Graphic processing units （GPUs） have been widely recognized as cost-efficient co-processors with acceptable size, weight, and power consumption. However, adopting GPUs in real-time systems is still challenging, due ...Graphic processing units （GPUs） have been widely recognized as cost-efficient co-processors with acceptable size, weight, and power consumption. However, adopting GPUs in real-time systems is still challenging, due to the lack in framework for real-time analysis. In order to guarantee real-time requirements while maintaining system utilization ~in modern heterogeneous systems, such as multicore multi-GPU systems, a novel suspension-based k-exclusion real-time locking protocol and the associated suspension-aware schedulability analysis are proposed. The proposed protocol provides a synchronization framework that enables multiple GPUs to be efficiently integrated in multicore real-time systems. Comparative evaluations show that the proposed methods improve upon the existing work in terms of schedulability.展开更多
Considering characteristic of mHealth communication and problems of existing methods, this paper presents a real-time communication method for mHealth based on extended XMPP protocol. The method can maintain the role ...Considering characteristic of mHealth communication and problems of existing methods, this paper presents a real-time communication method for mHealth based on extended XMPP protocol. The method can maintain the role status efficiently and reduce data latency during the communication process. Meanwhile, it can be extended flexibly to meet increasing communication demands of mHealth services. Furthermore, a system framework is presented to support telemonitoring scene. Finally, system implementation and feasibility tests verify the effectiveness of the method and framework.展开更多
This paper presents a novel real-time routing protocol, called CBRR, with less energy consumption for wireless sensor networks (WSNs). End-to-End real-time requirements are fulfilled with speed or delay constraint at ...This paper presents a novel real-time routing protocol, called CBRR, with less energy consumption for wireless sensor networks (WSNs). End-to-End real-time requirements are fulfilled with speed or delay constraint at each hop through integrating the contention and neighbor table mechanisms. More precisely, CBRR maintains a neighbor table via the contention mechanism being dependent on wireless broadcast instead of beacons. Comprehensive simulations show that CBRR can not only achieve higher performance in static networks, but also work well for dynamic networks.展开更多
In the era of Big Data, typical architecture of distributed real-time stream processing systems is the combination of Flume, Kafka, and Storm. As a kind of distributed message system, Kafka has the characteristics of ...In the era of Big Data, typical architecture of distributed real-time stream processing systems is the combination of Flume, Kafka, and Storm. As a kind of distributed message system, Kafka has the characteristics of horizontal scalability and high throughput, which is manly deployed in many areas in order to address the problem of speed mismatch between message producers and consumers. When using Kafka, we need to quickly receive data sent by producers. In addition, we need to send data to consumers quickly. Therefore, the performance of Kafka is of critical importance to the performance of the whole stream processing system. In this paper, we propose the improved design of real-time stream processing systems, and focus on improving the Kafka's data loading process.We use Kafka cat to transfer data from the source to Kafka topic directly, which can reduce the network transmission. We also utilize the memory file system to accelerate the process of data loading, which can address the bottleneck and performance problems caused by disk I/O. Extensive experiments are conducted to evaluate the performance, which show the superiority of our improved design.展开更多
Aiming at the problems of unreliable data transmission,poor steadiness,nonsupport of complex data types,direct couple between data transmission and exchange,a high-level method based on advanced message queuing protoc...Aiming at the problems of unreliable data transmission,poor steadiness,nonsupport of complex data types,direct couple between data transmission and exchange,a high-level method based on advanced message queuing protocol( AMQP) is proposed to integrate naval distributed tactical training simulation system after serious consideration with current information exchange features of military combat system. Transferring layer in traditional user datagram protocol is implemented by publishing and subscribing scheme of message middleware. By creating message model to standardize message structure,integration architecture is formulated to resolve potential information security risks from inconsistent data type and express data transmission. Meanwhile,a communication model is put forward based on AMQP,which is in the center position of the whole transmission framework and responsible for reliably transferring battlefield data among subsystems. Experiments show that the method can accurately post amounts of data to the subscriber without error and loss,and can get excellent real-time performance of data exchange.展开更多
