Development of a distributive control scheme for fluorescent lighting based on LonWorks technology

In this paper, a new distributive control system for indoor fluorescent lighting based on LonWorks technology is presented. The system features the following elements: microprocessor-controlled fluorescent lamp electronic ballast, communication system using the power line as communication media, and control software for Windows 95 environment. The electronic ballast has been especially designed to be operated under the proposed distributive control system. Thus, it features high-input power factor, high-frequency lamp supply, lamp power regulation against line voltage variations, dimming capability, and lamp failure detection. With this scheme, a low-cost distributive control system for lighting applications has been achieved, allowing energy and maintenance savings and increase in the reliability of the fluorescent lighting systems.     

The Impact of Reflections From Stratified Building Materials on the Wave Propagation in Future Indoor Terahertz Communication Systems

In order to derive reliable propagation models for future terahertz indoor pico-cellular communication systems, accurate reflectivity data of building materials is necessary. Here we present reflection terahertz time domain spectroscopy (THz-TDS) measurements and matching transfer matrix simulations of the frequency dependent reflection coefficient of multi layer building materials in the frequency range from 100 to 500 GHz for a set of angles, both in TE- and TM-polarization. Two prominent stratified structures, a double pane window and white paint on plaster are investigated as they usually account for large areas in indoor environments. Communication systems located above 100 GHz are expected to be strongly affected by the variations of the reflectivity over the frequency and incident angle of such stratified materials as they will rely both on line of sight (LOS) and non line of sight (NLOS) propagation. We discuss this impact on the power distribution in a sample scenario employing the ray-tracing method.     

Modeling and evaluation of the indoor power line transmission medium

The aim of this article is to outline the possibilities of indoor power lines when used to support local area networks in homes or small offices. For this purpose, the channel characteristics are described and a channel model is presented. This model is related to the physical nature of common indoor power lines, so its parameters can be defined in a straightforward way. Based on it, the performance of communication systems that use discrete multitone modulation, which appears to be the most suitable technique for these channels, is evaluated. Finally, a discussion about medium access control strategies is included.     

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。     

Millimetric wavelengths radiowave propagation for line-of-sightindoor microcellular mobile communications

Discusses millimeter waves for indoor microcellular communications. The results of propagation experiments conducted at 60.4 GHz (the oxygen absorption band) and 38.25 GHz to determine multipath characteristics in a number of indoor microcell channels employing omnidirectional antennas are presented. Cumulative distribution functions for received signal envelope, as well as corresponding power spectra are given. In addition, a comparison between the fading statistics measured at 60.4 GHz and 38.25 GHz under similar conditions is made. The change in multipath characteristics due to the presence of different building materials is also illustrated. A ray model is developed to represent indoor microcell propagation by considering a direct ray plus rays which have undergone single and double reflections from the walls. Specular floor-reflected and ceiling-reflected rays are included when the antennas radiation pattern does not preclude them. Using this simple model, the signal variations and the amplitude of reflected rays with respect to the line of sight (LOS) ray as functions of mobile receiver position are predicted and used to assist in interpreting experimental results. Theoretical results are found to be in good agreement with measured ones, with the model also being used to predict structure-induced root mean square (rms) delay spread along receiver routes in an indoor microcell environment. This parameter is a measure of multipath conditions in a mobile radio channel and is inversely proportional to the maximum usable data signalling rate of a channel     

新的时变信道下空时分组编码多用户系统解码器设计

该文提出了两种新的适用于时变信道下空时分组编码多用户系统的解码器设计方案。空时分组编码多用户系统下,传统的迫零(Zero Forcing, ZF)和最小均方误差(Minimum Mean Squared Error, MMSE)解码器设计均假定信道准静态衰落。信道时变时,这些传统解码器在解码某用户信号时引入符号间干扰(Inter-Symbol Interference, ISI),且这种干扰随信道时变增大而增加。基于此,该文设计了两种新的解码器,该解码器可显著降低信道时变的影响。仿真结果表明,随信噪比(Signal-to-Noise Ratio, SNR)增加,两种传统解码器均出现误码率性能平层,而新解码器获得了显著的性能改善。     

