Mobile radio propagation path loss studies at VHF/UHF bands inSouthern India

Field strength measurements at 200, 400 and 450 MHz (VHF/UHF band) were conducted with the field strength meter placed on board a vehicle in Southern India. Observed field strength values were converted into path losses and are compared with different path loss prediction methods like Hata (1980), Egli (1957), Blomquist-Ladell (1974), COST 231 Walfisch-Ikegami (Doble 1996), Walfisch-Bertoni (1988) and ITU-R. These path loss studies are carried out in urban, suburban and open areas in this region. The results showed that Hata's method gave better agreement with observed values in urban, suburban and open regions; the COST 231 Walfisch-Ikegami model is also in good agreement with the observed values in urban and suburban regions, the Egli and Blomquist-Ladell methods showed moderate agreement in open regions only. The agreement of the Walfisch-Bertoni and ITU-R methods with observed values is not good     

Some experimental investigations in the WiMAX band and comparison of propagation models in mixed urban environments of Western India

This paper presents the analysis of measurements taken at 2.3?GHz in the mixed urban environments of Western India for 17 WiMAX base stations. Coverage predictions using various models and their comparison with observed data have been carried out. Measured path loss is compared with the theoretical path loss values estimated by COST-231 Hata model, the SUI model, the ECC model, and ITU-R (P.1411-1) model. This investigation is essential to provide last mile broadband wireless access, before deploying WiMAX. Path loss exponents, mean errors, and standard deviations of all the prediction methods were deduced and suitable models for path loss prediction methods were identified.     

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。     

Experimental investigation of mobile radio propagation at 1.8 GHz over macrocellular dense urban regions of Delhi

The design of future-generation mobile communication systems depends critically on the suitability of path loss prediction methods and their suitability to various regions. To investigate the radio channel behavior, experimental measurements in the 1.8 GHz band were conducted in the dense urban regions of New Delhi for six GSM base stations. Path loss exponents and break point distances have been deduced, and observed results have been compared with various prediction methods, and their standard deviations have been presented. Measured regression line exhibited lowest standard deviations followed by rooftop propagation method compared with Cost 231 Hata and Cost 231 Walfisch–Ikegami (WI) prediction methods. Variation of observed results has been explained in terms of vertical and horizontal propagation mechanisms which is the novelty of this paper.     

Mobile radio propagation in Auckland at 76 MHz

A series of field trials in Auckland at 76 MHz have confirmed that propagation path loss is normally distributed and may be characterised by a fourth-power-law distance dependency. The path loss standard deviation has been found to be dependent on the mobile terminal's environment and on frequency, but is essentially independent of base station antenna height and path length. The excess path loss over plane earth predictions and the standard deviation of path loss have been measured as 14.6, 5.0, 0.8 and 1.0 dB and 6.2, 5.2, 3.7 and 5.0 dB for urban, light urban, suburban and rural environments, respectively.     

Prediction of urban propagation loss

Two significantly different methods to calculate the path loss in urban areas are investigated in order to test their applicability to predicting the received power of a broadband DAB signal for mobile reception. The results were verified by broadband measurements of the received power in a DAB single-frequency network recently installed in Munich. Although these methods use totally different approaches to calculate the path loss, their predictions of the mean received power are of comparable accuracy. However, in order to cope with the need of a coverage for 99% of the locations for a digital service and mobile reception, it is worthwhile to use rather complex methods that are capable of providing information about the local variation of the signal. One such method will be described in this paper     

Path Loss Models for Low-Height Mobiles in Forest and Urban

This paper presents path loss measurements at 2.1 GHz in forest and urban areas. Empirical path loss models have been presented for low-height dual-mobility channels. Three test scenarios are considered for the transmitter (Tx) and receiver (Rx) placed inside the test vehicle or on a test cart pushed at walking speed. Based on measurements, the in-leaf and single-slope path loss models are presented. The path loss exponents for the dual-mobility channels are found to be between 2.1 and 3.4 in urban and 8.0 in forest, with higher reference when antennas are placed inside the vehicle.     

Single knife edge diffraction propagation studies over a hillyterrain

Field strength measurements are made to study the single knife edge diffraction propagation in the hilly terrain of Tirupati, southern India. TV signals originating from Narayana Giri Hill in the VHF band are monitored at 4 different locations of Tirupati for this purpose. The observed values are converted into path loss values and are compared with prediction techniques. An attempt is made to study the adaptability of these techniques and it was found that the ITU-R, Epstein-Peterson (1953), Deygout (1966) and Edward-Durkins (1969) methods are in closer agreement with the observed path loss where as Blomquist-Ladell (1974) over estimates the observed path loss     

Hata based propagation loss formula using terrain criterion for 1800 MHz

Many mobile propagation models are going under intensive corrections; recently, to suit other new criteria's such as rough terrain areas. This proposed model modifies Hata main urban equation by adding a formula representing a logarithmic linear regression estimator of the standard deviation (σ) of the measuring campaign path in Amman city, Madaba city, and Jiza town, Jordan. High correlation factor of −96.7% is calculated between excess measured path loss compared to Hata urban path loss and log(σ). Root mean square error (RMSE) difference between this model and the measured raw data path loss has overcome RMSE calculated for Hata model, by an average of 21 dB, for open areas. The correction of suburban areas is calculated, on average, as 20 dB, and for urban areas as 17 dB.     

