基于3D电子地图和信道实测数据的市区路径损耗机器学习模型研究

随着5G移动通信系统的发展部署以及网络性能的优化,高精度和低复杂度的路径损耗预测模型尤为重要。该文针对大型城市场景,使用目前5G热点频段700 MHz, 2.4 GHz, 3.5 GHz的实测数据,将收发端位置、3维距离、相对余隙、建筑物密度、平均高度等作为环境特征,建立了基于3D电子地图的机器学习路径损耗预测模型,结果表明在复杂城市环境下,该文方法因其预测精度高而优于传统的基于收发端距离的路径损耗模型。另外,该文提出了基于频率迁移学习的路径损耗预测模型,并用均方误差、平均绝对百分比误差、均方根误差、决定系数等指标对其性能进行评估。该文方法可以解决建筑物遮挡严重的复杂城市环境以及在无大量测试数据的路径损耗预测问题,精确地预测城市环境中视距非视距混合信道的路径损耗值。     

Site-specific propagation prediction for wireless in-buildingpersonal communication system design

The paper describes a geometrical optics based model to predict propagation within buildings for personal communication system (PCS) design. A ray tracing model for predicting propagation based on a building blueprint representation is presented for a transmitter and receiver located on the same floor inside a building. Measured and predicted propagation data are presented as power delay profiles that contain the amplitude and arrival time of individual multipath components. Measured and predicted power delay profiles are compared on a location-by-location basis to provide both a qualitative and a quantitative measure of the model accuracy. The concept of effective building material properties is developed, and the effective building material properties are derived for two dissimilar buildings based upon comparison of measured and predicted power delay profiles. Time delay comparison shows that the amplitudes of many significant multipath components are accurately predicted by this model. Path loss between a transmitter and receiver is predicted with a standard deviation of less than 5 dB over 45 locations in two different buildings     

Mechanisms governing propagation between different floors inbuildings

The potential implementation of wireless radio local area networks (LANs) and personal communication services inside buildings requires a thorough understanding of signal propagation within buildings. In this work the authors develop a theory which explains propagation between a transmitter and a receiver located on different floors of a building. Depending on the structure of the building and the location of the antennas, either direct ray propagation through floors or diffraction outside the building will determine the propagation characteristics and range dependence of the signal sector average as the number of floors between the transmitter and the receiver is increased     

Multispot diffusing configuration for wireless infrared access

In order to combine the advantages and to overcome the drawbacks of a direct line-of-sight or a diffuse configuration for wireless infrared access, a multispot diffusing concept utilizing a holographic spot array generator is presented. Simulation results are presented and compared with those for a pure diffuse configuration in terms of link characteristics, when a single-element or a multibranch composite receiver is employed. The multispot transmitter ensures a more uniform signal power distribution. Improvements of about 2 dBo (optical decibels) can be achieved compared to a Lambertian pattern illumination. The increased power path loss at the edges of the communication cell is accompanied with a decrease in the delay spread resulting in an extension of the coverage range. Utilization of angle diversity detection improves the signal-to-noise ratio by more than 7 dB when selecting the best receiver branch and more than 10.5 dB in the case of maximal-ratio combining. Use of a multibeam transmitter and an angle diversity receiver reduces the likelihood of shadowing of the receiver due to an obstacle standing along the path between the receiver and the transmitter     

A comparison of time delay spread and signal level measurements within two dissimilar office buildings

A detailed analysis of time delay spread and signal level measurements at 850 MHz was performed within a large office building. The results were compared with studies of a much smaller and dissimilar office building. The results were found to be substantially the same, despite the physical differences of the buildings themselves. This may be due to external geographical features. Overall worst-case root mean square (rms) time delay spreads in the buildings were 250 ns and 218 ns in the larger and smaller building, respectively. However, these values improved to under 100 ns when there was a good direct path between the antennas. Time delay spread was also shown to be independent of relative antenna polarizations of the transmitter and receiver, even on line-of-sight paths. Received signal levels were below -90 dB with reference to the level at 0.3 m separation, in the worst cases.     

