Outdoor Propagation Research Articles

Retro-diffraction - importance for the calculation of road traffic noise

In geometric acoustics, "retro-diffraction" describes the loss of energy when reflected at the upper edges of noise screens. By bending the sound beam against the direction of propagation under consideration, reflected energy of the mirror sound source is reduced by up to 5 dB in addition to the absorption. This effect becomes particularly effective if the sound beam is blocked by a noise screen in the direction of propagation under consideration, meaning that diffraction also occurs in this direction. Sound attenuation by retro-diffraction can be found in the French standard NF S 31-133, an alternative method to ISO 9613-2 for calculating sound propagation outdoors. It was incorporated into the French noise forecasting procedure NMPB in 2008. We also take it into account by using it in the procedure for calculating environmental noise (European: CNOSSOS; German: BUB). This paper attempts to determine the impact of considering retro-diffraction in sound propagation. First, the equations from ISO 9613-2 and BUB regarding retro diffraction are compared in a simple geometric model. The level differences calculated in commercial sound propagation software are compared with those from measurements on a 1:20 scale model. An estimate of the relevance of retro-diffraction in calculating sound propagation is given.

Path loss modelling of mmwave outdoor propagation for 5G mobile systems at 28, 38, 60, and 73 GHz in four Nigerian cities

Millimetre-waves (mmWaves), a critical part of 5G, have not been extensively studied in the sub-Saharan tropical environment. This study was conducted to model the outdoor propagation path loss of mmWaves in four Nigerian cities at 28, 38, 60, and 73 GHz for 5G mobile systems: Abuja, Lagos, Ibadan, and Port Harcourt. The study utilised simulation data from a Composite Raytracing-Image-Method propagation model in MATLAB 2023a with OpenStreetMap 3D building maps to formulate the Close-In free-space Reference Distance (CI), Floating Intercept (FI), and Alpha–Beta-Gamma (ABG) large-scale path loss models. This model considered the specific atmospheric conditions, terrain, building materials and structures, and geographical layouts of each site. The study found that the path loss exponent ranged from 2.712 to 3.819 in line-of-sight scenarios, with shadow fading standard deviation (σCI) ranging from 11.778 to 37.199. In non-line-of-sight scenarios, the path loss exponent ranged from 3.375 to 5.033, with σCI ranging from 12.441 to 44.181 across the four frequencies studied. The ABG model consistently provided the most accurate predictions compared to CI and FI, particularly the mean absolute error and root mean square error values. However, performance varied across cities, frequencies, and scenarios, with Port Harcourt exhibiting the highest path loss values across all frequencies and scenarios, followed by Lagos. Furthermore, the omnidirectional large-scale path loss increases marginally as the frequency increases, except at 60 GHz, which had a higher path loss per distance than 73 GHz. Finally, the findings showed that the propagation characteristics of mmWaves for 5G networks in sub-Saharan tropical environments, such as Nigeria, exhibit significant variability based on factors such as atmospheric conditions, terrain, building materials, and geographical layouts. The formulated path loss models can be used to predict the coverage area and signal quality of millimetre-wave communication systems at these frequencies and locations.

Modeling noise from large-scale data center equipment

Data centers present unique noise modeling challenges due to the scale of equipment needed to meet cooling and backup power demands. Three-dimensional environmental noise modeling software that is based on ISO 9613-2 "Attenuation of sound during propagation outdoors" offers a range of modeling techniques. While more detailed modeling techniques may offer more accuracy in the near field, they also increase model calculation run times. Additionally, manufacturer sound emissions data often more closely align with simplified modeling techniques. This evaluation reviews common data center noise sources, reviews the range of manufacturer noise emissions data typically available for such sources, and compares noise modeling techniques with reference to on-site observations.

