Wideband indoor channel characterisation using microstrip patchantennas at 1.95 GHz with different antenna height configurations

Results highlighting the improvement in power loss factor n, RMS delay spread and correlation with distance of the indoor channel employing microstrip patch antennas mounted in an optimised height configuration are presented. Extensive power delay profile measurements with four different antenna height configurations in two laboratory environments were conducted using a vector network analyser at 1.95 GHz. Analysis of the measurement results shows improvement of n values from 2.9 to 2 and median RMS delay spread of 10.4 ns to 6.2 ns with changes of antenna configuration     

Angle and time of arrival statistics for the Gaussian scatterdensity model

Starting from a Gaussian distribution of scatterers around a mobile station, expressions are provided for the probability density function (PDF) in the angle of arrival, the power azimuth spectrum, the PDF in the time of arrival, and the time delay spectrum, all as seen from a base station. Expressions are also provided for some of the quantities of practical interest such as the root-mean-square (RMS) angular spread, the RMS delay spread, and the spatial cross-correlation function. Results for the Gaussian scatter density model are compared with those for the circular scattering model and the elliptical scattering model as well as with experimental results available for outdoor and indoor environments. Comparison is shown for the PDFs as well as for the power spectra in angle and delay. It is shown that the present model, in contrast to the previous models, produces results that closely agree with experimental results. With an appropriate choice of the standard deviation of the scattering region, the Gaussian density model can be made suitable both for environments with very small angular spreads as well as those with very large angular spreads. Consequently, the results provided in the paper are applicable to both macrocellular as well as picocellular environments     

5G毫米波频段不同天线形式信道参数测量及对比分析

基于5G毫米波应用频段,开展了全向天线、喇叭天线以及阵列天线的信道测量与信道参数对比分析研究. 利用空间交替广义期望最大化(space-alternating generalized expectation-maximization, SAGE)算法提取了多径信道参数,包括多径时延、到达角、多径强度等,基于多径分量距离（multipath component distance, MCD）对多径分量进行了分簇结果的对比,对比分析了相同测量点处不同天线形式得到的信道参数差异. 结果表明,同场景下不同天线的信道参数测量结果会有较大差别,全向天线路损指数最小,阵列天线均方根(root-mean-square, RMS)时延扩展和RMS角度扩展均最小,喇叭天线可以得到较多的簇. 本文为5G毫米波频段信道建模提供了不同天线形式信道参数结果对比分析数据.     

Vehicle position estimates by multibeam antennas in multipathenvironments

Vehicle positions in multipath environments are estimated from the angle of arrival of waves received by multibeam antennas installed at two base stations. The estimated root mean square (RMS) position error is about 350 m. This can be reduced to about 200 m by using two kinds of processes: the averaging of time series data and the averaging of two sets of data. The position estimate error is caused by reflection from buildings near the vehicles, and a large error exceeding 500 m is caused by reflections from high buildings located some distance from the vehicle. Precise estimation of vehicle position in multipath environments by measuring angle-of-arrival is difficult because of building reflection     

A Study of Radio Zone Length of Dual-Polarized Omnidirectional Antennas Mounted on Rooftop for Personal Handy-Phone System

This paper proposes a dual-polarized omnidirectional antenna for base-station antennas that are mounted on the rooftops of buildings. The antenna suppresses the degradation in the received-signal level due to the inclination of mobile antennas in the personal handy-phone system (PHS). The proposed polarization-diversity antenna is comprised of a dielectric-loaded slotted-cylinder antenna for horizontally polarized waves and a conventional collinear array antenna for vertically polarized waves in a height-diversity configuration. The structure of the proposed antenna and its fundamental characteristics, such as the input impedance and radiation pattern, are shown. The change in the radio zone length (RZL) due to the inclination angle of the mobile antenna is measured to estimate the improvement offered by the proposed antenna in an urban area. It is shown that the RZLs of the collinear antennas in line-of-sight (LOS) environments are decreased by 73% when the mobile antenna is inclined at 90 , whereas the proposed polarization-diversity antenna restrains the degradation to approximately 20%, regardless of the inclination angle without downtilt and from 20% to 40% for a 15 downtilt. The RZLs of the collinear tilt antennas in non-LOS (NLOS) environments are below approximately 20%, compared to those of the collinear tilt antennas for the LOS route. We show that the RZLs in the NLOS environments are short compared to those for the LOS environments in microcell systems such as PHS with a high-elevation base station, even when the polarization-diversity technique is applied to the base station.     

