By exploring the deterministic characteristics of the measurement data, a new propagation model with two deterministic clusters and stochastic arriving rays within each cluster is proposed. When considering the cumula...By exploring the deterministic characteristics of the measurement data, a new propagation model with two deterministic clusters and stochastic arriving rays within each cluster is proposed. When considering the cumulative distribution function （CDF） of the three key channel statistics, the proposed model fits the measurement data better than SV/IEEE 802.15.3, a model which is known as a standard model for UWB indoor propagation channel. Therefore, with the additional knowledge of the specific environment geometry, the proposed model generating impulse responses ＂resemble＂ the measured channel impulse responses better than IEEE model. Moreover, the proposed model＇s parameters obtaining procedure is simplified by utilizing simple parameters of the environment.展开更多
Atmospheric absorption, scattering, and scintillation are the major causes to deteriorate the transmission quality of terahertz（THz） wireless communications. An error control coding scheme based on low density parit...Atmospheric absorption, scattering, and scintillation are the major causes to deteriorate the transmission quality of terahertz（THz） wireless communications. An error control coding scheme based on low density parity check（LDPC） codes with soft decision decoding algorithm is proposed to improve the bit-error-rate（BER） performance of an on-off keying（OOK） modulated THz signal through atmospheric channel. The THz wave propagation characteristics and channel model in atmosphere is set up. Numerical simulations validate the great performance of LDPC codes against the atmospheric fading and demonstrate the huge potential in future ultra-high speed beyond Gbps THz communications.展开更多
In wireless networks, packet access is a popular mode, and the key problem is how to improve throughput and access delay performance, especially the throughput for wireless channels. These results will be a reference ...In wireless networks, packet access is a popular mode, and the key problem is how to improve throughput and access delay performance, especially the throughput for wireless channels. These results will be a reference for not only a wireless channel but also a common MAC protocol.展开更多
Equation based TCP-friendly rate control (TFRC) protocol has been proposed to support video streaming applications. In order to improve TFRC performance in wireless channels, the link level automatic repeat request (A...Equation based TCP-friendly rate control (TFRC) protocol has been proposed to support video streaming applications. In order to improve TFRC performance in wireless channels, the link level automatic repeat request (ARQ) scheme is usually deployed. However, ARQ cannot ensure strict delay guarantees, especially over multihop links. This paper introduces a theoretical model to deduce an equation for packet size adjustment in transport layer to minimize retransmission delay by taking into con- sideration the causative reasons inducing retransmission in link layer. An enhanced TFRC (ETFRC) scheme is proposed inte- grating TFRC with variable packet size policy. Simulation results demonstrate that higher goodput, lower packet loss rate (PLR), lower frame transmission delay and jitter with good fairness can be achieved by our proposed mechanism.展开更多
A novel Automatic repeat ReQuest (ARQ) protocol called cooperative ARQ is presented in this let-ter, where a relay terminal is requested to retransmit an erroneously received packet, instead of the source ter-minal. T...A novel Automatic repeat ReQuest (ARQ) protocol called cooperative ARQ is presented in this let-ter, where a relay terminal is requested to retransmit an erroneously received packet, instead of the source ter-minal. The data link layer Packet Error Rate (PER) performance of cooperative ARQ is derived in correlated wireless channel. The results show that even though the relay-destination channel is worse than the source-destination channel, the new protocol outperforms the traditional one as long as the average SNR of the relay-destination channel is better than a certain threshold. It is also demonstrated that a second order diversity gain can be achieved with the cooperative ARQ protocol.展开更多
In 5G era,it is expected to achieve wireless network coverage including offshore areas.Modeling of marine wireless channels is the basis of constructing a marine communication system.In this paper,a communication scen...In 5G era,it is expected to achieve wireless network coverage including offshore areas.Modeling of marine wireless channels is the basis of constructing a marine communication system.In this paper,a communication scene between an unmanned aerial vehicle(UAV)and a boat is simulated to study the marine wireless channel.Firstly,an improved spatial partitioning ray tracing algorithm is proposed to track the propagation path of electromagnetic waves at sea surface.Secondly,a mobile channel is simulated and modeled based on the track results.Finally,a loss measurement is carried out in the coastal waters based on the simple wireless channel loss measuring platform,and a path loss propagation model is built.Then we compare the actual measurement data with the simulation results and find that the two are have good consistency,which further verifies the reliability of the simulation.展开更多
