Received Power Level Research Articles

Measurements of Mobile Signal Received Power Level at Ringlet, Cameron Highland, Malaysia

Tenaga Nasional, the electric utility company in Peninsular Malaysia have been installing electronic meters that can establish wireless connectivity over the mobile phone network since 2005. Several locations including Ringlet, Cameron Highland have been pointed out as having difficulties in establishing a stable connection to the national main server. Empirical investigations had been carried out to determine the availability of service coverage and the associated signal received power levels at the said location. The findings are reported in this article. The outcomes from the measurement campaign were used to deduce the likely solution that is capable of establishing a more reliable link. Field trials involving installations of high-gain antennas and signal boosters as potential solutions were also carried out at selected sites within the district. It is the objective of the study to develop a total solution that can ultimately address the communication issue.

A Smart Cable Offering Selective and Distributed Antenna Radiation Using RF Switches and Non-Conventional Hybrid Couplers

A smart cable system and its elements for selective communications and sensor-based data collection within corridors, subways, and tunnels are proposed with applications to the aeronautical, transportation, and space sectors. The main hardware components of the cable system are defined by active and programmable radio-frequency (RF) switches that can enable controlled radiation at specific nodes or hotspots. More importantly, our proposed cable concept provides an evolution from the conventional coaxial cable with distributed antennas, as well as the classic leaky feeder cable, which is typically employed for communications within corridors and mines. Moreover, the proposed smart cable moves toward a hybrid wireless node and programmable system for selective coverage. Planar circuits and low-profile RF electronic components are employed for a low-cost implementation. In this communication, our focus is on the assessment of the proposed smart cable system, its radiating nodes (RNs), as well as the estimation of the system performance based on the measurements of the RN prototypes. Wireless networks, RFID sensors, and power transmission systems can be additional applications for the proposed smart cable. System performance estimations for a real corridor satisfy typical RFID sensitivity requirements with received power levels between −39 and −46 dBm in the worst case.

The Modelling of Tropical Weather Effects on Ultra-High Frequency (UHF) Radio Signals Using SmartPLS

The interference occurs in radio signals transmission in many communication technologies are attributed to weather variations as well as other environmental factors. This work evaluates some atmospheric variables that have a dominating impact on temporal signal strength fluctuations. The Received Power Level (RPL) of Ultra High Frequency (UHF) communication signals (1800 MHz and 2160 MHz) and three tropical weather predictors (humidity, temperature and wind) were collected using spectrum analyser (KEYSIGHT N9915A) and weather station (Vantage Pro 2) respectively for 24 hours in rainy days. SmartPLS 3.2.6 was used to determine the strongest predictors influence the RPL for UHF frequency. It has been found that changes in weather conditions have affected the signal in which all weather predictors provide a significant relationship to the signal where R2 (coefficient of determination) value is 0.314 for frequency 1800 MHz and 0.254 for frequency 2160 MHz. The findings also show that humidity, temperature and wind are anticorrelations to RPL. However, humidity is found to be the strongest predictor influences the RPL of communication signals for frequency 1800 MHz (β = −0.449, p = 0.000). This model may benefit many sectors such as telecommunication service provider, radio and TV transmission, radio astronomy study, Electromagnetic (EM) researcher and satellite broadcasting.

Performance Characterization of Spatial Diversity Based Optical Wireless Communication over Atmospheric Turbulence Channels

