scholarly journals Wireless Propagation Multipaths using Spectral Clustering and Three-Constraint Affinity Matrix Spectral Clustering

2021 ◽  
Vol 18 (2(Suppl.)) ◽  
pp. 1001
Author(s):  
Jojo Blanza
Keyword(s):  
Spectral Clustering ◽  
Channel Model ◽  
Channel Modeling ◽  
Jaccard Index ◽  
Affinity Matrix ◽  
Number Of Clusters ◽  
Alternative Clustering ◽  
Directional Cosine ◽  
Indoor Scenarios ◽  
The Cost

This study focused on spectral clustering (SC) and three-constraint affinity matrix spectral clustering (3CAM-SC) to determine the number of clusters and the membership of the clusters of the COST 2100 channel model (C2CM) multipath dataset simultaneously. Various multipath clustering approaches solve only the number of clusters without taking into consideration the membership of clusters. The problem of giving only the number of clusters is that there is no assurance that the membership of the multipath clusters is accurate even though the number of clusters is correct. SC and 3CAM-SC aimed to solve this problem by determining the membership of the clusters. The cluster and the cluster count were then computed through the cluster-wise Jaccard index of the membership of the multipaths to their clusters. The multipaths generated by C2CM were transformed using the directional cosine transform (DCT) and the whitening transform (WT). The transformed dataset was clustered using SC and 3CAM-SC. The clustering performance was validated using the Jaccard index by comparing the reference multipath dataset with the calculated multipath clusters. The results show that the effectiveness of SC is similar to the state-of-the-art clustering approaches. However, 3CAM-SC outperforms SC in all channel scenarios. SC can be used in indoor scenarios based on accuracy, while 3CAM-SC is applicable in indoor and semi-urban scenarios. Thus, the clustering approaches can be applied as alternative clustering techniques in the field of channel modeling.

scholarly journals An Improved K-Power Means Technique Using Minkowski Distance Metric and Dimension Weights for Clustering Wireless Multipaths in Indoor Channel Scenarios

2021 ◽  
Vol 20 (No.4) ◽  
pp. 541-563
Author(s):  
Lawrence Materum ◽  
Antipas T. Teologo Jr.
Keyword(s):  
Channel Model ◽  
Principal Component ◽  
Channel Modeling ◽  
Distance Metric ◽  
Minkowski Distance ◽  
Wireless Environment ◽  
Improved Performance ◽  
Two Parameters ◽  
Angular Domains ◽  
The Cost

Wireless multipath clustering is an important area in channel modeling, and an accurate channel model can lead to a reliable wireless environment. Finding the best technique in clustering wireless multipath is still challenging due to the radio channels’ time-variant characteristics. Several clustering techniques have been developed that offer an improved performance but only consider one or two parameters of the multipath components. This study improved the K-PowerMeans technique by incorporating weights or loads based on the principal component analysis and utilizing the Minkowski distance metric to replace the Euclidean distance. K-PowerMeans is one of the several methods in clustering wireless propagation multipaths and has been widely studied. This improved clustering technique was applied to the indoor datasets generated from the COST 2100 channel Model and considered the multipath components’ angular domains and their delay. The Jaccard index was used to determine the new method’s accuracy performance. The results showed a significant improvement in the clustering of the developed algorithm than the standard K-PowerMeans.

scholarly journals Spatial characterization of propagation channels for terahertz band

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Bilal Aghoutane ◽  
Mohammed El Ghzaoui ◽  
Hanan El Faylali
Keyword(s):  
Communication Systems ◽  
Indoor Environment ◽  
Channel Model ◽  
Path Loss ◽  
Propagation Loss ◽  
Terahertz Band ◽  
Indoor Scenarios ◽  
Transmission Windows ◽  
Sv Channel

AbstractThe aim of this work consists in characterizing the Terahertz (THz) propagation channel in an indoor environment, in order to propose a channel model for THz bands. We first described a propagation loss model by taking into account the attenuation of the channel as a function of distance and frequency. The impulse response of the channel is then described by a set of rays, characterized by their amplitude, their delay and their phase. Apart from the frequency selective nature, path loss in THz band is also an others issue associated with THz communication systems. This work based on the conventional Saleh-Valenzuela (SV) model which is intended for indoor scenarios. In this paper, we have introduced random variables as Line of sight (LOS) component, and then merging it with the SV channel model to adopt it to the THz context. From simulation, we noted an important effect when the distance between the transmitter and the receiver change. This effect produces variations in frequency loss. The simulations carried out from this model show that to enhance the performance of THz system it is recommended to transmit information over transmission windows instead over the whole band.

