Radio Propagation Characteristics Research Articles

Shadow fading analysis over asymmetric beam channel at 2.1 GHz in outdoor scenarios

AbstractIn this letter, we investigate the radio propagation characteristics in an open outdoor place through a frequency‐domain channel measurement campaign at a frequency band of 2.1 GHz via asymmetric beam patterns. Specifically, we focus on the large‐scale fading characteristics and analyze the transceivers' separation‐dependent and boresight direction‐dependent received power, shadow fading (SF), and SF auto‐correlation properties under the case of perfect beam alignment. Furthermore, the effects of asymmetric beamwidths are also thorough investigated. The measured results reveal that transceivers' beams can reduce the shadow fading variances evidently in contrast to the omnidirectional antennas' case. Besides, it is found that the pattern where mobile receiver (Rx) uses narrow beams and static transmitter (Tx) adopts the omnidirectional antenna yields a high SF auto‐correlation value compared to the other beam patterns. The conclusions help to understand the impacts of variable beamwidths on radio propagation.

Wireless channel characterizations in UMi scenarios via ray-tracing at 28 GHz: A perspective of asymmetric beams

As a novel communication pattern, the asymmetric beams adopt a strategy of different beamwidths for a specific link to reduce the beam alignment overheads and energy consumption. A good and thorough knowledge of the radio propagation characteristics is pivotal for further network deployment and optimization of wireless mobile communication systems. In this paper, a multiple-bounce beam channel model is proposed based on the ray-tracing considering the beamforming effects. Besides, a space–time–frequency (STF) power density profile reconstruction method is proposed. Relevant simulations are conducted to emulate an urban micro-cellular (UMi) street scenario at 28 GHz under the case of perfect beam alignment. On this basis, the beam-dependent small-scale fading properties (including STF power density profiles, delay spread, Doppler frequency shift spread, and angular spread) together with the large-scale fading characteristics (involving path loss and shadow fading) are fully investigated. Results reveal that the downlink of asymmetric beams presents more dispersions in contrast to the uplink in the STF domains. Furthermore, the shadow fading variances are asymmetric over different transceivers array element numbers.

A three‐dimensional parabolic equation with fast reordered‐alternate direction decomposition in atmosphere duct environment

AbstractIn the design and optimisation of marine wireless communication and navigation systems, a thorough investigation of radio wave propagation characteristics under atmospheric ducting conditions is essential. The authors aim to enhance the efficiency of radio wave propagation loss prediction in marine atmospheric ducting environments, proposing a prediction model based on Fast Reordered‐Alternate Direction Decomposition (FR‐ADD). By approximating the diffraction term into three independent components, exploiting the commutative properties of the Fourier transform to reduce the spatial dimensions, and incorporating a rapid algorithm for the parabolic equation, the model optimises the stepping process and significantly improves computational efficiency. Simulation experiments demonstrate that, in the long‐distance and complex marine ducting environments, the model not only maintains prediction accuracy but also substantially reduces computational load and prediction time, effectively realising over‐the‐horizon propagation prediction. In the experiment of radio wave propagation characteristics in the Yellow and Bohai Seas, the simulation data from the FR‐ADD model showed significant correlation with actual measurements and simulations from the AREPS software, confirming the method's efficiency and practicality.

A RT-FDTD method of analyzing wireless propagation characteristics in underground mine

Efficient communication is crucial in reducing injuries and fatalities in coal mine accidents, necessitating the study of simulation methods for mine communication. When transceiver antennas are positioned close to the same side of the tunnel, the simulation results from the Ray Tracing (RT) method exhibit significant errors. Additionally, the Finite-Difference Time-Domain (FDTD) method demands substantial computational resources. In response to these challenges, we propose a RT-FDTD method, guided by the law of conservation of energy. This approach involves dividing the mine tunnel into a cuboidal region, using the RT method to calculate the electric field strength on the cuboid’s surface, and then employing this as the excitation source for the FDTD method. Subsequently, the FDTD method is used to calculate the electric field strength within the cuboid. Experimental results demonstrate that the RT-FDTD method effectively mitigates the limitations of the RT and FDTD methods, enhancing both the efficiency and accuracy of simulations in underground mine.

