Low Earth orbit(LEO)satellite networks exhibit distinct characteristics,e.g.,limited resources of individual satellite nodes and dynamic network topology,which have brought many challenges for routing algorithms.To sa...Low Earth orbit(LEO)satellite networks exhibit distinct characteristics,e.g.,limited resources of individual satellite nodes and dynamic network topology,which have brought many challenges for routing algorithms.To satisfy quality of service(QoS)requirements of various users,it is critical to research efficient routing strategies to fully utilize satellite resources.This paper proposes a multi-QoS information optimized routing algorithm based on reinforcement learning for LEO satellite networks,which guarantees high level assurance demand services to be prioritized under limited satellite resources while considering the load balancing performance of the satellite networks for low level assurance demand services to ensure the full and effective utilization of satellite resources.An auxiliary path search algorithm is proposed to accelerate the convergence of satellite routing algorithm.Simulation results show that the generated routing strategy can timely process and fully meet the QoS demands of high assurance services while effectively improving the load balancing performance of the link.展开更多
Energy conservation is a significant task in the Internet of Things(IoT)because IoT involves highly resource-constrained devices.Clustering is an effective technique for saving energy by reducing duplicate data.In a c...Energy conservation is a significant task in the Internet of Things(IoT)because IoT involves highly resource-constrained devices.Clustering is an effective technique for saving energy by reducing duplicate data.In a clustering protocol,the selection of a cluster head(CH)plays a key role in prolonging the lifetime of a network.However,most cluster-based protocols,including routing protocols for low-power and lossy networks(RPLs),have used fuzzy logic and probabilistic approaches to select the CH node.Consequently,early battery depletion is produced near the sink.To overcome this issue,a lion optimization algorithm(LOA)for selecting CH in RPL is proposed in this study.LOA-RPL comprises three processes:cluster formation,CH selection,and route establishment.A cluster is formed using the Euclidean distance.CH selection is performed using LOA.Route establishment is implemented using residual energy information.An extensive simulation is conducted in the network simulator ns-3 on various parameters,such as network lifetime,power consumption,packet delivery ratio(PDR),and throughput.The performance of LOA-RPL is also compared with those of RPL,fuzzy rule-based energyefficient clustering and immune-inspired routing(FEEC-IIR),and the routing scheme for IoT that uses shuffled frog-leaping optimization algorithm(RISARPL).The performance evaluation metrics used in this study are network lifetime,power consumption,PDR,and throughput.The proposed LOARPL increases network lifetime by 20%and PDR by 5%–10%compared with RPL,FEEC-IIR,and RISA-RPL.LOA-RPL is also highly energy-efficient compared with other similar routing protocols.展开更多
Though the WiMedia supports higher data rates than other WPAN technologies,a WiMedia device cannot reach other devices that are separated from it by more than 10 m,which is the typical limited transmission range of th...Though the WiMedia supports higher data rates than other WPAN technologies,a WiMedia device cannot reach other devices that are separated from it by more than 10 m,which is the typical limited transmission range of the WiMedia protocol.In this work,we propose a multi-hop QoS routing protocol to enable WiMedia devices to transmit real-time data to devices that are located out of the transmission range.The proposed routing protocol is a hybrid algorithm,which mixes the table-driven and on-demand routing algorithms,searching one or more routes according to the number of hops to a destination device.WiMedia MAC is potentially capable of learning the existence of neighbor devices by using a beacon frame.By utilizing the neighbors' information,all devices can create routing entries for devices within 2-hops periodically.For devices beyond the 2-hop range,the newly designed on-demand routing algorithm is applied to multi-hop routing.If a