A low-power sigma-delta modulator for wireless communication receivers using adaptive biasing circuitry and cascaded comparator scheme

This paper represents the low-power signal-delta (ΣΔ) modulator for wireless communication receiver applications. The 2nd-order modulator has a single-loop structure with 11 quantization levels. An adaptive biasing scheme of the operational amplifier and cascaded comparator scheme are proposed in order to save the power consumption. The DAC with three-level references including the analog ground voltage can make the modulator be implemented with half of the input capacitances without degradation of linearity characteristics with the help of dynamic element matching technique. Peak SNR values of 74 dB and 68 dB are achieved with the input bandwidths of 615 kHz and 1.92 MHz for CDMA-2000 and WCDMA applications, respectively. The modulator is fabricated in a 0.13-μm standard digital CMOS technology and dissipates 4.3 mA for a single supply voltage of 2.8 V. Jinup Lim was born in Seoul, Korea, in 1973. He received the B.S. and the M.S. degrees in semiconductor engineering from University of Seoul, Seoul, Korea, in 1999 and 2001, respectively. From 2001 to 2002, he worked in GCT Semiconductor Inc., Seoul, Korea. He is currently working toward the Ph.D. degree in Electrical & Computer Engineering at the same university. He received the Best student paper award from IEEE SSCS/EDS Seoul Chapter in 2004 and the Samsung Best paper award third prize in ISOCC 2004. His research area is the design of high-performance discrete-time / continuous-time sigma-delta modulator circuits. Joongho Choi was born in Seoul, Korea, in 1964. He received the B.S. and the M.S. degrees in electronics engineering from Seoul National University, Seoul, Korea, in 1987 and 1989, respectively. In 1993, he received Ph.D. degree in electrical engineering from University of Southern California, CA, USA. From 1994 to 1996, he worked in IBM T. J. Watson Research Center, NY, USA. In 1996, he joined the University of Seoul, Seoul, where he is currently a professor in the Department of Electrical & Computer Engineering. His research area is the design of high-performance analog integrated circuits.     

室内无线光通信调制方式的性能研究

为了研究适用于室内无线光通信的调制方式,分析了开关键控（OOK）、脉冲位置调制（PPM）、差分脉冲位置调制（DPPM）、数字脉冲间隔调制（DPIM）和双头脉冲间隔调制（DH-PIM）的调制结构,详细推导了各调制方式的平均发射功率、带宽需求、传输容量和误包率的公式,并进行了仿真分析。结果表明,PPM的平均发射功率最小,DPIM、DPPM和DH-PIM次之,OOK的平均发射功率最大;OOK的带宽需求最小,DH-PIM、DPPM和DPIM次之,PPM的带宽需求最大;DPPM的传输容量最大,DPIM和DH-PIM次之,OOK和PPM的传输容量最小;在相同调制阶数的条件下,PPM的误包率最小,DPIM、DPPM和DH-PIM次之,OOK的误包率最大。     

Design considerations for broadband indoor infrared wireless communication systems

Recently there has been a growing interest in using infrared light for broadband indoor wireless communications. There are two major limitations for establishing a wideband infrared communications link. The first and most important limit is the power requirements of such a link. The second important impairment is the intersymbol interference caused by multipath dispersion. In this paper we address the issue of designing an optimized transmission system to provide the best power efficiency for an infrared link. Important parameters that should be considered for this design and some examples of efficient link designs are discussed. The suggested designs can improve the power efficiency of an indoor infrared link up to 4 to 8 dBo while providing a smaller rms delay spread, more robustness to shadowing and a more uniform distribution of power. Characteristics of the indoor infrared channel depends upon the directions of the receiver. This dependency can be used in designing a direction diversity receiver to decrease the rms delay spread of the received signal and to reduce the effects of noise by using proper combining techniques. We discuss the effects of receiver direction and field-of-view on the channel parameters and suggest a configuration for a direction diversity receiver.     

Multiple spot diffusing geometries for indoor optical wireless communication systems

In order to improve the performance of indoor optical wireless communication links, two multispot diffusing geometries based on diamond and line strip spot distribution geometries are proposed, analysed and compared to the known uniform spot distribution. Such geometries combine the advantages of the diffuse and the line‐of‐sight systems, giving great robustness and ease of use. The novel line strip multibeam transmitter geometry has resulted in a receiver signal‐to‐noise ratio (SNR) improvement of about 4 dB compared to the conventional diffuse system as well as a significant reduction in the pulse spread. Simulation and comparison results for both the conventional diffuse system and the three multispot diffusing geometries are presented. Further, pulse responses, SNR, and delay spread results at various locations are presented. Copyright © 2003 John Wiley & Sons, Ltd.     