Optical wireless communication is regarded as the next-generation high-speed technology. It has demonstrated its capability to deliver data faster than any other state-of-the-art wireless communication technique. This technology has drawn attention as a means of implementing reliable high capacity outdoor systems that cannot be implemented by conventional fiber optics. It has emerged recently as an efficient solution to match the larger bandwidth and high data rates requirement of the upcoming wireless communication systems. However, although FSO (free space optics) system has many appealing features, it has rather disappointing performance for long links due to the degrading effects of atmospheric turbulence-induced fading. In the presence of such type of performance impairments, the received signal exhibits random intensity fluctuations, which increase the BER (bit error-rate), where the severe weather conditions can have a detrimental impact on the performance, which may result in an inadequate availability. The MIMO wireless optical procedure, in which the spatial dimensions are used to improve the reliability and spectral efficiency of point-to-point links, provides a promising approach to mitigate turbulence effects due to its powerful performance enhancing capabilities. In this paper, we investigate a terrestrial atmospheric FSO communication system operating under the influence of strong atmospheric turbulences. Additionally, the MIMO technique with equal gain combining (EGC) is used in this work to enhance the data rate of the proposed system. Atmospheric turbulence impacts are modeled as a lognormal channel with due regard for geometric losses. With the use of NRZ line coding, an FSO highly sensitive receiver using either avalanche photodetector (APD) or PIN is designed and simulated for best system performance. The preference is achieved by using Bessel and Gaussian filters. It has been found that APD receiver using Gaussian filter is suitable for long-range links with APD gain value of 3. Also, the selection of APD gain is critical to the system performance. In addition, the optimal value of APD gain required for best system performance decreases as the size of the MIMO technique increases. The achievable performance improvements including received power levels, BER and Q-factor are also discussed. The results show that the system with optical amplifier at the transmitter gives an optimum performance. In addition the system performance is enhanced in most weather conditions by using an amplified 2×2 MIMO-FSO system with booster amplifier.

Single-Polarization, Optically Pre-Amplified Receiver With Gated, Burst-Mode Clock Recovery

We report a receiver using a single-polarization optical low-noise pre-amplifier and a burst-mode, time-gated clock recovery unit (CRU). Timing jitter and bit-error-ratio (BER) measurements are presented for data rates from 72 Mb/s to 2.880 Gb/s, both with and without atmospheric fading. At the lowest burst-mode data rate of 72 Mb/s, temporal gating improves the recovered clock’s timing jitter below receive power levels of −65 dBm, enabling comm-limited performance as opposed to CRU-limited performance. Gating extends the CRU and receiver range down to −88 dBm, a 3-dB sensitivity improvement over the non-gated case. For all data rates and channels measured, jitter values remain below 9 ps (3% of the clock period) with gating enabled. The BER performance is <2.5 dB from the theoretical limit across all data rates, both with and without atmospheric fading.

Direction-of-Arrival Estimation Enhancement for Closely Spaced Electrically Small Antenna Array

In this paper, compact direction finding systems using a scatterer of a high dielectric constant in between adjacent closely spaced electrically small antennas are examined. By adding a high-permittivity scatterer, the directional sensitivity can be enhanced. However, due to limited physical dimension, an electrically small antenna has highly reactive impedance. To enhance the received power level, a matching network is included. The highest directional sensitivity satisfying a given power constraint is compared for with and without scatterer cases. In addition, widely used matching approaches such as multiport-conjugate matching (MCM), self-conjugate matching (SCM), and eigenmode decoupling matching are investigated to increase the received power. The impact of these matching networks on the directional sensitivity is studied. The power and the directional-sensitivity bandwidth after matching are also analyzed. Finally, the two-monopole and a high-permittivity scatterer system with SCM and MCM circuits is fabricated and tested.

A Wide Dynamic Range Polarization Sensing Long Wave Infrared Detector

We present the design, fabrication, and characterization of an infrared (IR) polarization sensing detector with a wide dynamic range and sub-wavelength dimensions. The detector consists of two orthogonal slot antennas, each loaded with two microbolometers at its edges. The polarization of the incoming IR radiation is detected by comparing the received power levels in the bolometer pairs corresponding to each slot antenna. The IR radiation is sensed by applying a dc bias voltage to each antenna and measuring the changes in the dc current caused by the change of the bolometer resistance as they absorb the incoming IR radiation. In this design, the ratio of the absorbed power in the bolometers is a one to one function of the polarization of the incident wave. A prototype of this detector, designed to have maximum sensitivity at λ = 10.6 μm, was designed, fabricated, and characterized. The fabricated detector has an area of 0.7λ × 0.7λ, where λ is the free-space wavelength. The polarization sensing response is characterized under different angles of incidence. The measurement results show that the device has a dynamic range of 24 dB between two orthogonal orientations of EM wave polarization for incidence angles in the range of ±20° from boresight.

