A mode of process/thread communication between QNX and WINDOWS operating systems in isomerous computers is described. It is proved in practice to be an entirely feasible mode with high efficiency and reliability. A so...A mode of process/thread communication between QNX and WINDOWS operating systems in isomerous computers is described. It is proved in practice to be an entirely feasible mode with high efficiency and reliability. A socket created by Socket API is used to communicate between two operating systems.展开更多
Transmission Control Protocol (TCP) was originally designed for wired networks. Many compatibility problems exist when it is applied to wireless environments, and hence it needs to undergo modifications. Currently, th...Transmission Control Protocol (TCP) was originally designed for wired networks. Many compatibility problems exist when it is applied to wireless environments, and hence it needs to undergo modifications. Currently, there are several TCP performance enhancement techniques for application of TCP in wireless environments, but all of them conflict with IPsec. This paper not only analyzes these conflicts, but also proposes 4 solutions: replacing IPsec with Transport Layer Security/Secure Socket Layer (TLS/SSL) protocol, adopting the extended Encapsulating Security Payload (ESP) protocol, segmenting the TCP route, and modifying the end-to-end protection mode of IPsec. It also presents their strengths and weaknesses.展开更多
A new core-based shared tree algorithm, viz core-cluster combination-based shared tree （CCST） algorithm and the weighted version （i.e. w-CCST algorithm） are proposed in order to resolve the channel resources waste...A new core-based shared tree algorithm, viz core-cluster combination-based shared tree （CCST） algorithm and the weighted version （i.e. w-CCST algorithm） are proposed in order to resolve the channel resources waste problem in typical source-based multicast routing algorithms in low earth orbit （LEO） satellite IP networks. The CCST algorithm includes the dynamic approximate center （DAC） core selection method and the core-cluster combination multicast route construction scheme. Without complicated onboard computation, the DAC method is uniquely developed for highly dynamic networks of periodical and regular movement. The core-cluster combination method takes core node as the initial core-cluster, and expands it stepwise to construct an entire multicast tree at the lowest tree cost by a shortest path scheme between the newly-generated core-cluster and surplus group members, which results in great bandwidth utilization. Moreover, the w-CCST algorithm is able to strike a balance between performance of tree cost and that of end-to-end propagation delay by adjusting the weighted factor to meet strict end-to-end delay requirements of some real-time multicast services at the expense of a slight increase in tree cost. Finally, performance comparison is conducted between the proposed algorithms and typical algorithms in LEO satellite IP networks. Simulation results show that the CCST algorithm significantly decreases the average tree cost against to the others, and also the average end-to-end propagation delay ofw-CCST algorithm is lower than that of the CCST algorithm.展开更多
A lot of routing algorithms have been proposed for low earth orbit（LEO） satellite IP networks in recent years,but most of them cannot achieve global optimization.The dynamic characters of LEO satellite networks are ...A lot of routing algorithms have been proposed for low earth orbit（LEO） satellite IP networks in recent years,but most of them cannot achieve global optimization.The dynamic characters of LEO satellite networks are reflected in two aspects：topology and traffic change.The algorithms mentioned above are ＂hard routing＂ which only realize local optimization.A distributed soft routing algorithm combined with multi-agent system（MASSR） is proposed.In MASSR,mobile agents are used to gather routing information actively,and blackboard is introduced to achieve direct information exchange between agents.MASSR provides traffic adaptive routing and tracks the change of LEO satellite network topology.The performance of ant colony optimization（ACO） and MASSR are compared in Iridium constellation,and MASSR presents better end-to-end delay as well as enhanced robustness.展开更多
Taking into chief consideration the features of aviation nodes in satellite networks, such as high moving speed, long communication distance, and high connection frequency, this article proposes an aviation-oriented m...Taking into chief consideration the features of aviation nodes in satellite networks, such as high moving speed, long communication distance, and high connection frequency, this article proposes an aviation-oriented mobility management method for IP/low earth orbit （LEO） satellite networks. By introducing the concept of ground station real-time coverage area, the proposed method uses ground-station-based IP addressing method and cell paging scheme to decrease the frequency of IP binding update requests as well as the paging cost. In comparison with the paging mobile IP （P-MIP） method and the handover-independent IP mobility management method, as is verified by the mathematical analysis and simulation, the proposed method could decrease the management cost. It also possesses better ability to support the aviation nodes because it is subjected to fewer influences from increased node speeds and newly coming connection rates.展开更多
In this paper we have designed an implemented an integrated framework of QoS for Three Level Mobility Model(TLMM),which has been recently proved to be the optimal mobility management solution for next generation wirel...In this paper we have designed an implemented an integrated framework of QoS for Three Level Mobility Model(TLMM),which has been recently proved to be the optimal mobility management solution for next generation wireless IP-based networks.The QoS solution uses a combination of IntServ and DiffServ models incorporated in TLMM architecture.The paper also proposes an effi cient dynamic handover policy that takes care of false handover.Simulation and analytical results have shown that this infrastructure guarantees eff icient QoS handling and scalability among end users.To provide a comparative understanding of the QoS mechanism and signaling load of TLMM we have used TeleMIP(without QoS support) and MIP as alternative mobility management protocols.展开更多
Computerized power management system with fast and optimal communication network overcomes all major dicrepencies of undue or inadequate load relief that were present in old conventional systems. This paper presents t...Computerized power management system with fast and optimal communication network overcomes all major dicrepencies of undue or inadequate load relief that were present in old conventional systems. This paper presents the basic perception and methodology of modern and true intelligent load management scheme in micro grids topology by employing TCP/IP protocol for fast and intelligent switching. The network understudy performs load management and power distribution intelligently in a unified network. Generated power is efficiently distributed among local loads through fast communication system of server in the form of source and clients in the form of loads through TCP/IP. The efficient use of information between server and clients enables to astutely control the load management in a power system of micro grids system. The processing time of above stated system comes out to be 10ms faster than others which ensure very less delay as compared to conventional methods. The Micro Grids system operating through TCP/IP control has been implemented in MATLAB/Simulink and results have been verified.展开更多
This paper mainly introduces about how to use socket to design network program which can transfer data in different network platform in terms of TCP/IP Network Programming Standard.
