基于跳数场的无线传感器网络路由协议研究

研究了无线传感器网络路由机制;在分析了基于跳数场的多径路由协议的基础上,针对其存在节点负载不均衡的缺陷,提出了新的局部动态改变节点功率的路由算法,该算法在建立跳数场时选取出一跳扩展节点来分担一跳节点的负担,在数据传输过程中使用基于节点剩余能量和连通度的加权函数值作为转发节点的选择依据,均衡了中间节点的能耗;仿真实验表明,新的算法能够有效均衡负载,延长网络生存期.     

基于CICQ的动态重路由交换机制

针对现有路由交换机制存在计算复杂度过高以及端口争用问题,提出基于联合输入交叉节点排队交换结构的动态重路由交换机制。该机制依据互联网在路由拓扑层的路径多样化特点,在转发层为每个分组维护多个可选输出端口,并根据交换系统拥塞度实施分组动态重路由,从而实现网络流量的实时动态均衡。仿真结果表明,以该机制为构件的网络交换系统能获得良好的性能保障。     

基于通信代价的Zigbee网状网络路由选择算法

针对Zigbee网状网络AODVjr路由算法在路由发现过程中引起的节点能耗不均衡问题,提出了一种通过有效选择转发节点,动态建立通信路径的路由选择算法.该算法在定义通信代价函数的基础上,通过限定邻居前区集合来确定待选节点集,并综合考虑待选节点的剩余能量以及待选节点转发数据至下一跳的能量损耗,选择具有最小通信代价的节点转发数据,尽可能的减小节点在路由发现过程中所引起的不必要的能量损耗.仿真结果表明,该算法能够有效地均衡节点能量、降低网络能耗、延长网络生命周期.     

Mesh网络中基于效用转发的路由恢复算法

在文献[10]的无线M esh网络路由算法的基础上,提出一种改进的基于效用转发的路由快速恢复算法,根据不同网络环境下影响效用值的各因素所占权重不同的特点,利用节点的历史通信数据,动态获取权重值,使算法能更好适应真实的网络环境;综合利用网络时延、节点效用值和节点之间的跳数,选择最优的下一跳转发节点,减少网络中不必要的时延增加和资源浪费.ONE仿真结果表明,与其它4种路由协议进行对比分析,该算法能够提高数据包的转发效率,提升网络的性能.     

多下一跳路由机制下负载均衡算法研究*

多下一跳路由机制中,各个节点都预先建立多下一跳转发表。在路由收敛期间,数据通过多下一跳转发表转发,从而解决断流问题,提高网络的自愈能力。提出了一种多下一跳路由机制下的负载均衡转发算法。该算法包括三个部分,即选择候选下一跳集、数据流分配映射和基于过载链路的反馈式动态调整。采用哈希函数分配数据流保证了每个业务流的报文保序问题。通过对下一跳链路的实时信息统计,采用动态调整机制可以达到很好的均衡效果。     

基于邻居表的ZigBee网络树路由改进算法

针对ZigBee网络树路由算法路由跳数多、数据传输延时长等问题,提出一种基于邻居表的ZigBee网络树路由改进算法。借助一跳邻居节点地址信息,建立邻居节点选择策略,在节点的一跳邻居节点中,选择到达目的节点树路由跳数最少的邻居节点作为下一跳转发节点。在树路由跳数相同时,选取LQI值大的节点为下一跳转发节点。理论分析结果表明,该算法路由路径优于树路由算法和ITRA算法路由路径;实验结果表明,该算法能很好地减少转发节点个数,提高了网络数据传输的可靠性,达到网络性能提高的目的。     

一种均衡能量的自适应蚁群路由算法

由于网络结构多变和节点资源受限等问题,新型自组织网络都要求其路由协议不仅具有自适应性,而且要能够感知能量.提出一种能够均衡能量的自适应蚁群路由算法.该算法将作为节点参数的能量转化为链路参数,然后使用含有节点能量利用率的网络延迟作为路由代价度量,从而使得信息素既能够表示路径质量,又能够表示路径上的节点能量利用率,因此数据包逐跳路由时能够合理选择出下一跳节点.同时,蚁群优化使得该算法能够自适应网络变化,平衡流量.基于NS2的模拟实验证明该算法能够均衡节点能量从而具有较好的性能.     