routing entry for a destination device is not listed in the routing table,the source device sends a request packet to 2-hop range devices which could be found in the routing table.Since every device maintains routing entries for 2-hop range devices in the routing table,the request packet is replied in advance before its arrival at the destination device.Also,to decide the optimal route for a destination device,the number of medium access slots(MASs),received signal strength indicator(RSSI)and hop count are utilized to establish a QoS-enabled routing table.We perform ns-2 simulation to investigate the performance of the proposed routing protocol with AODV and DSDV.The simulation results show that the proposed protocol has better throughput and lower overhead than other protocols.展开更多
The application environments of wireless Ad hoc networks require that it should support Quality of Service (QoS). However, that is very difficult because of the inherent characteristics of the wireless channel and the...The application environments of wireless Ad hoc networks require that it should support Quality of Service (QoS). However, that is very difficult because of the inherent characteristics of the wireless channel and the frequent changes of network topology caused by nodes movement. An Ad hoc QoS Multicasting (AQM) protocol can solve this problem by previously reserving the neighbor nodes for tracking resource availability. By considering QoS restrictions of transport delay, loss ratio, bandwidth requirement, delay jitter, and throughout, and by finding the adaptive routing, the AQM protocol can obviously improve the efficiency of multicastsession. The results of network simulation show that QoS is essentially applicable to Ad hoc networks.展开更多
Most of the multimedia applications require strict Quality-of-Service (QoS) guarantee during the communication between a single source and multiple destinations. The paper mainly presents a QoS Multicast Routing algor...Most of the multimedia applications require strict Quality-of-Service (QoS) guarantee during the communication between a single source and multiple destinations. The paper mainly presents a QoS Multicast Routing algorithms based on Genetic Algorithm (QMRGA). Simulation results demonstrate that the algorithm is capable of discovering a set of QoS-based near optimized, non-dominated multicast routes within a few iterations, even for the networks environment with uncertain parameters.展开更多
Quality of service （QoS） routing and multicasting protocols in ad hoc networks are face with the challenge of delivering data to destinations through multihop routes in the presence of node movements and topology ch...Quality of service （QoS） routing and multicasting protocols in ad hoc networks are face with the challenge of delivering data to destinations through multihop routes in the presence of node movements and topology changes. The multicast routing problem with multiple QoS constraints is discussed, which may deal with the delay, bandwidth and cost metrics, and describes a network model for researching the ad hoc networks QoS multicast routing problem. It presents a distributed QoS multicast routing protocol （DQMRP）. The proof of correctness and complenty analysis of the DQMRP are also given. Simulation results show that the multicast tree optimized by DQMRP is better than other protocols and is fitter for the network situations with frequently changed status and the realtime multimedia application. It is an available approach to multicast routing decision with multiple QoS constraints.展开更多
In current days,the domain of Internet of Things(IoT)and Wireless Sensor Networks(WSN)are combined for enhancing the sensor related data transmission in the forthcoming networking applications.Clustering and routing t...In current days,the domain of Internet of Things(IoT)and Wireless Sensor Networks(WSN)are combined for enhancing the sensor related data transmission in the forthcoming networking applications.Clustering and routing techniques are treated as the effective methods highly used to attain reduced energy consumption and lengthen the lifetime of the WSN assisted IoT networks.In this view,this paper presents an Ensemble of Metaheuristic Optimization based QoS aware Clustering with Multihop Routing(EMOQoSCMR)Protocol for IoT assisted WSN.The proposed