According to the fact that the secondary users＇ delay requirements for data transmission are not unitary in cognitive radio networks, the secondary users are divided into two classes, denoted by SU1 and SU2, respecti...According to the fact that the secondary users＇ delay requirements for data transmission are not unitary in cognitive radio networks, the secondary users are divided into two classes, denoted by SU1 and SU2, respectively. It is assumed that SU1 has a higher priority to occupy the primary users＇ unutilized channels than SU2. A preemptive resume priority M/G/1 queuing network is used to model the multiple spectrum handoffs processing. By using a state transition probability matrix and a cost matrix, the average cumulative delays of SU1 and SU2 are calculated, respectively. Numerical results show that the more the primary user＇s traffic load, the more rapidly the SU2＇s cumulative handoff delay grows. Compared with the networks where secondary users are unitary, the lower the SUI＇s arrival rate, the more obviously both SUI＇s and SU2＇s handoff delays decrease. The admission access regions limited by the maximum tolerable delay can also facilitate the design of admission control rules for graded secondary users.展开更多
This paper proposes an algorithm for train delay propagation on double-track railway lines under First-Come-First-Serve(FCFS)management.The objective is to handle the challenges faced by the dispatchers as they encoun...This paper proposes an algorithm for train delay propagation on double-track railway lines under First-Come-First-Serve(FCFS)management.The objective is to handle the challenges faced by the dispatchers as they encounter train delays and their effects on the functioning of the railway system.We assume that the location and duration of disruptions are known,which are important inputs to the algorithm.This data enables calculation of delays experienced by each affected train.Our method analyzes factors such as train schedules,track capacities,and operation constraints to assess the manner in which delays would get propagated along railway lines.Key indicators of delay propagation,consisting of the number of delayed trains and stations,disruption settling time,and cumulative delays,are considered.Moreover,a numerical example is given to explain the practical application of this algorithm.Finally,we show that a tool like this would facilitate the dispatchers in managing and rescheduling trains in case of delays and will be improving resilience and efficiency of railway operations.展开更多
基金The National Natural Science Foundation of China(No.60972026,61271207)the National Science and Technology Major Project(No.2010ZX03006-002-01)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education(No.20090092110009)the Specialized Development Foundation for the Achievement Transformation of Jiangsu Province(No.BA2010023)
文摘According to the fact that the secondary users＇ delay requirements for data transmission are not unitary in cognitive radio networks, the secondary users are divided into two classes, denoted by SU1 and SU2, respectively. It is assumed that SU1 has a higher priority to occupy the primary users＇ unutilized channels than SU2. A preemptive resume priority M/G/1 queuing network is used to model the multiple spectrum handoffs processing. By using a state transition probability matrix and a cost matrix, the average cumulative delays of SU1 and SU2 are calculated, respectively. Numerical results show that the more the primary user＇s traffic load, the more rapidly the SU2＇s cumulative handoff delay grows. Compared with the networks where secondary users are unitary, the lower the SUI＇s arrival rate, the more obviously both SUI＇s and SU2＇s handoff delays decrease. The admission access regions limited by the maximum tolerable delay can also facilitate the design of admission control rules for graded secondary users.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB4300504-3).
文摘This paper proposes an algorithm for train delay propagation on double-track railway lines under First-Come-First-Serve(FCFS)management.The objective is to handle the challenges faced by the dispatchers as they encounter train delays and their effects on the functioning of the railway system.We assume that the location and duration of disruptions are known,which are important inputs to the algorithm.This data enables calculation of delays experienced by each affected train.Our method analyzes factors such as train schedules,track capacities,and operation constraints to assess the manner in which delays would get propagated along railway lines.Key indicators of delay propagation,consisting of the number of delayed trains and stations,disruption settling time,and cumulative delays,are considered.Moreover,a numerical example is given to explain the practical application of this algorithm.Finally,we show that a tool like this would facilitate the dispatchers in managing and rescheduling trains in case of delays and will be improving resilience and efficiency of railway operations.
