Network Selection for Maximum Coverage using Regression Analysis in Deep Fading Environment

Signal Strength Reduction Effects in OCT Angiography

Measurements of signal strength are reported for a study of UHF propagation on three transhorizon sea paths in the British Channel Islands. Enhancements of up to 30 dB from the mean occur for periods of hours or days, especially in the summer, and constitute about 5% of the overall data. The probability distribution of received power is tabulated for the three paths and various antenna heights, and is compared with predictions of signal strength using ITU‐R Recommendation P.1546‐2. The difference between median and upper decile in the data is much less than predicted, whereas the difference between upper decile and the upper percentile is much greater than predicted.

This research evaluates the impact of weather parameter (temperature, pressure, humidity and wind speed) on satellite dishes and how it affects the quality of reception it gives using the data obtained from the Automated Weather Station and Signal Strength in Enugu State University of Science and Technology. The atmospheric components and signal strength were measured every two minutes daily in different months, on different days, and at a different time of the day from the station for period of nine months. The average results of these measurements were then taken and the data obtained from the measurements were tabulated and subsequently plotted in a graph to ascertain the variation in signal strength triggered by change in temperature, humidity, pressure and wind speed. It was observed from this research that the rise in atmospheric temperature, humidity and pressure will lead to a drop in strength of the signal generated by this station and vice versa. This indicated that signal strength is inversely proportional to atmospheric temperature, pressure and humidity; provided that for any of the giving components, others were observed constant, including the wind speed and direction which affects the positioning of satellite dishes. The correlation of the signal strength and atmospheric temperature, pressure and humidity were respectively r=-0.93, -0.97 and -0.92. It was observed that the atmospheric temperature, humidity, pressure and wind speed are mathematically inversely related.

A new alignment mark implementation for color processing has been successfully tested in a joint activity between ASML and TOWER. Alignability and over lay performance have been proven by applying the combination of a pure high order mark design and a dual implementation using the ATHENA™ alignment sensor and a PAS5500/400 machine. By their very nature, the resists used in color filter processe s will absorb light at various wavelengths. While this makes them useful as color filters, it can noticeably reduce the si gnal strength of pattern images as seen by lithography alignment systems. The pure high order mark design enhances the signal strength. Exposing two of such mark pairs in a Metal Last layer with two different metal plateaus (in previous metal layers: “Metal Last - 1” and “Metal Last -2”) leads to two different optical mark depths and therefore mimics a four wavelength alignment system with ATHENA. In principle, the evaluated technique might be extended to more (than four) “wavelengths” as well as other process layers. Moreover, the use of scribe-line marks enhances productivity since no extra lithography step is required to expose Zero Layers. The performance of this implementation has been evaluated for 180-nm CMOS Image Sensor technology. This paper discusses the overlay and alignment results of the evaluation. Alignment parameters such as absolute signal strength and signal strength variation were studied in detail. It is shown that such mark implementation shows good alignability and easily meets the product overlay requirements of Image Sensor devices. Keywords : Alignment Sensor, Mark Design, Overlay, Color Resist, Image Sensor.

Signal-strength variations from a 100 mw, 107 MHz balloon-borne v.h.f.-f.m. transmitter have been explained in terms of interference between the direct wave and the wave reflected by the smooth surface surrounding the narrow-beam Yagi receiving antenna. A set of graphs of calculated signal strength for various representative reflecting surfaces (sea water, wet and dry soil and frozen snow-covered earth), which are smooth to within the Rayleigh criterion, show the need for consideration of these effects in the design of low-power v.h.f. telemetry systems. It is suggested that such predictable variations in signal strength can be used as a method of balloon range estimation over a range of 100-450 km whenever other methods are unavailable.

In this paper, we propose a simple and low-cost direction estimation method for a subject (e.g., a photographic subject) by observing the Wi-Fi signal strength using a directional antenna. Our goal is to find a specific person in a crowded environment such as an athletics tournament, where many people are identically dressed and in close proximity to each other. Our method suggests the direction of the moving subject to the photographer. In our system, a compact directional antenna attached to a camera receives Wi-Fi signals that originate from a device attached to the subject, and estimates the subject's direction on the basis of variances in the signal strength. Through experimental evaluations, we show that 68% of the results estimated on the basis of the variation in signal strength versus the swinging angle of the camera are accurate.