EMO-QoSCMR protocol aims to achieve QoS parameters such as energy,throughput,delay,and lifetime.The proposed model involves two stage processes namely clustering and routing.Firstly,the EMO-QoSCMR protocol involves crossentropy rain optimization algorithm based clustering(CEROAC)technique to select an optimal set of cluster heads(CHs)and construct clusters.Besides,oppositional chaos game optimization based routing(OCGOR)technique is employed for the optimal set of routes in the IoT assisted WSN.The proposed model derives a fitness function based on the parameters involved in the IoT nodes such as residual energy,distance to sink node,etc.The proposed EMOQoSCMR technique has resulted to an enhanced NAN of 64 nodes whereas the LEACH,PSO-ECHS,E-OEERP,and iCSHS methods have resulted in a lesser NAN of 2,10,42,and 51 rounds.The performance of the presented protocol has been evaluated interms of energy efficiency and network lifetime.展开更多
Ad hoe wireless networks consist of mobile nodes interconnected by multihop communication paths. Unlike conventional wireless networks, ad hoc networks have no fixed network infrastructure or administrative support. D...Ad hoe wireless networks consist of mobile nodes interconnected by multihop communication paths. Unlike conventional wireless networks, ad hoc networks have no fixed network infrastructure or administrative support. Due to bandwidth constraint and dynamic topology of mobile ad hoc networks, supporting Quality of Service （QoS） is an inherently complex, difficult issue and very important research issue. MAODV （Multicast Ad hoc Ondemand Distance Vector） routing protocol provides fast and efficient route establishment between mobile nodes that need to communicate with each other. MAODV has minimal control overhead and route acquisition latency. In addition to unicast routing, MAODV supports multicast and broadcast as well. The multicast routing problem with multiple QoS constraints, which may deal with the delay, bandwidth and packet loss measurements is discussed, and a network model for researching the ad hoc network QoS multicast routing problem is described. It presents a complete solution for QoS multicast routing based on an extension of the MAODV routing protocol that deals with delay, bandwidth and packet loss mesurements. The solution is based on lower layer specifics. Simulation results show that, with the proposed QoS multicast routing protocol, end-to-end delay, bandwidth and packet loss on a route can be improved in most of cases. It is an available approach to multicast routing decision with multiple QoS constraints.展开更多
The multicast routing problem with multiple QoS constraints in networks with uncertain parameters is discussed, and a network model that is suitable to research such QoS multicast routing problem is described. The QMR...The multicast routing problem with multiple QoS constraints in networks with uncertain parameters is discussed, and a network model that is suitable to research such QoS multicast routing problem is described. The QMRGA, a multicast routing policy for Internet, mobile network or other highperformance networks is mainly presented, which is based on the genetic algorithm(GA), and can provide QoSsensitive paths in a scalable and flexible way in the network environment with uncertain parameters. The QMRGA can also optimize the network resources such as bandwidth and delay, and can converge to the optimal or nearoptimal solution within few iterations, even for the network environment with uncertain parameters. The incremental rate of computational cost can be close to a polynomial and is less than exponential rate. The performance measures of the QMRGA are evaluated by using simulations. The results show that QMRGA provides an available approach to QoS multicast routing in network environment with uncertain parameters.展开更多