According to the security requirement of the short message service （SMS） industry application, a secure short message communication protocol is proposed. This is an application level protocol constructed on the stan...According to the security requirement of the short message service （SMS） industry application, a secure short message communication protocol is proposed. This is an application level protocol constructed on the standard SMS communication protocol using public key authentication and key agreement without the need of wireless public key infrastructure （WPKI）. Secure short message transmission and dynamic key agreement between mobile terminals and the accessing gateway axe realized. The security of the proposed protocol is validated through the BAN logic. Compared with the standard SMS protocol, the effective payload rate of our protocol can reach 91.4%, and subscriber identity module （SIM） tool kit （STK） applications based on our protocol suit well for all kinds of mobile terminals in practical application.展开更多
Based on the analysis of the covert channel＇s working mechanism of the internet control message protocol （ICMP） in internet protocol version 4 （IPv4） and Internet Protocol version 6 （IPv6）, the ICMP covert cha...Based on the analysis of the covert channel＇s working mechanism of the internet control message protocol （ICMP） in internet protocol version 4 （IPv4） and Internet Protocol version 6 （IPv6）, the ICMP covert channd＇s algorithms of the IPv4 and IPv6 are presented, which enable automatic channeling upon IPv4/v6 nodes with non-IPv4-compatible address, and the key transmission is achieved by using this channel in the embedded Internet terminal. The result shows that the covert channel＇s algorithm, which we implemented if, set correct, the messages of this covert channel might go through the gateway and enter the local area network.展开更多
One of the most important features of modem minor satellites is to realize autonomous moving. The perfomance of the satellite autonomous computer operating system acting as the control center is of utrnost importance....One of the most important features of modem minor satellites is to realize autonomous moving. The perfomance of the satellite autonomous computer operating system acting as the control center is of utrnost importance. The recent trend in operating system development is adopting microkernel architecture that holds such advantages as microminiaturization, modularity, portability and extendibility. IPC is the key of microkernel design. Message-based IPC mechanism is generally used in existing microkernel Operating system. It is of consistency, safety and reliability.However, it can not provide efficient support for real-time applications in satellite systems and it only applies to loose coupling multi-processor architecture. In this paper, an improvement solution for existing message-based IPC is proposed at first to obtain real-time performance. Then a new IPC mechanism is designed. It particulary applies to shared memory tight coupling multi-processor architecture.展开更多
Distributed speech recognition (DSR) applications have certain QoS (Quality of service) requirements in terms of latency, packet loss rate, etc. To deliver quality guaranteed DSR application over wirelined or wireless...Distributed speech recognition (DSR) applications have certain QoS (Quality of service) requirements in terms of latency, packet loss rate, etc. To deliver quality guaranteed DSR application over wirelined or wireless links, some QoS mechanisms should be provided. We put forward a RTP/RSVP transmission scheme with DSR-specific payload and QoS parameters by modifying the present WAP protocol stack. The simulation result shows that this scheme will provide adequate network bandwidth to keep the real-time transport of DSR data over either wirelined or wireless channels.展开更多
The Internet Control Message Protocol(ICMP)covert tunnel refers to a network attack that encapsulates malicious data in the data part of the ICMP protocol for transmission.Its concealment is stronger and it is not eas...The Internet Control Message Protocol(ICMP)covert tunnel refers to a network attack that encapsulates malicious data in the data part of the ICMP protocol for transmission.Its concealment is stronger and it is not easy to be discovered.Most detection methods are detecting the existence of channels instead of clarifying specific attack intentions.In this paper,we propose an ICMP covert tunnel attack intent detection framework ICMPTend,which includes five steps:data collection,feature dictionary construction,data preprocessing,model construction,and attack intent prediction.ICMPTend can detect a variety of attack intentions,such as shell attacks,sensitive directory access,communication protocol traffic theft,filling tunnel reserved words,and other common network attacks.We extract features from five types of attack intent found in ICMP channels.We build a multi-dimensional dictionary of malicious features,including shell attacks,sensitive directory access,communication protocol traffic theft,filling tunnel reserved words,and other common network attack keywords.For the high-dimensional and independent characteristics of ICMP traffic,we use a support vector machine(SVM)as a multi-class classifier.The experimental results show that the average accuracy of ICMPTend is 92%,training ICMPTend only takes 55 s,and the prediction time is only 2 s,which can effectively identify the attack intention of ICMP.展开更多
