在CTCS-3(Chinese Train Control System Level 3)级列控系统中,RBC(Radio Block Center)切换是影响列车安全高效运行的重要环节,现阶段对RBC切换协议进行验证分析所使用的形式化方法还存在状态爆炸或描述性质单一等问题。基于Timed RA...在CTCS-3(Chinese Train Control System Level 3)级列控系统中,RBC(Radio Block Center)切换是影响列车安全高效运行的重要环节,现阶段对RBC切换协议进行验证分析所使用的形式化方法还存在状态爆炸或描述性质单一等问题。基于Timed RAISE的形式化方法,结合域的模型,在对RBC切换流程分析的基础上,构建状态转移图,得到切换协议的形式化模型,使用等价和推断的推理规则对模型的正确性和实时性进行推理验证,得到的结果表明,RBC切换协议满足规范标准对正确性与实时性的要求,将验证结果与其他文献的结论进行比较分析,说明该方法具有通用性,对于推广其在列控系统场景验证中的应用有一定的实际意义。展开更多
The basic mobile IP protocol is simple but only suitable for wide area and low speed networks. In this paper, we propose a novel micro-mobile IP handoff scheme, that is the packet loss avoidance handoff scheme. By usi...The basic mobile IP protocol is simple but only suitable for wide area and low speed networks. In this paper, we propose a novel micro-mobile IP handoff scheme, that is the packet loss avoidance handoff scheme. By using an additional cache at the base station and distinguishing packets with packet IDs, the proposed scheme minimizes the number of lost packets during handoff. Network architecture and detailed handoff procedures are given. We also analyze the cache size at the base station, the associated network load with the handoff procedure, and the handoff delay. The scheme is investigated by computer simulations. Simulation results show that the proposed scheme is suitable for environments with fast mobility and frequent handoff.展开更多
A new coarse-grained differentiated least interference routing algorithm(CDLI) with DiffServ-Aware was presented.This algorithm is composed of off-line and on-line stages,taking into account both real-time traffic and...A new coarse-grained differentiated least interference routing algorithm(CDLI) with DiffServ-Aware was presented.This algorithm is composed of off-line and on-line stages,taking into account both real-time traffic and best-effort traffic.Off-line stage is to determine the shortest path set disjointed path(DP) database for real-time traffic,and to identify link critical value by traffic profile information of real-time traffic and DP database.On-line stage is at first to select route in the DP database for real-time traffic,if there is no path to meet the needs,the dynamic routing will be operated.On-line routing algorithm chooses the relatively short path for real-time traffic to meet their bandwidth requirements,and for best-effort traffic it chooses a lighter load path.The simulation results show that compared with the dynamic online routing algorithm(DORA) and constrained shortest path first(CSPF) algorithm,the new algorithm can significantly improve network throughput and reduce the average path length of real-time traffic.This guarantees quality of service(QoS) of real-time traffic while improving the utilization of network resources.展开更多
The rapid development of network raise the role of WAN. As a large-scale backbone network, the failure of network components can lead to huge loss of data and revenue. How to improve the data switching speed and Quali...The rapid development of network raise the role of WAN. As a large-scale backbone network, the failure of network components can lead to huge loss of data and revenue. How to improve the data switching speed and Quality of Service of network data is more and more important problem which Internet Server Provides cared. Multi-Protocol Lable Switching （MPLS） is a new WAN technology which is currently being standardized by IETF. This paper analysise the architecture of MPLS and describe the mechanism of label switching protocol. In addition, this study analyses the encapsulation of data packet at the Label Switching Routers which is on the boundary of MPLS network. A Label Switching Path （LSP） is built by Label Distribute Protocol in core network. A conclution of ＂one time routed, more times switching＂ routed was reached.展开更多
文摘在CTCS-3(Chinese Train Control System Level 3)级列控系统中,RBC(Radio Block Center)切换是影响列车安全高效运行的重要环节,现阶段对RBC切换协议进行验证分析所使用的形式化方法还存在状态爆炸或描述性质单一等问题。基于Timed RAISE的形式化方法,结合域的模型,在对RBC切换流程分析的基础上,构建状态转移图,得到切换协议的形式化模型,使用等价和推断的推理规则对模型的正确性和实时性进行推理验证,得到的结果表明,RBC切换协议满足规范标准对正确性与实时性的要求,将验证结果与其他文献的结论进行比较分析,说明该方法具有通用性,对于推广其在列控系统场景验证中的应用有一定的实际意义。
文摘The basic mobile IP protocol is simple but only suitable for wide area and low speed networks. In this paper, we propose a novel micro-mobile IP handoff scheme, that is the packet loss avoidance handoff scheme. By using an additional cache at the base station and distinguishing packets with packet IDs, the proposed scheme minimizes the number of lost packets during handoff. Network architecture and detailed handoff procedures are given. We also analyze the cache size at the base station, the associated network load with the handoff procedure, and the handoff delay. The scheme is investigated by computer simulations. Simulation results show that the proposed scheme is suitable for environments with fast mobility and frequent handoff.
基金Project(2003AA781011) supported by the National High-Tech Research and Development of Program of China Project(20072022) supported by Science and Technology Foundation of Liaoning Province,China
文摘A new coarse-grained differentiated least interference routing algorithm(CDLI) with DiffServ-Aware was presented.This algorithm is composed of off-line and on-line stages,taking into account both real-time traffic and best-effort traffic.Off-line stage is to determine the shortest path set disjointed path(DP) database for real-time traffic,and to identify link critical value by traffic profile information of real-time traffic and DP database.On-line stage is at first to select route in the DP database for real-time traffic,if there is no path to meet the needs,the dynamic routing will be operated.On-line routing algorithm chooses the relatively short path for real-time traffic to meet their bandwidth requirements,and for best-effort traffic it chooses a lighter load path.The simulation results show that compared with the dynamic online routing algorithm(DORA) and constrained shortest path first(CSPF) algorithm,the new algorithm can significantly improve network throughput and reduce the average path length of real-time traffic.This guarantees quality of service(QoS) of real-time traffic while improving the utilization of network resources.
文摘The rapid development of network raise the role of WAN. As a large-scale backbone network, the failure of network components can lead to huge loss of data and revenue. How to improve the data switching speed and Quality of Service of network data is more and more important problem which Internet Server Provides cared. Multi-Protocol Lable Switching （MPLS） is a new WAN technology which is currently being standardized by IETF. This paper analysise the architecture of MPLS and describe the mechanism of label switching protocol. In addition, this study analyses the encapsulation of data packet at the Label Switching Routers which is on the boundary of MPLS network. A Label Switching Path （LSP） is built by Label Distribute Protocol in core network. A conclution of ＂one time routed, more times switching＂ routed was reached.
