Height Of Station Research Articles

Mobile Network Coverage Prediction Using Multi-Modal Model Based on Deep Neural Networks and Semantic Segmentation.

A coverage prediction model helps network operators find coverage gaps, plan base station locations, evaluate quality of service, and build radio maps for spectrum sharing, interference management, localization, etc. Existing coverage prediction models rely on the height and transmission power of the base station, or the assistance of a path loss model. All of these increase the complexity of large-scale coverage predictions. In this paper, we propose a multi-modal model, DNN-SS, which combines a DNN (deep neural network) and SS (semantic segmentation) to perform coverage prediction for mobile networks. Firstly, DNN-SS filters the samples with a geospatial-temporal moving average filter algorithm, and then uses a DNN to extract numerical features. Secondly, a pre-trained model is used to perform semantic segmentation of satellite images of the measurement area. Thirdly, a DNN is used to extract features from the results after semantic segmentation to form environmental features. Finally, the prediction model is trained on the dataset consisting of numerical features and environmental features. The experimental results on campus show that for random location prediction, the model achieves a RMSE (Root Mean Square Error) of 1.97 dB and a MAE (Mean Absolute Error) of 1.41 dB, which is an improvement of 10.86% and 10.2%, respectively, compared with existing models. For the prediction of a test area, the RMSE and MAE of the model are 4.32 dB and 3.45 dB, respectively, and the RMSE is only 0.22 dB lower than that of existing models. However, the DNN-SS model does not need the height, transmission power, and antenna gain of the base station, or a path loss model, which makes it more suitable for large-scale coverage prediction.

Performance Evaluation and Analysis of Urban-Suburban 5G Cellular Networks

5G is the fifth-generation technology standard for the new generation of cellular networks. Combining 5G and millimeter waves (mmWave) gives tremendous capacity and even lower latency, allowing you to fully enjoy the 5G experience. 5G is the successor to the fourth generation (4G) which provides high-speed networks to support traffic capacity, higher throughput, and network efficiency as well as supporting massive applications, especially internet-of-things (IoT) and machine-to-machine areas. Therefore, performance evaluation and analysis of such systems is a critical research task that needs to be conducted by researchers. In this paper, a new model structure of an urban-suburban environment in a 5G network formed of seven cells with a central urban cell (Hot spot) surrounded by six suburban cells is introduced. With the proposed model, the end-user can have continuous connectivity under different propagation environments. Based on the suggested model, the related capacity bounds are derived and the performance of 5G network is studied via a simulation considering different parameters that affect the performance such as the non-orthogonality factor, the load concentration in both urban and suburban areas, the height of the mobile, the height of the base station, the radius, and the distance between base stations. Blocking probability and bandwidth utilization are the main two performance measures that are studied, however, the effect of the above parameters on the system capacity is also introduced. The provided numerical results that are based on a network-level call admission control algorithm reveal the fact that the investigated parameters have a major influence on the network performance. Therefore, the outcome of this research can be a very useful tool to be considered by mobile operators in the network planning of 5G.

Interference Analysis Between 5G System and Fixed Satellite Service in the 28 GHz Band

One of the most favorable frequency bands for 5G technology is the 27.5 - 28.5 GHz band which has been used by Fixed Satellite System (FSS) service in the uplink direction. This potentially causes interference between the two systems. This study aims to analyze the interference that occurs between satellite earth stations and 5G access points (AP), and between 5G AP and satellite sky stations. The analysis is carried out based on simulations using the Spectrum Engineering Advanced Monte Carlo Analysis Tool (SEAMCAT) software, with two scenarios. The first scenario is to analyze interference between the 5G AP and the FSS sky station. With the C/I interference criterion of 40.2 dB, the simulation results show that the 5G AP will not interfere with the FSS sky station. The second scenario is the interference simulation between FSS earth station and 5G AP. The simulation is carried out by varying the distance between the earth station and the 5G AP, the height of the earth station, and the height of the 5G AP. Based on the simulations, it is shown that the FSS earth station can interfere with 5G AP with a probability of up to 60%, so it is necessary to adjust the distance between systems and the height of the antenna to minimize the interference. The shortest distance needed to minimize interference is 36 km with an earth station height of 5 meters.