Due to the lack of authentication mechanism in BeiDou navigation satellite system(BDS),BD-Ⅱ civil navigation message(BDⅡ-CNAV) are vulnerable to spoofing attack and replay attack.To solve this problem,we present a s...Due to the lack of authentication mechanism in BeiDou navigation satellite system(BDS),BD-Ⅱ civil navigation message(BDⅡ-CNAV) are vulnerable to spoofing attack and replay attack.To solve this problem,we present a security authentication protocol,called as BDSec,which is designed by using China’s cryptography Shangyong Mima(SM) series algorithms,such as SM2/4/9 and Zu Chongzhi(ZUC)algorithm.In BDSec protocol,both of BDⅡ-CNAV and signature information are encrypted using the SM4 algorithm(Symmetric encryption mechanism).The encrypted result is used as the subject authentication information.BDSec protocol applies SM9 algorithm(Identity-based cryptography mechanism) to protect the integrity of the BDⅡ-CNAV,adopts the SM2 algorithm(Public key cryptosystem) to guarantee the confidentiality of the important session information,and uses the ZUC algorithm(Encryption and integrity algorithm) to verify the integrity of the message authentication serial number and initial information and the information in authentication initialization sub-protocol respectively.The results of the SVO logic reasoning and performance analysis show that BDSec protocol meets security requirements for the dual user identity authentication in BDS and can realize the security authentication of BDⅡ-CNAV.展开更多
By thorough research on the prominent periodic and aperiodic scheduling algorithms,anon-line hard real-time scheduler is presented,which is applicable to the scheduling of packets over a link.This scheduler,based on b...By thorough research on the prominent periodic and aperiodic scheduling algorithms,anon-line hard real-time scheduler is presented,which is applicable to the scheduling of packets over a link.This scheduler,based on both Rate Monotonic,pinwheel scheduling algorithm Sr and Polling Serverscheduling algorithms,can rapidly judge the schedulability and then automatically generate a bus tablefor the scheduling algorithm to schedule the packets as the periodic packets.The implementation of thescheduler is simple and easy to use,and it is effective for the utilization of bus link.The orderly executionof the bus table can not only guarantee the performance of the hard real time but also avoid the blockageand interruption of the message transmission.So the scheduler perfectly meets the demand of hard real-time communication system on the field bus domain.展开更多
Relying on CMPP (China Mobile Peer to Peer) protocol,we propose and design SMS (Short Message Service) gateway interface for early warning plan based on real-time meteorological database application,in order to form t...Relying on CMPP (China Mobile Peer to Peer) protocol,we propose and design SMS (Short Message Service) gateway interface for early warning plan based on real-time meteorological database application,in order to form the meteorological mobile internet service system which is 'One point connect,service the whole province' for short.Accessing interface system to each city's SMG (Short Message Gateway) through standard protocol,we establish the information transmitting channel of short message platform and mobile SMG to realize the store-forward and flow control of short message.In addition,the stable and dependable communication connect of interface system and mobile SMG should be ensure,and the connect could be reconstructed while encountering any error,as well as committing short message would be stopped due to interruption of connect.展开更多
To cope with the problem of low protocol efficiency of the standard ad hoc on-demand distance vector （AODV） routing protocol with the periodic Hello message broadcast mechanism, a new link availability prediction ba...To cope with the problem of low protocol efficiency of the standard ad hoc on-demand distance vector （AODV） routing protocol with the periodic Hello message broadcast mechanism, a new link availability prediction based strategy is introduced to reduce the amount of Hello messages. In this strategy, a novel wireless link availability prediction model under line-of-sight （LOS） propagation environments is proposed based on which the parameter of Hello Interval in AODV can be dynamically adjusted to achieve the goal of changing the frequency of Hello message broadcasts under different link stability degrees. Simulation results demonstrate that, compared with the standard AODV with the periodic Hello message broadcast mechanism, the proposed protocol effectively reduces unnecessary control message overhead and greatly improves the performance in terms of end-to-end delay and efficiency.展开更多