In the Internet, a group of replicated servers is commonly used in order to improve the scalability of network service. Anycast service is a new network service that can improve network load distribution and simplify ...In the Internet, a group of replicated servers is commonly used in order to improve the scalability of network service. Anycast service is a new network service that can improve network load distribution and simplify certain applications. In this paper, the authors described a simple anycast service model in the Internet without significant affecting the routing and protocol processing infrastructure that was already in place, and proposed an anycast QoS routing algorithm for this model. The algorithm used randomized method to balance network load and improve its performance. Several new techniques are proposed in the algorithm, first, theminimum hops for each node are used in the algorithm, which are used as metric for computing the probability of possible out links. The metric is pre computed for each node in the network, which can simplify the network complexity and provide the routing process with useful information. Second, randomness is used at the link level and depends dynamically on the routing configuration. This provides great flexibility for the routing process, prevents the routing process from overusing certain fixed routing paths, and adequately balances the delay of the routing path. the authors assess the quality of QoS algorithm in terms of the acceptance ratio on anycast QoS requests, and the simulation results on a variety of network topologies and on various parameters show that the algorithm has good performances and can balance network load effectively.展开更多
An efficient QoS routing algorithm was proposed for multiple constrained path selection. Making use of efficient pruning policy, the algorithm reduces greatly the size of search space and the computing time. Although ...An efficient QoS routing algorithm was proposed for multiple constrained path selection. Making use of efficient pruning policy, the algorithm reduces greatly the size of search space and the computing time. Although the proposed algorithm has exponential time complexity in the worst case, it can get the running results quickly in practical application. When the scale of network increases, the algorithm can efficiently control the size of search space by constraint conditions and prior queue. The results of simulation show that successful request ratio ( r ) of efficient algorithm for multi-constrained optimal path (EAMCOP) is better than that of heuristic algorithm for multi-constrained optimal path (H-MCOP), but average computing time ( t ) of EAMCOP is far less than that of H-MCOP. And it can be seen that the computing time of EAMCOP is only one fourth of that of H-MCOP in Advanced Research Projects Agency Network (ARPANet) topology.展开更多
A wireless ad-hoc network is a self-organized wireless network without fixed or backbone infrastructure. All nodes have routing capability and use peer-to-peer packet transmission or forward packets to other node usin...A wireless ad-hoc network is a self-organized wireless network without fixed or backbone infrastructure. All nodes have routing capability and use peer-to-peer packet transmission or forward packets to other node using multi hop communication. Now days mobile ad-hoc networks are being used for different applications and traffics, so it require quality of service (QoS) support in routing protocol. In this paper, a modified QoS routing protocol using directional antenna has been proposed. High and normal priority can be assigned based on type of traffic. All the nodes in the path used by high priority flow are reserved as high priority flow for that flow and normal priority flow will avoid the paths used by high priority flows. If no disjoint paths are available, there may be two possibilities: Normal priority flows are blocked and other is, normal priority flows are allow using the coupled path with high priority flow. Blocking the normal priority flow, QoS routing protocol improves the performance of high priority flow. This concept may be use in emergency communication. Simulation results show that by assigning the priorities to flows, performance of high priority flows are improved and it will further improved by blocking the normal priority flow.展开更多