UHF Band Short Range Propagation Model

The purpose of this study is to characterize the indoor and indoor–outdoor propagation in different scenarios, using monopole antennas working at 410 and 890 MHz. Propagation of narrow band and wide bands have been studied. In scenarios with a continuous variation of the distance between the transmitter and receiver antenna (1 D scenarios), we use a log-distance path loss model to determine the equations that describe the mean value of the path loss. In scenarios where the position of the receiver is not a uniform function of the distance between the transmitter and the receiver, we represent the basic propagation gain as a function of the measurement point index. Results show that the indoor propagation gain can be described using two slopes propagation model. For the multiwall attenuation loss it is shown that each wall has an attenuation of almost 2.5 dB at 410 MHz increasing to almost 4 dB at 890 MHz. The obstruction gain (loss) due to human beings shows that this can be within a 40 dB interval.     

Outdoor-to-Indoor Propagation Loss Prediction in 800-MHz to 8-GHz Band for an Urban Area

In mobile communication systems, it is important to clarify the outdoor-to-indoor propagation loss (building penetration loss) characteristics to improve the quality of communication within buildings. This paper proposes a penetration loss prediction formula that is derived based on measurement results. We measured and analyzed the building penetration loss at higher frequencies that are appropriate for the next-generation system. We measured the propagation loss on 71 floors in 17 buildings in an urban area using four frequencies in the 800-MHz to 8-GHz band. The measurement results showed that the attenuation based on the penetration distance is 0.6 dB/m, the floor height gain is 0.6 dB/m, the constant value for the penetration loss is 10 dB, and there is no frequency dependence of the penetration loss in the frequency range from 0.8 to 8 GHz.      

Propagation prediction in and through buildings

The potential implementation of wireless radio local area networks and personal communication services inside buildings require a thorough understanding of signal propagation in a building. In this paper, an in-building prediction is presented. This prediction model focuses on a single floor of a building, but is applicable to different floors of the building. This model is also applicable to the through-building propagation loss by applying the same principle. The validation of this model was done in two different buildings of similar construction in the 900-MHz band. A special feature of this model is its capability to handle different types of obstructions. The model is validated by gathering the measured values for a specific floor of a building and comparing them with the predicted values. The standard deviation for measured versus predicted signal is within 3 dB     

Results of a VHF propagation study

Beyond-line-of-sight ground-wave propagation measurements were made near 30 MHz, 54 MHz, and 148 MHz over two different propagation paths 42 km and 51 km in length. Data were collected over a period of six weeks using a vehicle-mounted vertically polarized transmitting antenna (whip) and fixed position Yagi receiving antennas. Results presented here include(S + N)/Nratios observed at the receiver for a 1-W transmitter, and a comparison between measured path loss and path loss predictions made by the Electromagnetic Compatibility Analysis Center (ECAC) using diffraction model techniques. The measured(S + N)/Nratio (against a 1-W transmitter) was between 5 and 13 dB for the two propagation paths and three test frequencies. Measured path-loss data demonstrated the usefulness of the ECAC model in providing path-loss predictions. ECAC predictions best agreed at the lowest test frequency.     

A CDMA-distributed antenna system for in-building personalcommunications services

To investigate applications of spread spectrum code division multiple access (CDMA) technology to in-building personal communications services (PCS), comprehensive studies have been conducted for a CDMA PCS distributed antenna system in the 1.8 GHz band. The CDMA PCS distributed antenna system was set up with three nodes, each having two time-delayed elements, in a Qualcomm two story office building in San Diego. This paper presents measurement and modeling results on coverage, voice quality (frame error rate), reduction of transmit power, and path diversity for the in-building CDMA PCS distributed antenna system. Wideband CDMA signal coverage was predicted by using a ray tracing tool to find optimum placement of the distributed antennas. Using three nodes mounted in the ceiling space between the first and second floors, with each active element transmitting at -5 dBm in the system, the ray-tracing prediction shows good signal coverage in both floors of the building. The prediction results are confirmed by measurements at numerous discrete points with a standard deviation of 3.3 dB. Measurements using various combinations of number of nodes and delay elements showed significant time and path diversity advantages for the CDMA-distributed antenna system in indoor radio environments. Trade-offs between diversity gain and self-interference due to uncaptured finger energy in fringe areas are discussed     