Time-sensitive networks(TSNs)support not only traditional best-effort communications but also deterministic communications,which send each packet at a deterministic time so that the data transmissions of networked con...Time-sensitive networks(TSNs)support not only traditional best-effort communications but also deterministic communications,which send each packet at a deterministic time so that the data transmissions of networked control systems can be precisely scheduled to guarantee hard real-time constraints.No-wait scheduling is suitable for such TSNs and generates the schedules of deterministic communications with the minimal network resources so that all of the remaining resources can be used to improve the throughput of best-effort communications.However,due to inappropriate message fragmentation,the realtime performance of no-wait scheduling algorithms is reduced.Therefore,in this paper,joint algorithms of message fragmentation and no-wait scheduling are proposed.First,a specification for the joint problem based on optimization modulo theories is proposed so that off-the-shelf solvers can be used to find optimal solutions.Second,to improve the scalability of our algorithm,the worst-case delay of messages is analyzed,and then,based on the analysis,a heuristic algorithm is proposed to construct low-delay schedules.Finally,we conduct extensive test cases to evaluate our proposed algorithms.The evaluation results indicate that,compared to existing algorithms,the proposed joint algorithm improves schedulability by up to 50%.展开更多
There is a lack of appropriate guidelines for realistic user traces, mobility models, routing protocols, considerations of real-life challenges, etc. for general-purpose mobile ad hoc networks （MANET）. In this paper...There is a lack of appropriate guidelines for realistic user traces, mobility models, routing protocols, considerations of real-life challenges, etc. for general-purpose mobile ad hoc networks （MANET）. In this paper, four laptops are used in an open field environment in four scenarios to evaluate the performances of Internet control message protocol （ICMP） based ping and transmission control protocol （TCP） based streaming video applications using optimised link state routing （OLSR） implementation in an IEEE 802.11g wireless network. Corresponding simulations are developed in Network Simulator ns-2 by setting simulation parameters according to the real experiments. Difficulties faced to regenerate real-life scenarios have been discussed and the gaps between reality and simulation are identified. A setup guideline to produce realistic simulation results has been established.展开更多
With the rapid development of the Internet,a large number of private protocols emerge on the network.However,some of them are constructed by attackers to avoid being analyzed,posing a threat to computer network securi...With the rapid development of the Internet,a large number of private protocols emerge on the network.However,some of them are constructed by attackers to avoid being analyzed,posing a threat to computer network security.The blockchain uses the P2P protocol to implement various functions across the network.Furthermore,the P2P protocol format of blockchain may differ from the standard format specification,which leads to sniffing tools such as Wireshark and Fiddler not being able to recognize them.Therefore,the ability to distinguish different types of unknown network protocols is vital for network security.In this paper,we propose an unsupervised clustering algorithm based on maximum frequent sequences for binary protocols,which can distinguish various unknown protocols to provide support for analyzing unknown protocol formats.We mine the maximum frequent sequences of protocolmessage sets in bytes.Andwe calculate the fuzzymembership of the protocolmessage to each maximum frequent sequence,which is based on fuzzy set theory.Then we construct the fuzzy membership vector for each protocol message.Finally,we adopt K-means++to split different types of protocol messages into several clusters and evaluate the performance by calculating homogeneity,integrity,and Fowlkes and Mallows Index(FMI).Besides,the clustering algorithms based onNeedleman–Wunsch and the fixed-length prefix are compared with the algorithm presented in this paper.Compared with these traditional clustering methods,we demonstrate a certain improvement in the clustering performance of our work.展开更多
