变电站内2.4 GHz无线信道路径损耗建模

为了评估变电站内电磁干扰对电力通信系统的干扰,采用频域测量方法对某市110 kV变电站、220 kV变电站的2.4 GHz电磁波路径损耗进行了测量和分析.针对测量数据,分别利用最小均方差和累积法对路径损耗模型中路径损耗指数和标准差相关参数进行估计,并建立了路径损耗模型,仿真结果表明,模型估计结果与测量值相差不大.另外,搭建了ZigBee仿真系统,在信噪比为5 dB和10 dB的情况下,仿真出误码率随距离的变化关系,为通信设备布置在变电站环境中提供了研究依据.     

2.4GHz无线局域网在室内外传播的路径损耗分析

路径损耗的计算是规划和设计无线局域网的一项重要工作。针对IEEE802. 11b标准的无线局域网,分析了在室内外不同环境条件下接收功率的计算表达式,通过对大型试验网络的实际测量数据的统计,提出了一种路径损耗计算的简化公式。本研究所取得的数据对构建无线局域网络具有实际参考价值。     

28 GHz室内毫米波信道路径损耗模型研究

毫米波信道建模是第五代（the 5th Generation,5G）移动通信系统的关键技术,而路径损耗是表征毫米波信道传播大尺度衰落影响的重要参数.为了更好地理解毫米波信道的传播特性,应进行广泛的信道测量与建模.因此,对28 GHz室内环境进行了信道测量,并给出了相应的毫米波信道路径损耗模型,同时基于入射及反弹射线法/镜像法仿真分析了路径损耗传播特性.研究结果表明:实测结果与仿真结果一致性吻合良好,从而验证了入射及反弹射线法/镜像法的正确性;自由空间邻近（Close-In,CI）参考距离路径损耗模型表达式更简洁,鲁棒性更强.最后,本文给出了一种普遍适用的用来表征室内视距（Line-of-Sight,LOS）与非视距（Non-Line-of-Sight,NLOS）环境28 GHz与60 GHz毫米波信道的路径损耗模型.     

5 GHz无线局域网信道特征与信道模型

本文介绍了5GHz典型无线局域网场景下的信道的一些特征和测量结果,然后结合信道特征,说明信道建模的原理和方法,并给出了有关的信道模型.     

城市微区移动无线信道的特征分析与建模

对城市微区移动无线信道的概念及其研究方法进行了系统分析和介绍，在此基础上分析研究了多径色散传播信道的基本特征以及信道的建模方法。     

基于UWB的矿井无线信道测量与建模

通过研究UWB技术的特点,分析UWB信道的传输特性,可以确定信号的发射和接收脉冲信号。文中从信道路径损耗和多径损耗方向进行公式推导和分析,明确了路径损耗和多径损耗在UWB信道中的传播特点,接着分析了Δ-k信道模型和修正后的Δ-k信道模型,并对S-V信道模型和修正后的S-V模型进行了分析,再针对传播特点建立了适合矿井巷道的经过修正的S-V信道模型,并对其进行了仿真实验。     

高速无线信道建模与仿真

在考虑了高速铁路地理环境和高速等因素的基础上,综合考虑了多普勒效应和多径效应的影响,针对现有小尺度衰落无线信道模型的不足,应用了一种适合高速铁路环境下的无线信道模型。在Jakes信道仿真器的基础上,建立高速铁路环境下的无线高速信道模型。应用Matlab仿真软件对信道多普勒功率谱密度和信道包络进行仿真,说明信号建模的合理性。仿真结果与理论分析吻合,从而说明了模型的有效性。     

利用信道状态信息的室内定位技术

多径效应导致基于信号接收强度（RSSI）的室内定位方法精度不高,采用更细粒度的物理层信道状态信息（CSI）可以区分不同路径,提高定位精度。在已有基于CSI室内定位方法的基础上,通过改进对数距离路径损耗模型,得到CSI与传输距离的关系,并结合目标位置所测得的CSI值回归出目标与发射端的距离,最后通过三边定位法预测出目标的位置坐标。实验表明,相比基于RSSI的定位方法以及已有的基于CSI的定位方法,所提方法2 m以内的误差概率提高了将近40%和20%,有效提高了定位精度。     