Anxel Beam Shrinkage Method and Heterogeneous Computing-Accelerated Full-Image Theory Method Ray Tracing Enabling Massive Outdoor Propagation Modeling

Anxel Beam Shrinkage Method and Heterogeneous Computing-Accelerated Full-Image Theory Method Ray Tracing Enabling Massive Outdoor Propagation Modeling

Tony Embleton—Distinguished researcher, successful manager, consummate acoustician

Tony F. W. Embleton was a distinguished researcher in acoustics. His early career focused on practical noise control projects and experimental non-linear acoustics. Later, Tony made important contributions to the understanding of sound propagation outdoors. Tony spent much of his career at the National Research Council of Canada (NRCC). His professional homes were the ASA and the CAA. Tony received numerous awards from the ASA for his work, including the R. Bruce Lindsay Award in 1964, the ASA Silver Medal in Noise in 1986, and the ASA Gold Medal in 2002 “For fundamental contributions to understanding outdoor sound propagation and noise control and for leadership in the Society.” Tony recognized the value of professional organizations and served the ASA as Vice-President (1977–78) and President (1980–81). He also understood the importance of practical applications in acoustics serving as ASA Standards Director (1993–97), navigating the organization through a tough period, and growing the program toward a solid future. Most importantly, Tony was known for his kind and generous spirit, and his outreach and inspiration to newer colleagues. Many of us are the grateful beneficiaries of his gentle enthusiasm.

An Adaptive Hybrid Outdoor Propagation Loss Prediction Modelling for Effective Cellular Systems Network Planning and Optimization

The frequent poor service network experienced by some mobile phone users within some deadlock areas in Nigeria is an issue which has been identified by different researchers due to wrong positioning and planning of the evolved NodeB (eNodeB) transmitter using existing propagation loss models. To effectively contribute towards this potential issue constantly experienced in some part of Nigeria, an adaptive hybrid propagation loss model that is based on wavelet transform and genetic algorithm methods has been developed for cellular network planning and optimization, with the capacity to resolve the problems absolutely. First, the signal strengths were measured within four selected eNodeB cell sites in long term evolution (LTE) at 2600MHz using drive-test method. Secondly, the measured data were denoised through wavelet tools. Thirdly, COST231 model was optimize and deduced to generic model with parameters. Fourthly, genetic optimization algorithm automatically developed the propagation loss models for denoised signal data (designated as wavelet-GA model) and unprocessed signal data (designated as GA model). The hybrid wavelet-GA propagation loss model, GA propagation loss model, and COST231 propagation loss model were compared based on three error metrics such as root mean square error (RMSE), mean absolute error (MAE) and correlation coefficient (R). The developed hybrid wavelet-GA model estimated the lowest RMSEs of 2.8813 dB, 3.9381 dB, 4.7643 dB, 6.9366 dB, whereas, COST231 model gave highest value of RMSE. The developed hybrid wavelet-GA model also derived the least value of MAE as compared with COST231 and the GA models, such as, 2.2016 dB, 2.8672 dB, 3.4766 dB, 5.8235 dB. The correlation coefficients were also compared, and it showed that the developed hybrid wavelet-GA model were 90.04%, 78.61%, 92.21% and 91.23% for the four cell sites. The developed hybrid wavelet-GA model was also validated to account for the performance level by checking for the correlation coefficient using another measured signal data from different eNodeB cell sites other than the once used for the developed of the hybrid wavelet-GA model. It was noticed that the developed hybrid wavelet-GA propagation loss model is 97.41% valid. Existing standard COST231 model are not able to predict propagation loss with high level of accuracy, as such not efficient to be applied within part of Port Harcourt, Nigeria. The proposed hybrid wavelet-GA model has proven to achieve high performance level and it is relevant to be utilized for cellular network planning and optimization. In future purposes, more regions and locations should be considered to form a broader view in the development of more robust propagation loss models.

