室内6.05 GHz和2.45 GHz多输入多输出无线信道特性对比分析

为了明确高频段室内多输入多输出（Multiple-Input Multiple-Output,MIMO)无线信道与传统低频段的差异,采用基于矢量网络分析仪搭建的测量平台对典型室内环境下6.05 GHz频段和2.45 GHz频段MIMO无线信道进行测量和对比分析.基于300组高低频宽带MIMO信道测量数据,对比传输损耗、时延扩展、空间相关等大小尺度衰落特性.并阐明高频段无线空时信道新特性,分析新特性为系统设计带来的新问题.对比发现,6.05 GHz高频段与传统的2.45 GHz频段室内MIMO无线信道存在显著的差异.与2.45 GHz相比,6.05 GHz频段的传输损耗更大,时延扩展更严重,空间相关更低.在将低频段MIMO移动通信向高频段扩展时,这些差异要给予充分的重视.     

舰船内部60 GHz毫米波信道特性研究

为研究船内复杂封闭空间60 GHz毫米波信道特性,建立了等比例船舱模型,并进行相应的仿真研究,针对四种舰船舱室环境模型：T型控制舱、L型起居室、矩形起居室及机械舱,分别研究了各舱室内部60 GHz毫米波信道的时延扩展及路径损耗,建立了简单的舱内路径损耗模型,并发现机械舱环境的损耗斜率明显高于其余三种舱内环境模型,主要由于机械舱内复杂的金属环境对电磁信号造成了大量的反射和散射。在对时延扩展研究中归纳并提取了四种多径信道模型：多径时延分布、多簇时延分布、衰减的指数功率及等功率分布。此四种信道模型在一定程度上表征了船舱环境的信道特性。结合仿真结果及舱室环境,简要论述了实现该舰船内部无线通信的可行性,并提出了船内无线传感网络的节点部署建议。     

城市交通环境下23GHz信道仿真建模

随着车载网络的发展,新的无线电技术已经成为人们关注的焦点.车辆间通信既要求超可靠低时延,同时又对通信数据速率有较高的要求.本文针对韩国大田的城市环境进行仿真,并表征23GHz车载移动通信信道的特性.利用射线跟踪仿真萃取路径损耗、莱斯K因子、均方根时延扩展和角度扩展等典型信道参数,定量地分析并总结其对车辆通信的影响,为毫米波车载移动通信系统的部署提供参考和指导性建议.     

基于皮肤-脂肪模型的太赫兹体内多输入多输出信道特性分析与建模

为探究太赫兹(THz)频段体内多输入多输出(MIMO)通信系统的传输特性,该文在0.8～1.2 THz下构建了精确的皮肤-脂肪模型,对皮肤-脂肪模型中垂直方向和水平方向的链路进行全波电磁仿真,分析太赫兹体内信道特性,建立路径损耗模型。首先,结合太赫兹频段人体组织的介电特性和人体皮肤的解剖学结构构建皮肤-脂肪模型。其次,对比分析了3条链路的路径损耗和阴影衰落,提出带有等效吸收因子的太赫兹体内路径损耗模型。最后,对3条链路的莱斯K因子、均方根时延扩展、MIMO容量进行分析。仿真分析表明,带有等效吸收因子的太赫兹体内路径损耗模型可以更准确地描述加长距离垂直链路2的路径损耗,发射端在体表可以增强MIMO容量。该文的工作可以为太赫兹体内通信系统的设计和优化提供参考。     

28 GHz MIMO无线信道特性分析与研究

基于室内视距(Line-of-Sight,LOS)和非视距(Non-Line-of-Sight,NLOS)无线信道测量数据,研究了28 GHz多输入多输出(Multiple-Input Multiple-Output,MIMO)信道参数和容量特性.具体地说,分析了莱斯K因子、时延扩展、出发角和到达角的角度扩展等信道参数,研究了MIMO信道容量及空间相关性对容量的影响.结果表明:莱斯K因子、时延扩展以及角度扩展值取决于测量环境及场景;LOS条件下时延扩展的累积分布函数(Cumulative Distribution Function,CDF)曲线与正态分布拟合优于NLOS条件下的数据;MIMO天线空间相关性越大信道容量越小.本文结果可为28 GHz无线通信系统设计提供有用信息.     

