Propagation effects for land mobile satellite systems: Overview of experimental and modeling results

Models developed and experiments performed to characterize the propagation environment associated with land mobile communication using satellites are discussed. Experiments were carried out with transmitters on stratospheric balloons, remotely piloted aircraft, helicopters, and geostationary satellites. This text is comprised of compiled experimental results for the expressed use of communications engineers, designers of planned Land Mobile Satellite Systems (LMSS), and modelers of propagation effects. The results presented here are mostly derived from systematic studies of propagation effects for LMSS geometries in the United States associated with rural and suburban regions. Where applicable, the authors also draw liberally from the results of other related investigations in Canada, Europe, and Australia. Frequencies near 1500 MHz are emphasized to coincide with frequency bands allocated for LMSS by the International Telecommunication Union, although earlier experimental work at 870 MHz is also included

Wireless Channel Path-Loss Modelling for Agricultural and Vegetation Environments: A Survey

This work undertakes an extensive survey of the channel modelling methods and path-loss characterization carried out in agricultural fields and vegetation environments in an attempt to study the state-of-the-art in this field, which, though vastly explored, still presents extremely diverse opportunities and challenges. The interface for communication between nodes in a typical agricultural field is the wireless channel or air interface, making it imperative to address the impairments that are exclusive to such a communication scenario by studying the characteristics of the medium. The performance of the channel is a direct indicator of the quality of communication. It is required to have a lucid understanding of the channel to ensure quality in transmission of the required information, while simultaneously ensuring maximum capacity by employing limited resources. The impairments that are the very nature of a typical wireless channel are treated in an explicit manner covering the theoretical and mathematical models, analytical aspects and empirical models. Although there are several propagation models characterized for generic indoor and outdoor environments, these cannot be applied to agricultural, vegetation, forest and foliage scenarios due to the various additional factors that are specific to these environments. Owing to the wide variety, size, properties and span of the foliage, it also becomes extremely challenging to develop a generic predictive model for all kinds of crops or vegetation. The survey is categorized into fields containing specific crops, greenhouse environment and forest/foliage scenarios and the key findings are presented

Experimental Validation of a Best-Fit Model for Predicting Radio Wave Propagation through Vegetation

In this study, a model for predicting radio wave propagation through vegetation at 900 and 1800MHz is proposed. An integrated model comprising of ground and foliage induced effects is evaluated with respect to experimental data obtained through drive test in and around a vegetation environment, using Test Mobile System (TEMS) investigation tools. Measured path loss was compared against predictions made by four empirical vegetation models. Results indicate that the European Cooperation in Science and Technology (COST) 235 model gives the best prediction and compare favourably with measured path loss in areas where vegetation is dominant. Although, this model showed the most accurate prediction of foliage loss in the investigated area, there is a need to modify it for enhanced signal prediction. The modified model was found to predict the measured path loss with Root Mean Square Errors (RMSEs) of 6.98dB and 10.00dB at 900 and 1800MHz, respectively. Overall, findings revealed that these RMSEs are within the acceptable range of up to 15.00dB, for quality signal prediction in related environment

An Assessment of Path Loss Tools and Practical Testing of Television White Space Frequencies for Rural Broadband Deployments

Broadband internet has grown to become a major part of our daily routines. With this growth increase, those without direct access will not be afforded the same opportunities that come with it. The need for ubiquitous coverage of broadband Internet is clear to provide everyone these opportunities. Rural environments are an area of concern of falling behind the growth as the low population densities make wired broadband solutions cost prohibitive. Wireless options are often the only option for many of these areas; WiFi, cellular, and WiMAX networks are currently used around the world, but with the opening of the unused broadcast television frequencies, deemed TV White Space (TVWS), a new option is hitting the market. This new technology needs to be assessed before it can be seen as a viable solution. The contribution of this work is two-fold. First, findings from a real, ongoing trial of commercially available TVWS radios in the area surrounding the University of New Hampshire campus are presented. The trial shows that though the radios can provide Internet access to a distance of at least 12.5 km, certain terrain and foliage characteristics of the path can form coverage holes in that region. The second contribution explores the use of empirical path loss models to predict the path loss, and compares the predictions to actual path loss measurements from the TVWS network setup. The Stanford University Interim (SUI) model and a modified version of the Okumura-Hata model provide the lowest root mean squared error (RMSE) for the setup. Additionally, the deterministic Longley-Rice model was explored with the Radio Mobile prediction software. It was determined that without extensively tuning the foliage component of the algorithm, the model could produce significant prediction errors, resulting in a trade-off between low cost, un-tuned predictions, and prediction accuracy

Mehanizmi prostiranja radio vala i empirijski modeli za fiksne radijske pristupne sustave

This paper provides a survey of the basic mechanisms which influence the propagation of electromagnetic waves at most. It also deals with features of empirical models often used in a process of fixed wireless access network planning and implementation. Four empirical models, SUI, COST 231-Hata, Macro and Ericsson, which are most suitable for path loss prediction for such a system, are presented. By using these propagation models the receiving signal levels are predicted for different types of environment for a WiMAX (Worldwide Interoperability for Microwave Access) system installed in the city Osijek, Croatia. Measurement results of receiving WiMAX power at 3,5 GHz are also presented and compared with the results predicted by using the propagation models.Ovaj rad daje pregled osnovnih mehanizama koji najviše utječu na prostiranje elektromagnetskih valova. Također se bavi značajkama empirijskih modela koji se često koriste u procesu planiranja i implementacije fiksnih radijskih pristupnih mreža. Predstavljena su četiri empirijska modela koja najbolje odgovaraju za predviđanje gubitaka za ove sustave: SUI, COST 231- Hata, Macro i Ericsson model. Korištenjem ovih modela prostiranja napravljena je predikcija razine prijemnog signala za različite tipove okruženja za WiMAX (eng. Worldwide Interoperability for Microwave Access) sustav postavljen u gradu Osijeku, u Hrvatskoj. Predstavljeni su i rezultati mjerenja prijemne snage WiMAX sustava na 3,5 GHz te su uspoređeni s rezultatima predviđenim uporabom modela prostiranja

