With the development of satellite communication,in order to solve the problems of shortage of on-board resources and refinement of delay requirements to improve the communication performance of satellite optical netwo...With the development of satellite communication,in order to solve the problems of shortage of on-board resources and refinement of delay requirements to improve the communication performance of satellite optical networks,this paper proposes a bee colony optimization algorithm for routing and wavelength assignment based on directional guidance(DBCO-RWA)in satellite optical networks.In D-BCORWA,directional guidance based on relative position and link load is defined,and then the link cost function in the path search stage is established based on the directional guidance factor.Finally,feasible solutions are expanded in the global optimization stage.The wavelength utilization,communication success probability,blocking rate,communication hops and convergence characteristic are simulated.The results show that the performance of the proposed algorithm is improved compared with existing algorithms.展开更多
The major challenge in elastic optical networks is to determine the path of a connection and to allocate spectral resources on the links of this path. This problem consists of two sub-problems, routing and spectrum al...The major challenge in elastic optical networks is to determine the path of a connection and to allocate spectral resources on the links of this path. This problem consists of two sub-problems, routing and spectrum allocation. In the literature, these sub-problems are solved with a predefined order for all topology node pairs. Recent work proposes hybrid resolution algorithms based on connection demand and network state to provide a solution to these problems. However, the blocking rate of new connection requests has become problematic. In this work, we propose a hybrid routing and spectrum assignment policy to improve blocking rate of new connection requests. The proposed solution consists to change the routing policy of a pair node if the connection request is blocked. This algorithm improves the blocking rate of new connection requests.展开更多
This paper introduces an ant colony routing and wavelength assignment algorithm based on cross-layer design(CL-ACRWA),which can overcome the adverse effects of Doppler wavelength shift on data transmission in optical ...This paper introduces an ant colony routing and wavelength assignment algorithm based on cross-layer design(CL-ACRWA),which can overcome the adverse effects of Doppler wavelength shift on data transmission in optical satellite networks. Firstly, a cross-layer optimization model is built, which considers the Doppler wavelength shift, the transmission delay as well as wavelength-continuity constraint. Then an ant colony algorithm is utilized to solve the cross-layer optimization model, resulting in finding an optimal light path satisfying the above constraints for every connection request. The performance of CL-ACRWA is measured by the communication success probability, the convergence property and the transmission delay. Simulation results show that CL-ACRWA performs well in communication success probability and has good global search ability as well as fast convergence speed. Meanwhile, the transmission delay can meet the basic requirement of real-time transmission of business.展开更多
Routing and wavelength assignment for online real-time multicast connection setup is a difficult task due to the dynamic change of availabilities of wavelengths on links and the consideration of wavelength conversion ...Routing and wavelength assignment for online real-time multicast connection setup is a difficult task due to the dynamic change of availabilities of wavelengths on links and the consideration of wavelength conversion delay in WDM networks. This paper presents a distributed routing and wavelength assignment scheme for the setup of real-time multicast connections. It integrates routing and wavelength assignment as a single process, which greatly reduces the connection setup time. The proposed routing method is based on the Prim’s MST (Minimum Spanning Tree) algorithm and the K-restricted breadth-first search method, which can produce a sub-minimal cost tree under a given delay bound. The wave-length assignment uses the least-conversion and load balancing strategies. Simulation results show that the proposed algorithm is suitable for online multicast connection establishment in WDM networks.展开更多
