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Subcarrier assignment considering path loss for multiuser OFDM systems with proportional fairness

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The Journal of China Universities of Posts and Telecommunications 2008年第2期15卷 12-17,25页

作者： XU Wen-jun HE Zhi-qiang School of Information Engineering Beijing University of Posts andTelecommunications Beijing 100876 China

This article studies downlink subcarrier assignment problem to maximize rate-sum capacity subject to total power and proportional rate constraints in orthogonal frequency division multiplexing （OFDM） systems. Previous algorithms assume that the initial power is equally distributed over all subcarriers. The presence of path loss makes the assumption not correct any more. This article proposes a novel subcarrier assignment algorithm which makes full use of path loss and rate proportionality information to improve rate-sum capacity. The proposed algorithm determines optimal initial power allocation according to path losses and rate proportionalities of different users, assigns subcarriers to users in a greedy fashion, and then exchanges subcarfiers between users to obtain fairer rate distribution. Simulation results show that the proposed algorithm approximately achieves double the capacity of static assignment schemes, such as fixed frequency band approach, and obtains better performance than previous subcarrier assignment algorithms in the presence of different path losses and proportional rate requirements..

关键词： OFDM subcarrier assignment path loss

Channel Measurement and path loss Modeling from 220 GHz to 330 GHz for 6G Wireless Communications

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China Communications 2021年第5期18卷 19-32页

作者： Pan Tang Jianhua Zhang Haoyu Tian Zhaowei Chang Jun Men Yuxiang Zhang Lei Tian Liang Xia Qixing Wang Jingsuo He State Key Lab of Networking and Switching Technology Beijing University of Posts and TelecommunicationsBeijing 100876China China Mobile Research Institute Beijing 100053China Capital Normal University Beijing 100048China

Terahertz(THz)communication has been envisioned as a key enabling technology for sixthgeneration(6G).In this paper,we present an extensive THz channel measurement campaign for 6G wireless communications from 220 GHz to 330 ***,the path loss is analyzed and modeled by using two single-frequency path loss models and a multiplefrequencies path loss *** is found that at most frequency points,the measured path loss is larger than that in the free *** at around 310 GHz,the propagation attenuation is relatively weaker compared to that in the free ***,the frequency dependence of path loss is observed and the frequency exponent of the multiple-frequencies path loss model is ***,the cellular performance of THz communication systems is investigated by using the obtained path loss *** results indicate that the current inter-site distance(ISD)for the indoor scenario is too small for THz ***,the tremendous capacity gain can be obtained by using THz bands compared to using microwave bands and millimeter wave ***,this work can give an insight into the design and optimization of THz communication systems for 6G.

关键词： terahertz channel measurement channel modeling path loss

Investigating path loss characteristics of UWB signals in vacancy indoor environment based on time-domain technique

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Journal of Systems Engineering and Electronics 2006年第2期17卷 296-302页

作者： Wang Yang Zhang Naitong Communication Research Center Harbin Inst. of Technology Harbin 150001 P.R. China

The path loss analysis model based on 5 rays in vacancy indoor environment is proposed. The relationship between multipath overlapping and the path loss is analyzed mathematically. Time-domain technique is introduced to compute reflection coefficient in a very short time interval. A 5 rays path loss calculation method, which is satisfactory accurate, is developed. 5 typical environments are involved to analyze and generalize the common path loss characteristics in vacancy indoor environment. The simulation result shows that the path loss can be characterized as 3 zones with different path loss exponent as distance between transmitter and receiver increasing.

关键词： UWB path loss time-domain multipath indoor environment.

A general altitude-dependent path loss model for UAV-to-ground millimeter-wave communications

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Frontiers of Information Technology & Electronic Engineering 2021年第6期22卷 767-776页

作者： Qiuming ZHU Mengtian YAO Fei BAI Xiaomin CHEN Weizhi ZHONG Boyu HUA Xijuan YE The Key Laboratory of Dynamic Cognitive System of Electromagnetic Spectrum Space College of Electronic and Information EngineeringNanjing University of Aeronautics and AstronauticsNanjing 211106China State Key Laboratory of Integrated Services Networks Xidian UniversityXi’an 710000China The Key Laboratory of Dynamic Cognitive System of Electromagnetic Spectrum Space College of AstronauticsNanjing University of Aeronautics and AstronauticsNanjing 211106China

A general empirical path loss(PL) model for air-to-ground(A2 G) millimeter-wave(mm Wave) channels is proposed in this paper. Different from existing PL models, the new model takes the height factor of unmanned aerial vehicles(UAVs) into account, and divides the propagation conditions into three cases(i.e., line-of-sight, reflection,and diffraction). A map-based deterministic PL prediction algorithm based on the ray-tracing(RT) technique is developed, and is used to generate numerous PL data for different cases. By fitting and analyzing the PL data under different scenarios and UAV heights, altitude-dependent model parameters are provided. Simulation results show that the proposed model can be effectively used to predict PL values for both low-and high-altitude *** prediction results of the proposed model better match the RT-based calculation results than those of the Third Generation Partnership Project(3 GPP) model and the close-in model. The standard deviation of the PL is also much smaller. Moreover, the new model is flexible and can be extended to other A2 G scenarios(not included in this paper) by adjusting the parameters according to the simulation or measurement data.

