Wireless Sensor Networks (WSNs) have inherent and unique characteristics rather than traditional networks. They have many different constraints, such as computational power, storage capacity, energy supply and etc;of ...Wireless Sensor Networks (WSNs) have inherent and unique characteristics rather than traditional networks. They have many different constraints, such as computational power, storage capacity, energy supply and etc;of course the most important issue is their energy constraint. Energy aware routing protocol is very important in WSN, but routing protocol which only considers energy has not efficient performance. Therefore considering other parameters beside energy efficiency is crucial for protocols efficiency. Depending on sensor network application, different parameters can be considered for its protocols. Congestion management can affect routing protocol performance. Congestion occurrence in network nodes leads to increasing packet loss and energy consumption. Another parameter which affects routing protocol efficiency is providing fairness in nodes energy consumption. When fairness is not considered in routing process, network will be partitioned very soon and then the network performance will be decreased. In this paper a Tree based Energy and Congestion Aware Routing Protocol (TECARP) is proposed. The proposed protocol is an energy efficient routing protocol which tries to manage congestion and to provide fairness in network. Simulation results shown in this paper imply that the TECARP has achieved its goals.展开更多
The nodes in the sensor network have a wide range of uses,particularly on under-sea links that are skilled for detecting,handling as well as management.The underwater wireless sensor networks support collecting pollut...The nodes in the sensor network have a wide range of uses,particularly on under-sea links that are skilled for detecting,handling as well as management.The underwater wireless sensor networks support collecting pollution data,mine survey,oceanographic information collection,aided navigation,strategic surveillance,and collection of ocean samples using detectors that are submerged inwater.Localization,congestion routing,and prioritizing the traffic is the major issue in an underwater sensor network.Our scheme differentiates the different types of traffic and gives every type of traffic its requirements which is considered regarding network resource.Minimization of localization error using the proposed angle-based forwarding scheme is explained in this paper.We choose the shortest path to the destination using the fitness function which is calculated based on fault ratio,dispatching of packets,power,and distance among the nodes.This work contemplates congestion conscious forwarding using hard stage and soft stage schemes which reduce the congestion by monitoring the status of the energy and buffer of the nodes and controlling the traffic.The study with the use of the ns3 simulator demonstrated that a given algorithm accomplishes superior performance for loss of packet,delay of latency,and power utilization than the existing algorithms.展开更多
The article intends to find a method to quantify traffic congestion＇s impacts on travelers to help transportation planners and policy decision makers well understand congestion situations. Three new congestion indica...The article intends to find a method to quantify traffic congestion＇s impacts on travelers to help transportation planners and policy decision makers well understand congestion situations. Three new congestion indicators, including transportation environment satisfaction （TES）, travel time satisfaction （TTS）, and traffic congestion frequency and feeling （TCFF）, are defined to estimate urban traffic congestion based on travelers＇ feelings. Data of travelers＇ attitude about congestion and trip information were collected from a survey in Shanghai, China. Based on the survey data, we estimated the value of the three indi- cators. Then, the principal components analysis was used to derive a small number of linear combinations of a set of variables to estimate the whole congestion status. A linear regression model was used to find out the significant variables which impact respondents＇ feelings. Two ordered logit models were used to select significant variables of TES and TTS. Attitudinal factor variables were also used in these models. The results show that attitudinal factor variables and cluster category variables are as important as sociodemographic variables in the models. Using the three congestion indicators, the government can collect travelers＇ feeling about traffic congestion and estimate the transportation policy that might be applied to cope with traffic congestion.展开更多
To meet the demand for high on-chip network performance, flexible routing algorithms supplying path diversity and congestion alleviation are required. We propose a CAOE-FA router as a combination of congestionawarenes...To meet the demand for high on-chip network performance, flexible routing algorithms supplying path diversity and congestion alleviation are required. We propose a CAOE-FA router as a combination of congestionawareness and fair arbitration. Buffer occupancies from downstream neighbors are collected to indicate the congestion levels, among the candidate outputs permitted by the odd-even(OE) turn model, the lightest loaded direction is selected; fair arbitration is employed for the condition of the same congestion level to replace random selection. Experimental results show that the CAOE-FA can reduce the average packet latency by up to 22.18% and improve the network throughput by up to 68.58%, with ignorable price of hardware cost.展开更多