In wavelength division multiplexing (WDM) networks without wavelengthconversion functionality, we convert the dynamic routing and wavelength assignment problem formulti-lightpath demands to the edge-disjoint paths pro...In wavelength division multiplexing (WDM) networks without wavelengthconversion functionality, we convert the dynamic routing and wavelength assignment problem formulti-lightpath demands to the edge-disjoint paths problem, and propose a new algorithm. Thecomputer simulations show that the proposed algorithm has better blocking probability performancethan a sequential algorithm, which first separates a multi-lightpath demand into mutilplesingle-lightpath demands, then uses the fixed-alternate routing-first fit wavelength assignment(AR-FF) algorithm for each single-lightpath demand.展开更多
Given a set of lightpath connection requests in an all-10 Gb/s optical dense wavelength division multiplexed (DWDM) Ethernet network, lightpaths are designed. In addition the wavelength channels are assigned subject t...Given a set of lightpath connection requests in an all-10 Gb/s optical dense wavelength division multiplexed (DWDM) Ethernet network, lightpaths are designed. In addition the wavelength channels are assigned subject to minimization of the channel blocking and provisional requests satisfying the limits due to accumulative linear dispersion effects over the hops. This paper proposes a routing and wavelength assignment scheme for DWDM long-haul optical networks that includes routing, assignment and reservation of different wavelength channels operating under the Generalized Multiprotocol Label Switching (GMPLS) environment. The GMPLS framework can offer an approach to implement IP over DWDM with variable weighting assignments of routes based on the limitations due to residual dispersion accumulated on the lightwave path. The modeling is implemented under the framework of an object-oriented modeling platform OMNeT++. Network performance tests are evaluated based mainly on a long-haul terrestrial fiber mesh network composed of as well as three topologies structured as chain, ring, and mesh configurations. Blocking probability of lightpath connection requests are examined with the average link utilization in the network employing variable number of wavelength channels in association with the limits of route distance due to linear chromatic and polarization mode dispersion effects.展开更多
In order to overcome the adverse effects of Doppler wavelength shift on data transmission in the optical satellite networks,a dynamic routing and wavelength assignment algorithm based on crosslayer design( CL-DRWA) is...In order to overcome the adverse effects of Doppler wavelength shift on data transmission in the optical satellite networks,a dynamic routing and wavelength assignment algorithm based on crosslayer design( CL-DRWA) is introduced which can improve robustness of the network. Above all,a cross-layer optimization model is designed,which considers transmission delay and wavelength-continuity constraint,as well as Doppler wavelength shift. Then CL-DRWA is applied to solve this model,resulting in finding an optimal light path satisfying the above constraints for every connection request. In CL-DRWA,Bellman-Ford method is used to find an optimal route and a distributed relative capacity loss method is implemented to get an optimal wavelength assignment result on the optimal route. Moreover,compared with the dynamic routing and wavelength assignment algorithm based on minimum delay strategy( MD-DRWA),CL-DRWA can make an improvement of 5. 3% on the communication success probability. Meanwhile,CL-DRWA can meet the requirement of transmission delay for real-time services.展开更多
In this paper, a Wavelength Division Multiplexing (WDM) network model based on the equivalent networks is described, and wavelength-dependent equivalent arc, equivalent networks, equivalent multicast tree and some oth...In this paper, a Wavelength Division Multiplexing (WDM) network model based on the equivalent networks is described, and wavelength-dependent equivalent arc, equivalent networks, equivalent multicast tree and some other terms are presented. Based on this model and relevant Routing and Wavelength Assign- ment (RWA) strategy, a unicast RWA algorithm and a multicast RWA algorithm are presented. The wave- length-dependent equivalent arc expresses the schedule of local RWA and the equivalent network expresses the whole topology of WDM optical networks, so the two algorithms are of the flexibility in RWA and the optimi- zation of the whole problem. The theoretic analysis and simulation results show the two algorithms are of the stronger capability and the lower complexity than the other existing algorithms for RWA problem, and the complexity of the two algorithms are only related to the scale of the equivalent networks. Finally, we prove the two algorithms’ feasibility and the one-by-one corresponding relation between the equivalent multicast tree and original multicast tree, and point out the superiorities and drawbacks of the two algorithms respectively.展开更多