Analysis of nonline-of-sight visible light communications

We analyze the channel properties of a nonline-of-sight (NLOS) ceiling-to-device and device-to-device visible light communication systems by considering various receivers' orientation and variable fields of view (FOVs). Analyses based on the recursive indoor channel model show that for a particular transmitter configuration, the pure NLOS path can offer higher 3-dB channel bandwidth (up to 14 MHz) compared with the link with LOS and NLOS components. We also show how the receiver rotation (orientation) influences the probability of receiving signals via the NLOS path compared with the LOS and NLOS paths. Moreover, based on the experimental campaign, we demonstrate that shadowing observed at the receiver due to people’s movement results in decreased received power level (up to 1.8 dB), thus resulting in reshaping of the probability density function of received power.

End-to-End Delay Model for Train Messaging over Public Land Mobile Networks

Modern train control systems rely on a dedicated radio network for train to ground communications. A number of possible alternatives have been analysed to adopt the European Rail Traffic Management System/European Train Control System (ERTMS/ETCS) control system on local/regional lines to improve transport capacity. Among them, a communication system based on public networks (cellular&amp;satellite) provides an interesting, effective and alternative solution to proprietary and expensive radio networks. To analyse performance of this solution, it is necessary to model the end-to-end delay and message loss to fully characterize the message transfer process from train to ground and vice versa. Starting from the results of a railway test campaign over a 300 km railway line for a cumulative 12,000 traveled km in 21 days, in this paper, we derive a statistical model for the end-to-end delay required for delivering messages. In particular, we propose a two states model allowing for reproducing the main behavioral characteristics of the end-to-end delay as observed experimentally. Model formulation has been derived after deep analysis of the recorded experimental data. When it is applied to model a realistic scenario, it allows for explicitly accounting for radio coverage characteristics, the received power level, the handover points along the line and for the serving radio technology. As an example, the proposed model is used to generate the end-to-end delay profile in a realistic scenario.

C-Band Single-Chip Radar Front-End in AlGaN/GaN Technology

This paper presents the design and measurement results of a single-chip front-end monolithic microwave integrated circuit (MMIC), incorporating a high-power amplifier, transmit–receive switch, low-noise amplifier, and calibration coupler, realized in 0.25 $\mu \text{m}$ AlGaN/GaN-on-SiC MMIC technology of UMS (GH25-10). The MMIC is operating in C-band (5.2–5.6 GHz) and is targeting the next generation spaceborne synthetic aperture radar. The use of GaN technology has resulted in a design that is robust against antenna load variation in transmit as well as against high received power levels, without the need for an additional limiter. By including a transmit-receive switch on the MMIC there is no need for an external circulator, resulting in a significant size and weight reduction of the transmit–receive module. The measured output power in transmit is higher than 40 W with 36% PAE. The receive gain is higher than 31 dB with better than 2.4 dB noise figure. To the best of the author’s knowledge this is the first time such performance has been demonstrated for a single-chip implementation of a C-band transmit–receive front-end.

An RF-gated wireless power transfer system for wireless MRI receive arrays.

In MRI systems, cable-free receive arrays would simplify setup while reducing the bulk and weight of coil arrays and improve patient comfort and throughput. Since battery power would limit scan time, wireless power transfer (WPT) is a viable option to continuously supply several watts of power to on-coil electronics. To minimize added noise and decouple the wireless power system from MRI coils, restrictions are placed on the coil geometry of the wireless power system, which are shown to limit its efficiency. Continuous power harvesting can also cause a large increase in the background noise of the image due to diode rectifier up-conversion of noise around the frequency of the transmitted power. However, by RF gating the transmitted power off during the MRI receive time while continuing to supply power from a storage capacitor, WPT is demonstrated to have minimal impact on image quality at received power levels up to 11 W. The integration of WPT with a 1.5T scanner is demonstrated.

