为了解决无线Ad hoc网络在负载较重时网络性能差等问题,提出了一种将TDMA(Time Division Media Access)与CCFD(Co-time Co-frequency Full Duplex)相结合的分布式全双工MAC(Media Access Control)协议.数据传输前节点首先在链路共存准...为了解决无线Ad hoc网络在负载较重时网络性能差等问题,提出了一种将TDMA(Time Division Media Access)与CCFD(Co-time Co-frequency Full Duplex)相结合的分布式全双工MAC(Media Access Control)协议.数据传输前节点首先在链路共存准则的基础上进行抑制检查,随后主链路按一定的优先级筛选二级链路并发起调度请求,调度所需的四次握手过程在业务时隙头部完成.本协议在不影响传统TDMA半双工通信的条件下,增加同一时隙中可以共存的链路数,改善网络的吞吐量和时延性能.展开更多
无线网络分布式链路调度技术通过发掘无线传输间的复用达到提高吞吐量的目的.链路调度策略的形成需要节点间公平地交互含有如节点ID、队列长度等信息的短报文,并且这些短报文同步传输,导致信道拥挤.由于存在信道空闲侦听开销,在拥挤信...无线网络分布式链路调度技术通过发掘无线传输间的复用达到提高吞吐量的目的.链路调度策略的形成需要节点间公平地交互含有如节点ID、队列长度等信息的短报文,并且这些短报文同步传输,导致信道拥挤.由于存在信道空闲侦听开销,在拥挤信道中频繁后退,以及隐藏终端和暴露终端的问题,传统的CSMA/CA(Carrier sense multiple access with collision avoidance)协议传输性能低下,难以为分布式无线链路调度技术服务.针对链路调度策略形成期间报文短、信道拥挤以及公平性要求的挑战.提出了一个简单的随机MAC(Media access control)协议DLSOMAC(Distributed link scheduling oriented MAC).DLSOMAC协议没有信道侦听过程,以降低短报文的传输延迟开销;基于分布式息票收集算法,均匀分散传输时刻来降低冲撞概率和提高公平性,以满足分布式链路调度技术对MAC层的需求.用排队论分析了DLSOMAC的报文传输延迟性能.仿真实验表明,在短报文情况下,无论网络负载轻重与否,DLSOMAC协议的报文传输延迟明显优于CSMA/CA,并且报文越短,性能相对越好.即使在长报文的情况下,当网络负载很重时,DLOSMAC协议也稍优于CSMA/CA协议,适合于为自组织网络的分布式链路调度技术服务.展开更多
无线信号之间的干扰阻碍了信号的并发传输,降低了无线网络的吞吐量.链路调度是提高无线网络吞吐量、减少信号传输延迟的一种有效方法.因为SINR (signal to interference plus noise ratio)模型准确地描述了无线信号传播的固有特性,能够...无线信号之间的干扰阻碍了信号的并发传输,降低了无线网络的吞吐量.链路调度是提高无线网络吞吐量、减少信号传输延迟的一种有效方法.因为SINR (signal to interference plus noise ratio)模型准确地描述了无线信号传播的固有特性,能够真实反映无线信号之间的干扰,提出一种在动态无线网络中基于SINR模型的常数近似因子的在线分布式链路调度算法(OLD_LS).在线的意思是指,在算法执行的过程中任意节点可以随时加入网络,也可以随时离开网络.节点任意加入网络或者从网络中离开体现了无线网络的动态变化的特性. OLD_LS算法把网络区域划分为多个正六边形,局部化SINR模型的全局干扰.设计动态网络下的领导者选举算法(LE),只要网络节点的动态变化速率小于1/ε, LE就可以在O(log n+log R)ε≤5(1-21-α/2)/6,α表示路径损耗指数, n是网络节点的规模, R是最长链路的长度.根据文献调研,所提算法是第1个用于动态无线网络的在线分布式链路调度算法.展开更多
Over the past few years, wireless networking technologies have made vast forays in our daily lives. In wireless ad-hoc networks, links are set up by a number of units without any permanent infrastructures. In this pap...Over the past few years, wireless networking technologies have made vast forays in our daily lives. In wireless ad-hoc networks, links are set up by a number of units without any permanent infrastructures. In this paper, the resource optimization is considered to maximize the network throughput by efficiently using the network capacity, where multi-hop functionality and spatial TDMA （STDMA） access scheme are used. The objective is to find the minimum frame length with given traffic distributions and corresponding routing information. Because of the complex structure of the underlying mathematical problem, previous work and analysis become intractable for networks of realistic sizes. The problem is