Network function virtualization is a new network concept that moves network functions from dedicated hardware to software-defined applications running on standard high volume severs. In order to accomplish network ser...Network function virtualization is a new network concept that moves network functions from dedicated hardware to software-defined applications running on standard high volume severs. In order to accomplish network services, traffic flows are usually processed by a list of network functions in sequence which is defined by service function chain. By incorporating network function virtualization in inter-data center(DC) network, we can use the network resources intelligently and deploy network services faster. However, orchestrating service function chains across multiple data centers will incur high deployment cost, including the inter-data center bandwidth cost, virtual network function cost and the intra-data center bandwidth cost. In this paper, we orchestrate SFCs across multiple data centers, with a goal to minimize the overall cost. An integer linear programming(ILP) model is formulated and we provide a meta-heuristic algorithm named GBAO which contains three modules to solve it. We implemented our algorithm in Python and performed side-by-side comparison with prior algorithms. Simulation results show that our proposed algorithm reduces the overall cost by at least 21.4% over the existing algorithms for accommodating the same service function chain requests.展开更多
In view of the problem that the multimodal transport network is vulnerable to attack and faces the risk of cascading failure,three low polarization linking strategies considering the characteristics of the multimodal ...In view of the problem that the multimodal transport network is vulnerable to attack and faces the risk of cascading failure,three low polarization linking strategies considering the characteristics of the multimodal transport network are proposed to optimize network robustness.They are the low polarization linking strategy based on the degree of nodes(D_LPLS),low polarization linking strategy based on the betweenness of nodes(B_LPLS),and low polarization linking strategy based on the closeness of nodes(C_LPLS).The multimodal transport network in the Sichuan-Tibet region is analyzed,and the optimization effects of these three strategies are compared with the random linking strategy under random attacks and intentional attacks.The results show that C_LPLS can effectively optimize the robustness of the network.Under random attacks,the advantages of C_LPLS are obvious when the ratio of increased links is less than 15%,but it has fewer advantages compared with B_LPLS when the ratio of increased links is 15%to 30%.Under intentional attacks,as the ratio of increased links goes up,the advantages of C_LPLS become more obvious.Therefore,the increase of links by C_LPLS is conducive to the risk control of the network,which can provide theoretical support for the optimization of future multimodal transport network structures.展开更多
A distributed relative navigation approach via inter-satellite sensing and communication for satellite clusters is proposed. The inter-satellite link(ISL)is used for ranging and exchanging data for the relative naviga...A distributed relative navigation approach via inter-satellite sensing and communication for satellite clusters is proposed. The inter-satellite link(ISL)is used for ranging and exchanging data for the relative navigation,which can improve the autonomy of the satellite cluster. The ISL topology design problem is formulated as a multi-objective optimization problem where the energy consumption and the navigation performance are considered. Further,the relative navigation is performed in a distributed fashion,where each satellite in the cluster makes observations and communicates with its neighbors via the ISL locally such that the transmission consumption and the computational complexity for the navigation are reduced. The ISL topology optimization problem is solved via the NSGA-Ⅱ algorithm,and the consensus Kalman filter is used for the distributed relative navigation. The proposed approach is flexible to varying tasks,with satellites joining or leaving the cluster anytime,and is robust to the failure of an individual satellite. Numerical simulations are presented to verify the feasibility of the proposed approach.展开更多
Geography rectangle is used to reduce signaling overhead of the LEO satellite networks.Moreover,a multi-path routing algorithm based on an improved ant colony system(MPRA-AC) is proposed.Matrix indicating the importan...Geography rectangle is used to reduce signaling overhead of the LEO satellite networks.Moreover,a multi-path routing algorithm based on an improved ant colony system(MPRA-AC) is proposed.Matrix indicating the importance of the link between satellites is introduced into MPRA-AC in order to find the optimal path more quickly.Simulation results show that MPRA-AC reduces the number of iterations to achieve a satisfactory solution.At the same time,the packet delivery ratio of LEO satellite networks when running MPRA-AC and DSR-LSN(dynamic source routing algorithm for LEO satellite networks) is compared.The packet delivery ratio is about 7.9%lower when running DSR-LSN.Moreover,because of the mechanism of active load balancing of MPRA-AC,simulation results show that MPRA-AC outperforms DSR-LSN in link utilization when data packets are transmitted in the networks.展开更多
