白光LED的无线光通信技术,具有发射功率高、不占用无线电频谱、无电磁干扰、无电磁辐射和节约能源等优点,能够同时实现照明和通信的双重功能.阐述了可见光通信技术的发展动态,介绍基于白光LED的室内可见光通信系统,并对提高系统整体性能的若干关键技术进行了研究讨论,为白光LED室内可见光通信系统进一步研究提供依据.     

室内LED可见光语音通信网络的信道分配算法研究

采用SIC算法对室内LED可见光语音通信网络的信道分配进行研究。通过对室内可见光通信系统、白光音频调频信号传输系统原理的分析,设计了语音通信收发机电路。电路信号接收效果较好,利用SIC检测算法进行通信网络信道功率分配,与采用线性工作范围为2.25~5 V,工作电流范围为0.1~1 A的商用照明LED进行性能仿真试验,结果表明,与传统的FCA算法相比,SIC算法的阻塞率要高于FCA算法,且算法引入了更小的系统干扰量,在服务区内使用户通信质量得到保证。     

基于极化码的可见光通信自适应调光方法研究

针对在可见光通信的闪烁问题,提出了一种通过曼彻斯特编码级联极化码进行调光控制的自适应打孔方法。极化码与曼彻斯特编码级联以便于在可见光系通信统系统中提供50 ％的调光,并且通过打孔和插入补偿比特的方式可以实现不等于50 ％的调光值。常规打孔方案应将曼彻斯特编码符号的所有比特都打孔,本文提出的方法可以根据选定的极化码的预定冻结比特自适应地打孔,并插入相对应的补偿比特。因此,与常规打孔方法相比,所提出的方法可以对曼彻斯特编码符号的更少比特进行打孔并且需要更少的补偿比特。仿真结果表明,所提出的方法具有比参考方法更好的差错性能性能。     

Novel Architecture for Efficient Implementation of Dimmable VPPM in VLC Lightings

In this paper, a new architecture is proposed to achieve complexity efficiency in implementing variable pulse position modulation (VPPM). VPPM, specified in IEEE 802.15.7, can support wireless communication and dimming control simultaneously using visible light. The proposed architecture is based on the VPPM signal property in which the transition point of the modulated output is obtained by counting the sample index and comparing it to both the assigned dimming factor and the transmitting data. Therefore, the proposed architecture can be composed of simple logics, including a counter, a comparator, and an inverter, all of which are insensitive to the dimming resolution in contrast to a conventional codeword‐table method. This paper describes the verification of the proposed algorithm through a register‐transfer level implementation of the codeword and proposed architectures. In comparison with the codeword‐table method, the proposed method gains a nine‐fold complexity reduction at a 1% dimming‐step resolution.     

Visible Light Communication Method for Personalized and Localized Building Energy Management

The Paris agreement at the 21st Conference of the Parties (COP21) emphasizes the reduction of greenhouse gas emissions and increase in energy consumption in all areas. Thus, an important aspect is energy saving in buildings where the lighting is a major component of the electrical energy consumption. This paper proposes a building energy management system employing visible light communication (VLC) based on LED lighting. The proposed management system has key characteristics including personalization and localization by utilizing such VLC advantages as secure communication through light and location‐information transmission. Considering the efficient implementation of an energy‐consumption adjustment using LED luminaires, this paper adopts variable pulse position modulation (VPPM) as a VLC modulation scheme with simple controllability of the dimming level that is capable of providing a full dimming range. This paper analyzes the VPPM performances according to variable dimming for several schemes, and proposes a VPPM demodulation architecture based on dimming‐factor acquisition, which can obtain an improved performance compared to a 2PPM‐based scheme. In addition, the effect of a dimming‐factor acquisition error is analyzed, and a frame format for minimizing this error effect is proposed.     

