Hybrid Propagation Model Research Articles

Efficient propagation modelling for open‐confined mixed space using a hybrid ray‐tracing/waveguide theory method

AbstractThe accurate prediction of radio wave propagation along highways plays an important role in the design of high‐speed highway communication systems. The open‐confined mixed space is a connection zone between the open space and confined tunnel along the highway. A hybrid propagation model is presented based on ray‐tracing (RT) and waveguide theory, for the efficient modelling of open‐confined mixed space. The proposed model employs RT to predict radio waves emitted by sources with arbitrary radiation patterns in open space sections, and utilises the waveguide theory approach to accelerate the prediction process in the confined tunnel sections. Both two‐ray and six‐ray RT models are included to take into account the suburban and urban environments. Numerical results are compared with simulated results generated by RT as well as experimental measurements. The validity and usefulness of the proposed model are demonstrated in an actual open‐confined mixed space environment.

An innovative hybrid modeling approach for simultaneous prediction of cell culture process dynamics and product quality.

The use of hybrid models is extensively described in the literature to predict the process evolution in cell cultures. These models combine mechanistic and machine learning methods, allowing the prediction of complex process behavior, in the presence of many process variables, without the need to collect a large amount of data. Hybrid models cannot be directly used to predict final product critical quality attributes, or CQAs, because they are usually measured only at the end of the process, and more mechanistic knowledge is needed for many classes of CQAs. The historical models can instead predict the CQAs better; however, they cannot directly relate manipulated process parameters to final CQAs, as they require knowledge of the process evolution. In this work, we propose an innovative modeling approach based on combining a hybrid propagation model with a historical data-driven model, that is, the combined hybrid model, for simultaneous prediction of full process dynamics and CQAs. The performance of the combined hybrid model was evaluated on an industrial dataset and compared to classical black-box models, which directly relate manipulated process parameters to CQAs. The proposed combined hybrid model outperforms the black-box model by 33% on average in predicting the CQAs while requiring only around half of the data for model training to match performance. Thus, in terms of model accuracy and experimental costs, the combined hybrid model in this study provides a promising platform for process optimization applications.

Millimeter Wave Massive MIMO Downlink Per-Group Communications With Hybrid Linear Precoding

We address the problem of analyzing and classifying into groups the downlink channel environment in a dense millimeter-wavelength cell, accounting for path loss, multipath fading, and User Equipment (UE) blocking, by employing a hybrid propagation and multipath fading model, thus using accurate inter-group interference modeling. The base station (BS) employs a large Uniform Planar Array (UPA) to facilitate massive Multiple-Input, Multiple-Output (MIMO) communications with high efficiency. UEs are equipped with a single antenna and are distributed uniformly within the cell. The key problem is analyzing and defining groups toward efficient precoding. Because balanced throughput is desired between groups, up to four separate frequency sub-carriers are employed in an Orthogonal Frequency Division Multiple Access (OFDMA) system. We show that by employing three or four OFDMA subcarriers, depending on the number of UEs in the cell and the cell range, the UEs can be efficiently separated into <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">high-throughput</i> groups, with each group employing Virtual Channel Model Beams (VCMB) based inner precoding, followed by efficient Multi-User Multiple-Input Multiple-Output (MU-MIMO) outer precoders. For each group, we study two different sub-grouping methods offering different advantages. We show that the improvement offered by Zero-Forcing Per-Group Precoding (ZF-PGP) over Matched Filter Precoding (MFP) and Zero-Forcing Precoding (ZFP) is very high when finite-alphabet inputs are used. We also show ZF-PGP with finite-alphabet inputs significantly outperforms MFP with Gaussian inputs in certain realistic setups. Finally, a new technique for power allocation among different UEs is proposed, called Optimized Per-Group Power Allocation (OPGPA), which achieves much higher power efficiency jointly with equal throughput among all UEs in each group.

Using Spreadsheet Maps for the Placement of Low Altitude Platform (LAP) Wireless Network Nodes After Disasters

Low altitude platform (LAP) architectures are an emerging platform for providing temporary wireless network connectivity to areas with a damaged fixed wireless network infrastructure. The authors propose a spreadsheet-based approach for practitioners to locate LAP nodes in the field. This approach does not require radio frequency propagation expertise and incorporates standard models to display the coverage areas for the placement of LAP aerial devices. The proposed tool allows the transmission range for a given aerial device to be visually optimized during deployment. The spreadsheet-based tool the authors are proposing is expressly suited for battery-powered LAP architecture devices with payload weight restrictions, such as those utilizing balloons or kites, that can be quickly deployed by emergency responders. An additional contribution of this work is the development of a hybrid propagation model for LAP device transmissions for deployments above 200 meters which is absent in the literature. This model is a linear combination of two existing models for free space radio propagation.

Propagation analysis of MIMO ad hoc network in hybrid propagation model and implement less propagation loss algorithm to find the minimum loss route

Developing applications, especially real time ones mobile ad hoc network (MANET) requires a reasonable assurance of the likely performance of the network. MANET is realised by mobile nodes which communicate difficult task. Amongst many important properties of radio propagation model has to be selected carefully. This paper presents a hybrid propagation model of ad hoc network with multiple numbers of antennas. The hybrid technique ensures improved accuracy and practicality of the entire modelling environment. Currently study a modelled network consisting of ad hoc nodes with multiple antennas in different terrain and the propagation loss is calculated of the modelled network for the each ad hoc node. A loss less routing algorithm is implemented here and finally minimum loss route is selected for propagation in different terrain.

