Over the past few decades, the world has witnessed a rapid growth in mobile and wireless networks（MWNs） which significantly change human life. However, proliferating mobile demands lead to several intractable challe...Over the past few decades, the world has witnessed a rapid growth in mobile and wireless networks（MWNs） which significantly change human life. However, proliferating mobile demands lead to several intractable challenges that MWN has to face. Software-defined network is expected as a promising way for future network and has captured growing attention. Network virtualization is an essential feature in software-defined wireless network（SDWN）, and it brings two new entities, physical networks and virtual networks. Accordingly, efficiently assigning spectrum resource to virtual networks is one of the fundamental problems in SDWN. Directly orienting towards the spectrum resource allocation problem, firstly, the fluctuation features of virtual network requirements in SDWN are researched, and the opportunistic spectrum sharing method is introduced to SDWN. Then, the problem is proved as NP-hardness. After that, a dynamic programming and graph theory based spectrum sharing algorithm is proposed.Simulations demonstrate that the opportunistic spectrum sharing method conspicuously improves the system performance up to around 20%–30% in SDWN, and the proposed algorithm achieves more efficient performance.展开更多
Solving the controller placement problem (CPP) in an SDN architecture with multiple controllers has a significant impact on control overhead in the network, especially in multihop wireless networks (MWNs). The generat...Solving the controller placement problem (CPP) in an SDN architecture with multiple controllers has a significant impact on control overhead in the network, especially in multihop wireless networks (MWNs). The generated control overhead consists of controller-device and inter-controller communications to discover the network topology, exchange configurations, and set up and modify flow tables in the control plane. However, due to the high complexity of the proposed optimization model to the CPP, heuristic algorithms have been reported to find near-optimal solutions faster for large-scale wired networks. In this paper, the objective is to extend those existing heuristic algorithms to solve a proposed optimization model to the CPP in software-<span>defined multihop wireless networking</span><span> (SDMWN).</span>Our results demonstrate that using ranking degrees assigned to the possible controller placements, including the average distance to other devices as a degree or the connectivity degree of each placement, the extended heuristic algorithms are able to achieve the optimal solution in small-scale networks in terms of the generated control overhead and the number of controllers selected in the network. As a result, using extended heuristic algorithms, the average number of hops among devices and their assigned controllers as well as among controllers will be reduced. Moreover, these algorithms are able tolower<span "=""> </span>the control overhead in large-scale networks and select fewer controllers compared to an extended algorithm that solves the CPP in SDMWN based on a randomly selected controller placement approach.展开更多
As communication technology and smart manufacturing have developed, the industrial internet of things(IIo T)has gained considerable attention from academia and industry.Wireless sensor networks(WSNs) have many advanta...As communication technology and smart manufacturing have developed, the industrial internet of things(IIo T)has gained considerable attention from academia and industry.Wireless sensor networks(WSNs) have many advantages with broad applications in many areas including environmental monitoring, which makes it a very important part of IIo T. However,energy depletion and hardware malfunctions can lead to node failures in WSNs. The industrial environment can also impact the wireless channel transmission, leading to network reliability problems, even with tightly coupled control and data planes in traditional networks, which obviously also enhances network management cost and complexity. In this paper, we introduce a new software defined network(SDN), and modify this network to propose a framework called the improved software defined wireless sensor network(improved SD-WSN). This proposed framework can address the following issues. 1) For a large scale heterogeneous network, it solves the problem of network management and smooth merging of a WSN into IIo T. 2) The network coverage problem is solved which improves the network reliability. 3) The framework addresses node failure due to various problems, particularly related to energy consumption.Therefore, it is necessary to improve the reliability of wireless sensor networks, by developing certain schemes to reduce energy consumption and the delay time of network nodes under IIo T conditions. Experiments have shown that the improved approach significantly reduces the energy consumption of nodes and the delay time, thus improving the reliability of WSN.展开更多