Indoor Positioning Based Ranging: A Review and Literature Survey of UWB and Li-Fi Technologies

Why IPS (Indoor Positioning Systems)? This issue is one of the most challenging things to solve in wireless localization due to the lack of a Global Positioning System (GPS) and the existence of distinctive radio propagation characteristics. Although there are different localization options available, the accuracy of localization cannot satisfy customers' requirements. Positioning algorithms could be grouped into two groups, including range-based and range-free techniques. Before actually putting a localization technique into practice, the accuracy of those techniques is of the utmost importance. Range-based methods can often attain great accuracy with the help of specialized hardware, and this accuracy can be dependent on either the distances between nodes or the angles between them. In this paper, a comparison of different strategies utilized for positioning is presented, as well as an analysis of the pros and cons associated with supporting technologies for each strategy. A literature survey of the recent IPS technologies range-based with focuses on Ultra-Wide Band (UWB) and Light Fidelity (Li-Fi) is presented with significant recommendations. This literature considered the accuracy, complexity, scalability, cost, latency, deployment, and usability, as well as strengths, shortcomings, approaches, and issues determined by each work. This paper highlights the most recent research gaps and reviews the most promising findings, with recommendations to the reader and researcher, in UWB and Li-Fi indoor positioning systems over the last five years based on range-based techniques. In addition, this paper serves as a guide that discusses all of the measures that may be utilized in the process of evaluating localization technologies, and it could be considered a roadmap for existing and new researchers to identify and characterize suitable technologies for creating innovative systems and apps via stand-alone range-based positioning.

Investigating of Signal Propagation Characteristics in a Realistic Rural Scenario using Verified Tools: A Case of South Chunya-Tanzania

Effective radio network planning requires understanding an area's radio propagation characteristics. This investigation uses dependable techniques to examine the movement of wireless signals in Tanzania's rural locations. Propagation characteristics in selected rural Tanzanian communities (South Chunya) are examined as a case study, and recommendations are made based on the findings, particularly for wireless service providers or researchers looking to improve wireless connectivity in rural communities. Important radio parameters such as Pathloss, Signal to Noise ratio, Bandwidth throughput, Spectral efficiency and Spectral band were examined. This was done after simulating signal transmission from the Base station transmitter to the Base station receiver and observing power and attenuation. Their corresponding results are discussed and evaluated. The general observation of the pass loss results for both operating frequencies 800MHz and 2000MHz have shown that only few areas are experiencing strong signal after initial signal power transmission, large areas served by these macro sites are experiencing huge path loss. This is evidently affected by the terrain of an area and the carrier frequency of operators.

Study on Improvement of Radio Propagation Characteristics of Cast Iron Boxes for Water Smart Meters.

Water utilities in Japan face a number of challenges, including declining water demand due to a shrinking population, shrinking workforce, and aging water supply facilities. Widespread use of smart water meters is crucial for solving these problems. The widespread use of smart water meters is expected to bring many benefits such as reduced labor by automating meter reading, early identification of leaks, and visualization of pipeline data to strengthen the infrastructure of water services, business continuity, and customer service, as detailed data can be obtained using wireless communication. Demonstration tests are actively conducted in Japan; however, many problems have been reported with cast iron meter boxes blocking radio waves. To address the issue, a low-cost slit structure for cast iron meter boxes is investigated in this study. The results confirm that the L-shaped tapered slit array structure with a cavity, which can be fabricated in a cast iron integral structure, satisfies the design loads required for road installation. The proposed slit structure achieved gain characteristics from -3.32 to more than 9.54 dBi in the 800 to 920 MHz band. The gain characteristics of conventional cast iron meter boxes range from -15 to -20 dBi, and the gain has been significantly improved. Antennas with a gain of -2.0 to +1.5 dB (0.8 to 2.5 GHz) were used for the transmitter antenna, which was found to have a higher gain than the transmit antenna in the 800 to 880 MHz frequency band. In the 1.5 to 2.0 GHz band, a high peak gain of 4.25 dBi was achieved at 1660 MHz, with no null and the lowest gain confirmed that this is an improvement of more than 10 dBi over conventional products.