Propagation considerations for the design of an indoor broad-bandcommunications system at EHF

This paper reports the measurement and analysis of wideband propagation data for indoor radio channels at 40 GHz. Propagation characteristics are reported for two open-concept office areas of different sizes in two different buildings. Also, the results of measurements in one building are compared for system configurations in which either an omnidirectional or a narrowbeam antenna is employed at a base station for communications to multiple work stations with omnidirectional antennas. It is reported that, on a statistical basis, at the 90th percentile, multipath dispersion is the same for the two base-station antenna radiation patterns. Dispersion was, however, found to be lower in the smaller of the two measurement areas, where transmit/receive ranges were shorter. The 90th percentile of static RMS delay spread for this area was 19 ns compared with 45 ns for the larger area. Multipath spreads at the -25 dB relative power level were about 370 ns, compared with 140 ns in the larger area. In the larger area, global propagation loss was found to be well modeled by the one-way propagation equation with different range exponents (1.5 and 4) before and after a breakpoint at a range of 25 m. In the smaller area, the range exponent was found to be greater, being equal to 3.5. This is considered to be a result of reduced multipath infill, which would accompany the reduced dispersion. Temporal fading on fixed links with omnidirectional antennas was found to have depths such that a 14-dB fade margin is required for 99% reliability. Finally, spatial variations in received power at a given range indicated the requirement for a power margin between 4-7 dB for 99% reliability. These results are used in a link budget example for a broad-band indoor extremely high frequency (EHF) digital communications system     

Path-loss and time dispersion parameters for indoor UWB propagation

The propagation of ultra wideband (UWB) signals in indoor environments is an important issue with significant impacts on the future direction and scope of the UWB technology and its applications. The objective of this work is to obtain a better assessment of the potentials of UWB indoor communications by characterizing the UWB indoor communication channels. Channel characterization refers to extracting the channel parameters from measured data. An indoor UWB measurement campaign is undertaken. Time-domain indoor propagation measurements using pulses with less than 100 ps width are carried out. Typical indoor scenarios, including line-of-sight (LOS), non-line-of-sight (NLOS), room-to-room, within-the-room, and hallways, are considered. Results for indoor propagation measurements are presented for local power delay profiles (local PDP) and small-scale averaged power delay profiles (SSA-PDP). Site-specific trends and general observations are discussed. The results for path-loss exponent and time dispersion parameters are presented.     

Performance analysis of energy efficient cooperations in WSNs over frequency-selective channels

Energy efficient cooperations in wireless sensor networks (WSNs) subject to flat fading channels have attracted a considerable amount of attention recently. However, wireless channels of WSNs operating in indoor environments are supposed to have a frequency-selective nature, yet a comprehensive analysis of cooperative communications in these WSNs practically does not exist. Therefore, this paper has studied energy efficient cooperative communications over frequency-selective fading channels. Investigations of the energy efficient decode-and-forward and the adaptive decode-and-forward cooperations are provided in terms of the optimal power allocation and the partner selection region. The study is based on a network geometry of a fixed source node and a destination node with a range of potential partner node locations. Numerical results of optimal power allocation and the partner selection region are generated, and contour graphs of the resulting cooperative energy savings achieved from cooperations are provided using MATLAB. Results have indicated that cooperations can seek for potential partner nodes within a specified region to form energy efficient communications in WSNs operating in indoor environments. Furthermore, we have compared our results to the existing work which studies cooperations over flat fading channels, and several interesting findings have been revealed.     