To study multi-radio multi-channel (MR-MC) Ad Hoc networks based on 802.11, an efficient cross-layer routing protocol with the function of joint channel assignment, called joint channel assignment and cross-layer ro...To study multi-radio multi-channel (MR-MC) Ad Hoc networks based on 802.11, an efficient cross-layer routing protocol with the function of joint channel assignment, called joint channel assignment and cross-layer routing (JCACR), is presented. Firstly, this paper introduces a new concept called channel utilization percentage (CUP), which is for measuring the contention level of different channels in a node’s neighborhood, and deduces its optimal value for determining whether a channel is overloaded or not. Then, a metric parameter named channel selection metric (CSM) is designed, which actually reffects not only the channel status but also corresponding node’s capacity to seize it. JCACR evaluates channel assignment by CSM, performs a local optimization by assigning each node a channel with the smaller CSM value, and changes the working channel dynamically when the channel is overloaded. Therefore, the network load balancing can be achieved. In addition, simulation shows that, when compared with the protocol of weighted cumulative expected transfer time (WCETT), the new protocol can improve the network throughput and reduce the end-to-end average delay with fewer overheads.展开更多
Cognitive Wireless Mesh Networks(CWMN) is a novel wireless network which combines the advantage of Cognitive Radio(CR) and wireless mesh networks.CWMN can realize seamless in-tegration of heterogeneous wireless networ...Cognitive Wireless Mesh Networks(CWMN) is a novel wireless network which combines the advantage of Cognitive Radio(CR) and wireless mesh networks.CWMN can realize seamless in-tegration of heterogeneous wireless networks and achieve better radio resource utilization.However,it is particularly vulnerable due to its features of open medium,dynamic spectrum,dynamic topology,and multi-top routing,etc..Being a dynamic positive security strategy,intrusion detection can provide powerful safeguard to CWMN.In this paper,we introduce trust mechanism into CWMN with intrusion detection and present a trust establishment model based on intrusion detection.Node trust degree and the trust degree of data transmission channels between nodes are defined and an algorithm of calcu-lating trust degree is given based on distributed detection of attack to networks.A channel assignment and routing scheme is proposed,in which selects the trusted nodes and allocates data channel with high trust degree for the transmission between neighbor nodes to establish a trusted route.Simulation re-sults indicate that the scheme can vary channel allocation and routing dynamically according to network security state so as to avoid suspect nodes and unsafe channels,and improve the packet safe delivery fraction effectively.展开更多
Opportunistic Routing (OR) involves multiple forwarding candidates to relay packets by taking advantage of the broadcast nature and multi-user diversity of a wireless medium. Compared with Traditional Routing (TR), OR...Opportunistic Routing (OR) involves multiple forwarding candidates to relay packets by taking advantage of the broadcast nature and multi-user diversity of a wireless medium. Compared with Traditional Routing (TR), OR is more suitable in the case of an unreliable wireless link and can evidently improve the end-to-end throughput of Wireless Mesh Networks (WMNs). In this paper, we focus on OR in Multi-Radio Multi-Channel WMNs (MRMC-WMNs). This problem has not been well examined and is considerably more challenging than the OR in single-radio wireless networks considered in the existing literature. First, we validate the advantage of OR in MRMC-WMNs. Second, we propose Low-complexity Channel Assignment for Opportunistic Routing (LcCAOR), which assigns channels to flows according to the interference state of every node. Third, we implement the LcCOAR in a fully distributed manner. The simulation result shows that compared with OR in Single-Radio Single-Channel WMNs (SRSC-WMNs), the proposed OR can significantly enhance the throughput to 87.11% and 100.3% in grid and tree WMNs, respectively.展开更多