Rapid Deployment Method for Multi-Scene UAV Base Stations for Disaster Emergency Communications

The collaborative deployment of multiple UAVs is a crucial issue in UAV-supported disaster emergency communication networks, as utilizing these UAVs as air base stations can greatly assist in restoring communication networks within disaster-stricken areas. In this paper, the problem of rapid deployment of randomly distributed UAVs in disaster scenarios is studied, and a distributed rapid deployment method for UAVs´ emergency communication network is proposed; this method can cover all target deployment points while maintaining connectivity and provide maximum area coverage for the emergency communication network. To reduce the deployment complexity, we decoupled the three-dimensional UAV deployment problem into two dimensions: vertical and horizontal. For this small-area deployment scenario, a small area UAVs deployment improved-Broyden–Fletcher–Goldfarb–Shanno (SAIBFGS) algorithm is proposed via improving the Iterative step size and search direction to solve the high computational complexity of the traditional Broyden–Fletcher–Goldfarb–Shanno (BFGS) algorithm. In a large area deployment scenario, aiming at the problem of the premature convergence of the standard genetic algorithm (SGA), the large-area UAVs deployment elitist strategy genetic algorithm (LAESGA) is proposed through the improvement of selection, crossover, and mutation operations. The adaptation function of connectivity and coverage is solved by using SAIBFGS and LAESGA, respectively, in the horizontal dimension to obtain the optimal UAV two-dimensional deployment coordinates. Then, the transmitting power and height of the UAV base station are dynamically adjusted according to the channel characteristics and the discrete coefficients of the ground users to be rescued in different environments, which effectively improves the power consumption efficiency of the UAV base station and increases the usage time of the UAV base station, realizing the energy-saving deployment of the UAV base station. Finally, the effectiveness of the proposed method is verified via data transmission rate simulation results in different environments.

Research on UWB indoor 3D positioning algorithm based on the least squares method

With the increased use of rescue robots in indoor scenarios, the requirements for indoor location services are becoming more stringent. Traditional GPS positioning cannot provide accurate location information indoors, while ultra-wideband (UWB) has been widely used for indoor positioning due to its high accuracy and penetrating power. When solving 3D positioning coordinates using UWB least squares in line-of-sight situations, the positioning accuracy is easily affected by the layout height of the base station. In this paper, we first improve the positioning algorithm and then find a better way of base station layout in the actual positioning environment to improve the tag positioning accuracy. The algorithm improvement is based on the following ideas: firstly, the initial positioning results of the tag are obtained using UWB least squares and spatial geometric relations, and the 3D coordinates of the tag are solved using Gauss-Newton iterative method, and finally combined with the Kalman filter for optimization. The base stations are laid out in such a way that adjacent base stations are not at the same horizontal height and relative base stations are at the same horizontal height.

Model experiment and support optimization analysis of primary support arch cover excavation of large-section metro station in sandy mudstone stratum

The span and height of the Xietaizi metro station of Chongqing Rail Transit Line 18 are all larger than 20 m. The concept of “primary support arch cover” is adopted in the construction method, which aims to give full play to the bearing capacity of sandy mudstone, greatly improve the construction efficiency, and reduce the economic cost. In this paper, the model experiment of primary support arch cover excavation of large-section metro station in sandy mudstone stratum was carried out and the progressive failure process of the initial arch cover was revealed. It is found that the ground surface settlement is not strictly symmetrical about the station center, which is more significant in the case of the measuring points are far away from the central axis of the cavern. Since the support structure installed, the steel arch stresses and anchor axial forces at the inner and outer sides are in a rapid growth stage, and then shows a slow growth trend until stable. For the stresses at the inner and outer sides, the steel arch at the left arch shoulder is characterized by overall compression. The vertical displacements and convergence of the station are more prominent than the horizontal displacements and convergence, which indicates that the significance of control the settlement of the arch crown. The vertical convergence of the station is mainly caused by the settlement of the crown. When the level of loading is large, the number of longitudinal cracks will be increased as penetrating crack and the bulging phenomena will occur at the left arch shoulder of the secondary lining structure. Based on the numerical simulation, the whole dynamic procedure of construction is optimized from the demolition timing of temporary support. The vertical displacements and horizontal convergences for overall demolition schemes are smaller than those for stepping demolition with the excavation of middle guide holes.

