Precise localization techniques for indoor Wi-Fi access points(APs)have important application in the security inspection.However,due to the interference of environment factors such as multipath propagation and NLOS(No...Precise localization techniques for indoor Wi-Fi access points(APs)have important application in the security inspection.However,due to the interference of environment factors such as multipath propagation and NLOS(Non-Line-of-Sight),the existing methods for localization indoor Wi-Fi access points based on RSS ranging tend to have lower accuracy as the RSS(Received Signal Strength)is difficult to accurately measure.Therefore,the localization algorithm of indoor Wi-Fi access points based on the signal strength relative relationship and region division is proposed in this paper.The algorithm hierarchically divide the room where the target Wi-Fi AP is located,on the region division line,a modified signal collection device is used to measure RSS in two directions of each reference point.All RSS values are compared and the region where the RSS value has the relative largest signal strength is located as next candidate region.The location coordinate of the target Wi-Fi AP is obtained when the localization region of the target Wi-Fi AP is successively approximated until the candidate region is smaller than the accuracy threshold.There are 360 experiments carried out in this paper with 8 types of Wi-Fi APs including fixed APs and portable APs.The experimental results show that the average localization error of the proposed localization algorithm is 0.30 meters,and the minimum localization error is 0.16 meters,which is significantly higher than the localization accuracy of the existing typical indoor Wi-Fi access point localization methods.展开更多
To meet the ever-increasing traffic demand and enhance the coverage of cellular networks,network densification is one of the crucial paradigms of 5G and beyond mobile networks,which can improve system capacity by depl...To meet the ever-increasing traffic demand and enhance the coverage of cellular networks,network densification is one of the crucial paradigms of 5G and beyond mobile networks,which can improve system capacity by deploying a large number of Access Points(APs)in the service area.However,since the energy consumption of APs generally accounts for a substantial part of the communication system,how to deal with the consequent energy issue is a challenging task for a mobile network with densely deployed APs.In this paper,we propose an intelligent AP switching on/off scheme to reduce the system energy consumption with the prerequisite of guaranteeing the quality of service,where the signaling overhead is also taken into consideration to ensure the stability of the network.First,based on historical traffic data,a long short-term memory method is introduced to predict the future traffic distribution,by which we can roughly determine when the AP switching operation should be triggered;second,we present an efficient three-step AP selection strategy to determine which of the APs would be switched on or off;third,an AP switching scheme with a threshold is proposed to adjust the switching frequency so as to improve the stability of the system.Experiment results indicate that our proposed traffic forecasting method performs well in practical scenarios,where the normalized root mean square error is within 10%.Furthermore,the achieved energy-saving is more than 28% on average with a reasonable outage probability and switching frequency for an area served by 40 APs in a commercial mobile network.展开更多
To improve the accuracy of indoor localization methods with channel state information(CSI)images,a localization method that used CSI images from selected multiple access points(APs)was proposed.The method had an off-l...To improve the accuracy of indoor localization methods with channel state information(CSI)images,a localization method that used CSI images from selected multiple access points(APs)was proposed.The method had an off-line phase and an on-line phase.In the off-line phase,three APs were selected from the four APs in the localization area based on the received signal strength indication(RSSI).Next,CSI data was collected from the three selected APs using a commercial Intel 5300 network interface card.A single-channel subimage was constructed for each selected AP by combining the amplitude information from different antennas and the phase difference information between neighboring antennas.These sub-images were then merged to form a three-channel RGB image,which was subsequently fed into the convolutional neural network(CNN)for training.The CNN model was saved upon completion of training.In the on-line phase,the CSI data from the target device was collected,converted into images using the same process as in the off-line phase,and fed into the well-trained CNN model.Finally,the real position of the target device was estimated using a weighted centroid algorithm based on the model’s output probabilities.The proposed method was validated in indoor environments using two datasets,achieving good localization accuracy.展开更多