This paper proposed two modifications on IKE protocol with pre-shared key authentication. The first modification can improve its immunity against DDoS attack by authenticating the initiator before the responder genera...This paper proposed two modifications on IKE protocol with pre-shared key authentication. The first modification can improve its immunity against DDoS attack by authenticating the initiator before the responder generates the computation-intensive Diffie-Hellman public value. The second modification can improve its efficiency when the attack on messages occurs because it can detect the attack quickly by replacing the centralized authentication in origical IKE protocol with immediate authentication. In addition, the two modifications can be integrated into one protocol compactly.展开更多
基金supported by the National Natural Science Foundation of China under Grant No.61003032/F020207
文摘Graphic processing units （GPUs） have been widely recognized as cost-efficient co-processors with acceptable size, weight, and power consumption. However, adopting GPUs in real-time systems is still challenging, due to the lack in framework for real-time analysis. In order to guarantee real-time requirements while maintaining system utilization ~in modern heterogeneous systems, such as multicore multi-GPU systems, a novel suspension-based k-exclusion real-time locking protocol and the associated suspension-aware schedulability analysis are proposed. The proposed protocol provides a synchronization framework that enables multiple GPUs to be efficiently integrated in multicore real-time systems. Comparative evaluations show that the proposed methods improve upon the existing work in terms of schedulability.
文摘Considering characteristic of mHealth communication and problems of existing methods, this paper presents a real-time communication method for mHealth based on extended XMPP protocol. The method can maintain the role status efficiently and reduce data latency during the communication process. Meanwhile, it can be extended flexibly to meet increasing communication demands of mHealth services. Furthermore, a system framework is presented to support telemonitoring scene. Finally, system implementation and feasibility tests verify the effectiveness of the method and framework.
文摘This paper presents a novel real-time routing protocol, called CBRR, with less energy consumption for wireless sensor networks (WSNs). End-to-End real-time requirements are fulfilled with speed or delay constraint at each hop through integrating the contention and neighbor table mechanisms. More precisely, CBRR maintains a neighbor table via the contention mechanism being dependent on wireless broadcast instead of beacons. Comprehensive simulations show that CBRR can not only achieve higher performance in static networks, but also work well for dynamic networks.
基金supported by the Research Fund of National Key Laboratory of Computer Architecture under Grant No.CARCH201501the Open Project Program of the State Key Laboratory of Mathematical Engineering and Advanced Computing under Grant No.2016A09
文摘In the era of Big Data, typical architecture of distributed real-time stream processing systems is the combination of Flume, Kafka, and Storm. As a kind of distributed message system, Kafka has the characteristics of horizontal scalability and high throughput, which is manly deployed in many areas in order to address the problem of speed mismatch between message producers and consumers. When using Kafka, we need to quickly receive data sent by producers. In addition, we need to send data to consumers quickly. Therefore, the performance of Kafka is of critical importance to the performance of the whole stream processing system. In this paper, we propose the improved design of real-time stream processing systems, and focus on improving the Kafka's data loading process.We use Kafka cat to transfer data from the source to Kafka topic directly, which can reduce the network transmission. We also utilize the memory file system to accelerate the process of data loading, which can address the bottleneck and performance problems caused by disk I/O. Extensive experiments are conducted to evaluate the performance, which show the superiority of our improved design.
基金Supported by the National Natural Science Foundation of China(No.61401496)
文摘Aiming at the problems of unreliable data transmission,poor steadiness,nonsupport of complex data types,direct couple between data transmission and exchange,a high-level method based on advanced message queuing protocol( AMQP) is proposed to integrate naval distributed tactical training simulation system after serious consideration with current information exchange features of military combat system. Transferring layer in traditional user datagram protocol is implemented by publishing and subscribing scheme of message middleware. By creating message model to standardize message structure,integration architecture is formulated to resolve potential information security risks from inconsistent data type and express data transmission. Meanwhile,a communication model is put forward based on AMQP,which is in the center position of the whole transmission framework and responsible for reliably transferring battlefield data among subsystems. Experiments show that the method can accurately post amounts of data to the subscriber without error and loss,and can get excellent real-time performance of data exchange.