Real Measurements and Evaluation of the Influence of Atmospheric Phenomena on FSO Combined with Modulation Formats

The influence of atmospheric environment is fundamental for Free-Space Optical link (FSO). The atmosphere can significantly degrade the communication quality of FSO up to so low received power/RSSI level that it can lead to the loss of communication. For this reason, authors used a professional weather station built on site of FSO link for measurement of real atmospheric conditions such as wind speed, temperature, relative air humidity, air pressure and solar radiation. Random changing of these atmosphere parameters creates atmospheric turbulences, absorption and dispersion centers. It is necessary to specify the value of refractive index structure parameter Cn2 because it determines the influence of atmosphere on the FSO. The first part of this article includes the theoretical calculation of Cn2, there are used two models PAMELA and Macroscale-Meteorological model. The evaluation of the atmospheric influences and the RSSI value of received power level and also simulation of different types of modulation formats OOK-RZ, OOK-NRZ and BPSK in Optiwave is in tegral part of this article.

Real Time Analysis of a 24 GHz Planar Microstrip Antenna for Vehicular Communications

A single patch antenna suitable for integration and operation in 24 GHz band for wireless inter vehicular communication is designed and developed. The requirements on the design are the large bandwidth, simple configuration, light weight and low profile. The antenna is fed by using inset feed line to provide impedance matching. Antenna gain values of ∼5.9 dBi are obtained in addition to a very less return loss of ~39 dB. The developed antenna provides a bandwidth of 120 MHz and an input impedance of ~50Ω. The antenna was tested in a real time environment and the received power levels are noted. A simple Rician channel is simulated for the measured values and the BER is tabulated.

Cluster-Based Collaborative Spectrum Sensing for Energy Harvesting Cognitive Wireless Communication Network

We consider a cluster-based collaborative spectrum sensing (CSS) scheme in energy harvesting cognitive wireless communication network (EH-CWCN), where cognitive nodes (CNs) are clustered based on their received power levels for enhancing sensing performance. In CSS scheme, time resource is limited and shared by energy harvesting, spectrum sensing, and data transmission. The purpose of this paper is to maximize the average throughput of EH-CWCN by identifying the optimal parameter set, including the durations of energy harvesting and spectrum sensing, local detection threshold, and the number of CNs. Moreover, it is hard to confirm the optimal local detection threshold at CNs with different received power levels. By constructing a fictitious cognitive node (FCN), which is assumed to have the same sensing performance as the sink node, the process for finding the optimal local detection threshold can be converted into the process for searching the optimal received signal-to-noise ratio of the FCN. Then, we formulate the general optimization problem under the collision constraint and energy constraint. Then, the existence and uniqueness of time fractions for energy harvesting and spectrum sensing are proved in this paper. The optimal parameter set is achieved by using the bisection method and a simplified linear search method. Finally, the theoretical analysis and the impact of the optimized parameters on the system performance are verified and shown through numerical simulations.

TFET-Based Power Management Circuit for RF Energy Harvesting

This paper proposes a Tunnel FET (TFET)-based power management circuit (PMC) for ultra-low power RF energy harvesting applications. In contrast with conventional thermionic devices, the band-to-band tunneling mechanism of TFETs allows a better switching performance at sub-0.2 V operation. As a result, improved efficiencies in RF-powered circuits are achieved, thanks to increased rectification performance at low power levels and to the reduced energy required for a proper PMC operation. It is shown by simulations that heterojunction TFET devices designed with III–V materials can improve the rectification process at received power levels below −20 dBm (915 MHz) when compared to the application of homojunction III–V TFETs and Si FinFETs. For an available power of −25 dBm, the proposed converter is able to deliver 1.1 ${\mu }\text{W}$ of average power (with 0.5 V) to the output load with a boost efficiency of 86%.

Performance study on the effect of filter curve in CWDM System for the access network

This paper presents the study on the effect of filter variation on the coarse wavelength division multiplexing (CWDM) system. The filter curve will affect the performance of the CWDM system due to changes of received power lever and isolation of the signal. The significant impact on the received power level and isolation can be found when the required signal is isolated from unwanted signal by the steep curve of filter. As a result, BER of 1.0x 10-12 was obtained corresponding to receive power level of -24.27 dBm with isolation of 23.22 dB. When the wavelength spacing is reduced to 1nm, the isolation is only 11.30 dB and BER increased to 5.49x10-7 with a received power of -15.39 dBm.