无线通信系统信道模型研究

随着通信技术的发展,对无线信道的建模研究也随之经历了不同的阶段。本文研究了在每个发展阶段出现的信道模型,并且详细研究了几种主要且常见的信道模型的特点和性能,对比了几种模型的适用范围,为在实际应用中选择合适的信道模型提供了一定的理论参考依据。     

基于平面波斜入射的人体信道远场路径损耗建模

人体信道路径损耗计算对植入式通信链路预估具有重要意义.文章利用有耗媒质的电磁场边界条件、反射和透射定理并引入切向等效波阻抗定义,推导出平面波向人体斜入射时各人体组织分界面上的入射角、透射角、反射系数、透射系数、切向等效波阻抗以及各人体组织中的电磁合成波,提出了一种基于平面波向多层有耗媒质斜入射的人体信道远场路径损耗解析模型.然后以植入在肌肉为例,计算了TM波和TE波在5个常用工业通信频率以不同角度斜入射的人体信道电磁场分布与路径损耗,结果显示,电磁波在入射面的反射是影响人体信道路径损耗的关键因素,当频率在1.4 GHz附近时总路径损耗最小,TM波性能优于TE波,且当入射角小于等于30°时,总路径损耗基本保持不变.最后采用COMSOL Multiphysics建立了有限元仿真模型验证解析模型,二者结果高度吻合,最大误差仅为0.039,有力证明了解析模型的正确性和有效性.     

Channel Measurement and Path Loss Modeling from 220 GHz to 330 GHz for 6G Wireless Communications

Terahertz (THz) communication has been envisioned as a key enabling technology for sixthgeneration (6G).In this paper,we present an extensive THz channel measur...     

近水面2.4GHz信号传播损耗模型的校正研究

无线传感器网络的性能很大程度上受限于无线信道的特性。随着物联网事业飞速发展,近水面环境下2.4 GHz信号传播路径损耗模型的研究已成为无线传感器网络研究的重要课题之一。在近水面的环境下,针对基于IEEE802.15.4标准的2.4 GHz信号传播特性进行了实测研究,并利用最小二乘法对双射线模型进行拟合分析得到经验公式。研究结果表明:校正后的经验公式更符合实际环境中的信号传播路径损耗特点,这也为未来大规模铺设近水面无线传感器网络提供理论指导作用。     

Propagation Loss Measurement of Wireless Body Area Network at 2.4 GHz and 3.35 GHz Bands

The main purpose of this work is to measure and analyze the propagation loss of the Wireless Body Area Network (WBAN) in frequency and time domain at two frequency bands, namely 2.4 GHz band with 80 MHz bandwidth and 3.35 GHz band with 500 MHz bandwidth. Four different scenarios (front to front, front to back, front to off-body node and back to off-body node) using many antenna´s locations on the body are used to investigate the channel response (path loss) of WBAN. It is found that the front to front channels and the front to off-body node channels have a low fading. The front to back channels and the back to off-body node channels have a high fading that can be approximated by the Distorted Rayleigh fading. Thus the WBAN range for the front to off-body node scenario is more than the range of the back to off-body node scenario.

     

利用2.4GHz无线设备实现连接

新兴技术 预计到2007年,所有新型PC人机界面设备(HID)--如鼠标和键盘等中的1/4都会实现无线工作.尽管成本较低,但27 MHz、IR及900 MHz的设备不足以支持不断发展的最终用户需求.上述技术带宽较低,等待时间较长,这就意味着设备相应于最终用户的输入会产生令人难以接受的延迟.27MHz产品只提供有限的工作范围,而且不是双向的,也容易受到干扰.同时,尽管900 MHz产品能够支持多用户(如在视频游戏环境中支持数个游戏者),但它同时却要大幅牺牲性能作为代价.此外,并非全球所有地方都提供900 MHz的频带,这就意味着开发人员不能使其产品在全球开展营销工作.     