Multi-constrained Quality-of-Service (QoS) routing is a big challenge for Mobile Ad hoc Networks (MANETs) where the topology may change constantly. In this paper a novel QoS Routing Algorithm based on Simulated Anneal...Multi-constrained Quality-of-Service (QoS) routing is a big challenge for Mobile Ad hoc Networks (MANETs) where the topology may change constantly. In this paper a novel QoS Routing Algorithm based on Simulated Annealing (SA_RA) is proposed. This algorithm first uses an energy function to translate multiple QoS weights into a single mixed metric and then seeks to find a feasible path by simulated annealing. The pa- per outlines simulated annealing algorithm and analyzes the problems met when we apply it to Qos Routing (QoSR) in MANETs. Theoretical analysis and experiment results demonstrate that the proposed method is an effective approximation algorithms showing better performance than the other pertinent algorithm in seeking the (approximate) optimal configuration within a period of polynomial time.展开更多
考虑了卫星Internet拓扑变化的可预测性和组播应用的服务质量QoS(quality of service)需求,设计了一种QoS组播路由机制.给出了卫星Internet中QoS组播路由问题模型及其数学描述,引入拉格朗日松弛,设定适应度函数,使用PRIM算法,基于次梯...考虑了卫星Internet拓扑变化的可预测性和组播应用的服务质量QoS(quality of service)需求,设计了一种QoS组播路由机制.给出了卫星Internet中QoS组播路由问题模型及其数学描述,引入拉格朗日松弛,设定适应度函数,使用PRIM算法,基于次梯度优化,寻找生存周期最大化的QoS组播路由树.基于NS2进行了仿真实现和性能评价.仿真结果表明,同传统的组播路由机制相比,该机制是可行和有效的,提高了QoS组播路由树生存周期,具有良好的性能.展开更多
1 引言目前的Internet网络中,一个会话的数据分组可以通过不同的传输路径到达目的节点,而且不同任务分组公平地共享网络资源,例如,链路带宽、交换缓冲区等。这种结构不能支持多媒体数据和实时数据传输。多媒体业务需求的日益增长推动了...1 引言目前的Internet网络中,一个会话的数据分组可以通过不同的传输路径到达目的节点,而且不同任务分组公平地共享网络资源,例如,链路带宽、交换缓冲区等。这种结构不能支持多媒体数据和实时数据传输。多媒体业务需求的日益增长推动了现有多媒体应用的进一步发展,这也对新一代网络提出了新的要求。服务质量(QoS,Quality of Services)的概念已经用于定量和定性地描述服务的提供者和服务的接受者之间协商的服务性能。服务质量可以由一些特定的参数来描述,服务的提供者允许服务的使用者在建立连接时对各种服务参数指定希望的、可接受的最低限度值。展开更多
基金National Key Research and Development Program(2021YFB2900604)。
文摘Low Earth orbit(LEO)satellite networks exhibit distinct characteristics,e.g.,limited resources of individual satellite nodes and dynamic network topology,which have brought many challenges for routing algorithms.To satisfy quality of service(QoS)requirements of various users,it is critical to research efficient routing strategies to fully utilize satellite resources.This paper proposes a multi-QoS information optimized routing algorithm based on reinforcement learning for LEO satellite networks,which guarantees high level assurance demand services to be prioritized under limited satellite resources while considering the load balancing performance of the satellite networks for low level assurance demand services to ensure the full and effective utilization of satellite resources.An auxiliary path search algorithm is proposed to accelerate the convergence of satellite routing algorithm.Simulation results show that the generated routing strategy can timely process and fully meet the QoS demands of high assurance services while effectively improving the load balancing performance of the link.
基金This research was supported by X-mind Corps program of National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT(No.2019H1D8A1105622)the Soonchunhyang University Research Fund.
文摘Energy conservation is a significant task in the Internet of Things(IoT)because IoT involves highly resource-constrained devices.Clustering is an effective technique for saving energy by reducing duplicate data.In a clustering protocol,the selection of a cluster head(CH)plays a key role in prolonging the lifetime of a network.However,most cluster-based protocols,including routing protocols for low-power and lossy networks(RPLs),have used fuzzy logic and probabilistic approaches to select the CH node.Consequently,early battery depletion is produced near the sink.To overcome this issue,a lion optimization algorithm(LOA)for selecting CH in RPL is proposed in this study.LOA-RPL comprises three processes:cluster formation,CH selection,and route establishment.A cluster is formed using the Euclidean distance.CH selection is performed using LOA.Route establishment is implemented using residual energy information.An extensive simulation is conducted in the network simulator ns-3 on various parameters,such as network lifetime,power consumption,packet delivery ratio(PDR),and throughput.The performance of LOA-RPL is also compared with those of RPL,fuzzy rule-based energyefficient clustering and immune-inspired routing(FEEC-IIR),and the routing scheme for IoT that uses shuffled frog-leaping optimization algorithm(RISARPL).The performance evaluation metrics used in this study are network lifetime,power consumption,PDR,and throughput.The proposed LOARPL increases network lifetime by 20%and PDR by 5%–10%compared with RPL,FEEC-IIR,and RISA-RPL.LOA-RPL is also highly energy-efficient compared with other similar routing protocols.