基于射线追踪技术的多类工业环境28GHz信道特性研究

工业物联网是第六代移动通信技术（6th Generation Mobile Communication Technology,6G）的典型应用场景,工业环境无线信道特性是构建工业物联网应用的基础。本文基于射线追踪技术,研究三类典型工业环境（车间工厂、食品工厂、仓库工厂）在28GHz频段的信道特性。研究结果表明不同工业环境的路径损耗特性相差较大,本文对差异的产生原因进行了阐述,还对比了视距与非视距情况下的均方根时延扩展特性。本文研究结果可以为室内多场景下28GHz信道特性的建模与研究提供帮助。     

太赫兹频段室内场景空-时域信道特性测量与建模研究

掌握太赫兹频段室内信道特性及模型,是太赫兹室内通信系统设计和技术评估的前提。为了解太赫兹频段室内空-时域的信道特性,选取典型室内办公室场景,分别完成视距(Line of Sight, LoS)和非视距(Non Line of Sight, NLoS)场景下100 GHz频段、带宽为1.2 GHz的信道测量。通过分析结果,发现两场景的均方根时延扩展值和均方根角度扩展值都服从正态分布,且NLoS场景的两种参数值都比LoS场景大。此外,由于太赫兹频段多径信号分量较少,且测量场景尺寸较小,使得实测的均方根时延扩展值的测量结果比3GPP标准值约小12 ns。通过建立对数距离模型探讨测量距离对两种参数的影响,发现均方根角度扩展值在NLoS场景中随距离的增加有上升趋势,而均方根时延扩展值在两场景中变化趋势相反。     

基于射线追踪法的毫米波高架桥信道仿真

信道特性分析是通信网络规划、设计通信系统的基础。针对高架桥毫米波信道特性问题，基于射线追踪法仿真了37GHz毫米波信道，分析了大尺度路径损耗模型和小尺度多径模型，分别得出了两者在高架桥场景下表示信道损耗的影响因子和参数，如路径损耗、莱斯因子等。使用正态分布对附加阴影损耗进行建模，得到路径损耗模型。对莱斯因子和均方时延扩展使用正态分布拟合累计分布函数，获得建模参数。该参数的明确，为高架桥信道建模提供了理论依据。     

室内60 GHz毫米波无线信道参数及其相关性研究

基于典型的室内走廊环境,对60 GHz毫米波通信信道参数及其相关特性进行了研究.在视距和非视距条件下,分析了信道参数包括多径个数、均方根时延扩展、莱斯因子、阴影衰落的特点及其分布模型,研究了信道参数之间的相关特性.结果表明:在视距条件下各参数之间普遍具有较强的相关性,而在非视距条件下只有均方根时延扩展和多径个数之间的相关性较强.利用信道参数的相关特性可从一个参数来预测另一参数,为60 GHz无线通信系统的设计提供有用信息.     

基于Wireless Insite的城镇厂区MIMO信道特性分析

为分析城镇厂区的MIMO信道特性,文中建立了特定厂区的3D确定性模型,并针对2.45 GHz和5.8 GHz两种载波频率,利用Wireless Insite软件对厂区MIMO信道的接收功率、路径损耗和时延扩展等信道特性参数进行了仿真分析。结果表明,4×4MIMO系统下两种载波频率路径损耗相差不大,2.45 GHz相对5.8 GHz能获得较高的接收功率,但时延扩展严重。综合考虑,5.8 GHz频段更适合城镇厂区MIMO信道的铺设,但需要考虑增加发射功率和减小覆盖范围等问题。     

A Propagation-Measurement-Based Evaluation of Channel Characteristics and Models Pertinent to the Expansion of Mobile Radio Systems to Frequencies Beyond 2 GHz