POWER SUPPLY OF RING ANTENNA USING DIRECTIONAL COUPLERS

Context. The circular polarization of radio waves is used in various electronic systems. This includes, for example, space communications stations, some radio relay communication systems, radar stations, data transmission systems and others. The characteristics of radio wave propagation are studied by using electromagnetic waves separated by circular orthogonal polarization in radiomonitoring and radiocontrol systems. Compared to other antenna types, circularly polarized antennas, such as rings, have superior design simplicity and excellent electrodynamics properties.
 Objective. The objective of this study is to analyse the characteristics and application of directional microstrip couplers for supplying power to ring antennas.
 Method. To better the performance of microstrip ring antennas, the reasons for their limited operating frequency range are analysed. These causes include the frequency-dependent parameters of the coupler, errors in calculating the directional coupler circuit, and radiation from asymmetric strip lines. To understand how supply lines, affect antenna characteristics, correlations between radiation fields determined in both its coordinate system and that of the primary axis are taken into account.
 Results. An analysis of the dependence graphs of the main characteristics of ring microstrip antennas with intricate power supply circuits for directional couplers and comparison with similar characteristics for simple circuits revealed that the shape of the radiation pattern in the higher radiation hemisphere became symmetrical about the axis, especially when symmetrically supplying the ring with branch-line couplers. The frequency band has also widened, at which there was an acceptable degree of deviation in the ellipticity coefficient from unity.
 Conclusions. The simulation results of microstrip ring antennas with power lines connected to directional couplers of different types showed that supplying the ring antenna with electricity via the directional coupler ensures circular polarization for the emitted electromagnetic waves. Additionally, the range of operating frequencies where there is only a small discrepancy in ellipticity coefficient remains at an acceptable level of –3 dB is quite broad. By utilizing directional branch-line couplers to power a ring antenna, it is possible to simultaneously emit both right and left circularly polarized waves with the same antenna.

Acceleration of Tensor Interpolation-Based Radio Map Estimation

The radio map of wireless communications should be surveyed in advance when installing base stations to efficiently utilize radio waves. Generally, this is calculated using radio wave propagation simulation. Because the simulation is time-consuming, a tensor-rank minimization-based interpolation method has been proposed as fast method. However, this method interpolates the radio map using an iterative algorithm. The number of iterations required for further acceleration should be reduced; therefore, we propose a tensor interpolation using rank minimization that considers the characteristics of radio wave propagation. Furthermore, we proved that the proposed method could interpolate with fewer iterations than the existing method.

Radio propagation characteristics of 40GHz band millimeter-wave on curved sections of railway environment

Radio propagation characteristics of 40GHz band millimeter-wave on curved sections of railway environment

Measurements and Modeling of Large-Scale Channel Characteristics in Subway Tunnels at 1.8 and 5.8 GHz

Radio propagation characteristics in subway tunnels are significant for designing reliable wireless communications. To obtain large-scale channel characteristics, extensive propagation measurements are conducted in a straight subway tunnel at 1.8 and 5.8 GHz, respectively. Based on the measurements, some typical large-scale channel parameters are extracted and modeled, such as path loss, shadow fading, and channel correlation. The path loss exponents are found to be 2.83 and 2.55 at 1.8 and 5.8 GHz, respectively, with shadow fading standard deviation of 1.58 and 2.58 dB. Shadow fading decorrelation distance is 8.71 m for 1.8 GHz and 11.65 m for 5.8 GHz, respectively. Moreover, cross-correlation coefficient of shadow fading in two dual-link scenarios is around 0.1, which shows that there is fairly low cross-correlation in a subway tunnel. The results in this letter are useful for link budget, handover scheme design, and network planning of subway communication system.