This work extends the use of wavelet-based denoising as an alternative processing scheme to improve measured mobile-radio channel power delay profiles. It has already been reported that, when applied on real domain da...This work extends the use of wavelet-based denoising as an alternative processing scheme to improve measured mobile-radio channel power delay profiles. It has already been reported that, when applied on real domain data (amplitude only), denoising provides mainly a qualitative improvement. Here, phase content was also considered, leading to significant qualitative and quantitative improvement of the processed profiles. Signal-to-noise ratios and dynamic ranges improvements as high as 50 dB have been observed.展开更多
Train-to-train(T2T)communication can provide protection for existing train-to-ground private network communication,and its channel characteristics directly affect the application of upper-layer communication technolog...Train-to-train(T2T)communication can provide protection for existing train-to-ground private network communication,and its channel characteristics directly affect the application of upper-layer communication technologies.In this study,based on the spatial distribution structure of railway operation scenarios and Fresnel zone theory,we propose a frequency allocation scheme for direct communication between tracking trains in flatland and long straight tunnel scenario.Then we use the estimation method of radio wave attenuation caused by rainfall to analyze the large-scale path loss fading of multi-band wireless channels.Furthermore,we derive the calculation equation of max Doppler frequency shift suitable for T2T communication and describe the multipath wave in the tunnel by ray tracing method to analyze small-scale fading.Simulation analysis shows that the Doppler shift value of T2T communication low frequency band is significantly lower than the frequency shift value of the train-to-ground communication under the same speed conditions.展开更多
Wireless channel modeling has always been one of the most fundamental highlights of the wireless communication research.The performance of new advanced models and technologies heavily depends on the accuracy of the wi...Wireless channel modeling has always been one of the most fundamental highlights of the wireless communication research.The performance of new advanced models and technologies heavily depends on the accuracy of the wireless CSI(Channel State Information).This study examined the randomness of the wireless channel parameters based on the characteristics of the radio propagation environment.The diversity of the statistical properties of wireless channel parameters inspired us to introduce the concept of the tomographic channel model.With this model,the static part of the CSI can be extracted from the huge amount of existing CSI data of previous measurements,which can be de ned as the wireless channel feature.In the proposed scheme for obtaining CSI with the tomographic channel model,the GMM(Gaussian Mixture Model)is applied to acquire the distribution of the wireless channel parameters,and the CNN(Convolutional Neural Network)is applied to automatically distinguish di erent wireless channels.The wireless channel feature information can be stored oine to guide the design of pilot symbols and save pilot resources.The numerical results based on actual measurements demonstrated the clear diversity of the statistical properties of wireless channel parameters and that the proposed scheme can extract the wireless channel feature automatically with fewer pilot resources.Thus,computing and storage resources can be exchanged for the nite and precious spectrum resource.展开更多
How to ensure the security of device access is a common concern in the Internet of Things(IoT)scenario with extremely high device connection density.To achieve efficient and secure network access for IoT devices with ...How to ensure the security of device access is a common concern in the Internet of Things(IoT)scenario with extremely high device connection density.To achieve efficient and secure network access for IoT devices with constrained resources,this paper proposes a lightweight physical-layer authentication protocol based on Physical Unclonable Function(PUF)and channel pre-equalization.PUF is employed as a secret carrier to provide authentication credentials for devices due to its hardware-based uniqueness and unclonable property.Meanwhile,the short-term reciprocity and spatio-temporal uniqueness of wireless channels are utilized to attach an authentication factor related to the spatio-temporal position of devices and to secure the transmission of authentication messages.The proposed protocol is analyzed formally and informally to prove its correctness and security against typical attacks.Simulation results show its robustness in various radio environments.Moreover,we illustrate the advantages of our protocol in terms of security features and complexity through performance comparison with existing authentication schemes.展开更多