Geometry‐based statistical channel model and performance for MIMO antennas

To test an adaptive array algorithm in cellular communications, we developed a geometry‐based statistical channel model for radio propagation environments, which provides the statistics of the angle of arrival and time of arrival of the multipath components. This channel model assumes that each multipath component of the propagating signal undergoes only one bounce traveling from the transmitter to the receiver and that scattering objects are located according to Gaussian and exponential spatial distributions, and a new scatterer distribution is proposed as a trade‐off between the outdoor and the indoor propagation environments. Using the channel model, we analyze the effects of directional antennas at the base station on the Doppler spectrum of a mobile station due to its motion and the performance of its MIMO systems. Copyright © 2014 John Wiley & Sons, Ltd.     

Transmitter diversity effect in TDMA/TDD mobile radio transmission

Transmitter diversity, which employs a single transmit/receive antenna at the portable stations and two transmit/receive antennas at the base station, is experimentally investigated for a TDMA/TDD (time division duplex) mobile radio system. Experimental results show that transmitter diversity can significantly improve the BER (bit error rate) performance of the portable station, due to AWGN (additive white gaussian noise), delay spread, and CCI (cochannel interference) in Rayleigh fading environments.<>     

Delay spread reduction effect of beam antenna and adaptively controlled beam facing access system in urban line-of-sight street microcells

The paper presents theoretical and experimental investigation results of the delay spread reduction effect of beam antennas in urban line-of-sight (LOS) street microcells. The 95% delay spread cumulative probability in a 600 m LOS cell length is reduced to 70% when the 3 dB beamwidth of the base station (BS) antenna is in the range from 80/spl deg/ to 140/spl deg/, compared with that (420 ns) in omnidirectional antennas. An adaptively controlled beam facing access (ABFA) system in which the beam antennas are used in both the base and mobile stations is further proposed. The beam direction of the BS antenna is fixed along the street, but that of the mobile station (MS) antenna is adaptively controlled as the maximum received power is obtained. Using ABFA, the 95% delay spread cumulative probability in the 300 m LOS microcell is reduced to less than 70 ns, when the antenna beam-width lies in the range from 20/spl deg/ to 140/spl deg/ in the BS and about 80/spl deg/ in the MS.     

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.     

Channel Capacity Between Antenna Arrays— Part I: Sky Noise Dominates

Space–time coding techniques can be used to achieve very high spectral efficiencies in highly scattering environments using multiple transmit and receive antennas. At the remote station, there is usually a more limited space allotted to the antenna array than at the base station. Since the spectral efficiency improves with the number of antennas, one is interested in how many antennas can be crammed into the limited space on the remote station. This paper (Part I of II) addresses some of the issues which affect the allowable density of antennas in the remote station. In particular, the mutual impedance between antenna elements in the remote array and the correlation between the signal and noise fields received by these elements are analyzed for their impact on the channel capacity achievable by such arrays. In particular, we assume the transmitter is radiating from$n_T$elements of uncoupled half-wave dipoles and knows nothing of the channel. A formula is given for the maximum channel capacity to a receiving array of$n_R$elements, coupled to each other in the presence of ambient noise or interference with a uniform angle of arrival distribution. This formula neglects amplifier noise in the receivers. It is shown that the channel capacity is already determined at the terminals of the receiving array, and can not be improved by internal coupling networks following the receiving array. When the propagation is by means of full three-dimensional scattering, the channel capacity is unaffected by mutual coupling in the receiving array.     

Signal Power Distribution in the Azimuth, Elevation and Time Delay Domains in Urban Environments for Various Elevations of Base Station Antenna

We investigate signal power distribution in the azimuth-of-arrival, elevation-of-arrival and time-of-arrival domains for various positions of the base station antenna located below the rooftop as well as at rooftop level. This article is based on a multiparametric stochastic model we introduced in 2004, as combination of a statistical part, describing an array of buildings randomly distributed at the terrain, and a waveguide model, describing a grid of straight streets with buildings along them. Joint signal power distributions in azimuth-time delay and elevation-azimuth planes are obtained and compared to high-resolution 3-D measurements carried out in downtown Helsinki. A good agreement between theoretical predictions and the measurements is obtained basically, and also regarding the wave-guiding effect and antenna height dependencies. A satisfactory physical explanation, which accounts for the character of the specific building topography, the height and tilt of the antennas, is found. Finally, we present a numerical experiment of changing the base station antenna height, its directivity, and tilt. By this we show that the proposed stochastic approach allows to predict and control a-priori main parameters of smart antenna based only on knowledge of specific features of built-up terrain.     