High-Precision ZTD Model of Altitude-Related Correction

Zenith tropospheric delay (ZTD) is one of the main error sources in space geodesy. The existing regional or global models, such as Global Pressure and Temperature 3 (GPT3), Global Tropospheric model, Global Hopfield, and Shanghai Astronomical observatory tropospheric delay model models, have good performance. However, the precision of these models is relatively low in regions with a large height difference, which becomes the focus of this article. A high-precision ZTD model considering the height effect on tropospheric delay is proposed, and China is selected as study area due to its large height difference, which is called the high-precision ZTD model for China (CHZ). The initial ZTD value is calculated on the basis of the GPT3 model, and the periodic terms of ZTD residual between the global navigation satellite system (GNSS) and GPT3 model, such as annual, semiannual, and seasonal periods, are determined by the Lomb–Scargle periodogram method in different subareas of China. The relationship between the ZTD periodic residual term and the height of the GNSS station is further analyzed at different seasons, and linear ZTD periodic residual models are obtained. A total of 164 GNSS stations derived from the Crustal Movement Observation Network of China and 87 radiosonde stations are selected to validate the proposed CHZ model, and hourly ZTD data derived from GNSS are used to establish the CHZ model. Statistical result shows that the averaged root mean square and Bias of the CHZ model are 21.12 and −2.51 mm, respectively, in the whole of China. In addition, the application of CHZ model in precision point positioning (PPP) show that the convergence time is improved by 34%, 15%, and 35%, respectively, in N, E, and U components when compared to GPT3-based PPP.

Enhancing Reliability and Security of UAV-Enabled NOMA Communications With Power Allocation and Aerial Jamming

In view of the scarce spectrum resources and inconvenient deployment in wireless communications, this work focuses on an unmanned aerial vehicle (UAV) enabled non-orthogonal multiple access (NOMA) system where a UAV deployed as a base station serves two users by NOMA. A joint power allocation and aerial jamming (PAAJ) scheme is proposed to achieve reliable and secure communications for the system in the presence of a malicious eavesdropper. To be specific, dynamic power allocation is adopted to ensure the reliability of the system and another friendly UAV jammer is introduced to improve the security of the system. The closed-form expressions of connection outage probability (COP), secrecy outage probability (SOP), and effective secrecy throughput (EST) are derived to evaluate the performance of the security-required user in the practical condition of probabilistic line-of-sight (LoS) and non-line-of-sight (NLoS) air-to-ground (A2G) channels. Moreover, the asymptotic EST is analyzed to obtain further insights. Numerical results show the validity of theoretical derivations and the superiority of the proposed PAAJ scheme over benchmark schemes. The EST of the UAV-enabled NOMA communication system outperforms the conventional terrestrial NOMA system at the low transmitting power from the UAV base station. There exists an optimal height of the UAV base station to maximize the EST, which provides a useful framework for designing UAV-enabled communication systems with heterogeneous service requirements.

Evaluating the Accuracy of Jason-3 Water Vapor Product Using PWV Data From Global Radiosonde and GNSS Stations

Jason-3 is equipped with the Advanced Microwave Radiometer-2 (AMR-2) to account for the zenith wet delay (ZWD) caused by the troposphere in the altimeter signal, from which the precipitable water vapor (PWV) can be deduced. In order to investigate the accuracy of PWV from Jason-3 AMR-2 on a global scale, we adopted PWV observations from 263 radiosonde stations and 103 Global Navigation Satellite System (GNSS) stations as reference PWV. These reference PWVs are recorded during Jason-3 cycles 0-119 and are globally distributed in coastal and island regions. Over 60 000 Jason-3 PWV versus radiosonde PWV comparison points and over 380 000 Jason-3 PWV versus GNSS PWV comparison points are used in this study. For GNSS PWV, two PWV height reduction methods (Kouba empirical method and European Centre for Medium-Range Weather Forecasts (ECMWF) method) are used to reduce the PWV from height of station to sea level. The comparison results indicate that the root-mean-square error (RMSE) of Jason-3 PWV evaluated using radiosonde PWV is 3.4 kg/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Jason-3 PWV has an RMSE of 3.0 kg/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> with GNSS PWV derived using ECMWF PWV height correction, while the RMSE between Jason-3 PWV and GNSS PWV derived using Kouba PWV height correction is 3.1 kg/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . In addition, the accuracy of Jason-3 PWV increases when the latitude of its footprints or the distance from its footprints to land increases.

