一种基于节能目的改进的AODV路由算法

移动AdHoc网络广泛用于各种条件比较艰苦的环境中,常用的AODV协议在设计之初没有考虑节点的能量问题,使用时可能导致某一关键节点的能量急剧下降而使链路失效。针对这一情况,新设计的IAODV协议在源节点新增了一条备用路径,各节点在周期性广播HELLO消息时主动报告节点的能量状态,在转发路由请求消息前,将节点的剩余能量和当前负载考虑进去,改进路由请求转发机制,通过这些方式,加强了整个协议的网络平衡和协调性,节省了单个节点的能量。在NS2这个模拟平台下,通过仿真可知IAODV协议平均端到端时延更短,丢包率更低。     

Routing of 100 Gb/s words in a packet-switched optical networkingdemonstration (POND) node

This paper presents the design and experimental results of an optical packet-switching testbed capable of performing message routing with single wavelength time division multiplexed (TDM) packet bit rates as high as 100 Gb/s. The physical topology of the packet-switched optical networking demonstration (POND) node is based on an eight-node ShuffleNet architecture. The key enabling technologies required to implement the node such as ultrafast packet generation, high-speed packet demultiplexing, and efficient packet routing schemes are described in detail. The routing approach taken is a hybrid implementation in which the packet data is maintained purely in the optical domain from source to destination whereas control information is read from the packet header at each node and converted to the electrical domain for an efficient means of implementing routing control. The technologies developed for the interconnection network presented in this paper can be applied to larger metropolitan and wide area networks as well     

DCMA: A Label Switching MAC for Efficient Packet Forwarding in Multihop Wireless Networks

This paper addresses the problem of efficient packet forwarding in a multihop, wireless "mesh" network. We present an efficient interface contained forwarding (ICF) architecture for a "wireless router," i.e., a forwarding node with a single wireless network interface card (NIC) in a multihop wireless network that allows a packet to be forwarded entirely within the NIC of the forwarding node without requiring per-packet intervention by the node's CPU. To effectively forward packets in a pipelined fashion without incurring the 802.11-related overheads of multiple independent channel accesses, we specify a slightly modified version of the 802.11 MAC, called data driven cut-through multiple access (DCMA) that uses multiprotocol label switching (MPLS)-like labels in the control packets, in conjunction with a combined ACK/RTS packet, to reduce 802.11 channel access latencies. Our proposed technique can be used in combination with "frame bursting" as specified by the IEEE 802.11e standard to provide an end-to-end cut-through channel access. Using extensive simulations, we compare the performance of DCMA with 802.11 DCF MAC with respect to throughput and latency and suggest a suitable operating region to get maximum benefits using our mechanism as compared to 802.11     

End-to-end performance models for variable bit rate voice overtandem links in packet networks

Analytical models are presented for computing the end-to-end voice call performance in a packet network that drops the less significant bits in voice packets during periods of congestion. These models provide information about the end-to-end quality likely to be experienced in future packet-switched integrated services networks. An existing single-node bit-dropping model is modified to include the situation resulting when the overall arrival process at an internal node consists of a mix of packets of different sizes due to bit dropping at previous nodes. A detailed model to capture bit-dropping effects in a tandem connection of nodes is presented. The model includes the effect of load fluctuations at each node, and also takes into account the dependencies in bit dropping experienced by a voice packet at successive nodes in a tandem connection. The model also incorporates the internodal dependence when reductions in packet service times occur at intermediate nodes due to bit dropping at previous nodes. Two approximation procedures are discussed that serve as upper and lower bounds. In particular, the upper bound is shown to be very tight for a practical range of loads, and hence serves as a good approximation with significant computational simplicity     

Congestion Aware Geographic Routing Protocol for Wireless Ad Hoc and Sensor Networks

Geographic routing protocols forward packets according to the geographical locations of nodes. Thus, the criteria used to select a forwarding node impacts on the performance of the protocols such as energy efficiency and end-to-end transmission delay. In this paper, we propose a congestion aware forwarder selection (CAFS) method for a geographic routing protocol. To design CAFS, we devise a cost function by combining not only the forward progress made to a packet but also the amount of energy required for packet forwarding, forwarding direction, and congestion levels of potential forwarders. Among the potential forwarders, CAFS selects the next forwarder having the minimum cost. In our simulation studies, we compare the performance of CAFS with those of the maximum progress (MP) method and the cost over progress (CoP) method in various network conditions. The results show that compared with MP, the length of a routing path in terms of the number of hops becomes longer when CAFS is used. However, the shorter hop distance helps to avoid unnecessary retransmissions caused by packet loss in a wireless channel. In addition, since CAFS considers congestion levels of candidate forwarders, it reduces the queuing delay in each forwarder. Therefore, CAFS is superior to the MP and the CoP in terms of the energy consumption, end-to-end packet transfer delay, and the successful packet delivery rate.     