With the rise of cloud computing in recent years, a large number of streaming media has yielded an exponential growth in network traffic. With the now present 5G and future 6G, the development of the Internet of Thing...With the rise of cloud computing in recent years, a large number of streaming media has yielded an exponential growth in network traffic. With the now present 5G and future 6G, the development of the Internet of Things (IoT), social networks, video on demand, and mobile multimedia platforms, the backbone network is bound to bear more traffic. The transmission capacity of Single Core Fiber (SCFs) may be limited in the future and Spatial Division Multiplexing (SDM) leveraging multi-core fibers promises to be one of the solutions for the future. Currently, Elastic optical networks (EONs) with multi-core fibers (MCFs) are a kind of SDM-enabled EONs (SDM-EON) used to enhance the capacity of transmission. The resource assignment in MCFs, however, will be subject to Inter-Core Crosstalk (IC-XT), hence, reducing the effectiveness of transmission. This research highlights the routing, modulation level, and spectrum assignment (RMLSA) problems with anycast traffic mode in SDM-EON. A multipath routing scheme is used to reduce the blocking rate of anycast traffic in SDM-EON with the limit of inter-core crosstalk. Hence, an integer linear programming (ILP) problem is formulated and a heuristic algorithm is proposed. Two core-assignment strategies: First-Fit (FF) and Random-Fit (RF) are used and their performance is evaluated through simulations. The simulation results show that the multipath routing method is better than the single-path routing method in terms of blocking ratio and spectrum utilization ratio. Moreover, the FF is better than the RF in low traffic load in terms of blocking ratio (BR), and the opposite in high traffic load. The FF is better than the RF in terms of a spectrum utilization ratio. In an anycast protection problem, the proposed algorithm has a lower BR than previous works.展开更多
In this paper, we propose a new multicast wavelength assignment algorithm called NGWA with complexity of O(N), where N is the number of nodes on a multicast tree. The whole procedure of NGWA algorithm is separated int...In this paper, we propose a new multicast wavelength assignment algorithm called NGWA with complexity of O(N), where N is the number of nodes on a multicast tree. The whole procedure of NGWA algorithm is separated into two phases: the partial wavelength assignment phase and the complete wavelength assignment phase. It tries to minimize the total number of wavelength conversions of the multicast tree. Meanwhile, the number of different wavelengths used is minimized locally. Through illustrative example and simulation experiments, it is proved that the NGWA algorithm works well and achieves satisfactory performance in terms of the average number of wavelength conversions and the average blocking probability.展开更多
After analyzing the merits and shortcomings of Fixed-Alternated Routing algorithm (FAR) and Least Loaded Routing algorithm (LLR),we propose one novel dynamic optical routing algorithm. Having considered the influences...After analyzing the merits and shortcomings of Fixed-Alternated Routing algorithm (FAR) and Least Loaded Routing algorithm (LLR),we propose one novel dynamic optical routing algorithm. Having considered the influences of path’s length and path’s congestion just like in FAR and LLR,we take into account the network resource status-amount of free wavelengths in the network. Proposed algorithm sets up connections on three possible paths according to amount of available free wave-lengths in the network,which effectively decreases the blocking probability. The National Science Foundation (NSF) network and mesh-torus network simulation results show that the performance of this algorithm is better than that of FAR and LLR.展开更多
Conventional optical burst switching(OBS)technique adopts purely statistical multiplex mechanismso that the bursts collide with each other very easily.To address this problem,a novel proactive con-tention avoidance sc...Conventional optical burst switching(OBS)technique adopts purely statistical multiplex mechanismso that the bursts collide with each other very easily.To address this problem,a novel proactive con-tention avoidance scheme is proposed,which assigns dedicated wavelengths to each ingress node,then st-numbering algorithm is used to construct the traffic load balanced spanning trees .In this way,contentioncan be eliminated at ingress nodes,and the amount of bursts that could be accommodated by ingressnodes will be maximized.Further,those unused wavelengths left by traffic load balanced spanning treeare also organized as partial trees to carry bursts,thus the link utilization can be improved effectively.Simulation result shows that our scheme can improve the burst loss performance significantly without thewavelength converters or optical buffers comparing to other popular routing and wavelength assignment(RWA)algorithms.展开更多