Propagation analysis of MIMO ad hoc network in hybrid propagation model and implement less propagation loss algorithm to find the minimum loss route

Developing applications, especially real time ones mobile ad hoc network MANET requires a reasonable assurance of the likely performance of the network. MANET is realised by mobile nodes which communicate difficult task. Amongst many important properties of radio propagation model has to be selected carefully. This paper presents a hybrid propagation model of ad hoc network with multiple numbers of antennas. The hybrid technique ensures improved accuracy and practicality of the entire modelling environment. Currently study a modelled network consisting of ad hoc nodes with multiple antennas in different terrain and the propagation loss is calculated of the modelled network for the each ad hoc node. A loss less routing algorithm is implemented here and finally minimum loss route is selected for propagation in different terrain.

Enhanced Propagation of Aviation Noise in Complex Environments: A Hybrid Approach

Accurate prediction of sound levels around airports and below flight paths can help faithfully represent the impact of aviation noise on communities. However, for large scale assessments, as are often performed by the U.S. Federal Aviation Administrationis environmental models, the accuracy of a model must be weighed against its efficiency. The hybrid propagation model (HPM) is capable of predicting propagation through complex environments. It is a composite of three methods—the generalized terrain parabolic equation (GTPE), fast field program (FFP), and straight ray models—each utilized in a different region of elevation angles from the source. If propagation conditions do not warrant use of the full model, one of the component models with faster runtime can be chosen as a surrogate. Analyses of cases using different source heights and including uneven terrain, refractive atmosphere, and ground type transitions, indicate when a detailed propagation model is needed, or when a simpler model is sufficient.

The effective sound speed approximation and its implications for en-route propagation

The effective sound speed approximation is widely used in underwater and outdoor sound propagation using common models such as ray tracing, the parabolic equation, and wavenumber integration methods such as the fast field program. It is also used in popular specialized propagation methods such as NORD2000 and the Hybrid Propagation Model (HPM). Long ago when the effective sound speed approximation was first introduced, its shortcomings were understood. But over the years, a common knowledge of those shortcomings has waned. The purpose of this talk is to remind everyone that for certain situations the effective sound speed approximation is not appropriate. One of those instances is for the propagation of sound from aircraft cruising at en-route altitudes when wind is present. This is one situation where the effective sound speed approximation can lead to substantially incorrect sound level predictions on the ground. [Work supported by the FAA. The opinions, conclusions, and recommendations in this material are those of the authors and do not necessarily reflect the views of FAA Center of Excellence sponsoring organizations.]

Performance analysis of wireless local area networks (WLAN) in a coal-mine tunnel environment

In order to establish an effective wireless communication system in an underground coal-mine environment, the propagation of radio waves through a rectangular-like mine tunnel was investigated by jointly, considering both the dielectric constant and the reflectance of a mine tunnel. By combining free space and modified waveguide propagation models, we propose a new hybrid propagation model based on ray tracing. Simulation results have shown the effectiveness of establishing a wireless Local Area Network (LAN) in this coal-mine environment. The results of this research will be very useful as a guide in the design and development of tunnel wireless LAN systems.

Model‐data comparisons of deep water ambient noise.

During the North Pacific Laboratory (NPAL) Philippine Sea 2009 experiment, a distributed vertical line array (DVLA) was deployed for several weeks in the northern Philippine Sea. The array, described in detail in a previous talk, consisted of two 1000‐m sections, one spanning the sound channel axis and the other covering the deep ocean, extending from above the surface conjugate depth down to within roughly 100 m of the bottom. In this paper, a hybrid propagation model for handling low‐frequency ocean noise will be presented. The model uses analytic solutions (rays) for ranges to 5 km, the parabolic equation for ranges from 5 to 100 km, and normal modes for ranges beyond that. The model predicts ambient noise levels vs depth. The fall off of the ambient noise with depth below the surface conjugate has been reported. The level of the fall off and its frequency dependence are sensitive to the local geo‐acoustics. A geo‐acoustic inversion will be performed using a range‐independent version of the acoustic mo...

Downlink capacity and interference statistics of wideband code division multiple access microcells for trains in long tunnels

The wideband code division multiple access downlink interference statistics and the capacity of equally spaced tunnel cigar-shaped microcells, used to serve users travelling in trains or metros, are analysed. The hybrid propagation model, with two defined modes, is used in the analysis. Fast fading because of multipath interference is superimposed with the main value of the loss and the slow fading up to a certain distance beyond which it can be neglected. To calculate the interference statistics and the capacity, a scenario with ten cigar-shaped microcells has been considered. The downlink capacity is then derived for different sector radii, train lengths, break point distances and propagation parameters. It is found that increasing the sector range up to 1250 m increases the sector downlink capacity. It is noticed that the maximum downlink capacity can be obtained for a sector radius of 1250–1750 m. It is also found that the increment of the propagation parameter γ reduces the sector downlink capacity. It is also noticed that increasing the train length increases the downlink capacity. It is also found that the bend loss increases the downlink capacity and reduces the maximum sector range.

A practical tropospheric scatter model using the parabolic equation

A simple method that accounts for tropospheric scatter using the parabolic equation portion of the radio physical optics (RPO) model is described. RPO is a hybrid propagation model that combines ray-optics and parabolic-equation methods to assess realistic range-dependent tropospheric effects at frequencies from 100 MHz to 20 GHz. A semiempirical scatter model adds a random refractive-index fluctuation to the mean refractive-index value at each height considered by the parabolic equation method. The results of this scatter model are compared with those of another scatter model and with a few sample radio measurements.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>