This paper concerns the measurement-based comparison of urban microcellular mobile radio channel characteristics at 1.9 GHz and a higher frequency, i.e., 5.8 GHz, where future wireless systems could operate. Characteristics that are reported include transmission loss, root-mean-square delay spread, frequency correlation, and envelope fading statistics. Conclusions are drawn concerning whether significant differences in the performance of mobile radio links operating under the same signal-to-noise ratio conditions in the two bands would be expected in the area where the measurements were made     

A reassessment of satellite communications in the 20 and 30 GHz bands

Notwithstanding the additional spectrum allocations of the 1979 World Administrative Radio Conference (WARC '79) and the ever-increasing sophistication of spacecraft antennas which allow more intensive spectrum reuse, saturation of the 6/4 and 14/11 GHz bands is foreseeable by the late-1990s. The next available frequency bands at 30/20 GHz were allocated at WARC '71, when knowledge of propagation phenomena and their effect on satellite communications systems performance was fragmentary. During the past 8 years, numerous experimental programmes have led to the acquisition of more precise information about hydrometeor-induced propagation disturbances. Analysis of the data reveals that even with corrective means such as diversity and coding, service reliability of satellite communications systems with up-links at 30 GHz and down-links at 20 GHz could not reach 99.99 per cent as currently available at the lower frequencies and could be 98.0 per cent, or lower, in certain parts of the world. Since the conventionally proposed use of the 30/20 GHz bands does not lead to optimal solutions, alternative approaches are needed. An approach which would involve a revision of the spectrum allocations at 30/20 GHz is proposed. Placing both up- and down-links around 20 GHz and redistributing the spectrum available at 20 GHz would prevent the intrinsic imbalance of the up- and down-links with consequent higher reliability, reduced earth-station transmitter power, reduced construction and operational costs, and simplification of the spacecraft transponders and antenna design. The use of frequencies around 30 GHz could be postponed until the 20 GHz bands became saturated. When the 30 GHz bands would eventually be used, there would be no imbalance of up- and down-links.     

全电子的300 GHz太赫兹无线通信

太赫兹波作为一种新的高频段资源,有着更高的载波频率,可以承受更大的带宽和传输速率,成为新一代宽带通信中的研究热点。本文基于纯电子学器件成功搭建300 GHz的太赫兹无线通信系统,其发射机结构简单,复杂度相比光子辅助系统更低。进行了无线距离50 m和100 m的信号传输实验,对系统的传输性能进行了实验探究,验证了传输性能和传输速率、发送电压之间的关系。目前,在不使用功率放大器(PA)的情况下,100 m是全电子太赫兹无线传输系统能达到的最远距离。     

基于功率合成技术的166GHz大功率源研制

冰云探测对于提高天气预报准确性、监测极端天气现象等具有重要的意义.考虑到冰云粒子尺寸、形状分布等因素,利用太赫兹频段被动遥感仪器能更好地解决冰云探测的难题. 664 GHz作为一个重要的探测频点,其接收机射频前端主要包括664 GHz二次谐波混频器、332 GHz二倍频器以及166 GHz大功率源.作者在太赫兹二倍频设计的基础上,利用两路功率合成技术实现166 GHz大功率源,目的是提供给后级的332 GHz二倍频器足够的输入功率,从而能够驱动谐波混频器工作.实验结果表明,上述大功率源在164~172 GHz频率范围内输出功率大于46m W;在168 GHz处有最大输出功率59 m W.以上研究有效解决了本振链路中G波段输出功率不足的问题,为研制更高频段的太赫兹系统提供了技术支撑.     

