In Vehicle-to-infrastructure(V2I)communication networks,mobile users are able to access Internet services,such as video streaming,digital map downloading,database access,online gaming,and even safety services like acc...In Vehicle-to-infrastructure(V2I)communication networks,mobile users are able to access Internet services,such as video streaming,digital map downloading,database access,online gaming,and even safety services like accident alarm,traffic condition broadcast,etc.,through fixed roadside units.However,the dynamics of communication environment and frequent changing topology critically challenge the design of an efficient transport layer protocol,which makes it difficult to guarantee diverse Quality of Service(QoS) requirements for various applications.In this paper,we present a novel transport layer scheme in infrastructure based vehicular networks,and aim to resolve some challenging issues such as source transfer rate adjustment,congestion avoidance,and fairness.By precisely detecting packet losses and identifying various causes of these losses(for example,link disconnection,channel error,packet collision,buffer overflow),the proposed scheme adopts different reacting mechanisms to deal with each of the losses.Moreover,it timely monitors the buffer size of the bottleneck Road-Side Unit(RSU),and dynamically makes transfer rate feedbacks to source nodes to avoid buffer overflow or vacancy.Finally,analysis and simulation results show that the proposed scheme not only successfully reduces packet losses because of buffer overflow and link disconnection but also improves the utilization efficiency of channel resource.展开更多
This paper analyzes a discrete-time multiple vacations finite-buffer queueing system with batch renewal input in which inter-arrival time of batches are arbitrarily distributed. Service and vacation times are mutually...This paper analyzes a discrete-time multiple vacations finite-buffer queueing system with batch renewal input in which inter-arrival time of batches are arbitrarily distributed. Service and vacation times are mutually independent and geometrically distributed. The server takes vacations when the system does not have any waiting jobs at a service completion epoch or a vacation completion epoch. The system is analyzed under the assumptions of late arrival system with delayed access and early arrival system. Using the supplementary variable and the imbedded Markov chain techniques, the authors obtain the queue-length distributions at pre-arrival, arbitrary and outside observer＇s ob- servation epochs for partial-batch rejection policy. The blocking probability of the first, an arbitrary- and the last-job in a batch have been discussed. The analysis of actual waiting-time distributions measured in slots of the first, an arbitrary- and the last-job in an accepted batch, and other performance measures along with some numerical results have also been investigated.展开更多
基金ACKNOWLEDGEMENT This work was partially supported by the Na- tional Natural Science Foundation of China under Grant No. 61101121 the Fundamental Research Funds for the Central Universities of China under Grant No. N110404002+2 种基金 the Key Laboratory Project Funds of Shenyang Ligong University under Grant No. 4771004kfs03 the Educational Committee of Liaoning Province Science and Technology Research Projects under Grant No. L2013096 the National Sci- ence and Technology Support Program under Grant No. 2012BAH82F04.
文摘In Vehicle-to-infrastructure(V2I)communication networks,mobile users are able to access Internet services,such as video streaming,digital map downloading,database access,online gaming,and even safety services like accident alarm,traffic condition broadcast,etc.,through fixed roadside units.However,the dynamics of communication environment and frequent changing topology critically challenge the design of an efficient transport layer protocol,which makes it difficult to guarantee diverse Quality of Service(QoS) requirements for various applications.In this paper,we present a novel transport layer scheme in infrastructure based vehicular networks,and aim to resolve some challenging issues such as source transfer rate adjustment,congestion avoidance,and fairness.By precisely detecting packet losses and identifying various causes of these losses(for example,link disconnection,channel error,packet collision,buffer overflow),the proposed scheme adopts different reacting mechanisms to deal with each of the losses.Moreover,it timely monitors the buffer size of the bottleneck Road-Side Unit(RSU),and dynamically makes transfer rate feedbacks to source nodes to avoid buffer overflow or vacancy.Finally,analysis and simulation results show that the proposed scheme not only successfully reduces packet losses because of buffer overflow and link disconnection but also improves the utilization efficiency of channel resource.
文摘This paper analyzes a discrete-time multiple vacations finite-buffer queueing system with batch renewal input in which inter-arrival time of batches are arbitrarily distributed. Service and vacation times are mutually independent and geometrically distributed. The server takes vacations when the system does not have any waiting jobs at a service completion epoch or a vacation completion epoch. The system is analyzed under the assumptions of late arrival system with delayed access and early arrival system. Using the supplementary variable and the imbedded Markov chain techniques, the authors obtain the queue-length distributions at pre-arrival, arbitrary and outside observer＇s ob- servation epochs for partial-batch rejection policy. The blocking probability of the first, an arbitrary- and the last-job in a batch have been discussed. The analysis of actual waiting-time distributions measured in slots of the first, an arbitrary- and the last-job in an accepted batch, and other performance measures along with some numerical results have also been investigated.