Ship-to-ship maritime wireless channel modeling under various sea state conditions based on REL model

The propagation of electromagnetic waves on land and sea is significantly different. Although the Los scenario is significant in marine wireless communication, the marine wireless channel exists an obvious two-ray phenomenon due to the strong reflection path reflected through the sea surface. By modeling the measured data of marine wireless channels, this paper calculates the radio propagation characteristics of the Pearl River estuary. In addition, the wave fluctuations and high humidity environment will also impact the properties of the marine wireless channel. Therefore, sea surface morphology models under multiple wind speeds are built. To estimate the path loss in the same area under different conditions, the Monte Carlo method is employed to quantify the results. The simulation results show that the electric wave propagation gradually degenerated from the round earth loss (REL) model to the free space model with increasing wind speed. Moreover, the distribution of the shadow fading varies with distance. The findings provide references for the network planning of marine communication.

MmWave Physical Layer Network Modeling and Planning for Fixed Wireless Access Applications.

The large bandwidths that are available at millimeter-wave frequencies enable fixed wireless access (FWA) applications, in which fixed point-to-point wireless links are used to provide internet connectivity. In FWA networks, a wireless mesh is created and data are routed from the customer premises equipment (CPE) towards the point of presence (POP), which is the interface with the wired internet infrastructure. The performance of the wireless links depends on the radio propagation characteristics, as well as the wireless technology that is used. The radio propagation characteristics depend on the environment and on the considered frequency. In this work, we analyzed the network characteristics of FWA networks using radio propagation models for different wireless technologies using millimeter-wave (mmWave) frequencies of 28 GHz, 60 GHz, and 140 GHz. Different scenarios and environments were considered, and the influence of rain, vegetation, and the number of subscribers was investigated. A network planning algorithm is presented that defines a route for each CPE towards the POP based on a predefined location of customer devices and considering the available capacity of the wireless links. Rain does not have a considerable effect on the system capacity. Even though the higher frequencies exhibit a larger path loss, resulting in a lower power of the received signal, the larger bandwidths enable a higher channel capacity.

Position Estimation of Radio Source Based on Fingerprinting With Physical Wireless Parameter Conversion Sensor Networks

Establishing a highly accurate positioning of radio sources for radio wave monitoring and frequency spectrum sharing is attracting considerable attention. Because the positioning method generally requires specific processing of the position target, it is not applicable when the position target cannot perform any processing. The location fingerprinting method uses multiple sensors to observe the received signal strength indication (RSSI) emitted by a radio source and estimates the position from the radio wave propagation characteristics. This does not require a certain process for the target position. However, it takes time to gather RSSI from many sensors by wireless communication. In this study, we propose an RSSI gathering method using physical wireless parameter conversion sensor networks (PhyC-SN) for the high-speed positioning of radio sources. In the proposed method, each sensor selects the radio carrier frequency corresponding to its measured RSSI and transmits the signal. Projecting the RSSI distribution of each sensor onto the frequency distribution of the received signal enables the center to detect the RSSI of multiple sensors simultaneously. Furthermore, to improve the gathering accuracy, we established a sensor group method by considering the regional characteristics and access timing control based on each sensor group. Computer simulations and experimental evaluations show that the proposed method significantly reduces the data-gathering time compared with conventional packet communications and achieves a high positioning accuracy.