OTDM-based optical communications networks at 160 Gbit/s and beyond

The virtually unlimited bandwidth of optical fibers has caused a great increase in data transmission speed over the past decade and, hence, stimulated high-demand multimedia services. Nowadays, opto-electronic conversion is still required at each network node to process the incoming signal. However, when the single channel bit rate increases beyond electronic speed limit, optical time division multiplexing (OTDM) becomes a forced choice, and all-optical processing must be performed to extract the information from the incoming packet. In this paper the state of art, the advantages and drawbacks of the OTDM technology will be discussed in order to highlight its potentialities in different application scenarios for optical communications networks, and its perspectives in different temporal horizons. In detail, a recent experiment of a 160 Gbit/s OTDM system is presented. Furthermore, a photonic node architecture suitable for optical packet switching networks is proposed, and possible solutions for the implementation of all the required subsystems are presented and compared in order to optimize the node performance. In particular innovative schemes for optical add/drop multiplexer, optical logic gates, optical switches, and optical flip-flop are introduced with a particular emphasis on emerging nonlinear materials and enabling technologies.     

E2EACK: an end-to-end acknowledgment-based scheme against collusion black hole and slander attacks in MANETs

Mobile ad hoc networks (MANETs) rely on the benevolence of nodes within the network to forward packets from a source node to a destination node. This network construction allows for the forwarding nodes, whether they are selfish or malicious, to drop packets hindering end-to-end communication. In this paper, a new scheme is proposed against collusion black hole and slander attacks in MANETs, named E2EACK. A novel method is used to detect collusion attacks due to collusive malicious nodes which cooperate in the route discovery, but refuse to forward data packets and do not disclose the misbehavior of each other. Contrary to existing methods that detect only collusion black hole attacks, the E2EACK also detects slander attacks and framing attacks. Moreover, the E2EACK uses ACKnowledgment packet to detect malicious nodes on the path and Message Authentication Code (MAC) to authenticate the sender of each data packet. Analytical and simulation results show that the proposed scheme considerably decreases the routing overhead and increases the packet delivery ratio compared to the existing methods.     

无线传感器网络路由协议的设计与实现

针对传统路由协议端到端时延长、丢包率过高的现实问题,提出了一种基于贪婪转发的能量感知多路径路由协议(Greedy Forward Energy-aware Multipath Routing Protocol,GFEMRP)。GFEMRP从传感器起始结点出发,如果遇到网络黑洞则选择周边转发方式,否则将选择吞吐量大、且更接近于目的结点的结点作为下一跳结点。利用了OMNET++5.0和INET框架对包括无线自组网按需平面距离向量路由协议(Ad hoc on-demand distance vector routing protocol,AODV),动态按需无线自组织网络(Dynamic MANET On-demand,DYMO),贪婪周边无状态路由无线网络(Greedy Perimeter Stateless Routing for Wireless Networks,GPSR)和GFEMRP协议在内的四种路由协议进行了仿真和比较,实验结果表明GFEMRP协议具有良好的端到端时延、丢包率等性能。     

Improved ant colony-based multi-constrained QoS energy-saving routing and throughput optimization in wireless Ad-hoc networks简

In order to establish a route supporting multi-constrained quality of service（QoS）, increase network throughput and reduce network energy consumption, an improved ant colony-based multi-constrained QoS energy-saving routing algorithm（IAMQER） is proposed. The ant colony algorithm, as one of the available heuristic algorithms, is used to find the optimal route from source node to destination node. The proposed IAMQER algorithm, which is based on the analysis of local node information such as node queue length, node forwarding number of data packets and node residual energy, balances the relationship between the network throughput and the energy consumption, thus improving the performance of network in multi-constrained QoS routing. Simulation results show that this IAMQER algorithm can find the QoS route that reduce average energy consumption and improves network packet delivery ratio under the end-to-end delay and packet loss ratio constraints.     

基于流量预测的物联网卫星节点动态缓存分配路由策略

针对低轨物联网卫星系统的路由问题,提出了基于流量预测的物联网卫星节点动态缓存分配路由策略。首先,分析低轨卫星覆盖区域内业务分布的时空特性,提出了端到端流量预测方法。然后,根据流量预测结果,提出了动态缓存分配路由策略。卫星节点通过对星间链路的流量负载进行周期性监测,动态分配与邻居节点间各条星间链路的缓存资源,分为初始化和系统运行2个阶段。同时,提出了节点拥塞时的业务分流及数据分组转发策略,通过比较排队时延和转发时延的大小,决定数据分组是否需要进行重路由。仿真结果表明,所提路由策略有效地降低了分组丢失率及平均端到端时延,改善了业务在全网的分布情况。     