Internet of Things(IoT) is one of the targeted application scenarios of fifth generation(5 G) wireless communication.IoT brings a large amount of data transported on the network.Considering those data,machine learning...Internet of Things(IoT) is one of the targeted application scenarios of fifth generation(5 G) wireless communication.IoT brings a large amount of data transported on the network.Considering those data,machine learning(ML) algorithms can be naturally utilized to make network efficiently and reliably.However,how to fully apply ML to IoT driven wireless network is still open.The fundamental reason is that wireless communication pursuits the high capacity and quality facing the challenges from the varying and fading wireless channel.So in this paper,we explore feasible combination for ML and IoT driven wireless network from wireless channel perspective.Firstly,a three-level structure of wireless channel fading features is defined in order to classify the versatile propagation environments.This three-layer structure includes scenario,meter and wavelength levels.Based on this structure,there are different tasks like service prediction and pushing,self-organization networking,self adapting largescale fading modeling and so on,which can be abstracted into problems like regression,classification,clustering,etc.Then,we introduce corresponding ML methods to different levelsfrom channel perspective,which makes their interdisciplinary research promisingly.展开更多
Wireless sensor networks are suffering from serious frequency interference.In this paper,we propose a channel assignment algorithm based on graph theory in wireless sensor networks.We first model the conflict infectio...Wireless sensor networks are suffering from serious frequency interference.In this paper,we propose a channel assignment algorithm based on graph theory in wireless sensor networks.We first model the conflict infection graph for channel assignment with the goal of global optimization minimizing the total interferences in wireless sensor networks.The channel assignment problem is equivalent to the generalized graph-coloring problem which is a NP-complete problem.We further present a meta-heuristic Wireless Sensor Network Parallel Tabu Search(WSN-PTS) algorithm,which can optimize global networks with small numbers of iterations.The results from a simulation experiment reveal that the novel algorithm can effectively solve the channel assignment problem.展开更多
In a wireless sensor network （WSN）, the energy of nodes is limited and cannot be charged. Hence, it is necessary to reduce energy consumption. Both the transmission power of nodes and the interference among nodes in...In a wireless sensor network （WSN）, the energy of nodes is limited and cannot be charged. Hence, it is necessary to reduce energy consumption. Both the transmission power of nodes and the interference among nodes influence energy consumption. In this paper, we design a power control and channel allocation game model with low energy consumption （PCCAGM）. This model contains transmission power, node interference, and residual energy. Besides, the interaction between power and channel is considered. The Nash equilibrium has been proved to exist. Based on this model, a power control and channel allocation optimization algorithm with low energy consumption （PCCAA） is proposed. Theoretical analysis shows that PCCAA can converge to the Pareto Optimal. Simulation results demonstrate that this algorithm can reduce transmission power and interference effectively. Therefore, this algorithm can reduce energy consumption and prolong the network lifetime.展开更多
Employing multiple channels in wireless multihop networks is regarded as an effective approach to increas-ing network capacity. This paper presents a centralized quasi-static channel assignment for multi-radio multi-c...Employing multiple channels in wireless multihop networks is regarded as an effective approach to increas-ing network capacity. This paper presents a centralized quasi-static channel assignment for multi-radio multi-channel Wireless Mesh Networks (WMNs). The proposed channel assignment can efficiently utilize multiple channels with only 2 radios equipped on each mesh router. In the scheme, the network end-to-end traffics are first modeled by probing data at wireless access points, and then the traffic load between each pair of neighboring routers is further estimated using an interference-aware estimation algorithm. Having knowledge of the expected link load, the scheme assigns channels to each radio with the objective of mini-mizing network interference, which as a result greatly improves network capacity. The performance evalua-tion shows that the proposed scheme is highly responsive to varying traffic conditions, and the network per-formance under the channel assignment significantly outperforms the single-radio IEEE 802.11 network as well as the 2-radio WMN with static 2 channels.展开更多
The body channel based wireless power transfer(BC-WPT)method utilizes the human body as the medium to transfer power for bioelectronics,which can achieve a lower transmission loss due to its higher conductivity.Howeve...The body channel based wireless power transfer(BC-WPT)method utilizes the human body as the medium to transfer power for bioelectronics,which can achieve a lower transmission loss due to its higher conductivity.However,except for the channel length,different on-body loca-tions of the transmitter and receiver also influence the power supply performance.This paper fo-cuses on the wrist-to-forehead path to show the potential of BC-WPT for the brain bioelectronics such as the brain computer interface device.The channel characteristics from 10 MHz to 60 MHz are measured by a vector network analyzer(VNA)and a prototype BC-WPT system with differ-ent copper electrodes and the lowest power loss locates between-22 dB and-33 dB.Furthermore,the minimum path loss limit is simulated in Advanced Design System(ADS)software and the low-est optimum path loss can reach nearly-13 dB.Finally,a rectifier circuit is also built at the receiv-er side to harvest d.c.voltage.The results show that the open-circuit voltage(OCV)can reach 1.75 V with the transmitter of 50Ωoutput impedance supplying 5V_(pp)sine voltage at 60 MHz when adopt-ing 1 cm-diameter circular electrodes.展开更多