Deployment of Ultra Dense Network Devices in Space. Part 1. Models and Methods of Geometric Factor

The use of the millimeter band (30 GHz–300 GHz) in fifth generation networks and the submillimeter or terahertz band (0.3–3 THz) in sixth generation networks, due to the physical characteristics of radio wave propagation, inevitably leads to a reduction in the radio communication range and the use of predominantly lineof-sight radio links. From the point of view of the network architecture, this circumstance entails an increase in the density of the spatial arrangement of devices, which, in turn, leads to the emergence of new tasks for the network organization at the physical, channel and network levels of the open systems inter-action model. One of the approaches to the spatial arrangement of the infrastructure of stationary network devices acting as a base station, access point and / or repeater / router can be the geometric factor of DOP (Dilution of Precision) in positioning accuracy known in classical radar and radio navigation. To date, from the analysis of open foreign sources, it can be argued that this approach has already become widespread in the tasks of finding and justifying the locations of base stations of fifth generation communication networks. This is due to the new role of positioning not only as a service of communication net-works, but also as an auxiliary means of solving the problems of net-work organization at the three lower levels of the data transmission medium. In connection with the ongoing convergence of infocommunication and positioning services provided by the infrastructure of communication networks of the fifth and subsequent generations, there is every reason to believe that the approach of placing network devices based on DOP deserves attention and can be used for communication networks of the sixth-generation of terahertz band, where the density of transceivers will already exceed 1 device per square meter. Subject of study. The article is devoted to mathematical and simulation modeling of methods for searching for locations of base station devices in space according to the criterion of the geometric factor of the dilution of precision for positioning accuracy of the user device. Method. Calculation of geometric factors for the dilution of precision of positioning accuracy in the horizontal plane HDOP (Horizontal DOP), in the vertical plane VDOP (Vertical DOP) and by location in space PDOP (Position DOP). Main results. The result of this work is the formalization of algorithmic, methodological and software for DOP calculations and search for locations of base station devices in space based on geometric factors of the DOP for the positioning accuracy of user devices. Practical significance. The results obtained make it possible to search for the locations of the base stations of an ultra-dense network in space under the condition of a fixed location of the user device, as well as to perform a quantitative and qualitative assessment of the obtained placements according to the DOP criteria.

IEEE 802.15.4g/4x-Based Orthogonal Frequency-Division Multiplexing Transmission Scheme for Wide-Area and Mobile IoT Communication Systems

Radio communication systems using the frequency-shift keying (FSK) scheme standardized by the IEEE 802.15.4g standard can realize low-power consumption and highly reliable communications and are mainly adopted for smart metering as part of the Internet of Things (IoT). However, smart metering has recently broadened its application expectations, with broadband and long-distance communications now required. To fulfill these requirements, orthogonal frequency-division multiplexing (OFDM) has been incorporated into the IEEE 802.15.4g and 802.15.4x standards. However, comprehensive transmission performance analysis of OFDM under static and multipath fading environments has not been conducted. In this article, we first evaluated the packet error rate (PER) of OFDM assuming fixed communications using computer simulations. We then evaluated the transmission distance of OFDM and showed that OFDM can communicate at transmission distances up to 3.0 times longer than those specified in IEEE 802.15.4g FSK. Next, the PER in a mobile communication environment was evaluated using computer simulations. When only the long training field (LTF) was used to estimate multipath radio channels, the required PER of 10% was not achieved, even in a mobile communication environment at a speed of several km/h. To solve this problem, we proposed a receiving scheme which included a new channel estimation scheme. This scheme successively utilized not only the LTF but also pilot signals inserted into the transmitter to estimate radio propagation characteristics. Computer simulation results showed that the required PER was achieved even in a mobile communication environment at 30–40 km/h by using the proposed scheme.