The Status of International Guidance and Standards for Environmental Noise Assessment

Since its first publication in 1971 of ISO/R 1996:1971 on Acoustics Assessment of Noise with Respect to Community Response, the International Organization for Standardization (ISO) has developed and published a range of standards for environmental noise assessment. The main ISO 1996 series of standards on Description, Measurement and Assessment of Environmental Noise has been developed in phases. And almost 30 years ago, ISO 9613 Attenuation of Sound During Propagation Outdoors was added. More recently, supporting standards such as the ISO PAS 20065 Objective Method for Assessing the Audibility of Tones in Noise and the ISO 17534 series concerning Software for the Calculation of Sound Outdoors have been added, and cooperation initiated with the International Electrotechnical Commission on the IEC 61400-11-2 Assessment of Wind Turbines Noise at receptor positions. This paper provides an overview of ISO standards related to environmental noise assessment. It also describes the historical development of the ISO 1996 series and related standards. Current developments, including their status, are described. Finally, it provides some suggestions and considerations for further research.

Vehicular Visible Light Communication System: Modeling and Visualizing Critical Outdoor Propagation Characteristics

We propose a practical vehicle-to-vehicle (V2V) visible light communications (VLC) propagation model by considering the impact of the outdoor propagation characteristics. Contrary to the existing literature, we emphasize a dynamic V2V-VLC model considering several propagation characteristics. Both line-of-sight (LOS) and non-line-of-sight (NLOS) V2V-VLC propagation models are proposed. To this end, we comprehensively demonstrate the impact of the considered propagation characteristics on the proposed LOS and NLOS V2V-VLC propagation models. To analyze the proposed propagation models, we also derive the closed-form expressions for the average path loss and discrete-input continuous-output (DCMC) capacity incorporating the considered propagation characteristics. With the help of derived closed-form expressions and simulations, we demonstrate comparative insights for the proposed LOS and NLOS V2V-VLC propagation models. Considering our key findings, it is observed that there is a path loss penalty of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\approx$</tex-math></inline-formula> 6 dB compared to the conventional path loss model for a worst-case weather scenario. Moreover, it is observed that the considered propagation characteristics have a significant impact on the V2V-VLC performance. Further, we observe that the ergodic DCMC capacity corresponding to the NLOS-road surface link indicates a dominant behavior compared to an NLOS link arising from an interfering vehicle; but up to a certain range of the link length.

A deep neural network based MU-MIMO beamforming training protocol for IEEE 802.11ay

IEEE 802.11ay supports a multi-user multiple-input-multiple-output (MU-MIMO) beamforming training (BFT); hence, an access point (AP) can perform data transmissions simultaneously with multiple stations (STAs). During MU-MIMO BFT, the AP sends a significant number of action frames to the STAs to determine appropriate directional antenna patterns. However, if transmit sectors (TSs) used in the transmission of action frames are selected inefficiently, the AP could perform redundant transmissions; this could eventually lead to the poor performance of the MU-MIMO BFT in terms of signaling and latency overhead. To select the appropriate TSs, the AP is required to accurately estimate the link qualities measured at the STAs when certain TSs are used simultaneously to transmit an action frame. Therefore, in this study, we propose a deep neural network (DNN)-based scheme that performs efficient MU-MIMO BFT. It achieves this by accurately estimating link qualities measured at the STAs when an action frame is transmitted through multiple TSs. Moreover, it performs this function without collecting any additional channel information that is not specified in the standard. For performance evaluation, we conducted extensive simulations with realistic mmWave channel and antenna array models in four indoor and outdoor propagation scenarios. The simulation results demonstrate that our scheme transmits fewer action frames and achieves a lower BFT time than existing schemes.