140 GHz关键射频组件研究

在基于超外差体制的太赫兹无线通信系统接收机和发射机中,混频器、滤波器和本振源是决定系统性能的关键器件。本文分别针对基于肖特基二极管技术的140 GHz次谐波混频器、基于微机电系统（MEMS）体硅工艺的140 GHz带通滤波器和V波段毫米波本振倍频源的仿真设计和关键工艺开展了研究。测试结果表明：140 GHz次谐波混频器单边带转换损耗为26 dB,140 GHz带通滤波器的带内插损为8 dB,V波段毫米波本振倍频源最大输出功率大于50 mW（63.2 GHz~67.2 GHz）。     

A 750 Mb/s, 12 pJ/b, 6-to-10 GHz CMOS IR-UWB Transmitter With Embedded On-Chip Antenna

This paper presents a novel impulse radio based ultra-wideband transmitter. The transmitter is designed in 0.18 mum CMOS process realizing extremely low complexity and low power. It exploits the 6-to-10 GHz band to generate short duration bi-phase modulated UWB pulses with a center frequency of 8 GHz. No additional RF filtering circuits are required since the pulse generator circuit itself has the functionality of pulse shaping. Generated pulses comply with the FCC spectral emission mask. Measured results show that the transmitter consumes 12 pJ/b to achieve a maximum pulse repetition rate of 750 Mb/s. An optional embedded on-chip antenna and a power amplifier operating in 6-10 GHz band are also designed and investigated as a future low cost solution for very short distance IR-UWB communications.     

A broad-band 11 GHz radio propagation experiment

The designer of a digital radio system (DRS) requires quantitative data on flat and frequency-selective fading in order to assess the need for diversity and equalization and also the feasibility of using the same repeater sites developed for systems in the lower bands. Preliminary results from an experiment which measured the statistical distribution of the complex channel response across a 1 GHz bandwidth at 11 GHz on a 36 km path are described. On this test path the cumulative distribution function of signal attenuation due to rain was found to be about an order of magnitude greater than that due to multipath fading. Incuded are typical records of the complex frequency response during frequency selective fading (showing large variations of group delay), joint cumulative distributions of amplitude, amplitude slope, and notch speed.     

Wideband Channel Sounder With Measurements and Model for the 60 GHz Indoor Radio Channel

In this paper, a wideband channel sounder and measurement results for the short range indoor 60 GHz channel are presented. The channel sounder is based on a 1 gigasamples/s dual channel arbitrary waveform generator and A/D converter/software demodulator, which synthesize and detect a baseband PN sequence with 500 MHz bandwidth. A heterodyne transmitter and receiver translate the baseband PN sequence to and from the 60 GHz band. Ten channel measurements taken across the 59 GHz to 64 GHz range are concatenated to provide a continuous channel measurement covering 5 GHz of bandwidth, resulting in 0.2 ns time domain channel impulse response resolution. The dynamic range and maximum sensitivity performance of the channel sounder are discussed in detail. Comparisons of results with a vector network analyzer based system are shown to verify the accuracy of the sounder. In an extensive measurement campaign with vertically polarized omnidirectional antennas, several different rooms (offices, labs, conference rooms and others) in four different buildings have been investigated. Over 700 channel measurements are the basis for a comprehensive characterization of the short range 60 GHz indoor radio channel with omnidirectional antennas. Finally, a simple stochastic static multipath channel model is derived from the measurement results.     

Broadband wireless local-area networks at millimeter waves around 60 GHz

During the past few years, research covering propagation, channel characterization, and wireless system performance has yielded a substantial knowledge of the 60 GHz channel. The unlicensed 60 GHz frequency band presents many attractive properties for wireless communications. This paper addresses some wideband propagation characteristics for broadband wireless LANs (BWLANs). Important system-design characteristics, from measured results obtained from two wideband 60 GHz LOS radio links, are presented. Measurements were undertaken using the swept-frequency channel-sounding method. Analysis from the complex frequency responses in a worst-case scenario has yielded a lower-coherence-bandwidth value of 5 MHz. Minimum and maximum B/sub 0.9/ coherence bandwidths, obtained with a directional-horn transmitting antenna and an omnidirectional receiving antenna, were 1.10 MHz and 105.33 MHz, respectively. It was observed that the coherence bandwidth fluctuated significantly with the location of the receiver with respect to the base station. These results can be used for the modeling and design of future BWLANs.