In this paper, we develop and analyze an energy efficient ARQ （automatic repeat request） initialized transmit diversity protocol for cooperative communications.Medium access control （MAC） layer packet retransmissi...In this paper, we develop and analyze an energy efficient ARQ （automatic repeat request） initialized transmit diversity protocol for cooperative communications.Medium access control （MAC） layer packet retransmission limit （similar to aShortRetryLimit or aLongRetryLimit [802.11-1997]） has been used as an actuator for transmit cooperative diversity initialization.We take the channel state information （CSI） as a function of retransmission tries and the number of retransmission tries is modeled as a random variable.Relays close to the source node are chosen for the transmit cooperation.Closed form expressions are obtained for symbol error rate （SER）, outage capacity and outage probability for the proposed scheme in shadowed fading channels.This cooperative scheme achieves lower signal-to-noise ratio （SNR）, stumpy outage probability, higher bandwidth, and transmit energy efficiencies for desired average symbol error rate （ASER） than the preceding ARQ based cooperative protocols.Finally, the results of computer simulations are included to demonstrate the efficacy of the proposed scheme and to verify the accuracy of the analytical expressions.展开更多
Cognitive Wireless Mesh Networks(CWMN) is a novel wireless network which combines the advantage of Cognitive Radio(CR) and wireless mesh networks.CWMN can realize seamless in-tegration of heterogeneous wireless networ...Cognitive Wireless Mesh Networks(CWMN) is a novel wireless network which combines the advantage of Cognitive Radio(CR) and wireless mesh networks.CWMN can realize seamless in-tegration of heterogeneous wireless networks and achieve better radio resource utilization.However,it is particularly vulnerable due to its features of open medium,dynamic spectrum,dynamic topology,and multi-top routing,etc..Being a dynamic positive security strategy,intrusion detection can provide powerful safeguard to CWMN.In this paper,we introduce trust mechanism into CWMN with intrusion detection and present a trust establishment model based on intrusion detection.Node trust degree and the trust degree of data transmission channels between nodes are defined and an algorithm of calcu-lating trust degree is given based on distributed detection of attack to networks.A channel assignment and routing scheme is proposed,in which selects the trusted nodes and allocates data channel with high trust degree for the transmission between neighbor nodes to establish a trusted route.Simulation re-sults indicate that the scheme can vary channel allocation and routing dynamically according to network security state so as to avoid suspect nodes and unsafe channels,and improve the packet safe delivery fraction effectively.展开更多
This paper proposes an adaptive joint source and channel coding scheme for H.264 video multicast over wireless LAN which takes into account the user topology changes and varying channel conditions of multiple users, a...This paper proposes an adaptive joint source and channel coding scheme for H.264 video multicast over wireless LAN which takes into account the user topology changes and varying channel conditions of multiple users, and dynamically allocates available bandwidth between source coding and channel coding, with the goal to optimize the overall system performance. In particular, source resilience and error correction are considered jointly in the scheme to achieve the optimal performance. And a channel estimation algorithm based on the average packet loss rate and the variance of packet loss rate is proposed also. Two overall performance criteria for video multicast are investigated and experimental results are presented to show the improvement obtained by the scheme.展开更多
This article presents a new multichannel medium access control (MAC) protocol to solve the exposed-terminal (ET) problem for efficient channel sharing in multi-hop wireless networks. It uses request-to-send and clear-...This article presents a new multichannel medium access control (MAC) protocol to solve the exposed-terminal (ET) problem for efficient channel sharing in multi-hop wireless networks. It uses request-to-send and clear-to-send (RTS/CTS) dialogue on a common channel and flexibly opts for conflict-free traffic channels to carry out the data packet transmission on the basis of a new channel selection scheme. The acknowledgment (ACK) packet for the data packet transmission is sent back to the sender over another ...展开更多
基金This project was supported by the key program of the National Natural Science Foundation of China (60432040).