Background:The use of mobile phone significantly improved the outcomes of tobacco cessation.However,its feasibility and acceptability were unclear in the Chinese population.This study was to explore the feasibility of...Background:The use of mobile phone significantly improved the outcomes of tobacco cessation.However,its feasibility and acceptability were unclear in the Chinese population.This study was to explore the feasibility of using Wi-Fi access points(APs)as a platform to provide smoking cessation help at 17 airports and 38 railway stations across China.Methods:This study was divided into two stages:platform development and population survey.In the first stage,a survey platform was developed and incorporated into Wi-Fi service at airports and railway stations,which could provide survey content as a pop-up window when participants tried to access the Wi-Fi service.In the second stage,a population survey was conducted to explore the intention to receive tobacco cessation support.Results:A total of 20,199 users participated and 13,628 users submitted the survey,with a response rate of 67.47%.The smoking rate was 30.9%.A total of 86.58%of smoking participants and 2.44%of non-smoking participants wished to receive tobacco cessation support,respectively.The multivariate analysis showed intention to receive support did not differ in age,gender,and heaviness of smoking(P>0.05).Conclusion:Providing tobacco cessation support via Wi-Fi APs is feasible and efficient,and smokers have high intention to receive tobacco cessation support.It is suggested hospitals,academia,information technology industries,and government agencies must work together to provide tobacco cessation support via mHealth.展开更多
The indoor positioning system based on fingerprint receives more and more attention due to its high positioning accuracy and time efficiency.In the existing positioning approaches,much consideration is given to the po...The indoor positioning system based on fingerprint receives more and more attention due to its high positioning accuracy and time efficiency.In the existing positioning approaches,much consideration is given to the positioning accuracy improvement by using the angle of signal,but the optimization of access points(APs)deployment is ignored.In this circumstance,an adaptive APs deployment approach is proposed.First of all,the criterion of reference points(RPs)effective coverage is proposed,and the number of deployed APs in target environment is obtained by using the region partition algorithm and full coverage algorithm.Secondly,the wireless signal propagation model is established for target environment,and meanwhile based on the initial APs deployment,the simulation fingerprint database is constructed for the sake of establishing the discrimination function with respect to fingerprint database.Thirdly,the greedy algorithm is applied to optimize APs deployment.Finally,the extensive experiments show that the proposed approach is capable of achieving adaptive APs deployment as well as improving positioning accuracy.展开更多
In this study, we investigate the optimal location of access points （APs） to connect end nodes with a service provider through power-line communication in smartgrid communication networks. APs are the gateways of po...In this study, we investigate the optimal location of access points （APs） to connect end nodes with a service provider through power-line communication in smartgrid communication networks. APs are the gateways of power-distribution communication networks, connecting users to control centers. Hence, they are vital for the reliable, safe, and economical operation of a power system. This paper proposes a planning method for AP allocation that takes into consideration economics, reliability, network delay, and （n-l） resilience. First, an optimization model for the AP location is established, which minimizes the cost of installing APs, while satisfying the reliability, network delay, and （n-1） resilience constraints. Then, an improved genetic algorithm is proposed to solve the optimization problem. The simulation results indicate that the proposed planning method can deal with diverse network conditions satisfactorily. Furthermore, it can be applied effectively with high flexibility and scalability.展开更多
The handover speed is always vital for the further development of Wireless Local Area Network (WLAN), which is enjoying a fast growth. Based on the handover technology specified in IEEE 802.11 WLAN, Manageable Fast Ha...The handover speed is always vital for the further development of Wireless Local Area Network (WLAN), which is enjoying a fast growth. Based on the handover technology specified in IEEE 802.11 WLAN, Manageable Fast Handover (MFHO) mechanism is proposed to speed up handover at the Access Point (AP), meet handover demands of services with different Quality of Service (QoS), and ensure service continuity. Adopting a handover policy named 'Make-before-break', this mechanism enables wireless APs to control and manage handover between two stations based on improving Inter-Access Point Protocol (IAPP). Tests have been carried out to compare functions and performance of MFHO and IAPP-based handover technology. The test results prove that MFHO provides a higher successful handover ratio and better handover performance than IAPP-based handover technology.展开更多