关键词： path loss UAV-to-ground channel Millimeter-wave(mm Wave)communication channel Ray-tracing Altitude-dependent

path loss Modeling: A Machine Learning Based Approach Using Support Vector Regression and Radial Basis Function Models

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Open Journal of Applied Sciences 2022年第6期12卷 990-1010页

作者： Stephen Ojo Arif Sari Taiwo P. Ojo College of Engineering Anderson University Anderson SC USA Department of Management Information Systems Girne American University Girne Cyprus Computer Science Department Florida A&M University Tallahassee FL USA

path loss prediction models are vital for accurate signal propagation in wireless channels. Empirical and deterministic models used in path loss predictions have not produced optimal results. In this paper, we introduced machine learning algorithms to path loss predictions because it offers a flexible network architecture and extensive data can be used. We introduced support vector regression (SVR) and radial basis function (RBF) models to path loss predictions in the investigated environments. The SVR model was able to process several input parameters without introducing complexity to the network architecture. The RBF on its part provides a good function approximation. Hyperparameter tuning of the machine learning models was carried out in order to achieve optimal results. The performances of the SVR and RBF models were compared and result validated using the root-mean squared error (RMSE). The two machine learning algorithms were also compared with the Cost-231, SUI, Egli, Freespace, Cost-231 W-I models. The analytical models overpredicted path loss. Overall, the machine learning models predicted path loss with greater accuracy than the empirical models. The SVR model performed best across all the indices with RMSE values of 1.378 dB, 1.4523 dB, 2.1568 dB in rural, suburban and urban settings respectively and should therefore be adopted for signal propagation in the investigated environments and beyond.

关键词： Support Vector Regression Radial Basis Function Machine Learning path loss Empirical Deterministic

Propagation path loss Models at 28 GHz Using K-Nearest Neighbor Algorithm

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通讯和计算机（中英文版） 2022年第1期19卷 1-8页

作者： Vu Thanh Quang Dinh Van Linh To Thi Thao Hanoi University of Science and Technology No.1 Dai Co Viet roadHanoiVietnam Academy of Cryptography Techniques 141 Chien Thang RoadHanoiVietnam Post and Telecommunications Institute HanoiVietnamKm 10Nguyen Trai RoadHanoiVietnam

In this paper,we develop and apply K-Nearest Neighbor algorithm to propagation pathloss *** path loss models present the dependency of attenuation value on distance using machine learning algorithms based on the experimental *** algorithm is performed by choosing k nearest points and training dataset to find the optimal k *** proposed method is applied to impove and adjust pathloss model at 28 GHz in Keangnam area,Hanoi,*** experiments in both line-of-sight and non-line-of-sight scenarios used many combinations of transmit and receive antennas at different transmit antenna heights and random locations of receive antenna have been carried out using Wireless Insite *** results have been compared with 3GPP and NYU Wireless path loss Models in order to verify the performance of the proposed approach.

关键词： K-nearest neighbor regression 5G millimeter waves path loss

Fine-grained grid computing model for Wi-Fi indoor localization in complex environments

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Journal of Electronic Science and Technology 2024年第1期22卷 42-52页

作者： Yan Liang Song Chen Xin Dong Tu Liu School of Computer Engineering Chengdu Technological UniversityChengdu611730China HAN Networks Corporation Limited Beijing100094China

The fingerprinting-based approach using the wireless local area network(WLAN)is widely used for indoor ***,the construction of the fingerprint database is quite *** when the position of the access point(AP)or wall changes,updating the fingerprint database in real-time is *** appropriate indoor localization approach,which has a low implementation cost,excellent real-time performance,and high localization accuracy and fully considers complex indoor environment factors,is preferred in location-based services(LBSs)*** this paper,we proposed a fine-grained grid computing(FGGC)model to achieve decimeter-level localization *** points(RPs)are generated in the grid by the FGGC ***,the received signal strength(RSS)values at each RP are calculated with the attenuation factors,such as the frequency band,three-dimensional propagation distance,and walls in complex *** a result,the fingerprint database can be established automatically without manual measurement,and the efficiency and cost that the FGGC model takes for the fingerprint database are superior to previous *** proposed indoor localization approach,which estimates the position step by step from the approximate grid location to the fine-grained location,can achieve higher real-time performance and localization accuracy *** mean error of the proposed model is 0.36 m,far lower than that of previous ***,the proposed model is feasible to improve the efficiency and accuracy of Wi-Fi indoor *** also shows high-accuracy performance with a fast running speed even under a large-size *** results indicate that the proposed method can also be suitable for precise marketing,indoor navigation,and emergency rescue.