Forests

In this paper, we provide an overview of positioning systems for moving resources in forest and fire management and review the related literature. Emphasis is placed on the accuracy and range of different localization and location-sharing methods, particularly in forested environments and in the absence of conventional cellular or internet connectivity. We then conduct a second review of literature and concepts related to several emerging, broad themes in data science, including the terms |, |, |, |, |, |, and |. Our objective in this second review is to inform how these broader concepts, with implications for networking and analytics, may help to advance natural resource management and science in the future. Based on methods, themes, and concepts that arose in our systematic reviews, we then augmented the paper with additional literature from wildlife and fisheries management, as well as concepts from video object detection, relative positioning, and inventory-tracking that are also used as forms of localization. Based on our reviews of positioning technologies and emerging data science themes, we present a hierarchical model for collecting and sharing data in forest and fire management, and more broadly in the field of natural resources. The model reflects tradeoffs in range and bandwidth when recording, processing, and communicating large quantities of data in time and space to support resource management, science, and public safety in remote areas. In the hierarchical approach, wearable devices and other sensors typically transmit data at short distances using Bluetooth, Bluetooth Low Energy (BLE), or ANT wireless, and smartphones and tablets serve as intermediate data collection and processing hubs for information that can be subsequently transmitted using radio networking systems or satellite communication. Data with greater spatial and temporal complexity is typically processed incrementally at lower tiers, then fused and summarized at higher levels of incident command or resource management. Lastly, we outline several priority areas for future research to advance big data analytics in natural resources.U01 OH010841/OH/NIOSH CDC HHSUnited States/U54 OH007544/OH/NIOSH CDC HHSUnited States

Brook Trout Behavioral Thermoregulation and Habitat Selection in a Small Michigan Coldwater Stream: Implications for Successful Management

Global warming and conversion of forests for urbanization, agriculture and mineral extraction are increasing water temperatures throughout Brook Trout’s range causing population declines; particularly in populations persisting in marginal habitats and in the southern limits of their distribution. The Brook Trout is an ectotherm that can cope with elevated water temperature by moving to coldwater refuge such as groundwater seeps, coldwater tributary confluences, and headwaters. Availability of coldwater refuge is vital for the survival of Brook Trout populations threatened by increasing water temperatures. I used radio telemetry to study the movement, habitat use, and behavioral thermoregulation of Brook Trout living in Cedar Creek, a stream in southwest Michigan impacted by the deleterious effects of agriculture and urbanization on stream temperature. I evaluated Brook Trout thermoregulatory effectiveness during the summer when ambient water temperatures often exceed the ideal range for Brook Trout. My results helped direct management efforts aimed at restoring Brook Trout habitat in Cedar Creek. Overall, Brook Trout body temperatures conformed closely to ambient water temperatures. Brook Trout in a forested section maintained body temperatures within the ideal range for growth for most of the summer and occupied habitats characterized by large woody debris and overhanging vegetation. In a section routinely clear-cut and bordered by agriculture, Brook Trout body temperatures were often above proximate ambient water temperatures, and Brook Trout occupied deep microhabitats with little cover. Several Brook Trout emigrated from the clear-cut section into a forested section; however, most Brook Trout were largely sedentary. My results illustrate the importance of a forested riparian corridor in providing woody cover and thermal refuge in a marginal trout stream. Management efforts to restore Brook Trout habitat should prioritize evaluating target systems to identify limiting factors that provide important ecological benefits to threatened populations

Winter Survival and Resource Use of Translocated Northern Bobwhite in the Mid-Atlantic United States

Northern bobwhite (Colinus virginianus; hereafter, bobwhite) in the Mid-Atlantic United States have been experiencing precipitous population declines due to a combination of habitat deterioration, urban and suburban sprawl, change in forest management regimes, and farming practices. In recent years, restocking of bobwhite through translocation efforts has gained interest to rebuild local populations. However, empirical studies are warranted to understand the limitations of translocation as it relates to its potential use for long-term population recovery and persistence in this region. Further, few studies nation-wide have evaluated resource use and survival during the non-breeding season on translocated sites. As such, we translocated 360 bobwhites from source populations from southern latitudes during March–April 2015–2017 into 2 different landscape types similar to the source population vegetative communities (agricultural cropland dominated in Maryland, USA versus pine forest dominated in New Jersey, USA) and tested the effects of habitat fragmentation on survival and habitat use during the subsequent non-breeding season. We found habitat fragmentation negatively affecting survival and resource use among translocated bobwhite on fragmented cropland-dominated sites as compared to larger unfragmented forested sites. Survival was lower on cropland sites compared to forested sites such that bobwhite in cropland-dominated landscapes were \u3e125 times less likely to survive the winter than those on forested sites. In our examination of resource use, bobwhite in structurally complex forested sites used cut pine, early-successional woody, early-successional herbaceous, and thinned pine more than what was available on the landscape. On the cropland sites bobwhite used food plots, early-successional woody, and mixed woods more than what was available on the landscape and only food plots at the home range scale. While larger unfragmented forested bobwhite habitat ultimately provided a more successful translocation landscape, birds still had large home ranges and relatively low survival. Therefore, proper pine management may be necessary to optimize habitat availability during the non-breeding season. Our findings provide rare information on demographic resiliency and resource use for translocated bobwhite during the non-breeding season. Further, this research provides valuable information to improve future translocation efforts in the Mid-Atlantic