Recently,cell-free(CF)massive multipleinput multiple-output(MIMO)becomes a promising architecture for the next generation wireless communication system,where a large number of distributed access points(APs)are deploye...Recently,cell-free(CF)massive multipleinput multiple-output(MIMO)becomes a promising architecture for the next generation wireless communication system,where a large number of distributed access points(APs)are deployed to simultaneously serve multiple user equipments(UEs)for improved performance.Meanwhile,a clustered CF system is considered to tackle the backhaul overhead issue in the huge connection network.In this paper,taking into account the more realistic mobility scenarios,we propose a hybrid small-cell(SC)and clustered CF massive MIMO system through classifications of the UEs and APs,and constructing the corresponding pairs to run in SC or CF mode.A joint initial AP selection of this paradigm for all the UEs is firstly proposed,which is based on the statistics of estimated channel.Then,closed-form expressions of the downlink achievable rates for both the static and moving UEs are provided under Ricean fading channel and Doppler shift effect.We also develop a semi-heuristic search algorithm to deal with the AP selection for the moving UEs by maximizing the weight average achievable rate.Numerical results demonstrate the performance gains and effective rates balancing of the proposed system.展开更多
With the advent and advancements in the wireless technologies,Wi-Fi ngerprinting-based Indoor Positioning System(IPS)has become one of the most promising solutions for localization in indoor environments.Unlike the ou...With the advent and advancements in the wireless technologies,Wi-Fi ngerprinting-based Indoor Positioning System(IPS)has become one of the most promising solutions for localization in indoor environments.Unlike the outdoor environment,the lack of line-of-sight propagation in an indoor environment keeps the interest of the researchers to develop efcient and precise positioning systems that can later be incorporated in numerous applications involving Internet of Things(IoTs)and green computing.In this paper,we have proposed a technique that combines the capabilities of multiple algorithms to overcome the complexities experienced indoors.Initially,in the database development phase,Motley Kennan propagation model is used with Hough transformation to classify,detect,and assign different attenuation factors related to the types of walls.Furthermore,important parameters for system accuracy,such as,placement and geometry of Access Points(APs)in the coverage area are also considered.New algorithm for deployment of an additional AP to an already existing infrastructure is proposed by using Genetic Algorithm(GA)coupled with Enhanced Dilution of Precision(EDOP).Moreover,classication algorithm based on k-Nearest Neighbors(k-NN)is used to nd the position of a stationary or mobile user inside the given coverage area.For k-NN to provide low localization error and reduced space dimensionality,three APs are required to be selected optimally.In this paper,we have suggested an idea to select APs based on Position Vectors(PV)as an input to the localization algorithm.Deducing from our comprehensive investigations,it is revealed that the accuracy of indoor positioning system using the proposed technique unblemished the existing solutions with signicant improvements.展开更多
Due to flexible deployment,unmanned aerial vehicle(UAV)mounted aerial access points are capable of expanding the coverage capabilities of existing terrestrial base stations(TBSs).Different from TBSs,however,UAV access...Due to flexible deployment,unmanned aerial vehicle(UAV)mounted aerial access points are capable of expanding the coverage capabilities of existing terrestrial base stations(TBSs).Different from TBSs,however,UAV access points(UAPs)are of high mobility in horizontal and vertical dimensions,which may deteriorate the coverage performance.Worsestill,the mobility of UAPs would as well increase the pressure of wireless backhaul.In this light,we investigate the performance of the cache-enabled UAV communications network(CUCN)in terms of network spatial throughput(ST)by analyzing the line of sight(LoS)connections and non-line of sight(NLoS)connections.It is found that the network ST is exponentially decreased with the square of UAP altitude.Furthermore,contrary to intuition,a large cache size may deteriorate the network ST when UAPs are over-deployed.The reason is that a large cache size increases the hit probability,which may increase the activation of UAPs and consequently result in complicated interference.Aiming to maximize the network ST,we optimize the cache strategy under limited backhaul.Remarkably,the results show that network ST could be substantially improved by the optimized cache strategy and the performance degeneration brought by UAP high mobility could be even eliminated especially when the UAP altitude is high.展开更多