addressed through mathematical programming approach, the linear integer formulation is developed for optimizing the network throughput, and then the similarity between the original problem and the graph edge coloring problem is shown through the conflict graph concept. A column generation solution is proposed and several enhancements are made in order to fasten its convergence. Numerical results demonstrate that the theoretical limit of the throughput can be efficiently computed for networks of realistic sizes.展开更多
Currently,there are two methods suggested to handle congestion. The first approach uses packet or link scheduling on multiple logical or physical queues to explicitly reserve and allocate output bandwidth to each clas...Currently,there are two methods suggested to handle congestion. The first approach uses packet or link scheduling on multiple logical or physical queues to explicitly reserve and allocate output bandwidth to each class of traffic. The second approach,called Active Queue management,uses advanced packet queuing disciplines on an outbound queue of a router to actively avoid congestion with the help of cooperative traffic sources. On the basis of analyzing the two approaches ,in order to efficiently support flow-controlled contnuous multimedia flows,we compare and analyze RED,FRED,CBT,D-CBT. Finally,we point out the shortcomings and the next research topic.展开更多
以压缩感知理论为基础,研究物理干扰模型下的无线传感器网络数据收集问题,将其建模为转发树构建和链路调度联合问题(forwarding tree construction and scheduling,FTCS)。FTCS问题属于NP难题,提出一种可以实现转发树构建和链路调度子...以压缩感知理论为基础,研究物理干扰模型下的无线传感器网络数据收集问题,将其建模为转发树构建和链路调度联合问题(forwarding tree construction and scheduling,FTCS)。FTCS问题属于NP难题,提出一种可以实现转发树构建和链路调度子问题的分布式求解算法,目标是确定一组转发树,在转发树调度后于最短调度周期内将测量数据发往汇点,在传输延时和采集能效间实现平衡。仿真结果表明,所提算法在降低数据传输延时和提高能效等方面的性能要优于目前典型的数据收集方法。展开更多
提出了一种基于图着色法的无线传感器网络分布式链路调度（DLS）协议以减小调度周期长度、降低网络能耗.采用的策略是先对任意节点构建两跳邻居范围内的冲突图,然后根据每条链路在干扰图中的优先级及干扰度决定时隙分配的先后顺序,从而...提出了一种基于图着色法的无线传感器网络分布式链路调度（DLS）协议以减小调度周期长度、降低网络能耗.采用的策略是先对任意节点构建两跳邻居范围内的冲突图,然后根据每条链路在干扰图中的优先级及干扰度决定时隙分配的先后顺序,从而解决传统随机调度方法调度周期较长及节点状态转换频繁的问题.由于该调度策略尽可能地为节点分配相邻时隙,减少了节点不必要的状态转换,从而降低了网络能耗.对基于干扰度和优先级的联合调度策略表现出的减小调度周期长度、降低网络能耗的特点进行了分析.网络仿真结果表明,DLS协议比DS-fPrIM（Distributed Scheduling-fixed Power Protocol Interference Model）及DRAND（Distributed RANDomized time slot sceduling）协议的调度周期长度少1～2个时隙,其能耗与DS-fPrIM协议的调度能耗相当,但二者都比DRAND协议的调度能耗低.另外DLS协议比DS-fPrIM及DRAND协议平均每周期少1次状态转换,说明提出的分布式链路调度协议能效较高.展开更多
文摘为了解决无线Ad hoc网络在负载较重时网络性能差等问题,提出了一种将TDMA(Time Division Media Access)与CCFD(Co-time Co-frequency Full Duplex)相结合的分布式全双工MAC(Media Access Control)协议.数据传输前节点首先在链路共存准则的基础上进行抑制检查,随后主链路按一定的优先级筛选二级链路并发起调度请求,调度所需的四次握手过程在业务时隙头部完成.本协议在不影响传统TDMA半双工通信的条件下,增加同一时隙中可以共存的链路数,改善网络的吞吐量和时延性能.