粮情监测系统传感器网络的混合路由算法

无线粮情监测系统传感器节点的立体晶格结构提供了有效的位置信息,针对LEACH协议簇内单跳能耗不均衡的问题,提出了一种O(n)复杂度的混合路由算法,该算法以网络能耗均值为阈值确定多跳节点,根据网络能耗均值和最低转发能耗选择最佳转发节点。仿真实验表明该混和路由算法降低了能耗方差,延长了网络生存时间,适用于无线粮情监测系统。     

多跳无线网络中反馈式机会路由研究

提出多跳无线网络中反馈式机会路由(FOR).给出基于EPDTX指标的转发候选集产生策略,有效地做到了减少网络重发包数和传输时间消耗的平衡.根据候选集中节点ACK返回情况,分析网络局部拥塞状况,动态调整转发候选集和转发优先级,并给出基于ACK反馈的启发式候选集产生算法.仿真试验表明,FOR比传统路由算法(AODV)和极端机会路由算法(ExOR)多跳传输性能上有明显提升,并具有较强的抗网络拥塞能力.     

数据中心网络光电交换架构下的流调度算法研究

研究了基于多级Clos数据中心网络的光电交换架构下的流量调度算法,以减少数据传输时延,同时也保证无丢包。传统ADAPT调度算法能实现加速比最小化,但仍然有一些空闲时间槽,而造成带宽未被充分利用。为了解决该问题,在多级Clos网络中,提出了一个多跳路由和调度（Multi-Hop Routing and Scheduling,MHRS）算法,该算法可以在不增加加速比的同时充分利用空闲的带宽。与ADAPT算法类似,MHRS算法先将流量矩阵分解为商矩阵和余矩阵,然后实现两步调度,即将单跳作为第一步,将多跳作为第二步。第一步将余矩阵中的一些数据包调度到商矩阵所形成的配置矩阵的空闲时间槽中,而当这些数据包不能在第一步中被直接调度时,则采用第二步绕道的多跳调度过程传输数据包。仿真结果证明,在多级Clos网络中MHRS算法比ADAPT算法性能更好。     

Achieve load balancing with a dynamic re-routing CICQ switching scheme

Multi-path based routing and switching can achieve network-wide load balancing and reduce the port conflicts of switching devices.Motivated by this novel idea,in this paper,through analyzing the feasibility of implementing multi-next-hops in core switching networks comprehensively,we advance a switching scheme called MHRS(multi-next-hop re-routing switch)and a forwarding table management scheme called HMFT(hierarchical multi-stage forwarding table)to support multi-next-hop dynamical re-routing.MHRS implements dynamical re-routing in the switches according its congestion status to achieve real-time load balancing,while HMFT can provide traffic with different forwarding paths based on their QoS requirements.Theoretical analysis and simulation results show that switches equipped with HMFT and MHRS can provide good delay and throughput performance.Besides,they can reduce port conflicts significantly.     

一种支持高速IPv6转发的路由器体系结构FIS

本文提出了一种在交换网络中执行转发操作的路由器体系结构,采用多个低速且具有独立转发和交换功能的转发交换结点FSN,组成多级流水线结构,以流水的方式执行报文转发和交换。本文对FIS中实现IPv6转发的关键技术—IPv6转发表的分解、转发表到FSN结点的映射、IPv6转发引擎的设计及报文调度算法进行了深入的研究,并基于FIS体系结构提出了易于硬件实现的IPv6查找机制和基于Hash老化的报文调度算法,为下一步FIS原型系统的实现提供了切实可行的方案。     

MPFS: A truly scalable router architecture for next generation Internet

A new generation architecture of IP routers called massive parallel forwarding and switching （MPFS） is proposed, which is totally different from modern routers. The basic idea of MPFS is mapping complicated forwarding process into multilevel scalable switch fabric so as to implement packet forwarding in a pipelining and distributed way. This processing mechanism is named forwarding in switching （FIS）. By interconnecting multi-stage, lower speed components, called forwarding and switching nodes （FSN）, MPFS achieves better scalability in forwarding and switching performance just like MPP. We put emphasis upon IPv6 lookup problem in MPFS and propose a method for partitioning IPv6 FIB and mapping them to switch fabric. Simulation and computation results suggest that MPFS routers can support line-speed forwarding with a million of IPv6 prefixes at 40 Gbps. We also propose an implementation of 160 Tbps core router based on MPFS architecture at last.     