关键词： Fine-grained grid computing (FGGC) Indoor localization path loss Random forest Reference points(RPs)

Field trial measurement and channel modeling for reconfigurable intelligent surface

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Digital Communications and Networks 2023年第3期9卷 603-612页

作者： Peng Zheng Jianwen Ding Dan Fei Jiayi Zhang Bo Ai Xiao Li Shi Jin Tiejun Cui School of Electronic and Information Engineering Beijing Jiaotong UniversityBeijing100044China State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong UniversityBeijing100044China National Research Center of Railway Safety Assessment Beijing Jiaotong UniversityBeijing100044China Key Laboratory of Railway Industry of Broadband Mobile Information Communications Beijing Jiaotong UniversityBeijing100044China Nanjing Rongcai Transportation Technology Research Institute Nanjing210096China Peng Cheng Laboratory Shenzhen518055China National Mobile Communications Research Laboratory Southeast UniversityNanjing211189China State Key Laboratory of Millimeter Waves Southeast UniversityNanjing210096China

With the advantage of programmable electromagnetic properties,Reconfigurable Intelligent Surfaces(RISs)havedrawn wide attention from both industry and ***-assisted communication systems can promote hugewireless channel quality improvement and remarkable coverage *** paper proposes generalpathloss model,radiation pattern and mirror beam effect of 1-bit RIS at sub-6 GHz *** trails have beencarried out in outdoor and indoor deployment *** proposed model is validated through extensivesimulations and field-trial *** addition,an optimized RIS phase-shit design process for the mirrorbeam elimination is proposed and validated with *** proposed theoretical model and measurementresults can promote future research and application in RIS-assisted communications.

关键词： Reconfigurable intelligent surfaces Channel measurement path loss Prototype

Propagation Characterization and Analysis for 5G mmWave Through Field Experiments

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Computers, Materials & Continua 2021年第8期68卷 2249-2264页

作者： Faizan Qamar Mhd Nour Hindia Tharek Abd Rahman Rosilah Hassan Kaharudin Dimyati Quang Ngoc Nguyen Centre for Cyber Security Faculty of Information Science and TechnologyUniversiti Kebangsaan Malaysia(UKM)43600BangiSelangorMalaysia Department of Electrical Engineering Faculty of EngineeringUniversity of Malaya50603Kuala LumpurMalaysia Wireless Communication Centre Faculty of Electrical EngineeringUniversiti Teknologi Malaysia81310SkudaiJohorMalaysia Department of Computer Science and Communications Engineering Faculty of Science and EngineeringWaseda UniversityTokyo169-8050Japan

The 5G network has been intensively investigated to realize the ongoing early deployment stage as an effort to match the exponential growth of the number of connected users and their increasing demands for high throughput,bandwidth with Quality of Service(QoS),and low *** that most of the spectrums below 6 GHz are nearly used up,it is not feasible to employ the traditional spectrum,which is currently in ***,a promising and highly feasible effort to satisfy this insufficient frequency spectrum is to acquire new frequency bands for next-generation mobile *** this end,the primary effort has been focused on utilizing the millimeter-wave(mmWave)as the most promising candidate for the frequency ***,though the mmWave frequency band can fulfill the desired bandwidth requirements,it has been demonstrated to endure several issues like scattering,atmospheric absorption,fading,and especially penetration losses compared to the existing sub-6 GHz frequency ***,it is fundamental to optimize the mmWave band propagation channel to facilitate the practical 5G implementation for the network ***,this study intends to investigate the outdoor channel characteristics of 26,28,36,and 38 GHz frequency bands for the communication infrastructure at the building to the ground floor in both Line of Sight(LOS)and Non-Line of Sight(NLOS)*** experimental campaign has studied the propagation path loss models such as Floating-Intercept(FI)and Close-In(CI)for the building to ground floor environment in LOS and NLOS *** findings obtained from the field experiments clearly show that the CI propagation model delivers much better performance in comparison with the FI model,thanks to its simple setup,accuracy,and precise function.

关键词： 5G mmWave propagation channel path loss channel characterization field experiment