Empirical Path Research Articles

Empirical Path Loss Models for Wireless Sensor Network Deployments in Short and Tall Natural Grass Environments

Extensive research has not been done on propagation modeling for natural short- and tall-grassy environments for the purpose of wireless sensor deployment. This study is essential for efficiently deploying wireless sensors in different applications such as tracking the grazing habits of cows on the grass or monitoring sporting activities. This study proposes empirical path loss models for wireless sensor deployments in grassy environments. The proposed models are compared with the theoretical models to demonstrate their inaccuracy in predicting the path loss between sensor nodes deployed in natural grassy environments. The results show that the theoretical model values deviate from the proposed model values by 12%–42%. In addition, the results of the proposed models are compared with those of the experimental results obtained from similar natural grassy terrains at different locations resulting in similar outcomes. Finally, the results of the proposed models are compared with those of the previous studies and other terrain models such as those in dense tree environments. These comparisons show that there is a significant difference in path loss and empirical model parameters. The proposed models as well as the measured data can be used for efficient planning and future deployments of wireless sensor networks in similar grass terrains.

The associations among maternal negative control, children’s social information processing patterns, and teachers’ perceptions of children’s behavior in preschool

The links between social information processing (SIP) and social behavior in preschool are well documented. However, the antecedents of SIP in that age group are less clear. A number of influential theoretical models suggest that a major contributor to SIP is the quality of the child’s relationships with the parent. Therefore, we examined the links among quality of the mother–child relationships (measured via direct observations of dyadic play interactions), the child’s SIP patterns (measured via direct interview with the child), and the child’s perceived behavior in preschool (measured via teacher reports) in a sample of 218 preschool and kindergarten children and their mothers. Applying structural equation modeling, we found support for our theoretical model with a specific emphasis on the negative nature of this association. Specifically, we found a strong indirect path from maternal negative control to the teacher’s negative perception of the child’s behavior in preschool and kindergarten via less competent SIP patterns. This empirical path remained intact after controlling for various variables such as the family income, the mother’s education level, and the child’s expressive language abilities, thereby providing further support for the robustness of this association.

Experimental Characterization of Radio Channel in Ruins Environment

This letter addresses the fading statistics of a radio propagation channel in a ruins environment, which is of vital importance for a pedestrian localization system based on cellphone signals. The channel of ruins is investigated in eight typical rescue scenarios at two common mobile communication bands (900 MHz and 1.8 GHz). To characterize the channel, an empirical path loss model is parameterized through experiments. Based on extensive measurements, large-scale fading characteristics at different polarizations and various antenna heights are examined and analyzed. Furthermore, the properties of small-scale fading including coherence bandwidth, decorrelation distance, and distance-dependent features are studied in this work. The results reported here can be applied to simulate the ruins channel and design the rescue system.

Adaptive Empirical Path Loss Prediction Models for Indoor WLAN

This paper presents robust empirical path loss models to characterize indoor propagation for access point (AP) deployed at different heights. The proposed models are developed with wireless local area network infrastructure at 2.4 GHz. The models are backed by extensive received signal strength (RSS) measurements acquired in line of sight and obstructed line of sight regions. The models are developed for two conditions, viz; quasi realistic and realistic RSS measurements. The quasi realistic measurements are taken after suppressing human intervention and electrical interferences to minimum. While the realistic RSS measurements are made in presence of all the human interventions and electrical interferences. The shadow fading component for both quasi realistic and realistic conditions is statistically modeled with the dependency on AP height. The proposed technique can be applied with higher confidence level to the buildings with similar construction features where RSS measurements are made upon. The results reveal that the performance of the proposed propagation models is significantly higher than the existing International Telecommunication Union-path loss model. The results also demonstrate that the realistic path loss model is more robust than the quasi realistic model.