The IP-based networks on aircraft serve to support Intemet services via satellites. However, in aeronautical satellite hybrid networks, the TCP protocol performance often deteriorates due to improper decreases and slo...The IP-based networks on aircraft serve to support Intemet services via satellites. However, in aeronautical satellite hybrid networks, the TCP protocol performance often deteriorates due to improper decreases and slow recovery of the congestion window. This paper proposes a window size determination and notification mechanism, onboard-gateway-based mechanism （OGBM）, which is based on the onboard gateway in the networks on aircraft. A cross-layer approach is adopted by the onboard gateway to obtain the satellite link bandwidth information. And then, by the gateway, through changing the receiver＇s advertised window field in ACK packets, TCP sources are notified of the window size of each TCP source calculated on the ground of bandwidth delay product and flow numbers. The mechanism is able to avoid improper changes of TCP window and serve multiple users. Simulation results show that the mechanism with the fairness index close to l improves TCP performance in aeronautical satellite networks.展开更多
Active Queue Management (AQM) is an active research area in the Internet community. Random Early Detection (RED) is a typical AQM algorithm, but it is known that it is difficult to configure its parameters and its ave...Active Queue Management (AQM) is an active research area in the Internet community. Random Early Detection (RED) is a typical AQM algorithm, but it is known that it is difficult to configure its parameters and its average queue length is closely related to the load level. This paper proposes an effective fuzzy congestion control algorithm based on fuzzy logic which uses the pre- dominance of fuzzy logic to deal with uncertain events. The main advantage of this new congestion control algorithm is that it discards the packet dropping mechanism of RED, and calculates packet loss according to a preconfigured fuzzy logic by using the queue length and the buffer usage ratio. Theo- retical analysis and Network Simulator (NS) simulation results show that the proposed algorithm achieves more throughput and more stable queue length than traditional schemes. It really improves a router's ability in network congestion control in IP network.展开更多
基金The project supported by the National Meg-science Engineering project of the Chinese Government
文摘A mode of process/thread communication between QNX and WINDOWS operating systems in isomerous computers is described. It is proved in practice to be an entirely feasible mode with high efficiency and reliability. A socket created by Socket API is used to communicate between two operating systems.
文摘Transmission Control Protocol (TCP) was originally designed for wired networks. Many compatibility problems exist when it is applied to wireless environments, and hence it needs to undergo modifications. Currently, there are several TCP performance enhancement techniques for application of TCP in wireless environments, but all of them conflict with IPsec. This paper not only analyzes these conflicts, but also proposes 4 solutions: replacing IPsec with Transport Layer Security/Secure Socket Layer (TLS/SSL) protocol, adopting the extended Encapsulating Security Payload (ESP) protocol, segmenting the TCP route, and modifying the end-to-end protection mode of IPsec. It also presents their strengths and weaknesses.
基金National Natural Science Foundation of China （60532030, 10577005, 60625102） Innovation Foundation of Aerospace Science and Technology of China
文摘A new core-based shared tree algorithm, viz core-cluster combination-based shared tree （CCST） algorithm and the weighted version （i.e. w-CCST algorithm） are proposed in order to resolve the channel resources waste problem in typical source-based multicast routing algorithms in low earth orbit （LEO） satellite IP networks. The CCST algorithm includes the dynamic approximate center （DAC） core selection method and the core-cluster combination multicast route construction scheme. Without complicated onboard computation, the DAC method is uniquely developed for highly dynamic networks of periodical and regular movement. The core-cluster combination method takes core node as the initial core-cluster, and expands it stepwise to construct an entire multicast tree at the lowest tree cost by a shortest path scheme between the newly-generated core-cluster and surplus group members, which results in great bandwidth utilization. Moreover, the w-CCST algorithm is able to strike a balance between performance of tree cost and that of end-to-end propagation delay by adjusting the weighted factor to meet strict end-to-end delay requirements of some real-time multicast services at the expense of a slight increase in tree cost. Finally, performance comparison is conducted between the proposed algorithms and typical algorithms in LEO satellite IP networks. Simulation results show that the CCST algorithm significantly decreases the average tree cost against to the others, and also the average end-to-end propagation delay ofw-CCST algorithm is lower than that of the CCST algorithm.