Advanced hashing schemes for packet forwarding using set associative memory architectures

Building a high performance IP packet forwarding (PF) engine remains a challenge due to increasingly stringent throughput requirements and the growing size of IP forwarding tables. The router has to match the incoming packet’s IP address against all entries in the forwarding table. The matching process has to be done at increasingly higher wire speed; hence, scalability and low power consumption are critical for PF engines.Various hash table based schemes have been considered for use in PF engines. Set associative memory can be used for hardware implementations of hash tables with the property that each bucket of a hash table can be searched in a single memory cycle. However, the classic hashing downsides, such as collisions and worst case memory access time have to be dealt with. While open addressing hash tables, in general, provide good average case search performance, their memory utilization and worst case performance can degrade quickly due to collisions (that lead to bucket overflows).The two standard solutions to the overflow problem are either to use predefined probing (e.g., linear or quadratic probing) or to use multiple hash functions. This work presents two new simple hash schemes that extend both aforementioned solutions to tackle the overflow problem efficiently. The first scheme is a hash probing scheme that is called Content-based HAsh Probing (CHAP). As the name suggests, CHAP, based on the content of the hash table, avoids the classical side effects of predefined hash probing methods (i.e., primary and secondary clustering phenomena) and at the same time reduces the overflow. The second scheme, called Progressive Hashing (PH), is a general multiple hash scheme that reduces the overflow as well. The basic idea of PH is to split the prefixes into groups where each group is assigned one hash function, then reuse some hash functions in a progressive fashion to reduce the overflow. Both schemes are amenable to high-performance hardware implementations with low overflow and constant worst-case memory access time. We show by experimenting with real IP lookup tables and synthetic traces that both schemes outperform other existing hashing schemes.     

基于缓存与指针推进的混合移动性管理策略

提出了一种将缓存策略与指针推进策略结合的混合位置管理策略(记为HCF策略),通过利用移动用户移动的移动性以及接受呼入的局部性,在缓存信息失效的情况下,可通过遍历起始于缓存中的推进指针链来获得移动用户的位置信息,从而避免直接访问归属位置寄存器HLR(Home Location Register)数据库。因此,该策略可有效的减少对HLR的访问,减少位置管理中的通信流量。实验结果显示,当一个移动用户的呼叫-移动率较高CMR(Call-to-Mobility Ratio)或HLR的通信流量较大时,提出的策略优于基本策略和现有的缓存策略。     

基于距离矢量的多下一跳路由信息协议

针对传统单下一跳路由协议总是选择最优路径进行路由,容易导致网络拥塞的问题,提出多下一跳路由信息协议。在邻居节点之间交换最优路由信息并构建路由有向图,为节点建立多下一跳路由表,以实现无环并行传输。基于扩展SSFNet的仿真结果表明,该协议可以降低网络拥塞风险。     

A mobility management scheme for wireless mesh networks based on a hybrid routing protocol

Recent advances in wireless mesh networks (WMNs) have overcome the drawbacks of traditional wired networks and wireless ad hoc networks. WMNs will play a leading role in the next generation of networks, and the question of how to provide seamless mobility management for WMNs is the driving force behind the research. The inherent characteristics of WMNs, such as relatively static backbones and highly mobile clients, require new mobility management solutions to be designed and implemented.In this paper, a hybrid routing protocol for forwarding packets is proposed: this involves both link layer routing and network layer routing. Based on the hybrid routing protocol, a mobility management scheme for WMNs is presented. Both intra-domain and inter-domain mobility management have been designed to support seamless roaming in WiFi-based WMNs. During intra-domain handoff, gratuitous ARP messages are used to provide new routing information, thus avoiding re-routing and location update. For inter-domain handoff, redundant tunnels are removed in order to minimize forwarding latency. Comprehensive simulation results illustrate that our scheme has low packet latency, low packet loss ratio and short handoff latency. As a result, real-time applications over 802.11 WMNs such as VoIP can be supported.     

基于邻居信息表的移动IPv6切换研究

分析标准移动IPv6(MIPv6)的快速切换机制,提出一种基于邻居信息表的移动IPv6快速切换解决方案。通过预配置和定时更新的方法使移动节点提前获取将要进入目标有限区域的信息表——邻居信息表,从而缩短切换中过程转交地址唯一性验证时间及移动检测延迟时间,降低切换过程中的丢包率。仿真结果表明,该机制不额外占用网络资源,能够减少切换过程中的丢包率和切换延迟时间。     

一种基于支撑树搜索的多下一跳路由算法*

基于通过搜索支撑树定势的思想,提出了一种新型多下一跳路由算法,具体包括四种可行的实现方案。该算法选路策略灵活,通过计算网络拓扑的支撑树完成对节点的定势,可以产生到目的地的大量路径同时进行分流传输,充分利用网络资源。仿真结果表明,相对于传统单下一跳路由算法,该算法能有效地提高吞吐量,减小丢包率,提升网络整体通信性能。