室内无线光通信信道分析

文章采用基于定点的迭代模型对非定向信道进行分析,得出了具体的迭代公式.在有家具的房间环境中,给出了可视光的增益公式,通过MATLAB编程实现了反射次数k=0、1、2三种情况下的脉冲响应,给出了仿真图形并加以说明.同时又对空房间的三种情况下的脉冲响应进行了仿真,通过与有家具的环境的比较,得出了随房间高度增加,非可视分量也增加的结论.     

水下无线光通信系统研究进展

水下无线光通信作为一种新兴的高速水下无线通信技术,在海洋生态环境监测、资源勘测以及军事作战等方面的作用不可小觑,并已成为全世界竞相争夺的关键性技术。对目前常用的3种水下无线通信方式进行比较,介绍了水下无线光通信的信道特性,并阐述水下无线光通信系统中光源、调制、信道编码以及探测等关键技术的研究进展。总结了水下无线光通信技术的发展趋势,为未来水下无线光通信系统的深入研究和实用化提供了参考。     

Using the node's experience from previous transmissions to improve the communication in an indoor localization system

Although originally the wireless sensor networks (WSN) were designed for transmitting environmental parameters with a low data rate, there is a growing need to use these networks for applications that require high throughput, such as real time localization systems (RTLS).     

Green indoor optical wireless communication systems: Pathway towards pervasive deployment

The Optical Wireless Communication (OWC) offers the high capacity of optical fiber communication with the flexibility of wireless communication. Since it works in the optical region of the ElectroMagnetic (EM) spectrum, it guarantees safety and security which are critical in radio and microwave frequency communication. The principal objective of this paper is to analyze the indoor OWC systems on these guaranteed features, and safety and security are jointly denoted by the term green. The high obstacle impermeability of optical signals and their directivity strengthen the security of indoor OWC data transmission. The confidentiality and authenticity of optical wireless data can also be preserved with the Quantum Key Distribution (QKD). This paper provides a technological overview and a review of literature about the OWC system that helps to identify the challenges in the path of a ubiquitous deployment of green wireless communication systems. Significant advancements in the sources and detectors are discussed together with the coding, modulation and multiplexing techniques for making highly robust OWC links. The ubiquitous deployment of green OWC necessitates the development of optical transmitters and receivers, performance enhancement techniques, incorporation of uplink and energy harvesting abilities, and safety and security enhancement techniques. Hence, a special emphasis is placed on these aspects and their challenges towards the green implementation. Furthermore, the paper explores some significant indoor applications based on the OWC that have great impacts on the Next Generation Networks (NGN) and the Internet of Things (IoT).     

一种基于激光通信浮标的潜艇水下双工通信方式

对现有潜艇水下通信技术进行比较分析,提出一种采用无线脉冲激光作为通信载波的系留浮标潜艇水下双工通信方式,并简要描述了该通信方式的应用体制及其可行性。     

无线激光通信类脉冲位置调制性能比较

为了比较各种类脉冲位置调制性能,对类脉冲位置调制的编码结构、平均发射功率、带宽需求、传信率、功率谱密度、信道容量等进行了比较,分析了其性能特点及使用场合.结果表明,开关键控调制方式容易实现,但功率利用率低;脉冲位置调制方式提高了功率利用率,但是带宽效率差,同时需要符号同步;数字脉冲间隔调制结构复杂,缩短了符号长度,带宽效率高,不需要符号同步;双头脉冲间隔调制方式提高了带宽效率和传输容量,不需要符号同步,大大简化系统实现复杂度.     

基于LDPC码和BPPM的无线光通信系统性能研究

为了克服光在弱湍流大气条件传输时,光强闪烁造成的突发错误,在已知信道衰落信息(CSI)和未知信道衰落信息(NCSI)条件下,研究了基于低密度奇偶校验(LDPC)码和二进制脉冲位置调制(BPPM)的无线光通信系统性能,论述了BPPM光通信信道对称性的特点,并与基于LDPC码和OOK调制的光通信系统性能进行了比较。结果表明,在NCSI和CSI情况下,基于LDPC码和BPPM的光通信系统相对于基于LDPC码和OOK调制的系统均有更优异的差错性能;在NCSI情况下,基于LDPC码和BPPM的光通信系统的性能相对于CSI情况下的系统性能损失并不大;且采用LDPC码BPPM相对于LDPC码OOK调制的光通信系统,随着湍流强度的增大系统性能损失较小。因此,基于LDPC码和BP-PM的光通信系统在不需要信道衰落信息估计的情况下,能获得较大的编码增益,便于工程实现,在无线光通信中将有一定的应用前景。     