Radio irregularity phenomenon is often considered as a shortcoming of wireless sensor networks. In this paper, the radio irregularity is regarded as a benefit of wireless networks. The proposed novel method for human presence detection, applied to the monitoring system for residential energy management, utilizes radio irregularity for an efficient human presence detection which increases user awareness and automates the power control. The method monitors 2.4GHz wireless (Zigbee) smart outlets and the communication signals between them to detect changes of the received signal strength indicator (RSSI) and its variations compared to the expected mean values. The signal strength variation is significantly increased due to human presence within the signal propagation path. By applying the algorithm for principal components analysis to the set of RSSI samples obtained from radio communication links within the detection area, it is possible to recognize a human presence. There is no need for additional presence sensors installation, because the proposed method applied to the smart outlets network is quite satisfactory to extend the entire system with the detection capability. Compared to the conventional sensor networks, the presented solution preserves the pervasiveness of smart energy and smart home systems, high level of sensorial intelligence, simplicity and low installation costs.

In recent years, intelligent manufacturing has developed rapidly. Industrial IoT technologies are applied to different industrial scenarios. OPC UA is a service-oriented architecture, which has good interoperability. At the same time, it is a cross-platform communication standard that can realize the interconnection between heterogeneous network devices and solve the problem of information silos in the industrial IoT field. However, with the gradual increase of industrial equipment, the amount of data transmission in the network is increasing. The traditional OPC UA communication method based on client/server mode has defects such as tight coupling and performance bottleneck. It cannot meet the high throughput demand of the network. Therefore, these phenomena lead to longer time delays and lower transmission efficiency of network communication systems. To solve the above problems, this paper proposes a publish/subscribe communication model based on OPC UA. We design the overall architecture of the OPC UA publish/subscribe model and adopt a message agent mechanism to realize distributed communication of OPC UA. This model has functions such as message modeling, address space construction, and publish/subscribe. The architecture of this communication model is compatible with the C/S model, which can ensure compatibility and coexistence with the traditional OPC UA communication system. Meanwhile, in order to improve the distinguished service capability of the OPC UA system, a multi-priority data scheduling algorithm is proposed and integrated into the publish/subscribe communication model to improve the efficiency of real-time data transmission in industrial networks. The experimental results show that the communication model can accomplish distributed communication in industrial networks and be better applied in wireless sensor networks. The scheduling algorithm included in the model significantly improves the efficiency of real-time data transmission and reduces the time delay.

This paper examines several MANET behaviors and suggests root causes using a stochastic model of received power. It focuses specifically on MANET mechanisms most impacted by fine-grain variations in signal strength. Specifically, it examines 1) the impact of MAC retries on performance, 2) a possible cause of excessive route persistence, 3) route stability in MANETs, and 4) difficulties in estimating the mean SNIR in a MANET. It does so through mathematical analysis, simulation and comparisons to published field results.

This study assesses the electromagnetic radiation emitted from AM and FM radio transmitters to evaluate potential exposure levels and their compliance with international safety standards. Field measurements were conducted at varying distances and in different environmental settings using a calibrated radiofrequency (RF) meter. The study considered factors such as terrain type, building density, and proximity to transmitter masts. Data were analyzed to determine spatial variations in signal strength, attenuation patterns, and possible human exposure risks. Results indicate that RF power densities decrease significantly with increasing distance from the transmitters, with urban environments showing more rapid attenuation due to obstructions. Measured values across all surveyed points remained below the International Commission on Non-Ionizing Radiation Protection (ICNIRP) recommended limits, suggesting minimal immediate public health risk. However, continuous monitoring is recommended to account for potential changes in broadcasting power, antenna configurations, and cumulative exposure from multiple sources. This research provides valuable baseline data for policymakers, health agencies, and broadcasting regulators in managing electromagnetic radiation in the environment.