基金Project supported by the Second Stage of Brain Korea 21 ProjectsProject(10035236)supported by the IT_R&D Program of MKE/KEIT,Korea
文摘Though the WiMedia supports higher data rates than other WPAN technologies,a WiMedia device cannot reach other devices that are separated from it by more than 10 m,which is the typical limited transmission range of the WiMedia protocol.In this work,we propose a multi-hop QoS routing protocol to enable WiMedia devices to transmit real-time data to devices that are located out of the transmission range.The proposed routing protocol is a hybrid algorithm,which mixes the table-driven and on-demand routing algorithms,searching one or more routes according to the number of hops to a destination device.WiMedia MAC is potentially capable of learning the existence of neighbor devices by using a beacon frame.By utilizing the neighbors' information,all devices can create routing entries for devices within 2-hops periodically.For devices beyond the 2-hop range,the newly designed on-demand routing algorithm is applied to multi-hop routing.If a routing entry for a destination device is not listed in the routing table,the source device sends a request packet to 2-hop range devices which could be found in the routing table.Since every device maintains routing entries for 2-hop range devices in the routing table,the request packet is replied in advance before its arrival at the destination device.Also,to decide the optimal route for a destination device,the number of medium access slots(MASs),received signal strength indicator(RSSI)and hop count are utilized to establish a QoS-enabled routing table.We perform ns-2 simulation to investigate the performance of the proposed routing protocol with AODV and DSDV.The simulation results show that the proposed protocol has better throughput and lower overhead than other protocols.
文摘The application environments of wireless Ad hoc networks require that it should support Quality of Service (QoS). However, that is very difficult because of the inherent characteristics of the wireless channel and the frequent changes of network topology caused by nodes movement. An Ad hoc QoS Multicasting (AQM) protocol can solve this problem by previously reserving the neighbor nodes for tracking resource availability. By considering QoS restrictions of transport delay, loss ratio, bandwidth requirement, delay jitter, and throughout, and by finding the adaptive routing, the AQM protocol can obviously improve the efficiency of multicastsession. The results of network simulation show that QoS is essentially applicable to Ad hoc networks.
基金Supported by the National Natural Science Foundation of China (No.90304018)Natural Science Foundation of Hubei Province (No.2004ABA014)Teaching Research Project of Higher Educational Institutions of Hubei Province (No.20040231).
文摘Most of the multimedia applications require strict Quality-of-Service (QoS) guarantee during the communication between a single source and multiple destinations. The paper mainly presents a QoS Multicast Routing algorithms based on Genetic Algorithm (QMRGA). Simulation results demonstrate that the algorithm is capable of discovering a set of QoS-based near optimized, non-dominated multicast routes within a few iterations, even for the networks environment with uncertain parameters.
基金This project was supported by the National Natural Science Foundation of China (60172035 ,90304018) NSF of HubeiProvince (2004ABA014) and Teaching Research Project of Higher Educational Institutions of Hubei Province (20040231)
文摘Quality of service （QoS） routing and multicasting protocols in ad hoc networks are face with the challenge of delivering data to destinations through multihop routes in the presence of node movements and topology changes. The multicast routing problem with multiple QoS constraints is discussed, which may deal with the delay, bandwidth and cost metrics, and describes a network model for researching the ad hoc networks QoS multicast routing problem. It presents a distributed QoS multicast routing protocol （DQMRP）. The proof of correctness and complenty analysis of the DQMRP are also given. Simulation results show that the multicast tree optimized by DQMRP is better than other protocols and is fitter for the network situations with frequently changed status and the realtime multimedia application. It is an available approach to multicast routing decision with multiple QoS constraints.
文摘In current days,the domain of Internet of Things(IoT)and Wireless Sensor Networks(WSN)are combined for enhancing the sensor related data transmission in the forthcoming networking applications.Clustering and routing techniques are treated as the effective methods highly used to attain reduced energy consumption and lengthen the lifetime of the WSN assisted IoT networks.In this view,this paper presents an Ensemble of Metaheuristic Optimization based QoS aware Clustering with Multihop Routing(EMOQoSCMR)Protocol for IoT assisted WSN.The proposed EMO-QoSCMR protocol aims to achieve QoS parameters such as energy,throughput,delay,and lifetime.The proposed model involves two stage processes namely clustering and routing.Firstly,the EMO-QoSCMR protocol involves crossentropy rain optimization algorithm based clustering(CEROAC)technique to select an optimal set of cluster heads(CHs)and construct clusters.Besides,oppositional chaos game optimization based routing(OCGOR)technique is employed for the optimal set of routes in the IoT assisted WSN.The proposed model derives a fitness function based on the parameters involved in the IoT nodes such as residual energy,distance to sink node,etc.The proposed EMOQoSCMR technique has resulted to an enhanced NAN of 64 nodes whereas the LEACH,PSO-ECHS,E-OEERP,and iCSHS methods have resulted in a lesser NAN of 2,10,42,and 51 rounds.The performance of the presented protocol has been evaluated interms of energy efficiency and network lifetime.