无线光通信中的脉冲宽度间隔调制方案

提出一种新的脉冲调制方案——脉冲宽度间隔调制(PWIM),给出了PWIM的符号结构,分析了其在平均发射功率、带宽需求和传输容量等方面的性能,并在加性高斯白噪声信道模型的基础上推导了PWIM的误包率。理论分析与仿真验证表明,PWIM不但在功率利用率和差错性能方面优于OOK和PWM,而且带宽效率和传输容量比PPM和DPIM的更高。     

无线光通信组合脉冲调制的差错性能分析

在简要介绍脉冲位置宽度调制(PPWM)、差分脉冲位置宽度调制(DPPWM)、双幅度脉冲位置调制(DAPPM)和双幅度脉冲间隔调制(DAPIM)等新型组合调制方式的符号结构的基础上,详细推导了它们的误包率表达式,通过数值模拟,在给定模型下分析了以上新型组合调制方式的差错性能.     

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.     

无线光通信自适应激光源研究

无线光通信由于其独特的工作原理,具有巨大的潜在应用价值,其中无线光通信的激光器光源技术是关系设备指标特性的关键技术之一。根据自适应可调节激光器的特点进行分析,介绍激光相干合成技术原理,根据无线光通信的工作原理,采用可编程控制器件,为核心设计一种可以降低各种环境干扰的可调激光源。实验结果表明设计的光源输出是稳定的。     

Generalized OSTBC‐based subcarrier intensity‐modulated MIMO optical wireless communication system

In this paper, we analyze an optical wireless communication (OWC) system having a source and a destination node, equipped with multiple transmit and receive apertures, respectively. We utilize generalized orthogonal space‐time block codes (OSTBCs) of any arbitrary order and subcarrier intensity modulation scheme for data transmission over gamma–gamma (GG) fading optical links using M ‐ary phase‐shift keying (PSK) constellation. A symbol‐wise decoding is utilized, and the closed‐form expression of the approximate average symbol error rate (SER) of multi‐aperture‐based OWC system is obtained for the generalized OSTBC and an arbitrary M ‐PSK constellation. Using the derived SER expression, we analytically evaluate the diversity order and the coding gain of the OWC system with GG atmospheric turbulence. It has been shown by the numerical results that the maximum possible diversity is achieved by using the symbol‐wise maximum likelihood decoding in the destination. Copyright © 2016 John Wiley & Sons, Ltd.     

高速无线通信技术研究综述

随着多个领域对无线通信的速率要求越来越高,从几百Mbps到几十Gbps,高速无线通信成为通信技术的一个前沿研究热点,并取得了重要的研究进展。详细介绍了微波毫米波通信系统、光通信系统和太赫兹通信系统3类主要的高速无线通信系统各自的研究现状及取得的成果,分析了它们采用的技术路线,并比较了各系统的优缺点,其中重点关注了它们各自采用的调制解调方式,最后展望了高速无线通信技术进一步的研究方向。     

空间光通信视音频同步无线传输技术研究

设计并演示一个可实现视音频信号同步无线传输的自由空间光通信系统。该系统包括信号发生、调制和接收模块。对由信号发生模块输出的视音频信号进行时分复用(TDM),复用信号以电信号形式作用于声光调制器(AOM)并将其加载于入射到AOM的激光束上,AOM输出调制光信号,最后接收模块还原出视音频信号。整个通信系统带宽为6.7 MHz,通过电-光-电转换过程,将时分复用和声光调制相结合实现了视音频信号同步无线传输。本系统针对具体工作环境,自建核心电路:时分复用/解复用电路和输出光端机电路,采用单片机调控输出信号质量。实验证明该系统具备成本低廉、实用性强和灵活性高等优点,为监控系统、应急通信等应用场合提供一种简易有效的视音频信号同步无线传输方案。     

基于以太网的红外无线通信系统

将红外无线通信应用于标准的室内10Base T以太网(Ethernet)中,在点对点红外无线通信的基础上实现了与以太网兼容的红外无线通信系统;通过红外无线适配卡将以太网的曼彻斯特编码转换成适于红外无线传输的4脉冲位置调制编码,同时将以太网帧格式在其物理层上进行处理,把以太网的传输媒质从有线的铜缆双绞线转换为红外光线;并根据红外器件的发光特性,应用光学准直透镜有效地拓展了传输距离。