文摘By exploring the deterministic characteristics of the measurement data, a new propagation model with two deterministic clusters and stochastic arriving rays within each cluster is proposed. When considering the cumulative distribution function （CDF） of the three key channel statistics, the proposed model fits the measurement data better than SV/IEEE 802.15.3, a model which is known as a standard model for UWB indoor propagation channel. Therefore, with the additional knowledge of the specific environment geometry, the proposed model generating impulse responses ＂resemble＂ the measured channel impulse responses better than IEEE model. Moreover, the proposed model＇s parameters obtaining procedure is simplified by utilizing simple parameters of the environment.
基金Project supported by the National Key Basic Research Program of China(Grant No.2014CB339803)the National High Technology Research and Development Program of China(Grant No.2011AA010205)+4 种基金the National Natural Science Foundation of China(Grant Nos.61131006,61321492,and 61204135)the Major National Development Project of Scientific Instrument and Equipment(Grant No.2011YQ150021)the National Science and Technology Major Project(Grant No.2011ZX02707)the International Collaboration and Innovation Program on High Mobility Materials Engineering of the Chinese Academy of Sciencesthe Shanghai Municipal Commission of Science and Technology(Grant No.14530711300)
文摘Atmospheric absorption, scattering, and scintillation are the major causes to deteriorate the transmission quality of terahertz（THz） wireless communications. An error control coding scheme based on low density parity check（LDPC） codes with soft decision decoding algorithm is proposed to improve the bit-error-rate（BER） performance of an on-off keying（OOK） modulated THz signal through atmospheric channel. The THz wave propagation characteristics and channel model in atmosphere is set up. Numerical simulations validate the great performance of LDPC codes against the atmospheric fading and demonstrate the huge potential in future ultra-high speed beyond Gbps THz communications.
基金This project was supported by the Scientific Research Foundation of Harbin Institute of Technology (HIT. 2001.01).
文摘In wireless networks, packet access is a popular mode, and the key problem is how to improve throughput and access delay performance, especially the throughput for wireless channels. These results will be a reference for not only a wireless channel but also a common MAC protocol.
基金Project supported by the National Natural Science Foundation ofChina (No. 60302004) and the Natural Science Foundation of HubeiProvince (No. 2005ABA264), China
文摘Equation based TCP-friendly rate control (TFRC) protocol has been proposed to support video streaming applications. In order to improve TFRC performance in wireless channels, the link level automatic repeat request (ARQ) scheme is usually deployed. However, ARQ cannot ensure strict delay guarantees, especially over multihop links. This paper introduces a theoretical model to deduce an equation for packet size adjustment in transport layer to minimize retransmission delay by taking into con- sideration the causative reasons inducing retransmission in link layer. An enhanced TFRC (ETFRC) scheme is proposed inte- grating TFRC with variable packet size policy. Simulation results demonstrate that higher goodput, lower packet loss rate (PLR), lower frame transmission delay and jitter with good fairness can be achieved by our proposed mechanism.
基金Supported by the National Natural Science Foundation of China (No.60472079), and Natural Science Founda-tion of Zhejiang Province (No.Z104252).
文摘A novel Automatic repeat ReQuest (ARQ) protocol called cooperative ARQ is presented in this let-ter, where a relay terminal is requested to retransmit an erroneously received packet, instead of the source ter-minal. The data link layer Packet Error Rate (PER) performance of cooperative ARQ is derived in correlated wireless channel. The results show that even though the relay-destination channel is worse than the source-destination channel, the new protocol outperforms the traditional one as long as the average SNR of the relay-destination channel is better than a certain threshold. It is also demonstrated that a second order diversity gain can be achieved with the cooperative ARQ protocol.
基金National Natural Science Foundation of China(Grant number 61971365)National Natural Science Foundation of China(Grant number 61871339)+1 种基金National Natural Science Foundation of China(Grant number 61901403)Xiamen Science and Technology Plan Project(No.3502Z20183008).