General multi-protocol label switching(GMPLS) based on traffic engineering is one of the possible methods to implement all-optical network. This method implements the network with IP technique and guarantees the quali...General multi-protocol label switching(GMPLS) based on traffic engineering is one of the possible methods to implement all-optical network. This method implements the network with IP technique and guarantees the quality of service with traffic engineering. Based on the establishment of selecting schemes of optical path and methods of traffic calculation, the wavelength routing algorithm of all-optical network based on traffic engineering is presented by combining with prior route of shortest path and traffic engineering, the algorithm procedures are given, and the actual examples are introduced as well as the analysis on simulation calculation. This research results have certain significance for the achievement of optical switching technique of all-optical network.展开更多
基金supported in part by the National Key Research and Development Program of China under Grant 2021YFB2900604in part by the National Natural Science Foundation of China(NSFC)under Grant U22B2033,61975234,61875230。
文摘With the development of satellite communication,in order to solve the problems of shortage of on-board resources and refinement of delay requirements to improve the communication performance of satellite optical networks,this paper proposes a bee colony optimization algorithm for routing and wavelength assignment based on directional guidance(DBCO-RWA)in satellite optical networks.In D-BCORWA,directional guidance based on relative position and link load is defined,and then the link cost function in the path search stage is established based on the directional guidance factor.Finally,feasible solutions are expanded in the global optimization stage.The wavelength utilization,communication success probability,blocking rate,communication hops and convergence characteristic are simulated.The results show that the performance of the proposed algorithm is improved compared with existing algorithms.
文摘The major challenge in elastic optical networks is to determine the path of a connection and to allocate spectral resources on the links of this path. This problem consists of two sub-problems, routing and spectrum allocation. In the literature, these sub-problems are solved with a predefined order for all topology node pairs. Recent work proposes hybrid resolution algorithms based on connection demand and network state to provide a solution to these problems. However, the blocking rate of new connection requests has become problematic. In this work, we propose a hybrid routing and spectrum assignment policy to improve blocking rate of new connection requests. The proposed solution consists to change the routing policy of a pair node if the connection request is blocked. This algorithm improves the blocking rate of new connection requests.
基金supported by the National Natural Science Foundation of China(No.61675033,61575026,61675233)National High Technical Research and Development Program of China(No.2015AA015504)
文摘This paper introduces an ant colony routing and wavelength assignment algorithm based on cross-layer design(CL-ACRWA),which can overcome the adverse effects of Doppler wavelength shift on data transmission in optical satellite networks. Firstly, a cross-layer optimization model is built, which considers the Doppler wavelength shift, the transmission delay as well as wavelength-continuity constraint. Then an ant colony algorithm is utilized to solve the cross-layer optimization model, resulting in finding an optimal light path satisfying the above constraints for every connection request. The performance of CL-ACRWA is measured by the communication success probability, the convergence property and the transmission delay. Simulation results show that CL-ACRWA performs well in communication success probability and has good global search ability as well as fast convergence speed. Meanwhile, the transmission delay can meet the basic requirement of real-time transmission of business.
基金This work was supported by the National Natural Science Foundation of China (No. 70674108/60703118) and the Natural Science Foundation of Shaanxi (No. 2007A01).
文摘Routing and wavelength assignment for online real-time multicast connection setup is a difficult task due to the dynamic change of availabilities of wavelengths on links and the consideration of wavelength conversion delay in WDM networks. This paper presents a distributed routing and wavelength assignment scheme for the setup of real-time multicast connections. It integrates routing and wavelength assignment as a single process, which greatly reduces the connection setup time. The proposed routing method is based on the Prim’s MST (Minimum Spanning Tree) algorithm and the K-restricted breadth-first search method, which can produce a sub-minimal cost tree under a given delay bound. The wave-length assignment uses the least-conversion and load balancing strategies. Simulation results show that the proposed algorithm is suitable for online multicast connection establishment in WDM networks.