Urban/suburban out-of-sight propagation modeling

A model for the calculation of the path loss characteristics of a direct sequence (DS) spread spectrum signal which occurs when a mobile user is out-of-sight of the base station due to building blockage is presented. The environments studied are common throughout the world. Results for the experiments in which a base station antenna was set at heights of 6.6 m or 3.3 m, while the mobile antenna was fixed at a height of 1.5 m are presented. The goal of the experiments was to demonstrate the use of broadband DS spread spectrum code-division multiple-access (CDMA) as an efficient means of communication     

Mobile propagation loss and delay spread characteristics with a lowbase station antenna on an urban road

Propagation loss and delay spread were studied experimentally, in order to design digital mobile communication systems. For propagation loss, the results were as follows, (i) When there are no obstacles on the road, the distance over which a radio wave propagates with only free-space loss increases with frequency. (ii) When there are obstacles (trucks and buses). and when the base station antenna heights are 5 and 15 m. the loss in excess of the free-space loss is 15 and 10 dB, respectively, at 1 km, (iii) Frequency dependence of this excess loss is not significant. (iv) On a cross road. the loss increases rapidly traveling away from the intersection. For the delay spread. the results were as follows. (i) The delay spread increases slightly with distance (less than 0.3 μs within 1 km). (ii) The standard deviation of the delay spread increases slightly with distance (less than 0.2 μs). Using the above results. a service area that extends along the road on which the base station is located and is limited in distance along cross roads can be predicted     

Path loss, scattering and multipath delay statistics in fourEuropean cities for digital cellular and microcellular radiotelephone

The authors present typical and worst-case root mean square (RMS) delay spreads and excess delay spreads (10 dB) and mean channel path loss at 900 MHz in four European cities using typical cellular and microcellular antenna locations. Several thousand power delay profile measurements were made at six typical cellular and microcellular base station locations in the four cities. The data were obtained at local worst-case time-dispersion locations over hundreds of kilometers of typical operating routes, such as highways, bridges, and city streets, and form the basis for statistical models which can be used to predict the percentage of locations or the percentage of time in which channels will possess particular values of RMS delay spread and excess delay spread. The effect of reference distance on wideband path loss and the propagation path loss laws for cellular and microcellular radio channels are given. Radar cross sections computed from the data for typical scatterers in cellular and microcellular radio channels are given     

Impulse response modeling of indoor radio propagation channels

If indoor radio propagation channels are modeled as linear filters, they can be characterized by reporting the parameters of their equivalent impulse response functions. The measurement and modeling of estimates for such functions in two different office buildings are reported. The resulting data base consists of 12000 impulse response estimates of the channel that were obtained by inverse Fourier transforming of the channel's transfer functions. It is shown that the number of multipath components in each impulse response estimate is a normally-distributed random variable with a mean value that increases with increasing antenna separations; a modified Poisson distribution shows a good fit to the arrival time of the multipath components; amplitudes are lognormally distributed over both local and global areas, with a log-mean value that decreases almost linearly with increasing excess delay; for small displacements of the receiving antenna, the amplitude of the multipath components are correlated; the amplitudes of adjacent multipath components of the same impulse response function show negligible correlations; and the RMS delay spread over large areas is normally distributed with mean values that increase with increasing antenna separation     

室内环境下2.6GHz同时同频全双工自干扰信道测量与建模

目前,对同时同频全双工的自干扰信道特性尚未进行研究.针对这一现状,采用基于网络分析仪的信道测量平台,对室内环境下2.6GHz同时同频全双工自干扰信道特性进行测量与分析.基于实测数据统计分析,得出了传输损耗模型与均方根时延扩展统计模型.结果表明：传输损耗服从断点损耗模型,天线间距在大于1m的传输损耗指数为1.86,天线间距小于1m的传输损耗指数为1.52;均方根时延扩展的统计特性随着天线间距在不同范围而不同,在天线间距大于1m时的均方时延扩展服从lognormal分布,在天线间距小于1m时,RMS时延扩展在不同的天线间距下服从lognormal分布,并且其分布的均值与标准差与天线间距呈现线性关系.     