基金This work was supported by the Mobile Police Project of China(No.J1GAB23W013)National High Technology Research and Development Program of China(863 Program,No.2007AA01Z479).
文摘According to the security requirement of the short message service （SMS） industry application, a secure short message communication protocol is proposed. This is an application level protocol constructed on the standard SMS communication protocol using public key authentication and key agreement without the need of wireless public key infrastructure （WPKI）. Secure short message transmission and dynamic key agreement between mobile terminals and the accessing gateway axe realized. The security of the proposed protocol is validated through the BAN logic. Compared with the standard SMS protocol, the effective payload rate of our protocol can reach 91.4%, and subscriber identity module （SIM） tool kit （STK） applications based on our protocol suit well for all kinds of mobile terminals in practical application.
基金Supported by the National Natural Science Foun-dation of China (90104005 ,66973034)
文摘Based on the analysis of the covert channel＇s working mechanism of the internet control message protocol （ICMP） in internet protocol version 4 （IPv4） and Internet Protocol version 6 （IPv6）, the ICMP covert channd＇s algorithms of the IPv4 and IPv6 are presented, which enable automatic channeling upon IPv4/v6 nodes with non-IPv4-compatible address, and the key transmission is achieved by using this channel in the embedded Internet terminal. The result shows that the covert channel＇s algorithm, which we implemented if, set correct, the messages of this covert channel might go through the gateway and enter the local area network.
文摘One of the most important features of modem minor satellites is to realize autonomous moving. The perfomance of the satellite autonomous computer operating system acting as the control center is of utrnost importance. The recent trend in operating system development is adopting microkernel architecture that holds such advantages as microminiaturization, modularity, portability and extendibility. IPC is the key of microkernel design. Message-based IPC mechanism is generally used in existing microkernel Operating system. It is of consistency, safety and reliability.However, it can not provide efficient support for real-time applications in satellite systems and it only applies to loose coupling multi-processor architecture. In this paper, an improvement solution for existing message-based IPC is proposed at first to obtain real-time performance. Then a new IPC mechanism is designed. It particulary applies to shared memory tight coupling multi-processor architecture.
文摘Distributed speech recognition (DSR) applications have certain QoS (Quality of service) requirements in terms of latency, packet loss rate, etc. To deliver quality guaranteed DSR application over wirelined or wireless links, some QoS mechanisms should be provided. We put forward a RTP/RSVP transmission scheme with DSR-specific payload and QoS parameters by modifying the present WAP protocol stack. The simulation result shows that this scheme will provide adequate network bandwidth to keep the real-time transport of DSR data over either wirelined or wireless channels.
基金This research was supported by National Natural Science Foundation of China(Grant Nos.61972048,62072051).
文摘The Internet Control Message Protocol(ICMP)covert tunnel refers to a network attack that encapsulates malicious data in the data part of the ICMP protocol for transmission.Its concealment is stronger and it is not easy to be discovered.Most detection methods are detecting the existence of channels instead of clarifying specific attack intentions.In this paper,we propose an ICMP covert tunnel attack intent detection framework ICMPTend,which includes five steps:data collection,feature dictionary construction,data preprocessing,model construction,and attack intent prediction.ICMPTend can detect a variety of attack intentions,such as shell attacks,sensitive directory access,communication protocol traffic theft,filling tunnel reserved words,and other common network attacks.We extract features from five types of attack intent found in ICMP channels.We build a multi-dimensional dictionary of malicious features,including shell attacks,sensitive directory access,communication protocol traffic theft,filling tunnel reserved words,and other common network attack keywords.For the high-dimensional and independent characteristics of ICMP traffic,we use a support vector machine(SVM)as a multi-class classifier.The experimental results show that the average accuracy of ICMPTend is 92%,training ICMPTend only takes 55 s,and the prediction time is only 2 s,which can effectively identify the attack intention of ICMP.