scholarly journals Joint UAV channel modeling and power control for 5G IoT networks

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Xiuhua Fu ◽  
Tian Ding ◽  
Rongqun Peng ◽  
Cong Liu ◽  
Mohamed Cheriet
Keyword(s):  
Energy Efficiency ◽  
Power Control ◽  
Channel Model ◽  
Path Loss ◽  
Channel Modeling ◽  
Signal Propagation ◽  
Spectrum Efficiency ◽  
Propagation Path ◽  
Control Factor ◽  
The Impact

AbstractThis paper studies the communication problem between UAVs and cellular base stations in a 5G IoT scenario where multiple UAVs work together. We are dedicated to the uplink channel modeling and the performance analysis of the uplink transmission. In the channel model, we consider the impact of 3D distance and multi-UAVs reflection on wireless signal propagation. The 3D distance is used to calculate the path loss, which can better reflect the actual path loss. The power control factor is used to adjust the UAV's uplink transmit power to compensate for different propagation path losses, so as to achieve precise power control. This paper proposes a binary exponential power control algorithm suitable for 5G networked UAV transmitters and presents the entire power control process including the open-loop phase and the closed-loop phase. The effects of power control factors on coverage probability, spectrum efficiency and energy efficiency under different 3D distances are simulated and analyzed. The results show that the optimal power control factor can be found from the point of view of energy efficiency.

scholarly journals Time-Varying Communication Channel High Altitude Platform Station Link Budget and Channel Modeling

Information ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 210
Author(s):  
Xiaoyang Liu ◽  
Hengyang Liu ◽  
Chao Liu ◽  
Ya Luo
Keyword(s):  
High Altitude ◽  
Channel Model ◽  
Channel Modeling ◽  
Link Quality ◽  
Communication Link ◽  
Noise Power ◽  
Golay Code ◽  
High Altitude Platform ◽  
Link Budget ◽  
High Altitude Platform Station

Because of the high BER (Bit Error Rate), low time delay and low channel transmission efficiency of HAPS (High Altitude Platform Station) in the near space. The link budget of HAPS and channel model are proposed in this paper. According to the channel characteristic, the channel model is set up, combined with different CNR (Carrier Noise Ratio), elevation angle, coding situations of wireless communication link by using Hamming code, PSK (Pulse Shift Keying) and Golay code respectively, then the situations of link quality and BER are analyzed. The simulation results show that the established model of the link budget and channel are suitable for the theoretical analysis results. The elevation of the HAPS communication link is smaller while the BER is increasing. The case of channel in the coding is better than in the un-coded situation. When every bit power and thermal noise power spectral density is larger, the BER of the HAPS communication link is becoming smaller.

scholarly journals Wireless Channel Models for Over-the-Sea Communication: A Comparative Study

2019 ◽  
Vol 9 (3) ◽  
pp. 443 ◽  
Author(s):  
Arafat Habib ◽  
Sangman Moh
Keyword(s):  
Wave Propagation ◽  
Comparative Study ◽  
Radio Wave ◽  
Marine Environment ◽  
Channel Model ◽  
Channel Modeling ◽  
Wireless Channel ◽  
Radio Wave Propagation ◽  
Channel Models ◽  
The Impact

Over the past few years, the modeling of wireless channels for radio wave propagation over the sea surface has drawn the attention of many researchers. Channel models are designed and implemented for different frequencies and communication scenarios. There are models that emphasize the influence of the height of the evaporation duct in the marine environment, as well as models that deal with different frequencies (2.5, 5, and 10 GHz, etc.) or the impact of various parameters, such as antenna height. Despite the increasing literature on channel modeling for the over-the-sea marine environment, there is no comprehensive study that focuses on key concepts that need to be considered when developing a new channel model, characteristics of channel models, and comparative analysis of existing works along with their possible improvements and future applications. In this paper, channel models are discussed in relation to their operational principles and key features, and they are compared with each other in terms of major characteristics and pros and cons. Some important insights on the design and implementation of a channel model, possible applications and improvements, and challenging issues and research directions are also discussed. The main goal of this paper is to present a comparative study of over-the-sea channel models for radio wave propagation, so that it can help engineers and researchers in this field to choose or design the appropriate channel models based on their applications, classification, features, advantages, and limitations.