基金This project was supported by the National Natural Science Foundation of China (60172035 ,90304018) NSF of HubeiProvince (2004ABA014) and Teaching Research Project of Higher Educational Institutions of Hubei Province (20040231)
文摘Ad hoe wireless networks consist of mobile nodes interconnected by multihop communication paths. Unlike conventional wireless networks, ad hoc networks have no fixed network infrastructure or administrative support. Due to bandwidth constraint and dynamic topology of mobile ad hoc networks, supporting Quality of Service （QoS） is an inherently complex, difficult issue and very important research issue. MAODV （Multicast Ad hoc Ondemand Distance Vector） routing protocol provides fast and efficient route establishment between mobile nodes that need to communicate with each other. MAODV has minimal control overhead and route acquisition latency. In addition to unicast routing, MAODV supports multicast and broadcast as well. The multicast routing problem with multiple QoS constraints, which may deal with the delay, bandwidth and packet loss measurements is discussed, and a network model for researching the ad hoc network QoS multicast routing problem is described. It presents a complete solution for QoS multicast routing based on an extension of the MAODV routing protocol that deals with delay, bandwidth and packet loss mesurements. The solution is based on lower layer specifics. Simulation results show that, with the proposed QoS multicast routing protocol, end-to-end delay, bandwidth and packet loss on a route can be improved in most of cases. It is an available approach to multicast routing decision with multiple QoS constraints.
文摘The multicast routing problem with multiple QoS constraints in networks with uncertain parameters is discussed, and a network model that is suitable to research such QoS multicast routing problem is described. The QMRGA, a multicast routing policy for Internet, mobile network or other highperformance networks is mainly presented, which is based on the genetic algorithm(GA), and can provide QoSsensitive paths in a scalable and flexible way in the network environment with uncertain parameters. The QMRGA can also optimize the network resources such as bandwidth and delay, and can converge to the optimal or nearoptimal solution within few iterations, even for the network environment with uncertain parameters. The incremental rate of computational cost can be close to a polynomial and is less than exponential rate. The performance measures of the QMRGA are evaluated by using simulations. The results show that QMRGA provides an available approach to QoS multicast routing in network environment with uncertain parameters.
基金TheNationalScienceFundforOverseasDistinguishedYoungScholars (No .6 992 82 0 1)FoundationforUniversityKeyTeacherbytheMinist
文摘In the Internet, a group of replicated servers is commonly used in order to improve the scalability of network service. Anycast service is a new network service that can improve network load distribution and simplify certain applications. In this paper, the authors described a simple anycast service model in the Internet without significant affecting the routing and protocol processing infrastructure that was already in place, and proposed an anycast QoS routing algorithm for this model. The algorithm used randomized method to balance network load and improve its performance. Several new techniques are proposed in the algorithm, first, theminimum hops for each node are used in the algorithm, which are used as metric for computing the probability of possible out links. The metric is pre computed for each node in the network, which can simplify the network complexity and provide the routing process with useful information. Second, randomness is used at the link level and depends dynamically on the routing configuration. This provides great flexibility for the routing process, prevents the routing process from overusing certain fixed routing paths, and adequately balances the delay of the routing path. the authors assess the quality of QoS algorithm in terms of the acceptance ratio on anycast QoS requests, and the simulation results on a variety of network topologies and on various parameters show that the algorithm has good performances and can balance network load effectively.