To overcome the problem of existing neighboring access point （AP） discovery methods in WLAN, for example they （PnP） of mul proposed. Us can not provide the accurate neighboring APs information needed for the Plug-...To overcome the problem of existing neighboring access point （AP） discovery methods in WLAN, for example they （PnP） of mul proposed. Us can not provide the accurate neighboring APs information needed for the Plug-and-Play ti-mode APs, three kinds of neighboring AP discovery and information exchange methods are ing these three neighboring AP discovery methods, passive discovery method, active discovery method and station assistant discovery method, the multi-mode AP can discover all neighboring APs and obtain needed information. We further propose two whole process flows, which combine three discovery methods in different manner, to achieve different goals. One process flow is to discover the neighboring AP as fast as possible, called fast discovery process flow. The other is to discover the neighboring AP with minimal interference to neighboring and accuracy of the method is confirmed APs, called the minimal interference process flow. The validity by the simulation.展开更多
A scheme of rogue access point(Rogue AP)detection based on AP's localization is proposed.Global position system(GPS)information and received signal strength(RSS)information are used to get the location of AP in a ...A scheme of rogue access point(Rogue AP)detection based on AP's localization is proposed.Global position system(GPS)information and received signal strength(RSS)information are used to get the location of AP in a smartphone,which is compared with the database located in a remote server.The proposed scheme can detect not only fake access point(Fake AP)but also Evil Twin AP.It can be a user-oriented solution to detecting Rogue AP threats,and users can use it flexibly.展开更多
We investigate the resource allocation problem of a cell-free massive multiple-input multiple-output system under the condition of colluding eavesdropping by multiple passive eavesdroppers.To address the problem of li...We investigate the resource allocation problem of a cell-free massive multiple-input multiple-output system under the condition of colluding eavesdropping by multiple passive eavesdroppers.To address the problem of limited pilot resources,a scheme is proposed to allocate the pilot with the minimum pollution to users based on access point selection and optimize the pilot transmission power to improve the accuracy of channel estimation.Aiming at the secure transmission problem under a colluding eavesdropping environment by multiple passive eavesdroppers,based on the local partial zero-forcing precoding scheme,a transmission power optimization scheme is formulated to maximize the system’s minimum security spectral efficiency.Simulation results show that the proposed scheme can effectively reduce channel estimation error and improve system security.展开更多
To understand the utilizability of TV white spaces （TVWS）, a comprehensive overview of the outdoor and indoor network design over TVWS is given. The related challenges are analyzed. The potential approaches to overc...To understand the utilizability of TV white spaces （TVWS）, a comprehensive overview of the outdoor and indoor network design over TVWS is given. The related challenges are analyzed. The potential approaches to overcoming these challenges are discussed. The open research issues are investigated. The result shows that： in the indoor scenario, the white space ratio is on average 18.4% higher than that in the outdoor scenario, which corresponds to 7.7 vacant TV channels. Both network design includes 7 key components： TV spectrum identification, access point （AP） discovery, AP association, spectrum allocation, band width adaptation, interface control and disruption handling. Due to building penetration loss, the indoor TVWS identification and AP placement should be carefully considered in the indoor scenario.展开更多
Hierarchical Mobile IPv6 (HMIPv6) can reduce the delay and the amount of signaling during handover compared with the basic mobile IPv6. However, the protocol still cannot meet the requirement for traffic that is delay...Hierarchical Mobile IPv6 (HMIPv6) can reduce the delay and the amount of signaling during handover compared with the basic mobile IPv6. However, the protocol still cannot meet the requirement for traffic that is delay sensitive, such as voice, especially in macro mobility handover. Duplicate address detection and the transmission time for the handover operation could cause high handover delay. This paper proposes a new mechanism to improve the fast handover algorithm's efficiency in HMIPv6 network. And we present and analyze the performance testing for our proposal by comparing it with the traditional HMIPv6 fast handover algorithm. The results of simulation show that our scheme can reduce the handover delay much more than the traditional fast handover method for HMIPv6 network.展开更多
基金The work presented in this paper is supported by the National Key R&D Program of China(No.2016YFB0801303,2016QY01W0105)the National Natural Science Foundation of China(No.U1636219,61602508,61772549,U1736214,61572052)+1 种基金Plan for Scientific Innovation Talent of Henan Province(No.2018JR0018)the Key Technologies R&D Program of Henan Province(No.162102210032).