命名数据网(named data networking,NDN)作为一种新型的互联网架构,旨在应对日益增长的数据流量.然而,随着用户需求进一步增长,拥塞控制对于多路径传输的命名数据网仍然是一个具有挑战性的问题,亟需一种能够快速地检测网络拥塞和有效地...命名数据网(named data networking,NDN)作为一种新型的互联网架构,旨在应对日益增长的数据流量.然而,随着用户需求进一步增长,拥塞控制对于多路径传输的命名数据网仍然是一个具有挑战性的问题,亟需一种能够快速地检测网络拥塞和有效地管理网络资源的拥塞控制机制.针对这一问题,提出了一种基于软件定义网络技术的、具有缓存感知功能的命名数据网节点拥塞控制策略,称BCMCC.首先,介绍了BCMCC的新型网络架构.利用软件定义网络控制平面与数据平面解耦合技术,该架构将拥塞控制功能集中于SDN控制器中,以实现集中式节点拥塞控制、降低节点运行负荷的目的.其次,基于新型网络架构,研究了BCMCC的缓存感知算法和多路径选择拥塞控制算法.其中,缓存感知算法实现了网络缓存内容的感知以及缓存内容全局流行度的计算,能够利用命名数据网的节点缓存特性,降低缓存内容对拥塞控制的影响;多路径选择拥塞控制算法协同节点更新转发端口信息以实现流量迁移、智能化管理多路径容量,达到提高网络资源利用率、有效避免和缓解网络拥塞的目的.最后,在ndnSIM仿真平台进行BCMCC的性能测试.实验结果表明,BCMCC在丢包量、网络吞吐量以及传输时延等方面优于Best-Route算法、NCC算法和Random算法.在网络流量相同的情况下,BCMCC平均传输时延比Random低14.16%,比NCC低22.68%,比Best-Route低17.24%,同时相比Best-Route具有更稳定的网络吞吐量.BCMCC可以有效解决命名数据网拥塞问题.展开更多
Cloud data centers now provide a plethora of rich online applications such as web search, social networking, and cloud computing. A key challenge for such applications, however, is to meet soft real-time constraints. ...Cloud data centers now provide a plethora of rich online applications such as web search, social networking, and cloud computing. A key challenge for such applications, however, is to meet soft real-time constraints. Due to the deadline-agnostic congestion control in Transmission Control Protocol（TCP）, many deadline-sensitive flows cannot finish transmission before their deadlines. In this paper, we propose an SDNbased Explicit-Deadline-aware TCP（SED） for cloud Data Center Networks（DCN）. SED assigns a base rate for non-deadline flows first and gives spare bandwidth to the deadline flows as much as possible. Subsequently,a Retransmission-enhanced SED（RSED） is introduced to solve the packet-loss timeout problem. Through our experiments, we show that SED can make flows meet deadlines effectively, and that it significantly outperforms previous protocols in the cloud data center environment.展开更多
基于802.11协议MAC层重传策略,提出一个衡量节点接入能力的参数CAM(capacity of access to medium),以体现节点周围信道的繁忙程度及其抢占信道能力。在此基础上,联合MAC层和网络层进行跨层设计,提出了一个拥塞感知路由CAOR(congestion ...基于802.11协议MAC层重传策略,提出一个衡量节点接入能力的参数CAM(capacity of access to medium),以体现节点周围信道的繁忙程度及其抢占信道能力。在此基础上,联合MAC层和网络层进行跨层设计,提出了一个拥塞感知路由CAOR(congestion aware on-demand routing)协议。仿真表明:该协议能够在降低开销的前提下,显著增加网络吞吐量,并降低平均端到端的时延。展开更多
文摘Wireless Sensor Networks (WSNs) have inherent and unique characteristics rather than traditional networks. They have many different constraints, such as computational power, storage capacity, energy supply and etc;of course the most important issue is their energy constraint. Energy aware routing protocol is very important in WSN, but routing protocol which only considers energy has not efficient performance. Therefore considering other parameters beside energy efficiency is crucial for protocols efficiency. Depending on sensor network application, different parameters can be considered for its protocols. Congestion management can affect routing protocol performance. Congestion occurrence in network nodes leads to increasing packet loss and energy consumption. Another parameter which affects routing protocol efficiency is providing fairness in nodes energy consumption. When fairness is not considered in routing process, network will be partitioned very soon and then the network performance will be decreased. In this paper a Tree based Energy and Congestion Aware Routing Protocol (TECARP) is proposed. The proposed protocol is an energy efficient routing protocol which tries to manage congestion and to provide fairness in network. Simulation results shown in this paper imply that the TECARP has achieved its goals.
文摘The nodes in the sensor network have a wide range of uses,particularly on under-sea links that are skilled for detecting,handling as well as management.The underwater wireless sensor networks support collecting pollution data,mine survey,oceanographic information collection,aided navigation,strategic surveillance,and collection of ocean samples using detectors that are submerged inwater.Localization,congestion routing,and prioritizing the traffic is the major issue in an underwater sensor network.Our scheme differentiates the different types of traffic and gives every type of traffic its requirements which is considered regarding network resource.Minimization of localization error using the proposed angle-based forwarding scheme is explained in this paper.We choose the shortest path to the destination using the fitness function which is calculated based on fault ratio,dispatching of packets,power,and distance among the nodes.This work contemplates congestion conscious forwarding using hard stage and soft stage schemes which reduce the congestion by monitoring the status of the energy and buffer of the nodes and controlling the traffic.The study with the use of the ns3 simulator demonstrated that a given algorithm accomplishes superior performance for loss of packet,delay of latency,and power utilization than the existing algorithms.