Sensor-Aided Learning for Wi-Fi Positioning With Beacon Channel State Information

Because each indoor site has its own radio propagation characteristics, a site survey process is essential to optimize a Wi-Fi ranging strategy for range-based positioning solutions. This study examines an unsupervised learning technique that autonomously learns an optimal ranging strategy for each site using Wi-Fi and sensor data accumulated while users access a positioning application. Using the collected sensor data, the device trajectory is regenerated, and a Wi-Fi ranging module is optimized to generate the shape of the estimated trajectory using Wi-Fi, similar to that obtained from sensors. In this process, the ranging module learns the way to identify the channel conditions from each Wi-Fi access point (AP) and produces ranging results accordingly. Furthermore, we collect the channel state information (CSI) from beacon frames to investigate the benefit of using CSI in addition to received signal strength measurements. With the CSI, the ranging module can identify diverse channel conditions from each AP and more accurately generate the reliability of each distance estimate to achieve accurate positioning results. The effectiveness of the proposed learning technique is verified using a real-time positioning application implemented on a PC platform.

Large-scale parameter modelling for millimeter-wave multiple-input multiple-output channel in 5G ultra-dense network

<span>Network densification (ND) in 5G has been suggested as a solution to improve network capacity. ND has small cell backhaul as its bottleneck in the ensuing ultra-dense network (UDN). Due to the new deployment scenarios of small cells, it becomes necessary to thoroughly investigate the radio-propagation characteristics of the new transmission path between the base station and the small cells. The problem of the impact of small cell height on the backhaul large-scale parameters under typical outdoor-to-indoor (high-rise) and outdoor-to-outdoor (street canyon) scenarios was first investigated. Next, the probability distribution functions of the various parameters were investigated and modeled. Novel use of 5G NR air interface using a deterministic ray-tracing engine to characterize the backhaul at <br /> 28 GHz center frequency and 100 MHz bandwidth using 4x4 cross-polarized uniform planar array (UPA) at the base station and 2x2 multiple input, multiple output (MIMO) antennas at the small cells was proposed. New sets of models for root mean square (RMS) delay spread and RMS angular spread suitable for predicting network deployment in the two scenarios and similar environments were presented.</span>

Large-Scale Dataset for the Analysis of Outdoor-to-Indoor Propagation for 5G Mid-Band Operational Networks

Understanding radio propagation characteristics and developing channel models is fundamental to building and operating wireless communication systems. Among others uses, channel characterization and modeling can be used for coverage and performance analysis and prediction. Within this context, this paper describes a comprehensive dataset of channel measurements performed to analyze outdoor-to-indoor propagation characteristics in the mid-band spectrum identified for the operation of 5th Generation (5G) cellular systems. Previous efforts to analyze outdoor-to-indoor propagation characteristics in this band were made by using measurements collected on dedicated, mostly single-link setups. Hence, measurements performed on deployed and operational 5G networks still lack in the literature. To fill this gap, this paper presents a dataset of measurements performed over commercial 5G networks. In particular, the dataset includes measurements of channel power delay profiles from two 5G networks in Band n78, i.e., 3.3–3.8 GHz. Such measurements were collected at multiple locations in a large office building in the city of Rome, Italy by using the Rohde & Schwarz (R&S) TSMA6 network scanner during several weeks in 2020 and 2021. A primary goal of the dataset is to provide an opportunity for researchers to investigate a large set of 5G channel measurements, aiming at analyzing the corresponding propagation characteristics toward the definition and refinement of empirical channel propagation models.

정밀 위치 확인을 위한 레이더 기반 실내 위치추적 시스템 설계에 관한 연구

As the use of smart devices increases, the importance of the IoT(Internet of Things) and AR(Augmented Reality) is growing. This leads increasing demand for accurate location-based services, but tracking indoor location using existed way is difficult and expensive. This paper devises a new method to address these shortcomings. The radar based method process conjoined four-directed beacons’ BLE(Bluetooth Low Energy) RSSI(Received Signal Strength Indicator) values to find out the direction and distance of the target. During the process Kalman filter is applied to reduce noise of RSSI caused by unpredictable radio propagation characteristics in various indoor environments, also using LSTM(Long Short Term Memory) to track the exact location.