基金Supported by the National High Technology Development 863 Program of China(2001AA122023)
文摘In wavelength division multiplexing (WDM) networks without wavelengthconversion functionality, we convert the dynamic routing and wavelength assignment problem formulti-lightpath demands to the edge-disjoint paths problem, and propose a new algorithm. Thecomputer simulations show that the proposed algorithm has better blocking probability performancethan a sequential algorithm, which first separates a multi-lightpath demand into mutilplesingle-lightpath demands, then uses the fixed-alternate routing-first fit wavelength assignment(AR-FF) algorithm for each single-lightpath demand.
文摘Given a set of lightpath connection requests in an all-10 Gb/s optical dense wavelength division multiplexed (DWDM) Ethernet network, lightpaths are designed. In addition the wavelength channels are assigned subject to minimization of the channel blocking and provisional requests satisfying the limits due to accumulative linear dispersion effects over the hops. This paper proposes a routing and wavelength assignment scheme for DWDM long-haul optical networks that includes routing, assignment and reservation of different wavelength channels operating under the Generalized Multiprotocol Label Switching (GMPLS) environment. The GMPLS framework can offer an approach to implement IP over DWDM with variable weighting assignments of routes based on the limitations due to residual dispersion accumulated on the lightwave path. The modeling is implemented under the framework of an object-oriented modeling platform OMNeT++. Network performance tests are evaluated based mainly on a long-haul terrestrial fiber mesh network composed of as well as three topologies structured as chain, ring, and mesh configurations. Blocking probability of lightpath connection requests are examined with the average link utilization in the network employing variable number of wavelength channels in association with the limits of route distance due to linear chromatic and polarization mode dispersion effects.
基金Supported by the National Natural Science Foundation of China(No.61675033,61575026,61675232,61571440)the National High Technology Research and Development Program of China(No.2015AA015504)
文摘In order to overcome the adverse effects of Doppler wavelength shift on data transmission in the optical satellite networks,a dynamic routing and wavelength assignment algorithm based on crosslayer design( CL-DRWA) is introduced which can improve robustness of the network. Above all,a cross-layer optimization model is designed,which considers transmission delay and wavelength-continuity constraint,as well as Doppler wavelength shift. Then CL-DRWA is applied to solve this model,resulting in finding an optimal light path satisfying the above constraints for every connection request. In CL-DRWA,Bellman-Ford method is used to find an optimal route and a distributed relative capacity loss method is implemented to get an optimal wavelength assignment result on the optimal route. Moreover,compared with the dynamic routing and wavelength assignment algorithm based on minimum delay strategy( MD-DRWA),CL-DRWA can make an improvement of 5. 3% on the communication success probability. Meanwhile,CL-DRWA can meet the requirement of transmission delay for real-time services.
基金Supported by the Natrual Science Foundation of Shaanxi (No.2004A02) and Outstanding Scholar Project of P. R. China (2002).
文摘In this paper, a Wavelength Division Multiplexing (WDM) network model based on the equivalent networks is described, and wavelength-dependent equivalent arc, equivalent networks, equivalent multicast tree and some other terms are presented. Based on this model and relevant Routing and Wavelength Assign- ment (RWA) strategy, a unicast RWA algorithm and a multicast RWA algorithm are presented. The wave- length-dependent equivalent arc expresses the schedule of local RWA and the equivalent network expresses the whole topology of WDM optical networks, so the two algorithms are of the flexibility in RWA and the optimi- zation of the whole problem. The theoretic analysis and simulation results show the two algorithms are of the stronger capability and the lower complexity than the other existing algorithms for RWA problem, and the complexity of the two algorithms are only related to the scale of the equivalent networks. Finally, we prove the two algorithms’ feasibility and the one-by-one corresponding relation between the equivalent multicast tree and original multicast tree, and point out the superiorities and drawbacks of the two algorithms respectively.