文摘Precise localization techniques for indoor Wi-Fi access points(APs)have important application in the security inspection.However,due to the interference of environment factors such as multipath propagation and NLOS(Non-Line-of-Sight),the existing methods for localization indoor Wi-Fi access points based on RSS ranging tend to have lower accuracy as the RSS(Received Signal Strength)is difficult to accurately measure.Therefore,the localization algorithm of indoor Wi-Fi access points based on the signal strength relative relationship and region division is proposed in this paper.The algorithm hierarchically divide the room where the target Wi-Fi AP is located,on the region division line,a modified signal collection device is used to measure RSS in two directions of each reference point.All RSS values are compared and the region where the RSS value has the relative largest signal strength is located as next candidate region.The location coordinate of the target Wi-Fi AP is obtained when the localization region of the target Wi-Fi AP is successively approximated until the candidate region is smaller than the accuracy threshold.There are 360 experiments carried out in this paper with 8 types of Wi-Fi APs including fixed APs and portable APs.The experimental results show that the average localization error of the proposed localization algorithm is 0.30 meters,and the minimum localization error is 0.16 meters,which is significantly higher than the localization accuracy of the existing typical indoor Wi-Fi access point localization methods.
基金partially supported by the National Natural Science Foundation of China under Grants 61801208,61931023,and U1936202.
文摘To meet the ever-increasing traffic demand and enhance the coverage of cellular networks,network densification is one of the crucial paradigms of 5G and beyond mobile networks,which can improve system capacity by deploying a large number of Access Points(APs)in the service area.However,since the energy consumption of APs generally accounts for a substantial part of the communication system,how to deal with the consequent energy issue is a challenging task for a mobile network with densely deployed APs.In this paper,we propose an intelligent AP switching on/off scheme to reduce the system energy consumption with the prerequisite of guaranteeing the quality of service,where the signaling overhead is also taken into consideration to ensure the stability of the network.First,based on historical traffic data,a long short-term memory method is introduced to predict the future traffic distribution,by which we can roughly determine when the AP switching operation should be triggered;second,we present an efficient three-step AP selection strategy to determine which of the APs would be switched on or off;third,an AP switching scheme with a threshold is proposed to adjust the switching frequency so as to improve the stability of the system.Experiment results indicate that our proposed traffic forecasting method performs well in practical scenarios,where the normalized root mean square error is within 10%.Furthermore,the achieved energy-saving is more than 28% on average with a reasonable outage probability and switching frequency for an area served by 40 APs in a commercial mobile network.
基金supported by Lanzhou Science and Technology Plan Project(No.2023-3-104)Gansu Province Higher Education Industry Support Plan Project(No.2023CYZC-40)Gansu Province Excellent Graduate“Innovation Star”Program(No.2023CXZX-546)。
文摘To improve the accuracy of indoor localization methods with channel state information(CSI)images,a localization method that used CSI images from selected multiple access points(APs)was proposed.The method had an off-line phase and an on-line phase.In the off-line phase,three APs were selected from the four APs in the localization area based on the received signal strength indication(RSSI).Next,CSI data was collected from the three selected APs using a commercial Intel 5300 network interface card.A single-channel subimage was constructed for each selected AP by combining the amplitude information from different antennas and the phase difference information between neighboring antennas.These sub-images were then merged to form a three-channel RGB image,which was subsequently fed into the convolutional neural network(CNN)for training.The CNN model was saved upon completion of training.In the on-line phase,the CSI data from the target device was collected,converted into images using the same process as in the off-line phase,and fed into the well-trained CNN model.Finally,the real position of the target device was estimated using a weighted centroid algorithm based on the model’s output probabilities.The proposed method was validated in indoor environments using two datasets,achieving good localization accuracy.