文摘无线网络分布式链路调度技术通过发掘无线传输间的复用达到提高吞吐量的目的.链路调度策略的形成需要节点间公平地交互含有如节点ID、队列长度等信息的短报文,并且这些短报文同步传输,导致信道拥挤.由于存在信道空闲侦听开销,在拥挤信道中频繁后退,以及隐藏终端和暴露终端的问题,传统的CSMA/CA(Carrier sense multiple access with collision avoidance)协议传输性能低下,难以为分布式无线链路调度技术服务.针对链路调度策略形成期间报文短、信道拥挤以及公平性要求的挑战.提出了一个简单的随机MAC(Media access control)协议DLSOMAC(Distributed link scheduling oriented MAC).DLSOMAC协议没有信道侦听过程,以降低短报文的传输延迟开销;基于分布式息票收集算法,均匀分散传输时刻来降低冲撞概率和提高公平性,以满足分布式链路调度技术对MAC层的需求.用排队论分析了DLSOMAC的报文传输延迟性能.仿真实验表明,在短报文情况下,无论网络负载轻重与否,DLSOMAC协议的报文传输延迟明显优于CSMA/CA,并且报文越短,性能相对越好.即使在长报文的情况下,当网络负载很重时,DLOSMAC协议也稍优于CSMA/CA协议,适合于为自组织网络的分布式链路调度技术服务.
基金This paper is supported by the National Natural Science Foundation of China under Grant Nos. 60241004 and 90104010, the National Basic Research 973 Program of China under Grant No, 2003CB314801, and the State Key Laboratory of Networking and Switching Technology,
文摘Over the past few years, wireless networking technologies have made vast forays in our daily lives. In wireless ad-hoc networks, links are set up by a number of units without any permanent infrastructures. In this paper, the resource optimization is considered to maximize the network throughput by efficiently using the network capacity, where multi-hop functionality and spatial TDMA （STDMA） access scheme are used. The objective is to find the minimum frame length with given traffic distributions and corresponding routing information. Because of the complex structure of the underlying mathematical problem, previous work and analysis become intractable for networks of realistic sizes. The problem is addressed through mathematical programming approach, the linear integer formulation is developed for optimizing the network throughput, and then the similarity between the original problem and the graph edge coloring problem is shown through the conflict graph concept. A column generation solution is proposed and several enhancements are made in order to fasten its convergence. Numerical results demonstrate that the theoretical limit of the throughput can be efficiently computed for networks of realistic sizes.
文摘Currently,there are two methods suggested to handle congestion. The first approach uses packet or link scheduling on multiple logical or physical queues to explicitly reserve and allocate output bandwidth to each class of traffic. The second approach,called Active Queue management,uses advanced packet queuing disciplines on an outbound queue of a router to actively avoid congestion with the help of cooperative traffic sources. On the basis of analyzing the two approaches ,in order to efficiently support flow-controlled contnuous multimedia flows,we compare and analyze RED,FRED,CBT,D-CBT. Finally,we point out the shortcomings and the next research topic.
文摘以压缩感知理论为基础,研究物理干扰模型下的无线传感器网络数据收集问题,将其建模为转发树构建和链路调度联合问题(forwarding tree construction and scheduling,FTCS)。FTCS问题属于NP难题,提出一种可以实现转发树构建和链路调度子问题的分布式求解算法,目标是确定一组转发树,在转发树调度后于最短调度周期内将测量数据发往汇点,在传输延时和采集能效间实现平衡。仿真结果表明,所提算法在降低数据传输延时和提高能效等方面的性能要优于目前典型的数据收集方法。
文摘提出了一种基于图着色法的无线传感器网络分布式链路调度（DLS）协议以减小调度周期长度、降低网络能耗.采用的策略是先对任意节点构建两跳邻居范围内的冲突图,然后根据每条链路在干扰图中的优先级及干扰度决定时隙分配的先后顺序,从而解决传统随机调度方法调度周期较长及节点状态转换频繁的问题.由于该调度策略尽可能地为节点分配相邻时隙,减少了节点不必要的状态转换,从而降低了网络能耗.对基于干扰度和优先级的联合调度策略表现出的减小调度周期长度、降低网络能耗的特点进行了分析.网络仿真结果表明,DLS协议比DS-fPrIM（Distributed Scheduling-fixed Power Protocol Interference Model）及DRAND（Distributed RANDomized time slot sceduling）协议的调度周期长度少1～2个时隙,其能耗与DS-fPrIM协议的调度能耗相当,但二者都比DRAND协议的调度能耗低.另外DLS协议比DS-fPrIM及DRAND协议平均每周期少1次状态转换,说明提出的分布式链路调度协议能效较高.