基金supported by the National Natural Science Foundationof China (60873195 61070220)+3 种基金the Natural Science Foundation of Anhui Province (070412049)the Outstanding Young Teacher Foundation of Anhui Higher Education Institutions of China (2009SQRZ167)the Natural Science Foundation of Anhui Higher Education Institutions of China (KJ2009B114)the Open Project Program of Engineering Research Center of Safety Critical Industry Measure and Control Technology (SCIMCT0802)
文摘To study multi-radio multi-channel (MR-MC) Ad Hoc networks based on 802.11, an efficient cross-layer routing protocol with the function of joint channel assignment, called joint channel assignment and cross-layer routing (JCACR), is presented. Firstly, this paper introduces a new concept called channel utilization percentage (CUP), which is for measuring the contention level of different channels in a node’s neighborhood, and deduces its optimal value for determining whether a channel is overloaded or not. Then, a metric parameter named channel selection metric (CSM) is designed, which actually reffects not only the channel status but also corresponding node’s capacity to seize it. JCACR evaluates channel assignment by CSM, performs a local optimization by assigning each node a channel with the smaller CSM value, and changes the working channel dynamically when the channel is overloaded. Therefore, the network load balancing can be achieved. In addition, simulation shows that, when compared with the protocol of weighted cumulative expected transfer time (WCETT), the new protocol can improve the network throughput and reduce the end-to-end average delay with fewer overheads.
基金Supported by the National High Technology Research and Development Program (No. 2009AA011504)
文摘Cognitive Wireless Mesh Networks(CWMN) is a novel wireless network which combines the advantage of Cognitive Radio(CR) and wireless mesh networks.CWMN can realize seamless in-tegration of heterogeneous wireless networks and achieve better radio resource utilization.However,it is particularly vulnerable due to its features of open medium,dynamic spectrum,dynamic topology,and multi-top routing,etc..Being a dynamic positive security strategy,intrusion detection can provide powerful safeguard to CWMN.In this paper,we introduce trust mechanism into CWMN with intrusion detection and present a trust establishment model based on intrusion detection.Node trust degree and the trust degree of data transmission channels between nodes are defined and an algorithm of calcu-lating trust degree is given based on distributed detection of attack to networks.A channel assignment and routing scheme is proposed,in which selects the trusted nodes and allocates data channel with high trust degree for the transmission between neighbor nodes to establish a trusted route.Simulation re-sults indicate that the scheme can vary channel allocation and routing dynamically according to network security state so as to avoid suspect nodes and unsafe channels,and improve the packet safe delivery fraction effectively.
基金supported by the National Basic Research Program of China (973) under Grant No.2012CB315801 the National Natural Science Foundation of China under Grants No.61003305,No.61173167,No.61173168,No.61070194 the Information Security Industrialization Fund from the National Development&Reform Commission of China (NDRC) under Grant No.NDRC[2009]1886
文摘Opportunistic Routing (OR) involves multiple forwarding candidates to relay packets by taking advantage of the broadcast nature and multi-user diversity of a wireless medium. Compared with Traditional Routing (TR), OR is more suitable in the case of an unreliable wireless link and can evidently improve the end-to-end throughput of Wireless Mesh Networks (WMNs). In this paper, we focus on OR in Multi-Radio Multi-Channel WMNs (MRMC-WMNs). This problem has not been well examined and is considerably more challenging than the OR in single-radio wireless networks considered in the existing literature. First, we validate the advantage of OR in MRMC-WMNs. Second, we propose Low-complexity Channel Assignment for Opportunistic Routing (LcCAOR), which assigns channels to flows according to the interference state of every node. Third, we implement the LcCOAR in a fully distributed manner. The simulation result shows that compared with OR in Single-Radio Single-Channel WMNs (SRSC-WMNs), the proposed OR can significantly enhance the throughput to 87.11% and 100.3% in grid and tree WMNs, respectively.