Sensory cortex is able to encode a broad range of stimulus features despite the great variation in signal strength. In cat primary visual cortex (V1), for example, neurons are able to extract stimulus features like orientation or spatial configuration over a wide range of stimulus contrasts. The contrast-invariant spatial tuning found in V1 neuron responses has been modeled as a gain control mechanism, but it has remained unclear as to at which stage of the visual pathway it emerges. Here we describe our findings that contrast-invariant spatial tuning occurs not only in the responses of lateral geniculate nucleus (LGN) relay cells but also in their afferent retinal input. Our evidence suggests that a similar contrast-invariant mechanism is found throughout the stages of the early visual pathway, and that the contrast-invariant spatial selectivity is evident in both retinal ganglion cells and LGN cell responses.

At low-beam elevation angles, measurements of microwave propagation from satellite to ground have exhibited large variations in signal strength under clear weather and cloudy conditions. Large nonuniformities in the three-dimensional (3-D) near-field region of an antenna focused to infinity have been computed. These field nonuniformities interacting with a dynamic turbulent troposphere can introduce phase errors at the antenna aperture, resulting in signal scintillation and loss.

QoS outing in multimedia applications over MANET is affected by limited resources, shared channel, unpredictable mobility, improper load balancing, and variation in signal strength. Existing works on MANET QoS routing focuses on only one of the factor such as bandwidth, mobility or energy neglecting dependent behaviour. In this paper, resource prediction-based routing is proposed wherein intelligent agents identify routes for communication with adequate future availability of buffer-space, energy and bandwidth resources considering mobile nodes. It has four steps of execution: resource prediction, resource prediction factor computation, route establishment, and route maintenance. Resources are predicted to compute resource prediction factors for reliable route establishment and route maintenance against link and node failure. Simulation results show an improvement in terms of packet delivery ratio, packet delivery latency, memory overhead and energy consumption.

This paper presents a new low delay centralized cooperative spectrum sensing method based on dynamic voting rule using multiple threshold level, for indoor hospital environment, where fading and direct path loss both are together responsible for variation in signal strength. In the proposed algorithm, weights of Cognitive Radios (CRs) in terms of assigned vote-count are estimated based on the sensed energy values with respect to multiple fixed threshold levels, so that the direct path loss can be dealt without further increasing the error, which occurs due to fading. For indoor hospital like environment, Rician fading model is more appropriate. Therefore, formulation, evaluation and analysis of various sensing performance parameters have been carried out considering Rician fading model. Comparative analysis and trade-off among three optimum parameters-energy threshold, total number of CRs participating in sensing and total error rate, are presented with respect to signal to noise ratio (SNR). Finally, the Monte Carlo simulation is designed and implemented considering the two conditions-only fading environment and fading along with direct path loss environment. It can be observed that in both cases, the proposed spectrum sensing rule outperforms the other contemporary rules.

Low frequency acoustic waves (infrasound) are generated by a variety of natural and anthropogenic phenomena. Although infrasound propagates throughout the atmosphere, the vast majority of acoustic studies utilize sensors on or near the Earth's surface. This paper describes results from two infrasound arrays launched into the stratosphere, one in August 2014 and the other in September 2015. The observations presented here are the first stratospheric infrasound measurements reported in scientific literature in 50 years. Acoustic signals recorded on the balloon borne sensors were different than those recorded by nearby infrasound stations on the ground. The 0.2 Hz ocean microbarom was detected in the stratosphere, but was not observed on nearby ground stations. A series of narrow band signals were also observed in the stratosphere, some of which varied in frequency over tens of minutes. The source of these signals is unclear. Wind noise decreased with altitude during the ascent, becoming negligible above 20 km. It was absent when the balloon was neutrally buoyant, although it was pervasive on ground stations operating in the same region during the day. Spectral characteristics of stratospheric infrasound were similar between the two flights and also resembled the last experiment in the early 1960s, but spatiotemporal variations in signal strength and frequency were also observed. Future efforts should focus on characterizing infrasound sensor operation in extreme environments and increasing spatial and temporal frequency of acoustic measurements in the free atmosphere. Results from this study have implications for long range detection of events such as nuclear blasts, the quantification of acoustic energy that heats the upper atmosphere, and calibration of a proposed mission to place airborne acoustic sensors on Venus.