RADIO PROPAGATION CHARACTERISTICS OF INDOOR LOCATION SYSTEM BASED ON RSSI AT 490 MHz

Localization and tracking technology based on received signal strength indicator (RSSI) is one of the most popular topics because of its low demand on hardware and cost. But the complexity of the indoor environment, leads to the uncertainty of the radio propagation which can seriously affect the positioning accuracy based on the received signal strength. Focused on the wall reflection in the indoor environment, the radio propagation characteristic based on ray-tracing model is analyzed and one strategy for the near wall localization is presented. The actual hardware platform and experimental test results show the applicability of the empirical logarithmic path loss model for localization and the effect of the wall reflection.

Le faire mathématique : une nouvelle ouverture théorique et méthodologique pour étudier les connaissances et les savoirs ?

In their research work, MAHEUX and PROULX propose to take distance from mathematical "knowledge" and "knowing" and to focus on mathematical doing. The both theoretical and empirical path that they investigate leads me to question further the role of mathematical knowledge and knowing in the research in didactic of mathematics. Do mathematical knowledge and knowing appear as 'real' or theoretical objects in didactic studies? How do "knowledge and knowing" influence the ways in which researcher may observe and analyse the learning/teaching of mathematics?

INVESTIGATION OF PATH LOSS PREDICTION IN DIFFERENT MULTI-FLOOR STAIRWELLS AT 900 MHZ AND 1800 MHZ

Wireless communication along the stairwell in a high rise building is important to ensure immediate response to take place via consistent relaying of necessary information or data in emergency situations. Thus, a good understanding of signal wave attenuation along the stairwell is necessary to allow a better wireless network planning. This paper presents empirical path loss prediction model for multi-floor stairwell environment. The proposed model is based on measurement at 4 different stairwells, at 900 MHz and 1800 MHz which are near public safety communication bands. The model incorporates the effect of different floor heights and unique path loss-to-distance relation on selected stair flights observed during measurement campaign. The proposed model demonstrates higher accuracy than 3 standard path loss models at 2 other stairwells.

공항 화물터미널 환경에서 실험적인 패스 로스에 관한 연구

공항 화물터미널 환경에서 실험적인 패스 로스에 관한 연구

Adjustment of Cost 231 Hata Path Model For Cellular Transmission in Rivers State

Path loss prediction models are essential tools in radio network planning for cellular transmission as they are used for received signal strength estimation, link budget design and analysis, cell size estimation, and interference optimization. This paper presents empirical path loss models developed for WCDMA microcells operating at 2100MHz on live radio Globacom Node Bs in the urban, suburban, and rural areas in Rivers state. The performance of COST 231 Hata model, Stanford University Interim, and Electronic Communication committee 33 were compared with measured field data. COST 231 Hata model gave a better prediction but with high RMSE and SD which are outside the acceptable value for a good radio signal propagation. COST 231 Hata model was for adjustment based on Linear Least Square Algorithm (LLSA). After adjustment and simulations, the adjusted COST 231 Hata model gave better predictions with minimum MSE and SD that are within the acceptable values. The adjusted COST 231 Hata can accurately be used for predicting the radio characteristic of Rivers State.

Empirical Path Loss Models for C-Band Airport Surface Communications

AeroMACS is a system currently under development for airport surface communications. It is based on the IEEE802.16-2009 standard, and is developed in cooperation with the WiMAX forum. The frequency band allocated to AeroMACS is 5091-5150 MHz. When specifying the AeroMACS system, knowledge of typical propagation conditions at airports is of importance. Typically, path loss models are used to estimate the range of a transmitter within different zones of the airport, and typically fading characteristics are used to estimate the performance of, e.g., the selected coding and modulation schemes. Propagation measurements have been performed at the Barajas airport in Madrid, Spain. The measurements includes Non-Line-Of-Sight (NLOS) as well as Line-Of-Sight (LOS) conditions. Based on these measurements, path loss parameters and path loss models are developed for different zones of large airports.