文摘With the rise of cloud computing in recent years, a large number of streaming media has yielded an exponential growth in network traffic. With the now present 5G and future 6G, the development of the Internet of Things (IoT), social networks, video on demand, and mobile multimedia platforms, the backbone network is bound to bear more traffic. The transmission capacity of Single Core Fiber (SCFs) may be limited in the future and Spatial Division Multiplexing (SDM) leveraging multi-core fibers promises to be one of the solutions for the future. Currently, Elastic optical networks (EONs) with multi-core fibers (MCFs) are a kind of SDM-enabled EONs (SDM-EON) used to enhance the capacity of transmission. The resource assignment in MCFs, however, will be subject to Inter-Core Crosstalk (IC-XT), hence, reducing the effectiveness of transmission. This research highlights the routing, modulation level, and spectrum assignment (RMLSA) problems with anycast traffic mode in SDM-EON. A multipath routing scheme is used to reduce the blocking rate of anycast traffic in SDM-EON with the limit of inter-core crosstalk. Hence, an integer linear programming (ILP) problem is formulated and a heuristic algorithm is proposed. Two core-assignment strategies: First-Fit (FF) and Random-Fit (RF) are used and their performance is evaluated through simulations. The simulation results show that the multipath routing method is better than the single-path routing method in terms of blocking ratio and spectrum utilization ratio. Moreover, the FF is better than the RF in low traffic load in terms of blocking ratio (BR), and the opposite in high traffic load. The FF is better than the RF in terms of a spectrum utilization ratio. In an anycast protection problem, the proposed algorithm has a lower BR than previous works.
文摘In this paper, we propose a new multicast wavelength assignment algorithm called NGWA with complexity of O(N), where N is the number of nodes on a multicast tree. The whole procedure of NGWA algorithm is separated into two phases: the partial wavelength assignment phase and the complete wavelength assignment phase. It tries to minimize the total number of wavelength conversions of the multicast tree. Meanwhile, the number of different wavelengths used is minimized locally. Through illustrative example and simulation experiments, it is proved that the NGWA algorithm works well and achieves satisfactory performance in terms of the average number of wavelength conversions and the average blocking probability.
文摘After analyzing the merits and shortcomings of Fixed-Alternated Routing algorithm (FAR) and Least Loaded Routing algorithm (LLR),we propose one novel dynamic optical routing algorithm. Having considered the influences of path’s length and path’s congestion just like in FAR and LLR,we take into account the network resource status-amount of free wavelengths in the network. Proposed algorithm sets up connections on three possible paths according to amount of available free wave-lengths in the network,which effectively decreases the blocking probability. The National Science Foundation (NSF) network and mesh-torus network simulation results show that the performance of this algorithm is better than that of FAR and LLR.
基金supported by the National Natural Science Foundation of China(No.60572050)the National High Technology Research and Development Programme of China(No.2008AA01Z211)
文摘Conventional optical burst switching(OBS)technique adopts purely statistical multiplex mechanismso that the bursts collide with each other very easily.To address this problem,a novel proactive con-tention avoidance scheme is proposed,which assigns dedicated wavelengths to each ingress node,then st-numbering algorithm is used to construct the traffic load balanced spanning trees .In this way,contentioncan be eliminated at ingress nodes,and the amount of bursts that could be accommodated by ingressnodes will be maximized.Further,those unused wavelengths left by traffic load balanced spanning treeare also organized as partial trees to carry bursts,thus the link utilization can be improved effectively.Simulation result shows that our scheme can improve the burst loss performance significantly without thewavelength converters or optical buffers comparing to other popular routing and wavelength assignment(RWA)algorithms.
基金National Key Lab of Broad Band Fiber Transmission and Communication System Technology , Ministry ofEducation
文摘General multi-protocol label switching(GMPLS) based on traffic engineering is one of the possible methods to implement all-optical network. This method implements the network with IP technique and guarantees the quality of service with traffic engineering. Based on the establishment of selecting schemes of optical path and methods of traffic calculation, the wavelength routing algorithm of all-optical network based on traffic engineering is presented by combining with prior route of shortest path and traffic engineering, the algorithm procedures are given, and the actual examples are introduced as well as the analysis on simulation calculation. This research results have certain significance for the achievement of optical switching technique of all-optical network.