文摘In 5G era,it is expected to achieve wireless network coverage including offshore areas.Modeling of marine wireless channels is the basis of constructing a marine communication system.In this paper,a communication scene between an unmanned aerial vehicle(UAV)and a boat is simulated to study the marine wireless channel.Firstly,an improved spatial partitioning ray tracing algorithm is proposed to track the propagation path of electromagnetic waves at sea surface.Secondly,a mobile channel is simulated and modeled based on the track results.Finally,a loss measurement is carried out in the coastal waters based on the simple wireless channel loss measuring platform,and a path loss propagation model is built.Then we compare the actual measurement data with the simulation results and find that the two are have good consistency,which further verifies the reliability of the simulation.
文摘This work extends the use of wavelet-based denoising as an alternative processing scheme to improve measured mobile-radio channel power delay profiles. It has already been reported that, when applied on real domain data (amplitude only), denoising provides mainly a qualitative improvement. Here, phase content was also considered, leading to significant qualitative and quantitative improvement of the processed profiles. Signal-to-noise ratios and dynamic ranges improvements as high as 50 dB have been observed.
基金National Natural Science Foundation of China(No.61763023)Lanzhou Jiaotong University-Tianjin University Innovation Fund(No.20180519)。
文摘Train-to-train(T2T)communication can provide protection for existing train-to-ground private network communication,and its channel characteristics directly affect the application of upper-layer communication technologies.In this study,based on the spatial distribution structure of railway operation scenarios and Fresnel zone theory,we propose a frequency allocation scheme for direct communication between tracking trains in flatland and long straight tunnel scenario.Then we use the estimation method of radio wave attenuation caused by rainfall to analyze the large-scale path loss fading of multi-band wireless channels.Furthermore,we derive the calculation equation of max Doppler frequency shift suitable for T2T communication and describe the multipath wave in the tunnel by ray tracing method to analyze small-scale fading.Simulation analysis shows that the Doppler shift value of T2T communication low frequency band is significantly lower than the frequency shift value of the train-to-ground communication under the same speed conditions.
基金This work is supported by the National Natural Science Foundation of China(No.61631013)National Key Basic Research Program of China(973 Program)(No.2013CB329002)+1 种基金National Major Project(No.2014ZX03003002-002)Program for New Century Excellent Talents in University(No.NCET-13-0321).
文摘Wireless channel modeling has always been one of the most fundamental highlights of the wireless communication research.The performance of new advanced models and technologies heavily depends on the accuracy of the wireless CSI(Channel State Information).This study examined the randomness of the wireless channel parameters based on the characteristics of the radio propagation environment.The diversity of the statistical properties of wireless channel parameters inspired us to introduce the concept of the tomographic channel model.With this model,the static part of the CSI can be extracted from the huge amount of existing CSI data of previous measurements,which can be de ned as the wireless channel feature.In the proposed scheme for obtaining CSI with the tomographic channel model,the GMM(Gaussian Mixture Model)is applied to acquire the distribution of the wireless channel parameters,and the CNN(Convolutional Neural Network)is applied to automatically distinguish di erent wireless channels.The wireless channel feature information can be stored oine to guide the design of pilot symbols and save pilot resources.The numerical results based on actual measurements demonstrated the clear diversity of the statistical properties of wireless channel parameters and that the proposed scheme can extract the wireless channel feature automatically with fewer pilot resources.Thus,computing and storage resources can be exchanged for the nite and precious spectrum resource.
基金supported by National Natural Science Foundation of China(No.61931020,No.U19B2024 and No.62371462).
文摘How to ensure the security of device access is a common concern in the Internet of Things(IoT)scenario with extremely high device connection density.To achieve efficient and secure network access for IoT devices with constrained resources,this paper proposes a lightweight physical-layer authentication protocol based on Physical Unclonable Function(PUF)and channel pre-equalization.PUF is employed as a secret carrier to provide authentication credentials for devices due to its hardware-based uniqueness and unclonable property.Meanwhile,the short-term reciprocity and spatio-temporal uniqueness of wireless channels are utilized to attach an authentication factor related to the spatio-temporal position of devices and to secure the transmission of authentication messages.The proposed protocol is analyzed formally and informally to prove its correctness and security against typical attacks.Simulation results show its robustness in various radio environments.Moreover,we illustrate the advantages of our protocol in terms of security features and complexity through performance comparison with existing authentication schemes.