基于PL3106的室内调光控制系统

针对室内布线不方便以及噪声干扰小的特点,设计了一种基于低压电力线载波通信芯片PL3106的室内调光控制系统。该系统以电力线为信息传输媒介,设计简单,节约成本。其关键要解决的电网噪声对通信的影响,从而延长通信距离。以PL3106为核心搭建了电力线载波通信的硬件电路,采用通信协议实现一对多通信,从而由总控制器控制多个照明节点。测试结果表明,该系统在400 m内通信稳定,能准确实现照明调光,取得了良好效果。     

A Novel Discrete Dimming Ballast for Linear Fluorescent Lamps

A novel discrete dimming ballast for linear fluorescent lamps is proposed in this paper. A proposed dimming control circuit is combined with a ballast module for multiple lamps to realize control of three discrete lighting levels. Compared with conventional step dimming or on– off control methods, the proposed discrete dimming method has the following advantages: 1) digital signal is generated by the dimming control circuit to control the lamps' turn- on and -off, which makes the system more reliable and integrated; 2) the proposed discrete dimming system replaces relays, which are necessary in conventional lamp on–off control, and therefore decreases the system cost; 3) the proposed dimming ballast can be installed by keeping the original wiring system. This makes the upgrading of a lighting system more effective and efficient; 4) the dimming control circuit also provides a good isolation for operating the low-voltage wall switches by hand safely. Both theoretical, simulation, and experimental results are in good agreement.      

基于电力线载波通信的智能调光系统设计

针对家用照明灯具远程测控系统的可靠性和经济性问题,设计了一套基于电力线载波通信的家居智能调光系统.整个系统以S3C6410智能网关为核心,内嵌Web服务器,结合GPRS/WIFI网络和电力线载波通信技术,实现了对室内LED灯具的调光控制、情景设置和定时开关等功能.介绍了该系统的总体设计方案、软硬件实现方法.测试结果表明,系统能够满足家居等对实时性要求不高的场合.系统结构简便、通信稳定、易于扩展.     

采用空间分集的LDPC编码协作系统性能研究

为了提高无线通信系统的可靠性,将协作通信技术和空间分集技术都引入到传统的信道编码系统中,提出了更高质量的无线传输方法。采用全盲瑞利信道来模拟实际的无线通信环境,用自适应算法LMS和RLS分别对信道进行估计,并比较2种算法的收敛特性。理论分析和仿真均表明,在原有的仅采用信道编码技术的基础上,提出的新传输方法能使无线通信系统获得更高的可靠性。     

一种新型无线数字窄带通信系统的设计与实现

提出了一种新型无线窄带通信系统的设计方案,该方案基于数字化的信源和信道编码方法,采用了两点调制和二次调制等技术,可兼容欧洲公众数字对讲机标准(DPMR),并通过研制得以实现.实测结果表明,系统接收灵敏度达-110 dBm,可满足远距离无线语音通信和中低码率的数据通信的要求.     

Dimming of High-Brightness LEDs by Means of Luminous Flux Thermal Estimation

Usually, pulsewidth modulation (PWM) operation is selected as the best dimming strategy to drive high-brightness LEDs. Nevertheless, to obtain an enhanced full linear dimming control of the device, the luminous flux should be measured. This paper proposes a control method based on an estimator of the luminous flux emitted by the LED. Based on the characterization of the LEDs, this estimator is defined. The estimator provides the flux value from only two temperature values (the case temperature and the ambient temperature). Once the estimator is validated, the electronic driver to supply the LEDs, as well as the digital control scheme, are presented. Such a control scheme is suitable for both AM and PWM dimming strategies. A prototype of the electronic driver has been built and tested, and experimental measurements of AM and PWM dimming are presented. It can be concluded that with the proposed estimator, the flux emitted by the LEDs can be accurately estimated. Thus, the output light control of the LEDs can be accomplished by sensing temperature rather than luminous flux. The final output characteristic of the system shows linearity between the output flux and the reference value, with AM as well as with PWM dimming of the LEDs.