基于SBR/IM的超宽带信号室内传播特性仿真和分析

基于入射及反弹射线法/镜像法对室内环境的超宽带信号传播进行了仿真和分析,仿真结果与测量结果的一致性良好,这验证了该方法的正确性.同时比较分析了仿真中得到的视距传播（LOS）和非视距传播（NLOS）的多径传播、接收波形、时延扩展和到达方向角分布等传播参数,仿真结果表明：（1）三次反射以上的射线对接收功率影响很小；（2）发射、接收天线极化方式一般可选择垂直极化；（3）超宽带（UWB）信号经历频率选择性衰落；（4）到达角分布近似于均匀分布.这些分析结果为超宽带通信系统室内覆盖提供了依据.     

Angular power distribution and mean effective gain of mobile antenna in different propagation environments

We measured the elevation angle distribution and cross-polarization power ratio of the incident power at a mobile station in different radio propagation environments at 2.15 GHz frequency. A novel measurement technique was utilized, based on a wideband channel sounder and a spherical dual-polarized antenna array at the receiver. Data were collected over 9 km of continuous measurement routes, both indoor and outdoor. Our results show that in non-line-of-sight situations, the power distribution in elevation has a shape of a double-sided exponential function, with different slopes on the negative and positive sides of the peak. The slopes and the peak elevation angle depend on the environment and base-station antenna height. The cross-polarization power ratio varied within 6.6 and 11.4 dB, being lowest for indoor and highest for urban microcell environments. We applied the experimental data for analysis of the mean effective gain (MEG) of several mobile handset antenna configurations, with and without the user's head. The obtained MEG values varied from approximately -5 dBi in free space to less than -11 dBi beside the head model. These values are considerably lower than what is typically used in system specifications. The result shows that considering only the maximum gain or total efficiency of the antenna is not enough to describe its performance in practical operating conditions. For most antennas, the environment type has little effect on the MEG, but clear differences exist between antennas. The effect of the user's head on the MEG depends on the antenna type and on which side of the head the user holds the handset.     

Multipath propagation model for line-of-sight street microcells inurban area

This paper proposes a multipath propagation model for line-of-sight (LOS) street microcells with building roof base sites (BS) in urban areas, Multipath propagation characteristics are of great importance in evaluating the performance of digital systems and designing wireless links. Typical delay profiles are measured to clarify their statistical characteristics in LOS street microcells. The channel sounder used is a sliding correlator with 30-Mb/s PN code and a center frequency of 2.6 GHz. The measurements clarify the features of delay profile and mean RMS delay spread. The proposed delay profile model explains one plausible mechanism of multipath propagation. The delay profiles calculated using the model agreed well with the measured profiles. Furthermore, the factors influencing the RMSs delay spread are investigated, and the regression equation of medium RMS delay spread on a sidewalk is established. The proposed model can evaluate the transmission characteristics of wireless digital communication systems in multipath propagation environments     

Propagation measurements for fixed wireless loops (FWL) in asuburban region with foliage and terrain blockages

We present the results of propagation measurements at 2.485 GHz for fixed wireless loops. Path loss measurements were performed and characterized at 43 subscriber locations around a base station antenna located on top of Crawford Hill in Holmdel, NJ. This suburban location is characterized by rolling hills, foliage, and terrain blockages. Temporal and horizontal motion path loss fluctuations were found to be uncorrelated, each characterized by a different Ricean distribution. Lower r.m.s. delay spreads were obtained with directive subscriber antennas than with omni-directional antennas. No substantial gain loss (less than 2 dB) of subscribers' directive antennas was observed. The effects of trees, with foliage, surrounding the base station upon the path loss and the ratio of scattered power to specular power are also examined. The distance exponent of path loss versus distance (about 1.5) was observed to be less than free-space. Diffraction loss from hilltop trees, shadowing the base station, are suspected to be the cause. This loss decreases as the remote moves further away and comes out of the shadow. Scattered power from directions other than line-of-sight was observed to be as high as one half of the specular contribution when tree scattering near the base station was significant