基金supported by National Science and Technology Major Program of the Ministry of Science and Technology(No.2018ZX03001031)Key program of Beijing Municipal Natural Science Foundation(No.L172030)+1 种基金Beijing unicipal Science and Technology Commission Project(No.Z181100003218007)National Key Technology Research and Development Program of the Ministry of Science and Technology of China(NO.2012BAF14B01)
文摘Internet of Things(IoT) is one of the targeted application scenarios of fifth generation(5 G) wireless communication.IoT brings a large amount of data transported on the network.Considering those data,machine learning(ML) algorithms can be naturally utilized to make network efficiently and reliably.However,how to fully apply ML to IoT driven wireless network is still open.The fundamental reason is that wireless communication pursuits the high capacity and quality facing the challenges from the varying and fading wireless channel.So in this paper,we explore feasible combination for ML and IoT driven wireless network from wireless channel perspective.Firstly,a three-level structure of wireless channel fading features is defined in order to classify the versatile propagation environments.This three-layer structure includes scenario,meter and wavelength levels.Based on this structure,there are different tasks like service prediction and pushing,self-organization networking,self adapting largescale fading modeling and so on,which can be abstracted into problems like regression,classification,clustering,etc.Then,we introduce corresponding ML methods to different levelsfrom channel perspective,which makes their interdisciplinary research promisingly.
基金supported by National Key Basic Research Program of China(973 program) under Grant No. 2007CB307101National Natural Science Foundation of China under Grant No.60833002,No.60802016,No.60972010+1 种基金Next Generation Internet of China under Grant No.CNGI-0903-05the Fundamental Research Funds for the Central Universities under Grant No.2009YJS011
文摘Wireless sensor networks are suffering from serious frequency interference.In this paper,we propose a channel assignment algorithm based on graph theory in wireless sensor networks.We first model the conflict infection graph for channel assignment with the goal of global optimization minimizing the total interferences in wireless sensor networks.The channel assignment problem is equivalent to the generalized graph-coloring problem which is a NP-complete problem.We further present a meta-heuristic Wireless Sensor Network Parallel Tabu Search(WSN-PTS) algorithm,which can optimize global networks with small numbers of iterations.The results from a simulation experiment reveal that the novel algorithm can effectively solve the channel assignment problem.
基金Project supported by the National Natural Science Foundation of China(Grant No.61403336)the Natural Science Foundation of Hebei Province,China(Grant Nos.F2015203342 and F2015203291)the Independent Research Project Topics B Category for Young Teacher of Yanshan University,China(Grant No.15LGB007)
文摘In a wireless sensor network （WSN）, the energy of nodes is limited and cannot be charged. Hence, it is necessary to reduce energy consumption. Both the transmission power of nodes and the interference among nodes influence energy consumption. In this paper, we design a power control and channel allocation game model with low energy consumption （PCCAGM）. This model contains transmission power, node interference, and residual energy. Besides, the interaction between power and channel is considered. The Nash equilibrium has been proved to exist. Based on this model, a power control and channel allocation optimization algorithm with low energy consumption （PCCAA） is proposed. Theoretical analysis shows that PCCAA can converge to the Pareto Optimal. Simulation results demonstrate that this algorithm can reduce transmission power and interference effectively. Therefore, this algorithm can reduce energy consumption and prolong the network lifetime.
文摘Employing multiple channels in wireless multihop networks is regarded as an effective approach to increas-ing network capacity. This paper presents a centralized quasi-static channel assignment for multi-radio multi-channel Wireless Mesh Networks (WMNs). The proposed channel assignment can efficiently utilize multiple channels with only 2 radios equipped on each mesh router. In the scheme, the network end-to-end traffics are first modeled by probing data at wireless access points, and then the traffic load between each pair of neighboring routers is further estimated using an interference-aware estimation algorithm. Having knowledge of the expected link load, the scheme assigns channels to each radio with the objective of mini-mizing network interference, which as a result greatly improves network capacity. The performance evalua-tion shows that the proposed scheme is highly responsive to varying traffic conditions, and the network per-formance under the channel assignment significantly outperforms the single-radio IEEE 802.11 network as well as the 2-radio WMN with static 2 channels.