Indoor height determination of the new absolute gravimetric station of L'Aquila

In this paper we describe all the field operations and the robust post-processing proceduresto determine the height of the new absolute gravimetric station purposely selected to belong to a new absolute gravimetric network and located in the Science Faculty of the L’Aquila University. This site has been realized indoor in the Geomagnetism laboratory, so that the height cannot be measured directly, but linking it to the GNSS antenna of AQUI benchmark located on the roof of the same building, by a classical topographic survey. After the topographic survey, the estimated height difference between AQUI and the absolute gravimetric site AQUIgis 14.9700.003 m. At the epoch of the 2018 gravimetric measures, the height of AQUI GNSS station was 712.9740.003 m, therefore the estimated ellipsoidalheight of the gravimetric site at the epoch of gravity measurements is 698.0040.005 m. Absolute gravity measurements are referred to the equipotential surface of gravity field, so that the knowledge of the geoidal undulation at AQUIg allows us to infer the orthometric height as 649.32 m.

Passive positioning method and error analysis of UAV based on TDOA

At present, the phenomenon of "black fly” and "flooding” of drones frequently occurs, which brings various security risks to the country, society and individuals. Aiming at the passive positioning problem of UAV, this paper proposes a method based on TDOA for direct closure to solve the target position.The four-station time difference method is analyzed. The position coordinates of UAV are expressed as a function of the radial distance between the UAV and the main station.Then solve the quadratic equation of the radial distance between the UAV and the main station.Finally, obtain the position coordinates of the UAV by radial distance.According to the distribution of the solution of the quadratic equation, the unique solution zone, the fuzzy solution zone and the non-solution zone are analyzed, and the fuzzy solution is solved. The method of defuzzification is proposed in the area.The positioning error is studied, and three factors affecting the positioning error are discussed: the distance between base stations, the height of the main station and the measurement accuracy of distance difference.The research conclusion has important guiding significance for the station design.

О ТОЧНОСТИ ПОСТРОЕНИЯ ПЛАНОВО-ВЫСОТНОЙ ГЕОДЕЗИЧЕСКОЙ РАЗБИВОЧНОЙ ОСНОВЫ НАЗЕМНЫМИ МЕТОДАМИ

The article gives comparative analysis of the creating horizontal and vertical geodetic control network for the purposes of research and building. It is recommended to create geodetic network on the territory up to 1–2 sq km by means of linear-angular measurements with the accuracy of urban fourth-order traverse. After centering the total station and the reflector with an error not more than 1 mm, the minimal network side is 140 m. The precalculation of geodetic control network accuracy with the given confidence level can be performed in CredoDAT. Creation of vertical and horizontal geodetic network should go simultaneously – by means of reciprocal trigonometric leveling of III–IV order accuracy. The height of the total station with use of specific tape measurer Leica can be measured with error of up to 1 mm. The requirements of the acting set of rules «Geodetic works in construction» are not always substantiated and require careful attitude.

New Method of Energy Efficient Subcarrier Allocation Based on Evolutionary Game Theory

Since there is a competition between subcarriers because FBMC (Filter Bank Multicarrier) modulation technology does not need subcarriers to be orthogonal to each other, we consider the evolutionary game method to optimize subcarrier allocation. Because the adjacent subcarriers do not need to be orthogonal to each other in FBMC, there is conflict and competition, thus the evolutionary game theory is used to optimize the subcarrier allocation problem. We innovatively introduced the channel state matrix to show the quality of subcarriers. Considering the height of secondary user and base station’s antenna, the total data transmission rate limit, total power consumption constraint and power consumption constraint on a single subcarrier, a nonlinear fractional programming problem is established where maximum energy efficiency is the objective function, total data transmission rate limit, total power consumption constraint and power consumption constraint on a single subcarrier are constraint conditions. The utility function for each secondary user is established when the evolutionary game operator is designed. When the utility function becomes optimal, the evolutionary game reaches Nash equilibrium, and the strategy combination is considered to be the energy efficient resource allocation scheme. Through experimental simulation, EESA-EG proposed in this paper gives the most reasonable subcarrier allocation scheme, allocates more subcarriers for the subcarriers with better channel state and the energy efficiency in EESA-EG is optimal.