宽带CDMA系统的自适应功率和速率控制性能分析

该文研究一种新的自适应功率和速率控制方案,导出了采用这种方案的宽带CDMA系统的误比特率(BER)公式,并分别给出了系统在平坦衰落信道和多径衰落信道中性能分析的数值结果。在这种方案中,移动台根据衰落信道的变化自适应地调整其发射功率和传输速率,而衰落信道的变化通过一种新的远程预测算法进行预测。首先将预测的总平均信道功率的概率密度函数划分为若干个面积相同的区间,从而得出这些区间之间的门限值;然后通过与传统功率控制技术相似的方式,将这些门限值用于自适应功率和速率控制。数值结果表明,采用这种方案能够有效地提高宽带CDMA系统的理论BER性能。     

Measurements and models of radio frequency impulsive noise forindoor wireless communications

The authors present the results of average and impulsive noise measurements inside several office buildings and retail stores. The noise measurement system operated at 918 MHz, 2.44 GHz, and 4 GHz with a nominal 40-MHz, 3-dB RF bandwidth. Omnidirectional and directional antennas were used to investigate the characteristics and sources of RF noise in indoor channels. Statistical analyses of the measurements are presented in the form of peak amplitude probability distributions, pulse duration distributions, and interarrival time distributions. Simple first-order mathematical models for these statistical characterizations are also presented. These analyses indicate that photocopiers, printers (both line printers and cash register receipt printers), elevators, and microwave ovens are significant sources of impulse noise in office and retail environments     

Spatial and temporal characteristics of 60-GHz indoor channels

This article presents measurement results and models for 60-GHz channels. Multipath components were resolved in time by using a sliding correlator with 10-ns resolution and in space by sweeping a directional antenna with 7° half power beamwidth in the azimuthal direction. Power delay profiles (PDPs) and power angle profiles (PAPs) were measured in various indoor and short-range outdoor environments. Detailed multipath structure was retrieved from PDPs and PAPs and was related to site-specific environments. Results show an excellent correlation between the propagation environments and the multipath channel structures. The measurement results confirm that the majority of the multipath components can be determined from image based ray tracing techniques for line-of-sight (LOS) applications. For non-LOS (NLOS) propagation through walls, the metallic structure of composite walls must be considered. From the recorded PDPs and PAPs, received signal power and statistical parameters of angle-of-arrival and time-of-arrival were also calculated. These parameters accurately describe the spatial and temporal properties of millimeter-wave channels and can be used as empirical values for broadband wireless system design for 60-GHz short-range channels     

基于电源线和位置指纹的室内定位技术

该文提出将室内环境不可或缺的电源线作为天线,通过在电源线上注入宽带高频信号构造室内空间的位置指纹,进而实现室内空间精确定位。首先介绍了电源线上宽带高频信号注入模块的实现技术,以及室内空间位置指纹的构造方法;其次,介绍了基于朴素贝叶斯分类算法的室内定位原理;最后,通过实验分析证明在多训练样本情况下,基于朴素贝叶斯分类算法的定位算法比基于K最邻近点(KNN)分类算法的定位算法有更好的定位准确率和时间迁移适应能力。     

Performance of M-QAM modulations for indoor radio communications with combined diversity and equalization techniques

Digital indoor radio communications systems have become an attractive proposal as they could provide the user high quality voice and low rate data services with total mobility. However, indoor communications are affected by multipath propagation that restricts their application imposing an upper limit on the system data rate. To overcome this drawback diversity and channel equalization could be considered. In this paper the performances of 4, 16 and 64-QAM modulations in a radio communications indoor environment are presented. The results show that a system without protection has very limited performance. Diversity techniques are efficient when the radio channel can be assumed to be non-selective. For systems operating in selective fading channels joint equalization and diversity techniques are necessary to fight the degrading effect introduced by the channel. Moreover, if correlation between the two diversity channels is taken into account, the system performances remain almost unchanged, assuming that the correlation coefficient between the two diversity branches is lower than 0.6 to 0.7 approximately.     

HPLC&RF双模系统中无线通信的导频设计

随着高速电力线载波通信(High-speed Power Line carrier Communication,HPLC)技术在电力物联网中的推广和应用,其面临的组网孤岛/孤点、停电事件上报成功率低、单跳通信距离短等问题逐步显现.无线(Radio Frequency,RF)通信能够有效地解决这些问题,从而成为了HPLC的有力补充.对于HP LC&RF双模系统中的无线通信,现有的导频设计没有充分考虑其典型应用信道的时频相关性,为此提出了一种新的导频设计方案.该方案增加了导频的频域密度,以更好地适应频率选择性高的信道;同时基于所有典型信道随时间变化缓慢的特性,降低了导频的时域密度;另外,重新设计了导频的时频位置,以进一步降低信道估计的复杂度.新方案的导频开销为原方案的1/2.仿真结果表明,所提方案的性能均优于原方案,且适用的信道估计方法简单,计算复杂度低,易于实现,能够更好地满足双模系统的推广应用需求.     