基金supported by a grant from the National Key Research and Development Program of China(Project No.2017YFC1309400).
文摘Background:The use of mobile phone significantly improved the outcomes of tobacco cessation.However,its feasibility and acceptability were unclear in the Chinese population.This study was to explore the feasibility of using Wi-Fi access points(APs)as a platform to provide smoking cessation help at 17 airports and 38 railway stations across China.Methods:This study was divided into two stages:platform development and population survey.In the first stage,a survey platform was developed and incorporated into Wi-Fi service at airports and railway stations,which could provide survey content as a pop-up window when participants tried to access the Wi-Fi service.In the second stage,a population survey was conducted to explore the intention to receive tobacco cessation support.Results:A total of 20,199 users participated and 13,628 users submitted the survey,with a response rate of 67.47%.The smoking rate was 30.9%.A total of 86.58%of smoking participants and 2.44%of non-smoking participants wished to receive tobacco cessation support,respectively.The multivariate analysis showed intention to receive support did not differ in age,gender,and heaviness of smoking(P>0.05).Conclusion:Providing tobacco cessation support via Wi-Fi APs is feasible and efficient,and smokers have high intention to receive tobacco cessation support.It is suggested hospitals,academia,information technology industries,and government agencies must work together to provide tobacco cessation support via mHealth.
基金supported by the National Natural Science Foundation of China (61771083,61704015)the Program for Changjiang Scholars and Innovative Research Team in University (IRT1299)+2 种基金the Special Fund of Chongqing Key Laboratory (CSTC)the Fundamental and Frontier Research Project of Chongqing (CSTC2017jcyj AX0380, CSTC2015jcyj BX0065)the University Outstanding Achievement Transformation Project of Chongqing (KJZH17117)
文摘The indoor positioning system based on fingerprint receives more and more attention due to its high positioning accuracy and time efficiency.In the existing positioning approaches,much consideration is given to the positioning accuracy improvement by using the angle of signal,but the optimization of access points(APs)deployment is ignored.In this circumstance,an adaptive APs deployment approach is proposed.First of all,the criterion of reference points(RPs)effective coverage is proposed,and the number of deployed APs in target environment is obtained by using the region partition algorithm and full coverage algorithm.Secondly,the wireless signal propagation model is established for target environment,and meanwhile based on the initial APs deployment,the simulation fingerprint database is constructed for the sake of establishing the discrimination function with respect to fingerprint database.Thirdly,the greedy algorithm is applied to optimize APs deployment.Finally,the extensive experiments show that the proposed approach is capable of achieving adaptive APs deployment as well as improving positioning accuracy.
基金supported by the National High Technology Research and Development Program of China(2012AA050801)
文摘In this study, we investigate the optimal location of access points （APs） to connect end nodes with a service provider through power-line communication in smartgrid communication networks. APs are the gateways of power-distribution communication networks, connecting users to control centers. Hence, they are vital for the reliable, safe, and economical operation of a power system. This paper proposes a planning method for AP allocation that takes into consideration economics, reliability, network delay, and （n-l） resilience. First, an optimization model for the AP location is established, which minimizes the cost of installing APs, while satisfying the reliability, network delay, and （n-1） resilience constraints. Then, an improved genetic algorithm is proposed to solve the optimization problem. The simulation results indicate that the proposed planning method can deal with diverse network conditions satisfactorily. Furthermore, it can be applied effectively with high flexibility and scalability.
文摘The handover speed is always vital for the further development of Wireless Local Area Network (WLAN), which is enjoying a fast growth. Based on the handover technology specified in IEEE 802.11 WLAN, Manageable Fast Handover (MFHO) mechanism is proposed to speed up handover at the Access Point (AP), meet handover demands of services with different Quality of Service (QoS), and ensure service continuity. Adopting a handover policy named 'Make-before-break', this mechanism enables wireless APs to control and manage handover between two stations based on improving Inter-Access Point Protocol (IAPP). Tests have been carried out to compare functions and performance of MFHO and IAPP-based handover technology. The test results prove that MFHO provides a higher successful handover ratio and better handover performance than IAPP-based handover technology.