A Micro 4-port THz MIMO antenna for nano communication networks

This paper proposes a micro nature inspired UWB 4-port MIMO antenna design with dimensions of 45μm × 45μmăoperating from (2.38–11.18) THz and 130% impedance bandwidth realised on a 2μm thick polyamide substrate. Each radiator is made by superimposing self-similar elliptic structures to create a palmate leaf-like pattern that ensures wideband response. The ground topology is made up of semi-elliptic orthogonal reflectors connected to a center-fed annular circle with rotationally symmetrical parasitic stubs that operate as an isolator, resonator, and neutralizer. The antenna elements are ordered orthogonally with an inter-element distance of d0 = 0.05λ0 (λ0 is the lowest working wavelength at 2.38 THz) and an inter-element port isolation distance of d0 = 0.05λ0. The parasitic stub inclusion increases the lower/higher band 10-dB impedance matching response, and the proposed ground structure has good isolation coefficients (18−22)dB. An equivalent circuit model with R-L-C lumped elements was modelled and simulated to validate. In both indoor and outdoor propagation environments, the MIMO diversity parameters (Envelope channel coefficient (ECC), Total active reflection coefficient (TARC), Diversity gain (DG), Channel capacity loss (CCL), Mean effective gain (MEG), and Multiplexing efficiency) show good characteristics to leverage. The suggested MIMO antenna can be employed for THz band and molecular/nano communication networks owing to its radiation performances (realised gain of > 8 dBi with > 60% radiation efficiency).

Эффект «волновода» при распространении сверхширокополосных сигналов в помещении

“Waveguide” effect that occurs by indoor propagation of ultrawideband signals is shown. The effect exhibits itself in the absence of interference factor of signal dissipation at any distance. Unlike outdoor propagation, the signal attenuation in multipath indoor environment is similar to free space. The effect occurs due to reflections of the incident wave from paired opposite surfaces, e.g., floor – ceiling, parallel walls. As a result, the distance range of indoor ultrawideband communications is essentially higher than outdoors. The effect is simulated in a three-ray reflection model.

Performance Evaluation of Directional Antennas in ZigBee Networks under NLOS Propagation Conditions

Many authors suggest directional antennas to enhance the transmission performance of ZigBee networks. For line-of-sight propagation, directional antennas can extend the transmission range or reduce the transmit power. Directional antennas may also reduce interference between networks operating in the same frequency channel. However, these antennas may not perform similarly under non-line-of-sight propagation conditions. This work presents a study with ZigBee modules comparing the performance of a directional antenna with an omnidirectional one. The measurements were conducted on a university campus for different propagation outdoor environments. A deconvolution technique was applied to estimate the received signal as a function of the azimuth angle. The results demonstrated that the received power followed the gain difference between antennas only for paths with low attenuation. Considering the same Effective Isotropic Radiated Power (EIRP), the system with directional antennas started to lose packets at the same distance as the omnidirectional antennas. The directional antenna did not allow the increase in the link range compared to the omnidirectional antenna. The power consumption was also measured for different transmit power levels of the ZigBee radio. The study showed that the control circuits of directional antennas typically consume more power than omnidirectional antennas operating at a higher transmit power level.

Measurement and Ray Tracing Simulation with Urban Microcell Environments at 28GHz Band

In this study, we investigate outdoor propagation measurements performed in an industrial park environment at 28.3 GHz band. The propagation characteristics were evaluated with the measurement result regarding the path loss characteristics. Ray tracing simulation was also studied and compared with the measurement data to evaluate the quantitative accuracy of ray tracing in millimeter-wave band wireless propagations. Ray tracing, whose accuracy was evaluated based on a comparison with the measurement results, can aid in the theoretical design of the coverage area and deterministic channel modeling.

EM DeepRay: An Expedient, Generalizable, and Realistic Data-Driven Indoor Propagation Model

Efficient and realistic indoor radio propagation modeling tools are inextricably intertwined with the design and operation of next-generation wireless networks. Machine-learning (ML)-based radio propagation models can be trained with simulated or real-world data to provide accurate estimates of wireless channel characteristics in a computationally efficient way. However, most of the existing research works on the ML-based propagation models focus on outdoor propagation modeling, while indoor data-driven propagation models remain site-specific with limited scalability. In this article, we present an efficient and credible ML-based radio propagation modeling framework for indoor environments. Specifically, we demonstrate how a convolutional encoder–decoder can be trained to replicate the results of a ray tracer, by encoding physics-based information of an indoor environment, such as the permittivity of the walls, and decoding it as the path loss (PL) heatmap for an environment of interest. Our model is trained over multiple indoor geometries and frequency bands, and it can eventually predict the PL for unknown indoor geometries and frequency bands within a few milliseconds. In addition, we illustrate how the concept of transfer learning can be leveraged to calibrate our model by adjusting its preestimate weights, allowing it to make predictions that are consistent with measurement data.