Energy Efficient Cooperation with Chip-Interleaved Transceivers in WSNs Over Frequency-Selective Fading Channels

Cooperative diversity techniques have been utilized to improve the energy efficiency of wireless sensor networks (WSNs) operating over flat fading channels in a considerable number of literature. However, wireless channels of WSNs operating in indoor environments are supposed to be characterised by frequency-selective fading. Theoretical analysis of energy efficient cooperative communications in WSNs operating in indoor environments are rarely addressed. Therefore, this paper studies the energy efficient cooperative communications in WSNs operating over frequency-selective fading channels. Closed-form bit error rate expressions are derived for systems over frequency-selective fading channels. In order to fully explore the energy conservation potential of cooperative communications, solutions of the optimal transmit power allocation and the partner node selection are provided. Moreover, it is proven that the communication quality can be greatly improved by using chip-interleaving techniques in WSNs subject to flat fading channels. Thus, this paper investigates the energy-saving potential of chip-interleaved transceivers in WSNs subject to frequency-selective fading. Numerical results show that significant energy savings can be achieved via cooperations with chip-interleaved transceivers in WSNs operating in indoor environments.

     

Adaptive equalization for high-speed indoor wireless data communication

The performance of a 4-QAM indoor wireless data communication system with adaptive equalizer is investigated. The effectiveness of using linear and decision-feedback equalizer for Rayleigh and Rician frequency-selective indoor channels is evaluated, and contrasted to the performance of a 4-QAM modem without equalizer. The effects of some important channel and system parameters (multipath spreads up to 200 ns, data rates up to 25 Mbit/s, signaling pulse rolloff factor between 0.5 and 1.0, and additive, white Gaussian noise) on the indoor communication system performance are examined and presented in the paper. The indoor propagation measurements, carried out in a research laboratory, provided data to be used for BER performance assessments of the system with and without equalizer. The performance results based on computer generated channels are then compared with those obtained for measured channel impulse responses.     

PHS、3G和WLAN共用室内分布系统分析

介绍了PHS、3G和WLAN三个无线业务使用同一套室内分布系统实现3种信号同时覆盖;首先讨论了这三个业务各自的室内覆盖系统及其具体设计参数等;然后介绍了共用系统中有源设备的合路情况;分析了共用系统中存在的功率匹配问题,得到了相关结论。对各工作频带间的相互干扰问题做出了相关分析并给出了部分解决方案。     

Interrogation of wavelength multiplexed fiber Bragg gratings using spectral filtering and amplitude-to-phase optical conversion

A technique for interrogating multiplexed FBG sensors using all-fiber low-cost devices is demonstrated. It is based on spectral filtering employing a fused biconical wavelength-division multiplexer and on amplitude-to-phase optical conversion to perform power referencing. Four FBG sensors are wavelength multiplexed in the network, and a 3-nm-wide tunable optical filter is employed at the detection block for sensor demultiplexing. With this technique an operation range of more than 2 nm is demonstrated for the sensors with achievable wavelength static resolution ranging from 1.9 to 13.4 pm/Hz/sup 1/2/ with no observable hysteresis. As for power referencing, the system is proven to be unaffected by power variations as high as 75% of the total power launched by the source. Finally, output-phase variations due to crosstalk are shown to be under 1% of the total output phase range, with more than 29-dB optical isolation between channels.     

楼道中的智能化照明系统设计

设计了一种节能照明控制装置,采用热释红外传感器检测、电力线载波通信、大功率APFC变换等技术。它适用于星级宾馆、大型商场等大面积室内场所,可以有效地对照明灯具进行节能控制,并且可以实时的了解照明系统中各部分的工作情况,以便于维护。