Planning of WiMAX Networks Based on Modified Empirical Path Loss Model

Abstract The prosperity and demand of wireless access technology have drawn tremendous attention from researchers for the Worldwide Interoperability for Microwave Access (WiMAX) over the past decade. This paper presents developed and adapted empirical path loss model (Samir Model) for the planning of WiMAX networks. The empirical propagation path loss models have a significant influence in wireless communication systems design. Predicting and finding the path loss are essential in planning and designing WiMAX networks. Three empirical models, the Stanford University Interim (SUI) model, the COST-231 Hata model and Samir model have been investigated in this work. Reference path loss of 3.5GHz WiMAX networks data is compared with the above mentioned models to demonstrate the responses of WiMAX systems based Samir empirical path loss model and confirm it is more comprehensive to combine both SUI and COST-231 Hata models . Many dependent parameters of the WiMAX planning problems are tested in different types of topography (rural, urban and suburban) such as path loss, base station and receiver antenna height, shadow fading, transmitting power and receiver sensitivity against distance between transmitter and receiver.

Geolocation‐aware security in a netcentric small unmanned‐aerial‐system for RF emitters

AbstractEnhancing security requires sensing devices surveilling over critical infrastructures for early warning of radio frequency (RF) emitter geolocations. Conventional geolocation of RF emitters has adopted active methodologies by illuminating targets, such as radar sensors. However, active geolocation draws unwanted attention of adversary, thus highly increases threats and vulnerabilities of the sensing devices. As security issues become a central concern in sensing applications, we propose a small unmanned‐aerial‐system for passive geolocation of RF emitters. Multiple electronic surveillance sensors are mounted on small unmanned‐aerial‐vehicles (UAVs) to provide geolocation awareness. Both sensors‐to‐UAV and UAVs‐to‐fusion‐center communications are investigated. Different with previous studies, our approach is based on an empirical path loss and log‐normal shadowing model, from a wireless communication and signal processing vision. The communication degradation from UAV to fusion center has been taken into consideration other than assuming lossless performance. The analyzed geolocation error and the error probability of distance shows that this approach provides robust performance at high frequencies, thus offers an effective solution for the security issue in RF emitter geolocation. Copyright © 2012 John Wiley & Sons, Ltd.

Path Loss through Pine Forest around Beach for Wireless Sea Wave Energy Sensor Network

This paper presents an empirical path loss model through forest for measuring sea wave energy using 2.4 GHz wireless sensor network (WSN). The empirical path loss model was determined from measurement campaign by using 18 dBm transmitter and the receivers with a low noise amplify. The conventional path loss models for forest environments were carried out such as Weissberger, ITU-R, COST 235 and Torrico models. From the results it is found that the proposed model provides a good agreement and is used for planning WSN.

Intra-, Inter-, and Extra-Container Path Loss for Shipping Container Monitoring Systems

This letter presents empirical path loss models for an environment of stacked shipping containers. Specifically, a system for wireless monitoring of containers is considered for which three different types of wireless links are identified, namely intra-, inter-, and extra-container links. Furthermore, the inter-container link is investigated for the two most common types of container stacking: row and block stacking. Intra- and inter-container path loss are investigated at IEEE 802.15.4 frequencies of 433, 868, and 2400 MHz. Extra-container path loss is examined at GSM/UMTS frequencies of 900, 1850, and 2100 MHz. Distance-dependent path loss models are proposed for the inter- and extra-container links (high-correlation coefficients between 0.76 and 0.86). The resulting path loss models can be used in link budget calculations for container monitoring systems.