基金supported by the Key Natural Science Foundation of China:Urban Transportation Planning Theory and Methods under the Information Environment, Grant No. 50738004/E0807
文摘The article intends to find a method to quantify traffic congestion＇s impacts on travelers to help transportation planners and policy decision makers well understand congestion situations. Three new congestion indicators, including transportation environment satisfaction （TES）, travel time satisfaction （TTS）, and traffic congestion frequency and feeling （TCFF）, are defined to estimate urban traffic congestion based on travelers＇ feelings. Data of travelers＇ attitude about congestion and trip information were collected from a survey in Shanghai, China. Based on the survey data, we estimated the value of the three indi- cators. Then, the principal components analysis was used to derive a small number of linear combinations of a set of variables to estimate the whole congestion status. A linear regression model was used to find out the significant variables which impact respondents＇ feelings. Two ordered logit models were used to select significant variables of TES and TTS. Attitudinal factor variables were also used in these models. The results show that attitudinal factor variables and cluster category variables are as important as sociodemographic variables in the models. Using the three congestion indicators, the government can collect travelers＇ feeling about traffic congestion and estimate the transportation policy that might be applied to cope with traffic congestion.
基金Project supported by the National Natural Science Foundation of China(No.61625403)
文摘To meet the demand for high on-chip network performance, flexible routing algorithms supplying path diversity and congestion alleviation are required. We propose a CAOE-FA router as a combination of congestionawareness and fair arbitration. Buffer occupancies from downstream neighbors are collected to indicate the congestion levels, among the candidate outputs permitted by the odd-even(OE) turn model, the lightest loaded direction is selected; fair arbitration is employed for the condition of the same congestion level to replace random selection. Experimental results show that the CAOE-FA can reduce the average packet latency by up to 22.18% and improve the network throughput by up to 68.58%, with ignorable price of hardware cost.
文摘命名数据网(named data networking,NDN)作为一种新型的互联网架构,旨在应对日益增长的数据流量.然而,随着用户需求进一步增长,拥塞控制对于多路径传输的命名数据网仍然是一个具有挑战性的问题,亟需一种能够快速地检测网络拥塞和有效地管理网络资源的拥塞控制机制.针对这一问题,提出了一种基于软件定义网络技术的、具有缓存感知功能的命名数据网节点拥塞控制策略,称BCMCC.首先,介绍了BCMCC的新型网络架构.利用软件定义网络控制平面与数据平面解耦合技术,该架构将拥塞控制功能集中于SDN控制器中,以实现集中式节点拥塞控制、降低节点运行负荷的目的.其次,基于新型网络架构,研究了BCMCC的缓存感知算法和多路径选择拥塞控制算法.其中,缓存感知算法实现了网络缓存内容的感知以及缓存内容全局流行度的计算,能够利用命名数据网的节点缓存特性,降低缓存内容对拥塞控制的影响;多路径选择拥塞控制算法协同节点更新转发端口信息以实现流量迁移、智能化管理多路径容量,达到提高网络资源利用率、有效避免和缓解网络拥塞的目的.最后,在ndnSIM仿真平台进行BCMCC的性能测试.实验结果表明,BCMCC在丢包量、网络吞吐量以及传输时延等方面优于Best-Route算法、NCC算法和Random算法.在网络流量相同的情况下,BCMCC平均传输时延比Random低14.16%,比NCC低22.68%,比Best-Route低17.24%,同时相比Best-Route具有更稳定的网络吞吐量.BCMCC可以有效解决命名数据网拥塞问题.
基金supported by the National Natural Science Foundation of China (Nos. 61370209 and 61402230)
文摘Cloud data centers now provide a plethora of rich online applications such as web search, social networking, and cloud computing. A key challenge for such applications, however, is to meet soft real-time constraints. Due to the deadline-agnostic congestion control in Transmission Control Protocol（TCP）, many deadline-sensitive flows cannot finish transmission before their deadlines. In this paper, we propose an SDNbased Explicit-Deadline-aware TCP（SED） for cloud Data Center Networks（DCN）. SED assigns a base rate for non-deadline flows first and gives spare bandwidth to the deadline flows as much as possible. Subsequently,a Retransmission-enhanced SED（RSED） is introduced to solve the packet-loss timeout problem. Through our experiments, we show that SED can make flows meet deadlines effectively, and that it significantly outperforms previous protocols in the cloud data center environment.
文摘基于802.11协议MAC层重传策略,提出一个衡量节点接入能力的参数CAM(capacity of access to medium),以体现节点周围信道的繁忙程度及其抢占信道能力。在此基础上,联合MAC层和网络层进行跨层设计,提出了一个拥塞感知路由CAOR(congestion aware on-demand routing)协议。仿真表明:该协议能够在降低开销的前提下,显著增加网络吞吐量,并降低平均端到端的时延。