基金This work was supported by the China National Key Research and Development Plan(No.2020YFB1807204).
文摘Recently,cell-free(CF)massive multipleinput multiple-output(MIMO)becomes a promising architecture for the next generation wireless communication system,where a large number of distributed access points(APs)are deployed to simultaneously serve multiple user equipments(UEs)for improved performance.Meanwhile,a clustered CF system is considered to tackle the backhaul overhead issue in the huge connection network.In this paper,taking into account the more realistic mobility scenarios,we propose a hybrid small-cell(SC)and clustered CF massive MIMO system through classifications of the UEs and APs,and constructing the corresponding pairs to run in SC or CF mode.A joint initial AP selection of this paradigm for all the UEs is firstly proposed,which is based on the statistics of estimated channel.Then,closed-form expressions of the downlink achievable rates for both the static and moving UEs are provided under Ricean fading channel and Doppler shift effect.We also develop a semi-heuristic search algorithm to deal with the AP selection for the moving UEs by maximizing the weight average achievable rate.Numerical results demonstrate the performance gains and effective rates balancing of the proposed system.
基金The authors extend their appreciation to National University of Sciences and Technology for funding this work through Researchers Supporting Grant,National University of Sciences and Technology,Islamabad,Pakistan.
文摘With the advent and advancements in the wireless technologies,Wi-Fi ngerprinting-based Indoor Positioning System(IPS)has become one of the most promising solutions for localization in indoor environments.Unlike the outdoor environment,the lack of line-of-sight propagation in an indoor environment keeps the interest of the researchers to develop efcient and precise positioning systems that can later be incorporated in numerous applications involving Internet of Things(IoTs)and green computing.In this paper,we have proposed a technique that combines the capabilities of multiple algorithms to overcome the complexities experienced indoors.Initially,in the database development phase,Motley Kennan propagation model is used with Hough transformation to classify,detect,and assign different attenuation factors related to the types of walls.Furthermore,important parameters for system accuracy,such as,placement and geometry of Access Points(APs)in the coverage area are also considered.New algorithm for deployment of an additional AP to an already existing infrastructure is proposed by using Genetic Algorithm(GA)coupled with Enhanced Dilution of Precision(EDOP).Moreover,classication algorithm based on k-Nearest Neighbors(k-NN)is used to nd the position of a stationary or mobile user inside the given coverage area.For k-NN to provide low localization error and reduced space dimensionality,three APs are required to be selected optimally.In this paper,we have suggested an idea to select APs based on Position Vectors(PV)as an input to the localization algorithm.Deducing from our comprehensive investigations,it is revealed that the accuracy of indoor positioning system using the proposed technique unblemished the existing solutions with signicant improvements.
基金supported in part by National Key Research and Development Program of China (Grant No. 2020YFB1807001)in part by Natural Science Foundation of China (Grant No. 62171344, 62121001, 61725103, 61931005)+1 种基金in part by Young Elite Scientists Sponsorship Program by CASTin part by Key Industry Innovation Chain of Shaanxi (Grant No. 2022ZDLGY05-01, 2022ZDLGY05-06)
文摘Due to flexible deployment,unmanned aerial vehicle(UAV)mounted aerial access points are capable of expanding the coverage capabilities of existing terrestrial base stations(TBSs).Different from TBSs,however,UAV access points(UAPs)are of high mobility in horizontal and vertical dimensions,which may deteriorate the coverage performance.Worsestill,the mobility of UAPs would as well increase the pressure of wireless backhaul.In this light,we investigate the performance of the cache-enabled UAV communications network(CUCN)in terms of network spatial throughput(ST)by analyzing the line of sight(LoS)connections and non-line of sight(NLoS)connections.It is found that the network ST is exponentially decreased with the square of UAP altitude.Furthermore,contrary to intuition,a large cache size may deteriorate the network ST when UAPs are over-deployed.The reason is that a large cache size increases the hit probability,which may increase the activation of UAPs and consequently result in complicated interference.Aiming to maximize the network ST,we optimize the cache strategy under limited backhaul.Remarkably,the results show that network ST could be substantially improved by the optimized cache strategy and the performance degeneration brought by UAP high mobility could be even eliminated especially when the UAP altitude is high.