This paper presents a link allocation and rate assignment algorithm for multi-channel wireless networks. The objective is to reduce network con-flicts and guarantee the fairness among links. We first design a new netw...This paper presents a link allocation and rate assignment algorithm for multi-channel wireless networks. The objective is to reduce network con-flicts and guarantee the fairness among links. We first design a new network model. With this net-work model, the multi-channel wireless network is divided into several subnets according to the num-ber of channels. Based on this, we present a link allocation algorithm with time complexity O（l^2）to al-locate all links to subnets. This link allocation algo-rithm adopts conflict matrix to minimize the network contention factor. After all links are allocated to subnets, the rate assignment algorithm to maximize a fairness utility in each subnet is presented. The rate assignment algorithm adopts a near-optirml al-gorithm based on dual decomposition and realizes in a distributed way. Simulation results demonstrate that, compared with IEEE 802.11b and slotted see-ded channel hopping algorithm, our algorithm de-creases network conflicts and improves the net-work throughput significantly.展开更多
The spectrum allocation for links in multi-hop cognitive radio networks is addressed.The links rent the vacant licensed bands offered by primary users for implementing directional transmission.To minimize the individu...The spectrum allocation for links in multi-hop cognitive radio networks is addressed.The links rent the vacant licensed bands offered by primary users for implementing directional transmission.To minimize the individual cost,the links share the licensed band and rental fee.An interference model for the directional transmission in cognitive radio networks is proposed to formulate the cooperative and dynamic behavior of the links using the theory of hedonic game,called spectrum allocation game.The game is proved to converge to the core stable state indicating that all links satisfy with their current conditions and do not deviate from their coalitions.Numerical results show that the game improves spectral efficiency and contributes to reducing the individual cost of the links.展开更多
It is widely believed that cooperative relay technologies can improve the throughput of multicasting in mobile cellular networks significantly, however, the mobility of the relay terrninals may cause frequent relay li...It is widely believed that cooperative relay technologies can improve the throughput of multicasting in mobile cellular networks significantly, however, the mobility of the relay terrninals may cause frequent relay link outage. This paper proposes a stream layered cooperative relay scheme to deal with this problem. In order to study the characteristics of layered relay channels in the scheme, the capacity region is determined based on a single and a multi relay abstract model with streams layering. Besides, to satisfy the cellular network scenario, the results are extended to a wireless Gaussian channel model. The analysis and simulation results show that the scheme guarantees the continuity of the multicast streams, and maintains the high bandwidth of relay channel, with a slight loss on system capacity.展开更多
基金supported by the National Natural Science Foundation of China(61501044)
文摘Network function virtualization is a new network concept that moves network functions from dedicated hardware to software-defined applications running on standard high volume severs. In order to accomplish network services, traffic flows are usually processed by a list of network functions in sequence which is defined by service function chain. By incorporating network function virtualization in inter-data center(DC) network, we can use the network resources intelligently and deploy network services faster. However, orchestrating service function chains across multiple data centers will incur high deployment cost, including the inter-data center bandwidth cost, virtual network function cost and the intra-data center bandwidth cost. In this paper, we orchestrate SFCs across multiple data centers, with a goal to minimize the overall cost. An integer linear programming(ILP) model is formulated and we provide a meta-heuristic algorithm named GBAO which contains three modules to solve it. We implemented our algorithm in Python and performed side-by-side comparison with prior algorithms. Simulation results show that our proposed algorithm reduces the overall cost by at least 21.4% over the existing algorithms for accommodating the same service function chain requests.
基金The National Key Research and Development Program of China(No.2018YFB1601400)。
文摘In view of the problem that the multimodal transport network is vulnerable to attack and faces the risk of cascading failure,three low polarization linking strategies considering the characteristics of the multimodal transport network are proposed to optimize network robustness.They are the low polarization linking strategy based on the degree of nodes(D_LPLS),low polarization linking strategy based on the betweenness of nodes(B_LPLS),and low polarization linking strategy based on the closeness of nodes(C_LPLS).The multimodal transport network in the Sichuan-Tibet region is analyzed,and the optimization effects of these three strategies are compared with the random linking strategy under random attacks and intentional attacks.The results show that C_LPLS can effectively optimize the robustness of the network.Under random attacks,the advantages of C_LPLS are obvious when the ratio of increased links is less than 15%,but it has fewer advantages compared with B_LPLS when the ratio of increased links is 15%to 30%.Under intentional attacks,as the ratio of increased links goes up,the advantages of C_LPLS become more obvious.Therefore,the increase of links by C_LPLS is conducive to the risk control of the network,which can provide theoretical support for the optimization of future multimodal transport network structures.