Deterministic angle clustering in rectangular buildings based on ray-tracing

Three-dimensional (3-D) ray-tracing and analysis is used to characterize the path angles in a rectangular building in which all interior walls are parallel or perpendicular to the exterior walls. Path angles are recorded for 500 random transmitter and receiver locations, maintaining constant range throughout a particular building model. The main contribution of this paper is the observation that when all of the path angles from all 500 trials are measured relative to one building wall and collectively analyzed in a signal strength distribution, clustering is clearly apparent. While this angle clustering in the ensemble of channels is not the same as clustering in a single channel trial, it may partially account for the clusters observed in single trials. As a practical matter, these results may impact the use and placement of directional antennas for wireless LANs in buildings of this type.     

815 MHz radio attenuation measured within two commercial buildings

Copolarized attenuation measurements were made at 815 MHz inside two office/laboratory buildings. For the propagation paths along a straight corridor and into a adjoining room received signal power decayed with distance as d^-3.6. Signal powers higher than their free-space values were routinely measured for line-of-sight paths along a corridor. As expected, isolation between floors and between parallel corridors is heavily dependent on building construction techniques. Energy propagates selectively in directions not blocked by large amounts of metal. Cross-floor isolations of 26 dB were measured between floors separated by solid sheet metal. Coupling between otherwise isolated corridors was produced by an open central cavity in the larger building     

室内多径时延扩展的实验研究

本文介绍关于室内环境中时延扩散的实验，实验采用基于伪随机码滑动相关法的无线信道探测器，在典型的室内环境中对ＵＨＦ（９００ＭＨｚ）无线信道功率时延曲线进行实地测量，通过对大量实测数据的处理和分析得出了一些很有价值的结论，如在ＬＯＳ及ＮＬＯＳ情况下的时延扩展均方根值和方差；时延扩散与收发距离、路径损耗及收发天线不同线极化方向的关系等等。     

Propagation observations at 3.2 millimeters

A millimeter-wave system for the transmission and reception of television signals has been constructed. The propagation path is 450 meters above sea level at the transmitter and traverses an 18.95-km path to the receiver, which is at an elevation of 39 meters atop a two-story building in El Segundo, Calif. The elevation angle is 1.17 degrees when corrected for curvature and refraction. Received picture quality and tropospheric scintillation and attenuation for various weather conditions are discussed. Tropospheric attenuation ranged from about 13 dB on a typical day to approximately 36 dB when moderate rainfall (∼4 mm/hr) occurred over much of the 18.95-km path. Tropospheric turbulence effects were almost nonexistent on days of heavy fog but reached peak-to-peak magnitudes of 20 dB or more in received signal fluctuations on dry, windy days. High quality television and voice reception were obtained over this link even during light to moderate rainfall periods (∼3 mm/hr). A transmitter output of approximately 100 mW, 0.61-m parabolas at each end of the link, and a receiver noise figure of 25 dB were the main system characteristics. Tropospheric attenuation measurements are in close agreement with values calculated from modified versions of the Van Vleck expressions for attenuation due to oxygen and water vapor. The average of measured tropospheric attenuation rates was approximately 0.7 dB/km for July 1965.     

Indoor broadband optical wireless communications: optical subsystems designs and their impact on channel characteristics

With proper system design, infrared multispot diffusing (MSD) configuration communications links promise several orders of magnitude higher bit rates than radio links. Essential to the communications system are the optical subsystems: transmitter and receiver optics. Preliminary experiments on fabrication of beamshaping optical elements for the transmitter and receiver optical front-end have been conducted. The impact of optical subsystems on channel characteristics is investigated, and the results undoubtedly prove the great potential of MSDC. Use of holographic optical elements at both transmitter and receiver increases the signal-to-noise ratio by at least 11 dB and at the same time significantly improves the power budget of the system by reducing path loss by more than 6 dB.     