基金supported in part by the National Key R&D Program of China(No.2022YFB3904503)National Natural Science Foundation of China(No.62172418)the joint funds of National Natural Science Foundation of China and Civil Aviation Administration of China(No.U2133203).
文摘Due to the lack of authentication mechanism in BeiDou navigation satellite system(BDS),BD-Ⅱ civil navigation message(BDⅡ-CNAV) are vulnerable to spoofing attack and replay attack.To solve this problem,we present a security authentication protocol,called as BDSec,which is designed by using China’s cryptography Shangyong Mima(SM) series algorithms,such as SM2/4/9 and Zu Chongzhi(ZUC)algorithm.In BDSec protocol,both of BDⅡ-CNAV and signature information are encrypted using the SM4 algorithm(Symmetric encryption mechanism).The encrypted result is used as the subject authentication information.BDSec protocol applies SM9 algorithm(Identity-based cryptography mechanism) to protect the integrity of the BDⅡ-CNAV,adopts the SM2 algorithm(Public key cryptosystem) to guarantee the confidentiality of the important session information,and uses the ZUC algorithm(Encryption and integrity algorithm) to verify the integrity of the message authentication serial number and initial information and the information in authentication initialization sub-protocol respectively.The results of the SVO logic reasoning and performance analysis show that BDSec protocol meets security requirements for the dual user identity authentication in BDS and can realize the security authentication of BDⅡ-CNAV.
基金Supported by the Emphases Science and Technology Project Foundation of Sichuan Province(NO.02GG006-037)
文摘By thorough research on the prominent periodic and aperiodic scheduling algorithms,anon-line hard real-time scheduler is presented,which is applicable to the scheduling of packets over a link.This scheduler,based on both Rate Monotonic,pinwheel scheduling algorithm Sr and Polling Serverscheduling algorithms,can rapidly judge the schedulability and then automatically generate a bus tablefor the scheduling algorithm to schedule the packets as the periodic packets.The implementation of thescheduler is simple and easy to use,and it is effective for the utilization of bus link.The orderly executionof the bus table can not only guarantee the performance of the hard real time but also avoid the blockageand interruption of the message transmission.So the scheduler perfectly meets the demand of hard real-time communication system on the field bus domain.
文摘Relying on CMPP (China Mobile Peer to Peer) protocol,we propose and design SMS (Short Message Service) gateway interface for early warning plan based on real-time meteorological database application,in order to form the meteorological mobile internet service system which is 'One point connect,service the whole province' for short.Accessing interface system to each city's SMG (Short Message Gateway) through standard protocol,we establish the information transmitting channel of short message platform and mobile SMG to realize the store-forward and flow control of short message.In addition,the stable and dependable communication connect of interface system and mobile SMG should be ensure,and the connect could be reconstructed while encountering any error,as well as committing short message would be stopped due to interruption of connect.
基金The National High Technology Research and Development Program of China (863Program)(No2006AA01Z268)
文摘To cope with the problem of low protocol efficiency of the standard ad hoc on-demand distance vector （AODV） routing protocol with the periodic Hello message broadcast mechanism, a new link availability prediction based strategy is introduced to reduce the amount of Hello messages. In this strategy, a novel wireless link availability prediction model under line-of-sight （LOS） propagation environments is proposed based on which the parameter of Hello Interval in AODV can be dynamically adjusted to achieve the goal of changing the frequency of Hello message broadcasts under different link stability degrees. Simulation results demonstrate that, compared with the standard AODV with the periodic Hello message broadcast mechanism, the proposed protocol effectively reduces unnecessary control message overhead and greatly improves the performance in terms of end-to-end delay and efficiency.