To Develop a Model for 4g LTE and Predictable 5G at 3500 Mhz that Would Predict the Path Loss for the Environment in Semi-Urban or Mixture of Urban and Rural Surroundings at Specific Geographical Locations

Abstract: In wireless communication, a planned network is given by the path loss model. Link budgeting, coverage prediction, and system performance optimization are indispensable in developing an accurate, simple, and general path loss model. To predict path loss in a particular environment each type of path loss propagation model is designed, it may be inaccurate in another different environment. In this paper, we are trying to predict a path loss model of Durgapur considering a particular place with a mixture of high-rise buildings, sub-urban, open, and foliage environments. For this proposal, the model area has been divided into twelve sectors taking 30° sectoring of radii 5 km and applying the path loss model for the calculation of path loss. Index Terms: Path loss, Predicted model, Outdoor propagation model consideration, Cell site selection, results, and discussions.

End-To-End Fully-Informed Network Nodes Associated with 433 MHz Outdoor Propagation Environment

Internet of Things (IoT) is operationally defined in this study as “an end-to-end fully-informed network associated with 433 MHz outdoor propagation environment”. The work is motivated by the fact that minimizing delay and transmission time is crucial to maintaining fully-informed network under 433 MHz propagation. This is intended to answers two questions: “how transmission delay affect early detection of network failure:” and “how faster is necessary to recover from a network failure?”. Endto- end fully-informed network was designed and constructed. An experimental analysis for data transmission on the network were performed. The experimental analysis has shown that the antenna height and the distance between transmitter and receiver have the most effective impact on the transmission success. Furthermore, the high rate bandwidths have shown a negative effect on the data integrity and total dysfunctionality above 50 meters. Thus, in end-to-end fully-informed network, it is revealed that transmitting more than 8 KB (at both 57600 bps and 115200 bps) has a drawback in end-to-end fully-informed network. However, transmission over 80 meters the most stable bandwidth that keeps the data integrity in end-to-end network is (9600 bps). Experimental analysis reveals that delay is thus reduced as well as transmission times increases.

A 3D Indoor Positioning Method of Wireless Network with Single Base Station in Multipath Environment

The proliferation of indoor location-based services has increased the demand of indoor positioning technology. Severe multipath and coherence effects are the difference between signal propagation indoors and outdoors. Most existing indoor localization methods build their models in 2-dimensional space and try to avoid the influence of multipath. We propose a method to realize 3-dimensional indoor positioning with single base station by using multipath channel. The angles of multipath coherent signals are estimated by MIMO antenna and the delays are estimated by OFDM signal. To avoid the complicated calculation in joint estimation of angles and delays in 3-dimensional space, the angles and delays are estimated separately and matched by the proposed algorithm. The line-of-sight channel is differentiated by time delay, and the reflection paths for non-line-of-sight channels are established with angle information and indoor maps. Finally, combine the angle information of the reflection paths and the line-of-sight path to obtain the target position in 3-dimensional indoor space. We verified the method through simulation in an indoor space of 6 m × 8 m × 4.5 m . The positioning errors are submeter level in 95 % cases and less than 0.4m in 60 % cases. The proposed method requires only one base station and can be applied in most wireless networks. Compared with existing indoor localization methods, it has lower computational complexity and higher application potential.