Cascadia tremor spectra: Low corner frequencies and earthquake-like high-frequency falloff

The discovery of non-volcanic tremor (NVT) has opened a new window to observe major Earth plate boundaries. However, the spectral characteristics of NVT have not been well studied due to poor signal-to-noise ratio (SNR) on individual seismograms. We estimate the spectral content of Cascadia tremor between 2.5 and 20 Hz by suppressing noise using array analysis, and compute empirical path corrections using nearby small earthquakes. We demonstrate that the displacement spectra of the Cascadia tremor have corner frequencies around 3–8 Hz and fall off at f−2 to f−3 at higher frequencies. Our results have the following implications. (1) The high-frequency falloff of tremor agrees with the observations of regular earthquakes, suggesting that tremor can be analyzed using standard spectral models. Prior analyses that have shown a tremor spectral falloff proportional to f−1 may reflect only the spectral behavior over a limited frequency band. (2) Tremor may be no different from a swarm of microearthquakes with abnormally small stress drops on the order of kPa, likely due to the presence of fluids. Alternatively the low corner frequencies of tremor may reflect abnormally slow ruptures. (3) Fitting a standard Brune (1970) spectral model implies a moment release rate of Cascadia tremor of 3.8 × 1010 N·m/s assuming the tremor signals are P waves (or 1.4 × 1010 N·m/s assuming S-waves). This implies that a typical 20-day long tremor episode releases moment equivalent to Mw 5.1 (P-wave) or Mw 4.9 (S-wave), although these may be underestimates if the spectra deviate substantially from the Brune model at very low frequencies.

A Topology Of The Sensible

A TOPOLOGY OF THE SENSIBLE Michel Serres, The Five Senses: A Philosophy of Mingled Bodies, London, Continuum, 2008; 364pp, £19.99 paperback There is a tendency towards the hagiographie that runs through commentary on Michel Serres. Some of this is undoubtedly well deserved as recompense for the relative neglect of his work in the Anglophone academic world. The translation into English of only limited parts of his now extensive body of publications (running to 50 plus books) has robbed this contemporary of Foucault and Deleuze of the critical attention and acclaim lavished on his peers. Matters may well now be changing with the recent re-publication of die translation of one of his finest works - The Parasite - and the very welcome and long overdue translation of The Five Senses. Whilst there is much to celebrate here, a few words of caution are also in order. Published originally in 1985, this is a long book that demonstrates that by this mid-point in his career Serres was unconstrained by the demands of prudent editing. The tone of much of the book is poetic, rhapsodic and allusive - readers in search of clear citation or footnotes, which show the 'workings out', will need to brace themselves. Structurally the book is elliptical and rather bloated in places (the third chapter in particular is a long haul). There are wince-inducing moments throughout, notably around the gender and class politics of the text. The sections that reflect Serres' complex relationship to Christianity will also likely leave some readers cold, as will the unpalatable bon vivant theme diat dominates one chapter which the publisher has mystifyingly chosen to highlight on the front cover and the back cover text. ARE YOU STILL HERE? Good. Now the reasons why you nevertheless need to read this book. Much has rightly been made of the theoretical turn toward affect and sensibility. Yet much of it is mired in somewhat outmoded notions of perception, such as the idea of the senses acting as automatic filters of inputs structured by habit. In such an approach the tendency is to insist on the prioritisation of one 'repressed' sense (e.g. touch) above another 'dominant' sense (e.g. vision). Thus the agenda is set to turn from visual culture to auditory culture, olfactory culture and so on. Serres, by contrast, provides a challenge to the template on which we consider sensation itself and its relationship to philosophies of knowledge. Rather than consider these issues in the abstract or through direct discussion of key philosophical precursors, Serres chooses an empirical path. Every page is alive with rich descriptions of feeling, sensing, apprehending, engaging, living. This is a vibrant text that is at times overwhelming in its channelling of the noise of the world as it erupts through the body. Serres' writing is well known for its insistence on 'taking the long way home', as Tom Waits has it. The journey here is particularly circuitous, beginning with a tall tale of a fire on a ship and passing by way of the death of Socrates, the drunken Platonic symposium, the Last Supper, Orpheus in the underworld and Ulysses navigating Scylla and Charybdis. In its course look out for tattoos, trampolines, ritual dismemberment, the fairytale 'glass' slipper, Captain Nemo and a bottle of 1 947 Yquem. But also prepare for stunning meditations on the nature of empiricism, the resistance of the body to language, and subjectivity as a multiply mediated distribution of sensory engagements. The division of the body's sensory capacities into a fivefold scheme is deeply embedded in Western Culture. It has its roots in the Aristotelian conception of special senses which would underpin common sense. With die assistance of memory and imagination, these senses form the 'passive' components of consciousness. Being rooted in the world of appearance, they are considered as inferior, yet necessary, capacities in contrast with the power of thought and geometric reason. …