Channel and Error Modeling for Wireless Body Area Networks

Wireless Body Area Networks (WBANs) have been developed as the human-body monitoring systems to predict, diagnose, and treat diseases. Since the signal transmission in WBANs takes place in or around the human body the channel fading significantly affects packet error rate and overal network performance. In this work, we discuss the channel models and error performance formalization for WBANs. In the first phase of this work, we study channel fading models for WBANs. In the second phase, we survey the models which calculate the error performance metrics in WBANs. We select most appropriate error models to design and develop the error performance evaluation models for IEEE 802.15.6-based WBANs and show how to integrate them with the error model in Medium Access Control (MAC). We then discuss integrated PHY and MAC error performance in WBANs.     

2.4GHz频段无线技术标准

为了满足人们对无线通信技术的需求,现对工作于2.4 GHz（ISM）频段常用的短距离无线通信中ZigBee、蓝牙（Bluetooth）、WiFi三者的技术优势、缺点及总的市场趋势做了详细分析,证明它们的关系是既互为补充又相互竞争的。     

一种适用于2.4GHz无线语音的IFA天线设计

设计了一种用于2.4GHz无线语音的IFA( Inverted -F Antenna)天线,该天线能够满足2.4GHz频段无线语音传输对天线尺寸、价格和性能的要求.使用有限元法进行数值仿真和设计,该天线可达到较好的效果.该天线的仿真和实测结果表明,在2.46 GHz的中心工作频率下,回波损耗为19.9 dB,带宽约为5...     

A BER-Based Partitioned Model for a 2.4GHz Vehicle-to-Vehicle Expressway Channel

Statistical channel models based on BER performance are presented for a frequency- and time-selective vehicle-to-vehicle wireless communications link in an expressway environment in Atlanta, Georgia, where both vehicles traveled in the same direction. The models are developed from measurements taken using the direct sequence spread spectrum (DSSS) technique at 2.45GHz. A collection of tapped delay line models, referred to as a “partitioned” model in the paper, is developed to attempt to capture the extremes of BER performance of the recorded channel. Overall and partition models are compared to the recorded channel in terms of the BER statistics obtained when the channels are inserted in a dedicated short range radio (DSRC) standard simulation system. The quality of the match between synthesized and recorded channel BER statistics is analyzed with respect to type of modulation (fixed or adaptive), the frame length, and the length of the interval over which the BER was calculated. Guillermo Acosta was born in Mexico City, Mexico, in 1962. He is a Ph.D. Candidate and a graduate research assistant in the School of Electrical and Computer Engineering at the Georgia Institute of Technology, in Atlanta, Georgia. He obtained his Bachelor of Engineering with Honors and Master of Engineering, both in Electrical Engineering, from Stevens Institute of Technology, Hoboken, New Jersey, in 1985 and 1987, respectively. He also obtained a Master of Business Administration with Honors from the Instituto Tecnologico Autonomo de Mexico (ITAM), Mexico City, Mexico, in 1996. Mr. Acosta has held technical and managerial positions in the recording, radio, and TV industries and in the Communications Ministry of Mexico. He has been an adjunct instructor in Electrical Engineering in the Instituto Tecnologico y Estudios Superiores de Monterrey Campus Estado de Mexico (ITESM-CEM) and the Universidad Iberoamericana. He is member of the IEEE, INCE, Tau Beta Pi, and Eta Kappa Nu. Mary Ann Ingram received the B.E.E. and Ph.D. degrees from the Georgia Institute of Technology, in Atlanta, Georgia, in 1983 and 1989, respectively. From 1983 to 1986, she was a Research Engineer with the Georgia Tech Research Institute in Atlanta, performing studies on radar electronic countermeasure (ECM) systems. In 1986, she became a graduate research assistant with the School of Electrical and Computer Engineering at the Georgia Institute of Technology, where in 1989, she became a Faculty Member and is currently Professor. Her early research areas were optical communications and radar systems. In 1997, she established the Smart Antenna Research Laboratory (SARL), which emphasizes the application of multiple antennas to wireless communication systems. The SARL performs system analysis and design, channel measurement, and prototyping, relating to a wide range of wireless applications, including wireless local area network (WLAN) and satellite communications, with focus on the lower layers of communication networks. Dr. Ingram is a Senior Member of the IEEE.