The Impact of Antenna Height on 3D Channel: A Ray Launching Based Analysis

Three-dimensional (3D) multi-input-multi-output (MIMO) is one of the enabling technologies for next-generation mobile communication. As the elevation angle in the 3D MIMO channel model might vary against the height of the base station (BS) antenna, it should be considered within channel modeling. In this paper, the impact of antenna height on the channel characteristics of the 3D MIMO channel is investigated by using the intelligent ray launching algorithm (IRLA). Three typical street scenarios, i.e., the straight street, the forked road, and the crossroad, are selected as benchmarks. The joint and marginal probability density functions (PDFs) of both the elevation angle of departure (EAoD) and the elevation angle of arrival (EAoA) are obtained through simulations. Moreover, the elevation angle spread (AS) and the elevation delay spread (DS) under various antenna heights are jointly discussed. Simulation results show that the characteristics of the PDFs of EAoD will vary under different street scenarios. It is observed that in order to obtain the maximum or minimum value of the AS and the DS, the BS antenna should be deployed at half of the building height.

A Graphic Method to Estimate the Wind Speed under Urban Canopy Layer

This article is based on a graphic method introduced by author to determine around buildings for levels less than 10 meters. By help of graphs produced in this research architect is able to estimate in every terrain and every height less than 10 meters above ground - that is deferent from height and terrain of meteorology station - without being involved with calculation procedure. According to importance of turbulent in spaces, this article produced a table by using equivalent steady (Vs) supporting graphic method to determine acceptable around buildings. This table will be used by help of a CFD simulation to estimate proportion of equivalent steady around building (Vs) to mean (Vz) in same level of terrain (Vs/Vz). It will help architect to predict important thresholds of acceptable around buildings in his/her own design to prevent unpleasant conditions. Referring to meteorology data of place, graph will show duration, time and direction of that may cause unpleasant conditions. Therefore it will lead designer to correct design and reduce uncomfortable situations. above air dome, which is called urban boundary layer. The is called gradient wind and its velocity is called gradient velocity. The variation with height is divided into two specific sub-layers (1). The obstructed sub-layer or canopy sub-layer which extends from ground surface up to building's height; and free surface layer or boundary layer which extends above rooftops. The flow in obstructed or canopy sub-layer is driven by interaction of flow field above and is influenced by local effects of topography, building geometry and dimensions, streets, traffic and other local features such as presence of trees. In general way, in canopy layer is much lower when compared to undisturbed (2). The field is characterized by two parameters: profile of mean speed and the turbulence spectrum. Both are affected and modified by profile of terrain and, in an setup, by structure (3). This article is more concentrating on first parameter: the vertical profile of mean speed and it is supposed to achieve a graphic method to estimate in a terrain according to turbulence occurs around buildings by help of CFD simulation.

A STUDY ON THE EFFECTS OF RAIN ATTENUATION FOR AN X-BAND SATELLITE SYSTEM OVER MALAYSIA

In this paper, the effect of rain attenuation on the FSS allocation in the 7250–7750 MHz in the Space-to-Earth direction is studied for a satellite at 78.5◦E longitude. A simulation model based on the ITU-R P618-10 rain model is used to predict the rain attenuation in the C-, Kuand X-bands in 15 different locations with varying rainfall intensities of between 145–300 mm/hr in East and West Malaysia. The simulations assume a 1.8m receive antenna with 65% aperture efficiency, QPSK modulation and use of either vertical or horizontal polarization. The downlink centre frequencies used in this study are 4200MHz, 7750 MHz and 11200 MHz for C-, Xand Ku-bands respectively. The average free-space path loss calculated for each band is used to estimate the signal attenuation due to rain and the corresponding Eb/No (dB) is computed at varying rain intensities. The results show that when using vertical receive polarization, all 15 locations of study with a rainfall intensity of up to 200mm/hr could receive the X-band signal. At 200mm/hr rain intensity in the horizontal receive, most of the X-band links could achieve the threshold Eb/No of 7.68 dB with a ULPC adjustment of approximately 1.5 dB where required. At 300 mm/hr rain intensity, video signals in the X-band were no longer receivable in both polarizations. At 145mm/hr rain intensity, only one location with high satellite elevation and greater height above mean sea level maintained the Ku-band link in the horizontal receive. In the vertical receive, the Ku-band link was receivable at all locations at 145mm/hr but were no longer receivable at 200 mm/hr. The study concluded that the elevation angle towards the satellite is a major factor in determining the quality of the signal in the X-band. The other factors that affected the receive Eb/No was the polarization, depth of rain and height of the earth station above Received 31 August 2012, Accepted 15 October 2012, Scheduled 19 October 2012 * Corresponding author: Thiagarajah Siva Priya (sivapriya.thiagarajah@gmail.com). 38 Siva Priya and Nizhanthi mean sea level. In comparison to the Ku-band, the X-band was able to maintain a good quality satellite link in rain intensities of up to 200mm/hr in the vertical receive. The results indicate that there is high potential for the use of X-band to provide for video transmission over Malaysia in spite of the high rain intensities.