Empirical pathloss model for indoor geolocation using UWB measurements

A novel empirical approach is presented for modelling the path loss behaviour of the direct path (DP) between the transmitter and receiver, which is important for time-of-arrival-based indoor geolocation coverage characterisation. Using ultra wideband (UWB) measurements in four sites and three ranging scenarios, pathloss models at 500 MHz and 3 GHz system bandwidths are provided, centred on 4.5 GHz for DP and total signal power. In addition, ranging coverage analysis is provided using the DP models     

A Statistical Model for Indoor Multipath Propagation

The results of indoor multipath propagation measurements using 10 ns, 1.5 GHz, radarlike pulses are presented for a medium-size office building. The observed channel was very slowly time varying, with the delay spread extending over a range up to about 200 ns and rms values of up to about 50 ns. The attenuation varied over a 60 dB dynamic range. A simple statistical multipath model of the indoor radio channel is also presented, which fits our measurements well, and more importantly, appears to be extendable to other buildings. With this model, the received signal rays arrive in clusters. The rays have independent uniform phases, and independent Rayleigh amplitudes with variances that decay exponentially with cluster and ray delays. The clusters, and the rays within the cluster, form Poisson arrival processes with different, but fixed, rates. The clusters are formed by the building superstructure, while the individual rays are formed by objects in the vicinities of the transmitter and the receiver.     

Modeling of nondirected wireless infrared channels

We show that realistic multipath infrared channels can be characterized well by only two parameters: optical path loss and RMS delay spread. Functional models for the impulse response, based on infrared reflection properties, are proposed and analyzed. Using the ceiling-bounce functional model, we develop a computationally efficient method to predict the path loss and multipath power requirement of diffuse links based on the locations of the transmitter and receiver within a room. Use of our model is a simple, yet accurate, alternative to the use of an ensemble of measured channel responses in evaluating the impact of multipath distortion     

A 3.1 GHz–8.0 GHz Single-Chip Transceiver for MB-OFDM UWB in 0.18-$mu$ m CMOS Process

This paper presents the design and integration of a fully-integrated dual-conversion zero-IF2 CMOS transceiver for 9-band MB-OFDM UWB systems from 3.1 GHz to 8.0 GHz. The transceiver integrates all building blocks including a variable-gain wideband LNA, a single combined mixer for both RF down-conversion in RX and up-conversion in TX, a fast-settling frequency synthesizer, and IQ ADCs and DACs. Fabricated in a standard 0.18- mum CMOS process, the receiver measures maximum S11 of - 13 dB, maximum NF of 8.25 dB, in-band IIP3 of better than -13.7 dBm, and variable gain from 25.3 to 84.0 dB. IQ path gain and phase mismatches of the receiver chain are measured to be 0.8 dB and 4 ^deg, respectively. The transmitter achieves a minimum output P-1 dB of -8.2 dBm, sideband rejection of better than -42.2 dBc, and LO leakage of smaller than - 46.5 dBc.     

Statistical channel impulse response models for factory and openplan building radio communicate system design

Statistical radio channel impulse response models are presented for the analysis and design of wireless factory and open plan office communication systems. The models incorporate first- and second-order statistics to characterize the discrete impulse responses of indoor radio channels for both line-of-sight (LOS) and obstructed (OBS) topographies. The effects of large-scale transmitter-receiver separation distance, small-scale receiver movement, and models for the correlation of multipath component amplitudes over 1 m local areas are developed from 1.3 GHz measurements. SIRCIM, a computer simulator based on the models presented, has recreated multipath power delay profiles and CW fading profiles that are representative of measured data. Large-scale models for path loss are implicitly included in this work