文摘An efficient QoS routing algorithm was proposed for multiple constrained path selection. Making use of efficient pruning policy, the algorithm reduces greatly the size of search space and the computing time. Although the proposed algorithm has exponential time complexity in the worst case, it can get the running results quickly in practical application. When the scale of network increases, the algorithm can efficiently control the size of search space by constraint conditions and prior queue. The results of simulation show that successful request ratio ( r ) of efficient algorithm for multi-constrained optimal path (EAMCOP) is better than that of heuristic algorithm for multi-constrained optimal path (H-MCOP), but average computing time ( t ) of EAMCOP is far less than that of H-MCOP. And it can be seen that the computing time of EAMCOP is only one fourth of that of H-MCOP in Advanced Research Projects Agency Network (ARPANet) topology.
文摘A wireless ad-hoc network is a self-organized wireless network without fixed or backbone infrastructure. All nodes have routing capability and use peer-to-peer packet transmission or forward packets to other node using multi hop communication. Now days mobile ad-hoc networks are being used for different applications and traffics, so it require quality of service (QoS) support in routing protocol. In this paper, a modified QoS routing protocol using directional antenna has been proposed. High and normal priority can be assigned based on type of traffic. All the nodes in the path used by high priority flow are reserved as high priority flow for that flow and normal priority flow will avoid the paths used by high priority flows. If no disjoint paths are available, there may be two possibilities: Normal priority flows are blocked and other is, normal priority flows are allow using the coupled path with high priority flow. Blocking the normal priority flow, QoS routing protocol improves the performance of high priority flow. This concept may be use in emergency communication. Simulation results show that by assigning the priorities to flows, performance of high priority flows are improved and it will further improved by blocking the normal priority flow.
基金Supported by the National Natural Science Foundation of China (No.60472104), the Natural Science Research Program of Jiangsu Province (No.04KJB510094).
文摘Multi-constrained Quality-of-Service (QoS) routing is a big challenge for Mobile Ad hoc Networks (MANETs) where the topology may change constantly. In this paper a novel QoS Routing Algorithm based on Simulated Annealing (SA_RA) is proposed. This algorithm first uses an energy function to translate multiple QoS weights into a single mixed metric and then seeks to find a feasible path by simulated annealing. The pa- per outlines simulated annealing algorithm and analyzes the problems met when we apply it to Qos Routing (QoSR) in MANETs. Theoretical analysis and experiment results demonstrate that the proposed method is an effective approximation algorithms showing better performance than the other pertinent algorithm in seeking the (approximate) optimal configuration within a period of polynomial time.
文摘考虑了卫星Internet拓扑变化的可预测性和组播应用的服务质量QoS(quality of service)需求,设计了一种QoS组播路由机制.给出了卫星Internet中QoS组播路由问题模型及其数学描述,引入拉格朗日松弛,设定适应度函数,使用PRIM算法,基于次梯度优化,寻找生存周期最大化的QoS组播路由树.基于NS2进行了仿真实现和性能评价.仿真结果表明,同传统的组播路由机制相比,该机制是可行和有效的,提高了QoS组播路由树生存周期,具有良好的性能.
文摘1 引言目前的Internet网络中,一个会话的数据分组可以通过不同的传输路径到达目的节点,而且不同任务分组公平地共享网络资源,例如,链路带宽、交换缓冲区等。这种结构不能支持多媒体数据和实时数据传输。多媒体业务需求的日益增长推动了现有多媒体应用的进一步发展,这也对新一代网络提出了新的要求。服务质量(QoS,Quality of Services)的概念已经用于定量和定性地描述服务的提供者和服务的接受者之间协商的服务性能。服务质量可以由一些特定的参数来描述,服务的提供者允许服务的使用者在建立连接时对各种服务参数指定希望的、可接受的最低限度值。