基金supported by the National Natural Science Foundation of China (60532030)
文摘A lot of routing algorithms have been proposed for low earth orbit（LEO） satellite IP networks in recent years,but most of them cannot achieve global optimization.The dynamic characters of LEO satellite networks are reflected in two aspects：topology and traffic change.The algorithms mentioned above are ＂hard routing＂ which only realize local optimization.A distributed soft routing algorithm combined with multi-agent system（MASSR） is proposed.In MASSR,mobile agents are used to gather routing information actively,and blackboard is introduced to achieve direct information exchange between agents.MASSR provides traffic adaptive routing and tracks the change of LEO satellite network topology.The performance of ant colony optimization（ACO） and MASSR are compared in Iridium constellation,and MASSR presents better end-to-end delay as well as enhanced robustness.
基金National Natural Science Foundation of China (60532030)National Natural Science Foundation for Distinguished Young Scholars (60625102)
文摘Taking into chief consideration the features of aviation nodes in satellite networks, such as high moving speed, long communication distance, and high connection frequency, this article proposes an aviation-oriented mobility management method for IP/low earth orbit （LEO） satellite networks. By introducing the concept of ground station real-time coverage area, the proposed method uses ground-station-based IP addressing method and cell paging scheme to decrease the frequency of IP binding update requests as well as the paging cost. In comparison with the paging mobile IP （P-MIP） method and the handover-independent IP mobility management method, as is verified by the mathematical analysis and simulation, the proposed method could decrease the management cost. It also possesses better ability to support the aviation nodes because it is subjected to fewer influences from increased node speeds and newly coming connection rates.
文摘In this paper we have designed an implemented an integrated framework of QoS for Three Level Mobility Model(TLMM),which has been recently proved to be the optimal mobility management solution for next generation wireless IP-based networks.The QoS solution uses a combination of IntServ and DiffServ models incorporated in TLMM architecture.The paper also proposes an effi cient dynamic handover policy that takes care of false handover.Simulation and analytical results have shown that this infrastructure guarantees eff icient QoS handling and scalability among end users.To provide a comparative understanding of the QoS mechanism and signaling load of TLMM we have used TeleMIP(without QoS support) and MIP as alternative mobility management protocols.
文摘Computerized power management system with fast and optimal communication network overcomes all major dicrepencies of undue or inadequate load relief that were present in old conventional systems. This paper presents the basic perception and methodology of modern and true intelligent load management scheme in micro grids topology by employing TCP/IP protocol for fast and intelligent switching. The network understudy performs load management and power distribution intelligently in a unified network. Generated power is efficiently distributed among local loads through fast communication system of server in the form of source and clients in the form of loads through TCP/IP. The efficient use of information between server and clients enables to astutely control the load management in a power system of micro grids system. The processing time of above stated system comes out to be 10ms faster than others which ensure very less delay as compared to conventional methods. The Micro Grids system operating through TCP/IP control has been implemented in MATLAB/Simulink and results have been verified.
文摘This paper mainly introduces about how to use socket to design network program which can transfer data in different network platform in terms of TCP/IP Network Programming Standard.
基金National Natural Science Foundation of China (60532030)
文摘The IP-based networks on aircraft serve to support Intemet services via satellites. However, in aeronautical satellite hybrid networks, the TCP protocol performance often deteriorates due to improper decreases and slow recovery of the congestion window. This paper proposes a window size determination and notification mechanism, onboard-gateway-based mechanism （OGBM）, which is based on the onboard gateway in the networks on aircraft. A cross-layer approach is adopted by the onboard gateway to obtain the satellite link bandwidth information. And then, by the gateway, through changing the receiver＇s advertised window field in ACK packets, TCP sources are notified of the window size of each TCP source calculated on the ground of bandwidth delay product and flow numbers. The mechanism is able to avoid improper changes of TCP window and serve multiple users. Simulation results show that the mechanism with the fairness index close to l improves TCP performance in aeronautical satellite networks.
基金Supported by the National High Technology Research and Development of China (863 Program) (No.2003AA121560)the High Technology Research and Development Program of Jiangsu Province (No.BEG2003001).
文摘Active Queue Management (AQM) is an active research area in the Internet community. Random Early Detection (RED) is a typical AQM algorithm, but it is known that it is difficult to configure its parameters and its average queue length is closely related to the load level. This paper proposes an effective fuzzy congestion control algorithm based on fuzzy logic which uses the pre- dominance of fuzzy logic to deal with uncertain events. The main advantage of this new congestion control algorithm is that it discards the packet dropping mechanism of RED, and calculates packet loss according to a preconfigured fuzzy logic by using the queue length and the buffer usage ratio. Theo- retical analysis and Network Simulator (NS) simulation results show that the proposed algorithm achieves more throughput and more stable queue length than traditional schemes. It really improves a router's ability in network congestion control in IP network.