Effect of Quasi-Isotropic Antenna Orientation on Indoor Multipath Propagation Characteristics in RSN Applications

In the RFID sensor networks (RSN), the orientations of the antennas used in the network nodes have a significant influence on the propagation characteristics. In this article, we investigated the effects of the two antennas’ orientation of different radiation and polarization on the multipath propagation characteristics. This study is evaluated in a typical indoor environment by computer simulations based on the three-dimensional (3D) ray-tracing method. This method is based on geometric optics and uniform diffraction theory and also it offers significant advantages in terms of accurate and comprehensive prediction of propagation characterization. The simulations have been performed at frequency 915 MHz and the propagation characteristics are compared in terms of received power level (Pr) and Root-Mean-Square (RMS) delay spread for a quasi-isotropic 3D cubic antenna with circular polarization and for an omnidirectional dipole with linear polarization in the LOS, NLOS, and OLOS scenarios.

A power adjusting anchors with improved localization algorithm for mobile wireless sensor networks

ABSTRACTIn Mobile Wireless Sensor Networks (MWSNs), localization is one of the key technologies since it plays a critical role for many location-aware protocols and applications. Existing range-free localization algorithms for MWSNs are usually based on the Sequential Monte Carlo localization algorithm. They suffer from low sampling efficiency, high communication computation cost or require high beacon density to achieve high localization accuracy. In this paper, we propose a novel algorithm called ‘Power Adjusting Anchors’ that outperforms in terms of accuracy. In this algorithm, mobile sensor node localizes its position based on the received power levels transmitted by the neighbouring anchors and by constructing a refined prediction area with the hop-distance estimations between elected anchor nodes. This area will be divided into square grids, and sensor node selects all the grids which owns the highest elections, and then, computes the centroid of such grids. The calculated centroid is considered as the estimated location of the sensor node. In addition, the algorithm addresses the information state provided by the radio communication between sensor nodes and anchor nodes to the success of the localization. Simulation results show that the algorithm is very competitive by achieving high localization accuracy with better localization success.

Distributed Wireless Power Transfer With Energy Feedback

Energy beamforming (EB) is a key technique for achieving efficient radio-frequency transmission enabled wireless energy transfer (WET). By optimally designing the waveforms from multiple energy transmitters (ETs) over the wireless channels, they can be constructively combined at the energy receiver (ER) to achieve an EB gain that scales with the number of ETs. However, the optimal design of EB waveforms requires accurate channel state information (CSI) at the ETs, which is challenging to obtain practically, especially in a distributed system with ETs at separate locations. In this paper, we study practical and efficient channel training methods to achieve optimal EB in a distributed WET system. We propose two protocols with and without centralized coordination, respectively, where distributed ETs either sequentially or in parallel adapt their transmit phases based on a low-complexity energy feedback from the ER. The energy feedback only depends on the received power level at the ER, where each feedback indicates one particular transmit phase that results in the maximum harvested power over a set of previously used phases. Simulation results show that the two proposed training protocols converge very fast in practical WET systems even with a large number of distributed ETs, while the protocol with sequential ET phase adaptation is also analytically shown to converge to the optimal EB design with perfect CSI by increasing the training time. Numerical results are also provided to evaluate the performance of the proposed distributed EB and training designs as compared to other benchmark schemes.

Adaptive Power Control for A-CDMA Systems Over K-Distributed Fading Channels

Energy adaptation for Asynchronous CDMA (A-CDMA) systems over Rayleigh and Rician fading distributions with and without diversity combining techniques has been discussed in literature. In this work, adaptive power control for A-CDMA systems over channels undergoing K-distribution is discussed in detail. K-distribution is a valid model to represent the envelope statistics of the backscattered echo, and is used to simulate the effects of a dense urban environment with the average received power level fluctuating slowly due to shadowing effects. Performance measures, such as probability density and cumulative distribution functions of (a) probability of error and (b) signal energy-to-noise ratio and, system parameters, such as fading margin, mean transmitter energy gain, and percentage points are computed for K-distribution channels as a function of probability of error specification and the probability of unsatisfactory operation.