Software-defined networks （SDN） have attracted much attention recently because of their flexibility in terms of network management. Increasingly, SDN is being introduced into wireless networks to form wireless SDN. ...Software-defined networks （SDN） have attracted much attention recently because of their flexibility in terms of network management. Increasingly, SDN is being introduced into wireless networks to form wireless SDN. One enabling technology for wireless SDN is network virtualization, which logically divides one wireless network element, such as a base station, into multiple slices, and each slice serving as a standalone virtual BS. In this way, one physical mobile wireless network can be partitioned into multiple virtual networks in a software-defined manner. Wireless virtual networks comprising virtual base stations also need to provide QoS to mobile end-user services in the same context as their physical hosting networks. One key QoS parameter is delay. This paper presents a delay model for software-defined wireless virtual networks. Network calculus is used in the modelling. In particular, stochastic network calculus, which describes more realistic models than deterministic network calculus, is used. The model enables theoretical investigation of wireless SDN, which is largely dominated by either algorithms or prototype implementations.展开更多
为解决高密度无线局域网中接入拥塞、资源失衡及流量混传导致的性能瓶颈问题,从接入层面、资源层面及流量层面分析无线局域网接入拥塞问题,并从3个层面提出基于软件定义网络(Software Defined Network,SDN)流量调度的应对策略。实践案...为解决高密度无线局域网中接入拥塞、资源失衡及流量混传导致的性能瓶颈问题,从接入层面、资源层面及流量层面分析无线局域网接入拥塞问题,并从3个层面提出基于软件定义网络(Software Defined Network,SDN)流量调度的应对策略。实践案例验证了该策略在提升网络吞吐量、降低传输时延方面具有明显成效。展开更多
To provide ubiquitous Internet access under the explosive increase of applications and data traffic,the current network architecture has become highly heterogeneous and complex,making network management a challenging ...To provide ubiquitous Internet access under the explosive increase of applications and data traffic,the current network architecture has become highly heterogeneous and complex,making network management a challenging task.To this end,software-defined networking(SDN) has been proposed as a promising solution.In the SDN architecture,the control plane and the data plane are decoupled,and the network infrastructures are abstracted and managed by a centralized controller.With SDN,efficient and flexible network control can be achieved,which potentially enhances network performance.To harvest the benefits of SDN in wireless networks,the software-defined wireless network(SDWN) architecture has been recently considered.In this paper,we first analyze the applications of SDN to different types of wireless networks.We then discuss several important technical aspects of performance enhancement in SDN-based wireless networks.Finally,we present possible future research directions of SDWN.展开更多
为了实时掌握长大铁路隧道在施工及运营期间的健康状况,需要将监测数据传输至数据平台。然而,长大隧道具有多径、遮挡、干扰源多等特征,不利于信号的传输。编码正交频分复用(Coded Orthogonal Frequency Division Multiplexing,COFDM)...为了实时掌握长大铁路隧道在施工及运营期间的健康状况,需要将监测数据传输至数据平台。然而,长大隧道具有多径、遮挡、干扰源多等特征,不利于信号的传输。编码正交频分复用(Coded Orthogonal Frequency Division Multiplexing,COFDM)具有抗多径干扰、良好的绕射和穿透能力,适合于铁路长大隧道复杂环境下的通信要求。基于COFDM和前向纠错(Forward Error Correction,FEC)技术,利用软件定义无线电(Software Defined Radio,SDR)实现长大隧道的AdHoc无线自组网系统,具有无中心、无需基础设施、抗多径、多跳数据传输、自适应调制路由、可调带宽、高速率等优点。展开更多
传统边缘分布式存储系统中网络配置繁琐,优化网络所需的网络状态信息测量操作开销大,当终端设备对数据存储和检索的业务需求处于高峰时,会导致网络链路负载过重从而影响数据转发传输的性能。此外,现有分布式存储系统在进行数据的存储节...传统边缘分布式存储系统中网络配置繁琐,优化网络所需的网络状态信息测量操作开销大,当终端设备对数据存储和检索的业务需求处于高峰时,会导致网络链路负载过重从而影响数据转发传输的性能。此外,现有分布式存储系统在进行数据的存储节点选择时,只考虑了节点剩余存储空间,没有考虑网络状态和节点自身负载对系统存储性能的影响。为解决上述问题,设计和实现了一种基于软件定义网络(Software Defined Network,SDN)和无人机辅助的边缘分布式存储系统,利用SDN技术测量网络状态、网络节点自身负载和存储节点负载状态信息,通过无人机移动节点飞行到重负载网络节点的上方进行分流以平衡各条链路的流量负载;对于重负载网络节点和存储节点的选择,提出了一种基于多属性决策模型综合考虑网络状态和节点自身负载状态的节点选择算法,选择出重负载网络节点和合适的存储节点,然后通过对无人机的位置部署,实现网络链路流量的分流,平衡网络链路的流量负载。经实验测试,结果显示在无线Mesh网络拓扑中,所提无线边缘分布式存储系统的存储性能优于现有边缘分布式存储系统,存储时间明显缩短,在增加流量负载的情况下依然可以保持良好的存储性能,具有良好的负载均衡性能。展开更多
面向低空通信复杂环境,构建融合有线主干与无线接入的分层异构网络体系,设计基于路径分流与动态调度机制的自适应传输协议。通过引入软件定义网络(Software Defined Network,SDN)控制、整数线性规划(Integer Linear Programming,ILP)资...面向低空通信复杂环境,构建融合有线主干与无线接入的分层异构网络体系,设计基于路径分流与动态调度机制的自适应传输协议。通过引入软件定义网络(Software Defined Network,SDN)控制、整数线性规划(Integer Linear Programming,ILP)资源优化与多链路容错切换策略,实现对带宽、延迟、链路稳定性的综合管控。仿真对比结果表明,该机制在端到端时延控制、吞吐效率提升与链路重构响应方面表现出结构性优势,可为高动态低空组网提供技术基础。展开更多
基金supported by the National Natural Science Foundation of China(6102100161133015+4 种基金61171065)the National Natural Science Foundation of China(973 Program)(2013CB329001)the National High Technology ResearchDevelopment Program(863 Program)(2013AA0106052013AA013500)