基金partially supported by National Key Research and Development Program of China(2018YFB1700200)National Natural Science Foundation of China(61972389,61903356,61803368,U1908212)+2 种基金Youth Innovation Promotion Association of the Chinese Academy of Sciences,National Science and Technology Major Project(2017ZX02101007-004)Liaoning Provincial Natural Science Foundation of China(2020-MS-034,2019-YQ-09)China Postdoctoral Science Foundation(2019M661156)。
文摘Time-sensitive networks(TSNs)support not only traditional best-effort communications but also deterministic communications,which send each packet at a deterministic time so that the data transmissions of networked control systems can be precisely scheduled to guarantee hard real-time constraints.No-wait scheduling is suitable for such TSNs and generates the schedules of deterministic communications with the minimal network resources so that all of the remaining resources can be used to improve the throughput of best-effort communications.However,due to inappropriate message fragmentation,the realtime performance of no-wait scheduling algorithms is reduced.Therefore,in this paper,joint algorithms of message fragmentation and no-wait scheduling are proposed.First,a specification for the joint problem based on optimization modulo theories is proposed so that off-the-shelf solvers can be used to find optimal solutions.Second,to improve the scalability of our algorithm,the worst-case delay of messages is analyzed,and then,based on the analysis,a heuristic algorithm is proposed to construct low-delay schedules.Finally,we conduct extensive test cases to evaluate our proposed algorithms.The evaluation results indicate that,compared to existing algorithms,the proposed joint algorithm improves schedulability by up to 50%.
文摘There is a lack of appropriate guidelines for realistic user traces, mobility models, routing protocols, considerations of real-life challenges, etc. for general-purpose mobile ad hoc networks （MANET）. In this paper, four laptops are used in an open field environment in four scenarios to evaluate the performances of Internet control message protocol （ICMP） based ping and transmission control protocol （TCP） based streaming video applications using optimised link state routing （OLSR） implementation in an IEEE 802.11g wireless network. Corresponding simulations are developed in Network Simulator ns-2 by setting simulation parameters according to the real experiments. Difficulties faced to regenerate real-life scenarios have been discussed and the gaps between reality and simulation are identified. A setup guideline to produce realistic simulation results has been established.
基金National Natural Science Foundation of China under Grant No.61872111Sichuan Science and Technology Program(No.2019YFSY0049)the“Project for the Development and Application of Safety Testing and Verification Platform for Industrial Robots”of the Ministry of Industry and Information Technology.
文摘With the rapid development of the Internet,a large number of private protocols emerge on the network.However,some of them are constructed by attackers to avoid being analyzed,posing a threat to computer network security.The blockchain uses the P2P protocol to implement various functions across the network.Furthermore,the P2P protocol format of blockchain may differ from the standard format specification,which leads to sniffing tools such as Wireshark and Fiddler not being able to recognize them.Therefore,the ability to distinguish different types of unknown network protocols is vital for network security.In this paper,we propose an unsupervised clustering algorithm based on maximum frequent sequences for binary protocols,which can distinguish various unknown protocols to provide support for analyzing unknown protocol formats.We mine the maximum frequent sequences of protocolmessage sets in bytes.Andwe calculate the fuzzymembership of the protocolmessage to each maximum frequent sequence,which is based on fuzzy set theory.Then we construct the fuzzy membership vector for each protocol message.Finally,we adopt K-means++to split different types of protocol messages into several clusters and evaluate the performance by calculating homogeneity,integrity,and Fowlkes and Mallows Index(FMI).Besides,the clustering algorithms based onNeedleman–Wunsch and the fixed-length prefix are compared with the algorithm presented in this paper.Compared with these traditional clustering methods,we demonstrate a certain improvement in the clustering performance of our work.
文摘This paper proposed two modifications on IKE protocol with pre-shared key authentication. The first modification can improve its immunity against DDoS attack by authenticating the initiator before the responder generates the computation-intensive Diffie-Hellman public value. The second modification can improve its efficiency when the attack on messages occurs because it can detect the attack quickly by replacing the centralized authentication in origical IKE protocol with immediate authentication. In addition, the two modifications can be integrated into one protocol compactly.