Spectrum sharing between wireless medical capsule endoscopy and LTE system

Wireless medical capsule endoscopy (WMCE) is an innovative technology that can be used to detect diseases of the human gastrointestinal tract. This technology utilizes a miniature camera capsule (CapCam) as a convenient alternative tool for treating small intestines with no pain and non-invasive method with very low levels of medical hazards compared to traditional methods. The CapCam technology operates in industrial, scientific, and medical (ISM) bands including 915 and 2400 MHz. However, co-channel and adjacent channel bands in the ISM bands are identified for mobile service, represented by long term evolution (LTE) system, on a primary basis (915 MHz) and a co-primary basis (2400 MHz) in the three ITU Regions. Such a condition creates a potential and mutual interference between the CapCam and LTE systems and it can highly affect human health. This paper proposes a model to study the potential interference scenarios between the CapCam and LTE systems in possible shared frequency bands for co-channel and adjacent channel scenarios based on a real urban macrocell (UMa) where line of sight (LOS) and non-LOS (NLOS) conditions are available. In this study, four propagation environment models are involved in estimating the total propagation losses including outdoor propagation, building penetration, indoor propagation, and propagation through a human body. The obtained results using the carrier to interference ratio (CIR), as a spectrum sharing criterion, showed that the interference from the LTE system is dominant. In addition, the concurrent operation of the CapCam and LTE systems with minimum distance seems more likely for the NLOS environment with higher frequency band (2400 MHz) and adjacent frequency scenario. Also, the channel capacity of the LTE and CapCam systems, under various CIR levels, displayed a good agreement with previous studies.

Measurement‐based delay, angular dispersion and propagation loss characteristics of outdoor propagation in beam domain and multi‐beam operation at 38 GHz for 5‐G communication systems

Owing to the global bandwidth shortage in frequency bands below 6 GHz, higher frequency bands such as millimetre-wave bands will play integral roles in fifth-generation (5-G) communication systems. Beamforming is necessary for high-frequency bands to maintain system coverage and increase system capacity through spatial division multiple access. Moreover, more than one beam might be used simultaneously to enhance signal quality and prevent blockages. Recent studies have investigated, focussed on power loss characteristics in multi-beam operation, and compared the channel characteristics for single-beam operation. To provide robust channel characteristics, knowledge of the multipath characteristics in multi-beam operation is required in the design of 5-G communication systems. To fill this gap such as the multipath dispersion characteristics of outdoor-to-outdoor propagation in delay and angular domains, the present study analysed outdoor data measured at 38 GHz and presented the propagation losses (path losses and shadowing), root-mean-square delay spread, and angular spread in multi-beam operation. We believe that the dispersion statistics (delay and angular spreads) and propagation loss characteristics in multi-beam operation would be useful in the development of 5-G communication systems in high-frequency bands.

Modelling Television White Space Frequencies for Broadband Internate Connectivity in The Rural Area of Nigeria Using Dynamic Spectrum Access Technique

As a result of the switchover from analogue to digital transmission, Television White Space (TVWS) presented itself as good opportunity to supplement the existing licensed spectrum to ease the spectrum scarcity. Rural communities were usually not connected due to poor returns to the internet providers to provide broadband access to the areas. This research has prepared the framework and feasibility study for deploying broadband internet services using Television White Space (TVWS) technology in Ugbawka, a rural area in Enugu state, Nigeria. In this work, a Network Ping was run on five websites using three major internet service providers as backhaul to establish facts of poor or even non-existent internet services. Using Ping Plotter 5 Pro, accessing ieee.com using MTN yielded a Round Trip (RT) average of 846.433 ms, with a loss of 83.8% packet over 10mins count. Radio Frequency (RF) Explorer and Carlson transceiver, Customer Premise Equipment (CPE) were used for field trials to determine availability of TVWS Frequencies. A database app was developed by writing some codes in the Basic for Android (B4A) Intermediate Development Environment (IDE). Empirical outdoor propagation model was developed with a 2.15 pathloss exponent. An algorithm was developed, titled, TVWS Optimization Quadrature Amplitude Algorithm, (TOQA), where throughput of this project performed better by giving 60Mbps and 70 Mbps at Signal-Noise-Ratio (SNR) of 5dB while the conventional algorithm gave 30Mbps and 25 Mbps at same SNR value. The Bit Error Rate was lower than the conventional models used, giving the TOQA values of 10-3 at SNR of 5 dB and 10-6 at SNR of 30 dB while the conventional method gave 10-1 and 10-3 respectively at the same SNR values. A 34.0% improvement was achieved when the dynamic access technique offered by this project was implemented on the TVWS network.