基金NTT-DoCoMo Beijing Communication Labs the National High Technology Research and Development Program of China(No.2006AA01Z276).
文摘To overcome the problem of existing neighboring access point （AP） discovery methods in WLAN, for example they （PnP） of mul proposed. Us can not provide the accurate neighboring APs information needed for the Plug-and-Play ti-mode APs, three kinds of neighboring AP discovery and information exchange methods are ing these three neighboring AP discovery methods, passive discovery method, active discovery method and station assistant discovery method, the multi-mode AP can discover all neighboring APs and obtain needed information. We further propose two whole process flows, which combine three discovery methods in different manner, to achieve different goals. One process flow is to discover the neighboring AP as fast as possible, called fast discovery process flow. The other is to discover the neighboring AP with minimal interference to neighboring and accuracy of the method is confirmed APs, called the minimal interference process flow. The validity by the simulation.
基金The KCC(Korea Communications Commission),Korea,under the R&D program supervised by the KCA(Korea Communications Agency)(KCA-2012-08-911-05-001)
文摘A scheme of rogue access point(Rogue AP)detection based on AP's localization is proposed.Global position system(GPS)information and received signal strength(RSS)information are used to get the location of AP in a smartphone,which is compared with the database located in a remote server.The proposed scheme can detect not only fake access point(Fake AP)but also Evil Twin AP.It can be a user-oriented solution to detecting Rogue AP threats,and users can use it flexibly.
基金supported by the National Natural Science Foundation of China(Nos.62071485,61671472,and 62271503)the Natural Science Foundation of Jiangsu Province,China(Nos.20201334 and 20181335)。
文摘We investigate the resource allocation problem of a cell-free massive multiple-input multiple-output system under the condition of colluding eavesdropping by multiple passive eavesdroppers.To address the problem of limited pilot resources,a scheme is proposed to allocate the pilot with the minimum pollution to users based on access point selection and optimize the pilot transmission power to improve the accuracy of channel estimation.Aiming at the secure transmission problem under a colluding eavesdropping environment by multiple passive eavesdroppers,based on the local partial zero-forcing precoding scheme,a transmission power optimization scheme is formulated to maximize the system’s minimum security spectral efficiency.Simulation results show that the proposed scheme can effectively reduce channel estimation error and improve system security.
基金supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,the Cooperative Education Project of Ministry of Education(201602012019,201602021032)the Program for Excellent Talents of Fujian Province,the Special Research Fund for Higher Education of Fujian(JK2015027)the New Century and Excellent Talents Support Programs of Minnan Normal University(MX1602,MJ14006)
文摘To understand the utilizability of TV white spaces （TVWS）, a comprehensive overview of the outdoor and indoor network design over TVWS is given. The related challenges are analyzed. The potential approaches to overcoming these challenges are discussed. The open research issues are investigated. The result shows that： in the indoor scenario, the white space ratio is on average 18.4% higher than that in the outdoor scenario, which corresponds to 7.7 vacant TV channels. Both network design includes 7 key components： TV spectrum identification, access point （AP） discovery, AP association, spectrum allocation, band width adaptation, interface control and disruption handling. Due to building penetration loss, the indoor TVWS identification and AP placement should be carefully considered in the indoor scenario.
文摘Hierarchical Mobile IPv6 (HMIPv6) can reduce the delay and the amount of signaling during handover compared with the basic mobile IPv6. However, the protocol still cannot meet the requirement for traffic that is delay sensitive, such as voice, especially in macro mobility handover. Duplicate address detection and the transmission time for the handover operation could cause high handover delay. This paper proposes a new mechanism to improve the fast handover algorithm's efficiency in HMIPv6 network. And we present and analyze the performance testing for our proposal by comparing it with the traditional HMIPv6 fast handover algorithm. The results of simulation show that our scheme can reduce the handover delay much more than the traditional fast handover method for HMIPv6 network.