基金supported by the National Natural Science Foundation of China(No.61801213)。
文摘A distributed relative navigation approach via inter-satellite sensing and communication for satellite clusters is proposed. The inter-satellite link(ISL)is used for ranging and exchanging data for the relative navigation,which can improve the autonomy of the satellite cluster. The ISL topology design problem is formulated as a multi-objective optimization problem where the energy consumption and the navigation performance are considered. Further,the relative navigation is performed in a distributed fashion,where each satellite in the cluster makes observations and communicates with its neighbors via the ISL locally such that the transmission consumption and the computational complexity for the navigation are reduced. The ISL topology optimization problem is solved via the NSGA-Ⅱ algorithm,and the consensus Kalman filter is used for the distributed relative navigation. The proposed approach is flexible to varying tasks,with satellites joining or leaving the cluster anytime,and is robust to the failure of an individual satellite. Numerical simulations are presented to verify the feasibility of the proposed approach.
基金Supported by the National High Technology Research and Development Programme of China(No.SS2013AA010503)the National Natural Science Foundation of China(No.61271281,61201151,61275158)the Fundamental Research Funds for the Central Universities(No.2482012PTB0004)
文摘Geography rectangle is used to reduce signaling overhead of the LEO satellite networks.Moreover,a multi-path routing algorithm based on an improved ant colony system(MPRA-AC) is proposed.Matrix indicating the importance of the link between satellites is introduced into MPRA-AC in order to find the optimal path more quickly.Simulation results show that MPRA-AC reduces the number of iterations to achieve a satisfactory solution.At the same time,the packet delivery ratio of LEO satellite networks when running MPRA-AC and DSR-LSN(dynamic source routing algorithm for LEO satellite networks) is compared.The packet delivery ratio is about 7.9%lower when running DSR-LSN.Moreover,because of the mechanism of active load balancing of MPRA-AC,simulation results show that MPRA-AC outperforms DSR-LSN in link utilization when data packets are transmitted in the networks.
基金This work was supported by the National Natural Science Foundation of China under Cxant No. 60902010 the Research Fund of State Key Laboratory of Mobile Communications un-der Crant No. 2012A03.
文摘This paper presents a link allocation and rate assignment algorithm for multi-channel wireless networks. The objective is to reduce network con-flicts and guarantee the fairness among links. We first design a new network model. With this net-work model, the multi-channel wireless network is divided into several subnets according to the num-ber of channels. Based on this, we present a link allocation algorithm with time complexity O（l^2）to al-locate all links to subnets. This link allocation algo-rithm adopts conflict matrix to minimize the network contention factor. After all links are allocated to subnets, the rate assignment algorithm to maximize a fairness utility in each subnet is presented. The rate assignment algorithm adopts a near-optirml al-gorithm based on dual decomposition and realizes in a distributed way. Simulation results demonstrate that, compared with IEEE 802.11b and slotted see-ded channel hopping algorithm, our algorithm de-creases network conflicts and improves the net-work throughput significantly.
基金Supported by the National High Technology Research and Development Programme of China(No.2011AA010503)the National Natural Science Foundations of China(No.60903192)
文摘The spectrum allocation for links in multi-hop cognitive radio networks is addressed.The links rent the vacant licensed bands offered by primary users for implementing directional transmission.To minimize the individual cost,the links share the licensed band and rental fee.An interference model for the directional transmission in cognitive radio networks is proposed to formulate the cooperative and dynamic behavior of the links using the theory of hedonic game,called spectrum allocation game.The game is proved to converge to the core stable state indicating that all links satisfy with their current conditions and do not deviate from their coalitions.Numerical results show that the game improves spectral efficiency and contributes to reducing the individual cost of the links.
基金Supported by the State Key Program of National Natural Science Foundation of China （No. 60832009）, Natural Science Foundation of Bcijing （No. 4102044）, Innovative Project for Young Researchers in Central Higher Education Institutions, China （No. 2009RC0119） and New Generation of Broadband Wireless Mobile Communication Networks of Major Projects of National Science and Technology （No.2009ZX03003-003-01）.
文摘It is widely believed that cooperative relay technologies can improve the throughput of multicasting in mobile cellular networks significantly, however, the mobility of the relay terrninals may cause frequent relay link outage. This paper proposes a stream layered cooperative relay scheme to deal with this problem. In order to study the characteristics of layered relay channels in the scheme, the capacity region is determined based on a single and a multi relay abstract model with streams layering. Besides, to satisfy the cellular network scenario, the results are extended to a wireless Gaussian channel model. The analysis and simulation results show that the scheme guarantees the continuity of the multicast streams, and maintains the high bandwidth of relay channel, with a slight loss on system capacity.