文摘The body channel based wireless power transfer(BC-WPT)method utilizes the human body as the medium to transfer power for bioelectronics,which can achieve a lower transmission loss due to its higher conductivity.However,except for the channel length,different on-body loca-tions of the transmitter and receiver also influence the power supply performance.This paper fo-cuses on the wrist-to-forehead path to show the potential of BC-WPT for the brain bioelectronics such as the brain computer interface device.The channel characteristics from 10 MHz to 60 MHz are measured by a vector network analyzer(VNA)and a prototype BC-WPT system with differ-ent copper electrodes and the lowest power loss locates between-22 dB and-33 dB.Furthermore,the minimum path loss limit is simulated in Advanced Design System(ADS)software and the low-est optimum path loss can reach nearly-13 dB.Finally,a rectifier circuit is also built at the receiv-er side to harvest d.c.voltage.The results show that the open-circuit voltage(OCV)can reach 1.75 V with the transmitter of 50Ωoutput impedance supplying 5V_(pp)sine voltage at 60 MHz when adopt-ing 1 cm-diameter circular electrodes.
基金Supported by the National Natral Science Foundation of China (Grant No 60602058)the National High Technology Research and Development Program of China (Grant No 2006AA01Z257)
文摘In this paper, we develop and analyze an energy efficient ARQ （automatic repeat request） initialized transmit diversity protocol for cooperative communications.Medium access control （MAC） layer packet retransmission limit （similar to aShortRetryLimit or aLongRetryLimit [802.11-1997]） has been used as an actuator for transmit cooperative diversity initialization.We take the channel state information （CSI） as a function of retransmission tries and the number of retransmission tries is modeled as a random variable.Relays close to the source node are chosen for the transmit cooperation.Closed form expressions are obtained for symbol error rate （SER）, outage capacity and outage probability for the proposed scheme in shadowed fading channels.This cooperative scheme achieves lower signal-to-noise ratio （SNR）, stumpy outage probability, higher bandwidth, and transmit energy efficiencies for desired average symbol error rate （ASER） than the preceding ARQ based cooperative protocols.Finally, the results of computer simulations are included to demonstrate the efficacy of the proposed scheme and to verify the accuracy of the analytical expressions.
基金Supported by the National High Technology Research and Development Program (No. 2009AA011504)
文摘Cognitive Wireless Mesh Networks(CWMN) is a novel wireless network which combines the advantage of Cognitive Radio(CR) and wireless mesh networks.CWMN can realize seamless in-tegration of heterogeneous wireless networks and achieve better radio resource utilization.However,it is particularly vulnerable due to its features of open medium,dynamic spectrum,dynamic topology,and multi-top routing,etc..Being a dynamic positive security strategy,intrusion detection can provide powerful safeguard to CWMN.In this paper,we introduce trust mechanism into CWMN with intrusion detection and present a trust establishment model based on intrusion detection.Node trust degree and the trust degree of data transmission channels between nodes are defined and an algorithm of calcu-lating trust degree is given based on distributed detection of attack to networks.A channel assignment and routing scheme is proposed,in which selects the trusted nodes and allocates data channel with high trust degree for the transmission between neighbor nodes to establish a trusted route.Simulation re-sults indicate that the scheme can vary channel allocation and routing dynamically according to network security state so as to avoid suspect nodes and unsafe channels,and improve the packet safe delivery fraction effectively.
文摘This paper proposes an adaptive joint source and channel coding scheme for H.264 video multicast over wireless LAN which takes into account the user topology changes and varying channel conditions of multiple users, and dynamically allocates available bandwidth between source coding and channel coding, with the goal to optimize the overall system performance. In particular, source resilience and error correction are considered jointly in the scheme to achieve the optimal performance. And a channel estimation algorithm based on the average packet loss rate and the variance of packet loss rate is proposed also. Two overall performance criteria for video multicast are investigated and experimental results are presented to show the improvement obtained by the scheme.
基金National Natural Science Foundation of China (10577005, 60532030)National Outstanding Youth Science Foundation of China (60625102)NSBS Program of Beijing University of Aeronau-tics and Astronautics, China (221235)
文摘This article presents a new multichannel medium access control (MAC) protocol to solve the exposed-terminal (ET) problem for efficient channel sharing in multi-hop wireless networks. It uses request-to-send and clear-to-send (RTS/CTS) dialogue on a common channel and flexibly opts for conflict-free traffic channels to carry out the data packet transmission on the basis of a new channel selection scheme. The acknowledgment (ACK) packet for the data packet transmission is sent back to the sender over another ...