Evaluation of the suitability of troposcatter prediction techniques over Northern India

The design of any radio communication system requires a suitable prediction technique for calculating the received signal levels. The optimum prediction method helps to reduce the interference problems, and improves reliability of links. In the present study the path loss values deduced from various prediction techniques are compared against observed path loss values over two troposcatter links situated in northern India. The results show that April and May are the worst months and the present space and frequency diversity configuration is not able to effectively overcome the link outages. A comparison of different path loss prediction techniques showed that Yeh’s prediction method and itu-r’s method I comes close to the observed values. The predicted path loss values for worst month using itu-r’s method deviated considerably from the observed values. The present study provides valuable inputs to the itu-r study group from the tropical countries by evaluating the itu-r prediction methods against the experimental data.     

Path loss prediction in microcellular environments at 900 MHz

A model is proposed to estimate path loss in urban environments at 900 MHz when the base station antenna is below the average height of the buildings. It shows that the percentage of area occupied by buildings explains more than 20 dB of variation of the mean path loss.     

Neural network-based path loss model for cellular mobile networks at 800 and 1800 MHz bands

Cellular radio communication systems have become essential for data/voice/video/multimedia applications. The performance of cellular communication radio systems is assessed by considering the design specifications of frequency planning, channel assignment and interference mitigation strategies among others. Frequency planning is the most important component to improve capacity or quality of cellular radio systems. Large-scale path loss values between the base station and mobile stations are the key regulating factors that limit the performance of cellular systems, especially in urban/vegetation region. There is a necessity to develop a suitable path loss prediction model for predicting path loss values based on received signal strength measurements. In this paper, an ANN-based path loss model was used for macro cell measurement data obtained in the Vijayawada urban region, India. The Multi-Layer Perceptron (MLP) neural network model was considered. The prediction results indicate that the ANN model outperformed the Auto Regressive Moving Average (ARMA) and COST-231-WImodels. The outcome of this research work will be immensely useful for improving coverage and ensuring better frequency planning of cellular radio systems.     

Variability of mobile radio path loss in Auckland at 465 MHz

A series of field trials in Auckland at 465 MHz have confirmed that the variability of mobile radio path loss is approximately normally distributed and can, therefore, be represented by a standard deviation. This standard deviation has been found to be dependent on the mobile terminal's environment and on frequency, but is essentially independent of base-station antenna height and path length. Standard deviations have been measured as 5.2, 4.4, 5.4 and 5.2 dB for rural, suburban, light urban and urban environments, respectively.     

Non-parametric Method of Path Loss Estimation for Endoscopic Capsule Localization

Localization of the wireless video capsule endoscope (VCE) is necessary for proper diagnosis and treatment of the lesions in the gastrointestinal tract. In this paper, we propose path loss based VCE localization algorithm using weighted average of the sensors position. The main challenge in path loss based localization in human body is the scattered random deviation of path loss caused by the shadowing and multipath propagation of non-homogeneous medium. To address the randomness issue of the scattered path loss, we propose three non-parametric methods of path loss estimation using moving averaging, local weighted regression and local Gaussian weighted average. Then we use the degree based estimated path loss to calculate the weight of the sensors position. We propose a heuristic method of degree estimation for the estimated path loss. We develop a simulation platform using MATLAB to evaluate the performance of our proposed methods. The results show significant improvement in accuracy without any prior knowledge of distance related channel parameters.     

The influence of land usage on UHF wave propagation in the receivernear range

Scattering, diffraction, and attenuation of UHF wave propagation in the receiver near range (RNR) may cause significant additional path loss. Wave-propagation models for rural areas consider mainly the influence of topography and often ignore the effects due to land usage in the vicinity of mobile receivers. In some models, this path loss is accounted for either by empirical corrections or by additional knife edges. In this paper, new ray optical approaches for the calculation of the additional path loss for receiver sites within forested and suburban environments are presented. Typical macro situations are defined to describe the RNR. For urban areas, the additional path loss is determined by means of the uniform theory of diffraction (UTD), whereas in forested areas, a lateral wave-propagation approach is used. The resulting RNR model is tested in an operating global system for mobile communication (GSM) network. The results show good agreement with both wide- and narrow-band measurements     

Mobile radio propagation in Auckland at 465 MHz

A series of field trials in Auckland at 465 MHz have confirmed that propagation path loss may be characterised by a fourth-power-law distance dependency. The excess loss over plane earth predictions has been measured as 37.8, 26.4, 18.6 and 14.1 dB for urban, light urban, suburban and rural environments, respectively.     

一种新的无线电波传播路径损耗模型

使用渗流网格建模无线电波的随机传播环境,在此基础上使用随机射线方法,从概率论的角度得到若干路径损耗的解析公式.经过与经典路径损耗模型以及其他由非波动方法得到的路径损耗模型的比较之后,从逻辑上推断出一个新的路径损耗模型.对新模型中参数的取值范围进行了讨论和分析,最后使用城市密集传播地区的测量数据验证新的路径损耗模型的精确性.     

超短波频段复杂城区场景的信道测量与建模

为了准确反映复杂城区环境下移动自组织网络（mobile ad hoc network,MANET）通信节点间的无线信道传播特性,以150 MHz频点为例对山东省青岛市典型城区场景的超短波无线信道进行了外场测量.基于测量数据开展统计分析,提取了路径损耗指数、阴影衰落标准差、多径时延拓展以及频率相关性等信道参数,并针对准视距（quasi-light-of-sight,QLOS）区和非视距（non-light-of-sight,NLOS）区建立了大尺度衰落模型和小尺度抽头延迟线模型.分析和建模结果表明:在MANET城市通信场景下,路径损耗指数随距离增加呈现出双斜率特性;当累积分布函数（cumulative distribution function,CDF）为0.9时,均方根时延在QLOS区为726 ns,在阻挡严重的NLOS区为967 ns;相关带宽在QLOS区和NLOS区分别为700 kHz和300 kHz.论文所建信道模型有利于准确衡量MANET通信设备在复杂城区的通信性能,并为相关通信系统设计提供参考.