scholarly journals Spectral clustering in regression-based biological networks

2019 ◽  
Author(s):  
Sheila M. Gaynor ◽  
Xihong Lin ◽  
John Quackenbush
Keyword(s):  
Community Detection ◽  
Biological Networks ◽  
Spectral Clustering ◽  
Complex Structure ◽  
Gene Clusters ◽  
Biological Data ◽  
Tuning Parameter ◽  
Affinity Matrix ◽  
The Matrix ◽  
The Stability

AbstractBiological networks often have complex structure consisting of meaningful clusters of nodes that are integral to understanding biological function. Community detection algorithms to identify the clustering, or community structure, of a network have been well established. These algorithms assume that data used in network construction is observed without error. However, oftentimes intermediary analyses such as regression are performed before constructing biological networks and the associated error is not propagated in community detection. In expression quantitative trait loci (eQTL) networks, one must first map eQTLs via linear regression in order to specify the matrix representation of the network. We study the effects of using estimates from regression models when applying the spectral clustering approach to community detection. We demonstrate the impacts on the affinity matrix and consider adjusted estimates of the affinity matrix for use in spectral clustering. We further provide a recommendation for selection of the tuning parameter in spectral clustering. We evaluate the proposed adjusted method for performing spectral clustering to detect gene clusters in eQTL data from the GTEx project and to assess the stability of communities in biological data.

scholarly journals Research on Channel Model and Price Dispersion of E-Commerce Market Based on Blockchain Technology

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Qifeng Zhang ◽  
Fei Liu
Keyword(s):  
Empirical Research ◽  
Channel Model ◽  
Price Dispersion ◽  
Research Result ◽  
Theoretical Models ◽  
Search Costs ◽  
Blockchain Technology ◽  
The Cost ◽  
Price Differences ◽  
Predictive Effect

In order to accurately predict the channels and prices of the e-commerce market, and thereby control the cost of the e-commerce market, this paper studies the channel model and price dispersion of the e-commerce market from the perspective of suppliers. First, this paper establishes a model to analyze the price dispersion structure under different proportions of informed consumers and theoretically analyzes the objective reasons for continued price dispersion in the e-commerce market where search costs have fallen sharply. Then, this article combines theoretical models with empirical research to study the price and price differences between the two types of retailers. The results show that as consumers’ interest in retailers changes, prices will also change, and the degree of price dispersion in the e-commerce market has not yet converged. This research result has a good predictive effect on the pricing and market estimation of the e-commerce market and can control the cost of e-commerce operation and improve the competitiveness of the e-commerce market.

scholarly journals Channel Modeling for Underwater Acoustic Network Simulation

2020 ◽  
Author(s):  
Nils Morozs ◽  
Wael Gorma ◽  
Benjamin Henson ◽  
Lu Shen ◽  
Paul Mitchell ◽  
...  
Keyword(s):  
Channel Model ◽  
Network Simulation ◽  
World Ocean ◽  
Empirical Evaluation ◽  
Channel Modeling ◽  
Protocol Design ◽  
Simulation Code ◽  
Modeling Tool ◽  
Underwater Acoustic ◽  
Underwater Acoustic Network

This manuscript was submitted to IEEE Access on 12 Jun 2020.<div><br></div><div>Abstract:</div><div><br></div><div>Simulation forms an important part of the development and empirical evaluation of underwater acoustic network (UAN) protocols. The key feature of a credible network simulation model is a realistic channel model. A common approach to simulating realistic underwater acoustic (UWA) channels is by using specialised beam tracing software such as BELLHOP. However, BELLHOP and similar modeling software typically require knowledge of ocean acoustics and a substantial programming effort from UAN protocol designers to integrate it into their research. In this paper, we bridge the gap between low level channel modeling via beam tracing and automated channel modeling, e.g. via the World Ocean Simulation System (WOSS), by providing a distilled UWA channel modeling tutorial from the network protocol design point of view. The tutorial is accompanied by our MATLAB simulation code that interfaces with BELLHOP to produce channel data for UAN simulations. As part of the tutorial, we describe two methods of incorporating such channel data into network simulations, including a case study for each of them: 1) directly importing the data as a look-up table, 2) using the data to create a statistical channel model. The primary aim of this paper is to provide a useful learning resource and modeling tool for UAN protocol researchers. Initial insights into the UAN protocol design and performance provided by the statistical channel modeling approach presented in this paper demonstrate its potential as a powerful modeling tool for future UAN research.<br></div>

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