Predicting coverage in wireless local area networks with obstacles using kriging and neural networks

In this paper, a new approach based on ordinary kriging is proposed to predict network coverage in wireless local area networks. The proposed approach aims to reduce the cost of active site surveys by estimating path loss at points where no measurement data is available using samples taken at other points. To include the effect of obstacles on the covariance among points, a distance measure is developed based on an empirical path loss model. The proposed approach is tested in a simulated wireless local area network. The results show that ordinary kriging is able to estimate path loss with acceptable error levels.

Empirically Derived Path Reduction Factor for Terrestrial Microwave Links Operating at 15 Ghz in Peninsula Malaysia

This paper describes the technique of deriving path reduction factor from experimental rain rate and rain attenuation data over seven DIGI MINI-LINKs operating at 15 GHz in Malaysia (Lat.: 1.45°N and Long.: 103.75°E). The relationship between experimental path reduction factors with different link lengths has been studied, using multiple non-linear curve-fitting techniques. Based on these studies, an empirical path reduction factor model has been proposed and compared with the ITU-R model. The test results have shown that the ITU-R prediction model may not be appropriate for predicting rain-induced attenuation for the tropical Malaysian climate.

An Empirical Path Loss Model and Fading Analysis for High-Speed Railway Viaduct Scenarios

Based on the narrowband 930-MHz measurements taken along the “Zhengzhou-Xi'an” high-speed railway in China, an empirical path loss model is proposed. It is applicable to high-speed railway viaduct scenarios, considering the influences of viaduct height H and base station antenna relative height h, which are not well-covered by existing large-scale models. The path loss exponents are investigated, based on which the influence of viaduct on propagation is discussed. The fading depth up to 15.96 dB and the Ricean K -factor with mean value of 3.79 dB are obtained.

Comparative Analysis of Different Parameters in Propagation Model for Mobile Communication System

Nowadays the wireless technology becomes popular and receives growing acceptance as a Broadband Wireless Access (BWA) system. Wireless system has potential success in its line-of-sight (LOS) and non line-of-sight (NLOS) conditions which operating with different frequency. Estimation of path loss is very important in initial deployment of wireless network and cell planning. Numerous path loss (PL) models (e.g. Okumura Model, Hata Model) are available to predict the propagation loss, but they are inclined to be limited to the lower frequency bands. Radio propagation is essential for emerging technologies with appropriate design deployment and management strategies for any wireless network. It is site specific and can vary significantly depending on terrain, frequency of operation, velocity of mobile terminal, interface sources and other dynamic factor. Accurate characterization of radio channel through key parameters and a mathematical model is important for predicting signal coverage, achievable data rates, specific performance attributes of alternative signaling and reception schemes. Empirical path loss models for macro cells such as free path loss, Hata Okumura, COST 231 Hata and ECC 33 models are analyzed and compared. The received signal strength is calculated with respect to distance to determine the model that can be adopted to minimize the number of handoffs and avoid ping pong effect. This paper proposes a comparison study of different propagation model such as Okumara-Hata model, COST 231 Hata model, ECC-33 to calculate path loss for highway and urban between Bhubaneswar and Cuttack. Comparative study with real time measurement obtained from Bharat Sanchar Nigam Limited (BSNL) a GSM based wireless networks for Bhubaneswar and Cuttack has been implemented. A suitable empirical model for different environments is to be proposed. Also calculate received signal strength for each environment under all three models and calculate the probability for each case. Keywords: Cellular mobile, Handoff, Path loss, Ping Pong, Received signal strength.