文摘Over the past few decades, the world has witnessed a rapid growth in mobile and wireless networks（MWNs） which significantly change human life. However, proliferating mobile demands lead to several intractable challenges that MWN has to face. Software-defined network is expected as a promising way for future network and has captured growing attention. Network virtualization is an essential feature in software-defined wireless network（SDWN）, and it brings two new entities, physical networks and virtual networks. Accordingly, efficiently assigning spectrum resource to virtual networks is one of the fundamental problems in SDWN. Directly orienting towards the spectrum resource allocation problem, firstly, the fluctuation features of virtual network requirements in SDWN are researched, and the opportunistic spectrum sharing method is introduced to SDWN. Then, the problem is proved as NP-hardness. After that, a dynamic programming and graph theory based spectrum sharing algorithm is proposed.Simulations demonstrate that the opportunistic spectrum sharing method conspicuously improves the system performance up to around 20%–30% in SDWN, and the proposed algorithm achieves more efficient performance.
文摘Solving the controller placement problem (CPP) in an SDN architecture with multiple controllers has a significant impact on control overhead in the network, especially in multihop wireless networks (MWNs). The generated control overhead consists of controller-device and inter-controller communications to discover the network topology, exchange configurations, and set up and modify flow tables in the control plane. However, due to the high complexity of the proposed optimization model to the CPP, heuristic algorithms have been reported to find near-optimal solutions faster for large-scale wired networks. In this paper, the objective is to extend those existing heuristic algorithms to solve a proposed optimization model to the CPP in software-<span>defined multihop wireless networking</span><span> (SDMWN).</span>Our results demonstrate that using ranking degrees assigned to the possible controller placements, including the average distance to other devices as a degree or the connectivity degree of each placement, the extended heuristic algorithms are able to achieve the optimal solution in small-scale networks in terms of the generated control overhead and the number of controllers selected in the network. As a result, using extended heuristic algorithms, the average number of hops among devices and their assigned controllers as well as among controllers will be reduced. Moreover, these algorithms are able tolower<span "=""> </span>the control overhead in large-scale networks and select fewer controllers compared to an extended algorithm that solves the CPP in SDMWN based on a randomly selected controller placement approach.
基金supported by the National Natural Science Foundation of China(61571336)the Science and Technology Project of Henan Province in China(172102210081)the Independent Innovation Research Foundation of Wuhan University of Technology(2016-JL-036)
文摘As communication technology and smart manufacturing have developed, the industrial internet of things(IIo T)has gained considerable attention from academia and industry.Wireless sensor networks(WSNs) have many advantages with broad applications in many areas including environmental monitoring, which makes it a very important part of IIo T. However,energy depletion and hardware malfunctions can lead to node failures in WSNs. The industrial environment can also impact the wireless channel transmission, leading to network reliability problems, even with tightly coupled control and data planes in traditional networks, which obviously also enhances network management cost and complexity. In this paper, we introduce a new software defined network(SDN), and modify this network to propose a framework called the improved software defined wireless sensor network(improved SD-WSN). This proposed framework can address the following issues. 1) For a large scale heterogeneous network, it solves the problem of network management and smooth merging of a WSN into IIo T. 2) The network coverage problem is solved which improves the network reliability. 3) The framework addresses node failure due to various problems, particularly related to energy consumption.Therefore, it is necessary to improve the reliability of wireless sensor networks, by developing certain schemes to reduce energy consumption and the delay time of network nodes under IIo T conditions. Experiments have shown that the improved approach significantly reduces the energy consumption of nodes and the delay time, thus improving the reliability of WSN.