The challenge of estimating regional trace gas emissions from atmospheric observations

This paper discusses some of the major issues that surround estimating regional emissions of trace gases from atmospheric observations through inversion modelling. Inversion methods use modelled knowledge of how emissions dilute in the atmosphere as they travel from their source to an observation point, together with the observations, to calculate a grid of emissions. The problem is one of minimizing the mismatch between a modelled and observed time series of concentration. There are many methods of comparing time series, some involving a priori knowledge others without. The location, terrain and height of the observation station can also be very significant in determining how well a model can represent the dilution from emission source to receptor. The inversion solution (emission map) will assign some of the sources incorrectly for a variety of reasons, e.g. local sources, intermittent releases, errors in the modelled transport or observation, and the choice of the spatial and temporal resolution of the emission map. The reasons for uncertainty in the modelled emissions are discussed along with suggestions as to how some of these can be minimized. Using multiple stations to further constrain the inversion should reduce the uncertainty; however, care is needed if the potential improvements are to be realized.

3D DOPs for Positioning Applications Using Range Measurements

For terrestrial positioning, some applications require three dimensional coordinates. The Dilution of precisions (DOPs) for position systems using range measurement are reviewed and the average values of DOPs for different deployments of base station geometries are examined. It is shown that to obtain the lowest DOPs, the base stations for different types of positioning systems need to be deployed differently. Changing the N-sided regular polygon to an (N - 1)-sided polygon with one base station in the centre of the polygon can decrease the value of DOP in general for a pseudorange time of arrival (TOA) system but not for an absolute range TOA system. The height of the base station in the centre can also change the DOP significantly. The finding can be used to optimize the deployment of the base stations for range measurement positioning systems.

3D Numerical Simulation and Performance Predication of Vertical Axial Flow Pumping Station by RNG Turbulent Model

Vertical axial flow pumping stations have advantages of large capacity and low head. This type of pumping station has been widely used for water transportation or irrigation and drainage. Most of the pumping stations presently under construction for the East Routine of South-to-North Water Transfer Project adopt this type. The flow pattern and hydraulic performance of vertical pumping station with bell inlet and worm outlet are studied. The incompressible N-S equations are solved by using the finite volume method. Based on the RNG k-e model with wall-function law, SIMPLEC algorithm is applied for the solution of the discretization governing equation. By using multiple reference frames, the flow detail of whole vertical pumping system is attained. The relation between the axial flow distributing law of inlet bellmouth with rotating impeller and installation height of pumping station is analyzed. The reference nominal height of pump is put forward. The numerical hydraulic performance is predicted. A good agreement is achieved between the predicted data and experimental data under designed operating condition. 3D numerical computation and model test show that this type of pumping station can be applied in the East Route of South-to-North Water Transfer Project.

New Method for Evaluating Height Gain at Subscriber Station for Wireless Access Systems in Microwave Band

This paper presents a model for the variation in height of the subscriber station (SS) antenna with respect to the path loss for microwave-band wireless access systems. The propagation mechanism that causes the dependency of the height variation characteristics of the received level at an SS on the SS location and operating frequency is clarified in terms of geometrical optics (GO) using the uniform geometrical theory of diffraction (UTD). The height variation characteristics strongly depend on whether or not regular reflected waves that have a higher level than that of the diffracted wave arrive at the SS. A representation of the model is shown. The model is validated using measured data at 2.2, 5.2, and 25.15 GHz and the validity of the model is shown. This model is useful in the radio zone design of microwave-band broadband wireless access (BWA) systems operating in a non-line-of-sight environment, and in estimating the height gain at a mobile station antenna for mobile communications.