基金supported in part by the grant from the National Natural Science Foundation of China (60973129)
文摘Software-defined networks （SDN） have attracted much attention recently because of their flexibility in terms of network management. Increasingly, SDN is being introduced into wireless networks to form wireless SDN. One enabling technology for wireless SDN is network virtualization, which logically divides one wireless network element, such as a base station, into multiple slices, and each slice serving as a standalone virtual BS. In this way, one physical mobile wireless network can be partitioned into multiple virtual networks in a software-defined manner. Wireless virtual networks comprising virtual base stations also need to provide QoS to mobile end-user services in the same context as their physical hosting networks. One key QoS parameter is delay. This paper presents a delay model for software-defined wireless virtual networks. Network calculus is used in the modelling. In particular, stochastic network calculus, which describes more realistic models than deterministic network calculus, is used. The model enables theoretical investigation of wireless SDN, which is largely dominated by either algorithms or prototype implementations.
文摘为解决高密度无线局域网中接入拥塞、资源失衡及流量混传导致的性能瓶颈问题,从接入层面、资源层面及流量层面分析无线局域网接入拥塞问题,并从3个层面提出基于软件定义网络(Software Defined Network,SDN)流量调度的应对策略。实践案例验证了该策略在提升网络吞吐量、降低传输时延方面具有明显成效。
基金supported by the US National Science Foundation(Nos.CNS-1247955 and CNS-1320664)the Wireless Engineering Research and Education Center(WEREC)at Auburn University,Auburn,USA
文摘To provide ubiquitous Internet access under the explosive increase of applications and data traffic,the current network architecture has become highly heterogeneous and complex,making network management a challenging task.To this end,software-defined networking(SDN) has been proposed as a promising solution.In the SDN architecture,the control plane and the data plane are decoupled,and the network infrastructures are abstracted and managed by a centralized controller.With SDN,efficient and flexible network control can be achieved,which potentially enhances network performance.To harvest the benefits of SDN in wireless networks,the software-defined wireless network(SDWN) architecture has been recently considered.In this paper,we first analyze the applications of SDN to different types of wireless networks.We then discuss several important technical aspects of performance enhancement in SDN-based wireless networks.Finally,we present possible future research directions of SDWN.
文摘为了实时掌握长大铁路隧道在施工及运营期间的健康状况,需要将监测数据传输至数据平台。然而,长大隧道具有多径、遮挡、干扰源多等特征,不利于信号的传输。编码正交频分复用(Coded Orthogonal Frequency Division Multiplexing,COFDM)具有抗多径干扰、良好的绕射和穿透能力,适合于铁路长大隧道复杂环境下的通信要求。基于COFDM和前向纠错(Forward Error Correction,FEC)技术,利用软件定义无线电(Software Defined Radio,SDR)实现长大隧道的AdHoc无线自组网系统,具有无中心、无需基础设施、抗多径、多跳数据传输、自适应调制路由、可调带宽、高速率等优点。
文摘传统边缘分布式存储系统中网络配置繁琐,优化网络所需的网络状态信息测量操作开销大,当终端设备对数据存储和检索的业务需求处于高峰时,会导致网络链路负载过重从而影响数据转发传输的性能。此外,现有分布式存储系统在进行数据的存储节点选择时,只考虑了节点剩余存储空间,没有考虑网络状态和节点自身负载对系统存储性能的影响。为解决上述问题,设计和实现了一种基于软件定义网络(Software Defined Network,SDN)和无人机辅助的边缘分布式存储系统,利用SDN技术测量网络状态、网络节点自身负载和存储节点负载状态信息,通过无人机移动节点飞行到重负载网络节点的上方进行分流以平衡各条链路的流量负载;对于重负载网络节点和存储节点的选择,提出了一种基于多属性决策模型综合考虑网络状态和节点自身负载状态的节点选择算法,选择出重负载网络节点和合适的存储节点,然后通过对无人机的位置部署,实现网络链路流量的分流,平衡网络链路的流量负载。经实验测试,结果显示在无线Mesh网络拓扑中,所提无线边缘分布式存储系统的存储性能优于现有边缘分布式存储系统,存储时间明显缩短,在增加流量负载的情况下依然可以保持良好的存储性能,具有良好的负载均衡性能。
文摘面向低空通信复杂环境,构建融合有线主干与无线接入的分层异构网络体系,设计基于路径分流与动态调度机制的自适应传输协议。通过引入软件定义网络(Software Defined Network,SDN)控制、整数线性规划(Integer Linear Programming,ILP)资源优化与多链路容错切换策略,实现对带宽、延迟、链路稳定性的综合管控。仿真对比结果表明,该机制在端到端时延控制、吞吐效率提升与链路重构响应方面表现出结构性优势,可为高动态低空组网提供技术基础。