Intelligent beaconless geographical forwarding for urban vehicular environments

A Vehicular Ad hoc Network is a type of wireless ad hoc network that facilitates ubiquitous connectivity between vehicles in the absence of fixed infrastructure. Source based geographical routing has been proven to perform well in unstable vehicular networks. However, these routing protocols leverage beacon messages to update the positional information of all direct neighbour nodes. As a result, high channel congestion or problems with outdated neighbour lists may occur. To this end, we propose a street-aware, Intelligent Beaconless (IB) geographical forwarding protocol based on modified 802.11 Request To Send (RTS)/ Clear To Send frames, for urban vehicular networks. That is, at the intersection, each candidate junction node leverage digital road maps as well as distance to destination, power signal strength of the RTS frame and direction routing metrics to determine if it should elect itself as a next relay node. For packet forwarding between Intersections, on the other hand, the candidate node considers the relative direction to the packet carrier node and power signal strength of the RTS frame as routing metrics to elect itself based on intelligently combined metrics. After designing the IB protocol, we implemented it and compared it with standard protocols. The simulation results show that the proposed protocol can improve average delay and successful packet delivery ratio in realistic wireless channel conditions and urban vehicular scenarios.     

Mitigation of Packet Loss Using Data Rate Adaptation Scheme in MANETs

Node’s mobility, bursty data traffic, and dynamic nature of the network make congestion avoidance and control a challenging task in Mobile Adhoc Networks (MANETs). Congestion results in high packet loss rate, increased delays, and wastage of network resources due to re-transmissions. In this paper, we propose In-route data rate adaptation to avoid packet loss. Proposed scheme is based on the analysis of queue length of the forwarding nodes, number of data source nodes, and rate of link changes. In proposed technique, queue length of forwarding nodes is communicated periodically to the neighbor nodes using existing control messages of the underlying routing protocol. Keeping in view the queue length of forwarding nodes, number of data source nodes, and rate of link changes, initially the intermediate nodes buffer the incoming data packets upto some threshold and then, gradually shift the effect of congestion to the data source nodes. Then, the source node adapts its sending data rate to avoid congestion and to ensure reliable data communication. We have performed simulations in NS-2 simulator by varying different network metrics such as data rate, number of source nodes, and node speed. Results show that proposed technique improves network performance in terms of packet delivery ratio upto 15 %, reduction of average end-to-end delay and packet loss due to interface queue overflow upto 25 % and 14 % respectively, as compared to the static rate adaptation scheme.     

软件定义无人机自组网高效自适应路由维护机制

为解决软件定义无人机自组网路由维护存在的控制开销和数据包延迟偏大的问题,基于现有的OpenFlow协议提出了一种高效自适应的软件定义无人机自组网路由维护机制( Efficient and Adaptive Software-defined Unmanned Aerial Vehicle Ad Hoc Network R...     

Design and implementation of an optical burst-switched network testbed

Optical burst switching has been receiving increased attention as a promising technology for building the next-generation optical Internet. This article presents the design and discusses the implementation of an overlay mode optical burst-switched network testbed. A flexible "transceiver + forwarding" edge node architecture is proposed to perform both electronic burst assembly/disassembly and optical burst forwarding. It is designed to provide class of service and wavelength selection for locally generated bursts, and transparency to cut-through bursts. The functional modules of the control plane and related key design issues are presented. In particular, we discuss a scheduling mechanism that efficiently combines two different contention resolutions in space and wavelength domains. Experimental results show the effectiveness of this scheme in reducing burst blocking probability. Furthermore, the performance of the network testbed and corresponding methods of improving it are discussed.     

Fair data collection in wireless sensor networks: analysis and protocol

In general, wireless sensor networks (WSNs) consist of many sensors which transmit data to a central node, called the sink, possibly over multiple hops. This many-to-one data routing paradigm leads to nonuniform traffic distribution for the different sensors (e.g., nodes closer to the sink transfer more traffic than those farther away). In this paper, we perform an analysis of the fairness issue by presenting a tree-based WSN and derive the throughput, delay, and energy distribution for each sensor under the fairness constraint. Based on the analysis, we design our fair data collection protocol in which each node decides its media access and packet forwarding strategies in a distributed manner. Finally, we demonstrate the effectiveness of our solution through simulations. The results for the proposed protocol show the accuracy of the analysis and show that the protocol ensures the fair delivery of packets and reduces end-to-end delay. Based on the analysis, we also quantitatively determine the energy required for each of the nodes and show that a nonuniform energy distribution can maximize the network lifetime for the WSN scenario under study.     

An ellipse-guided routing algorithm in wireless sensor networks

In wireless sensor networks, sensor nodes are deployed to collect data, perform calculations, and forward information to either other nodes or sink nodes. Recently, geographic routing has become extremely popular because it only requires the locations of sensor nodes and is very efficient. However, the local minimum phenomenon, which hinders greedy forwarding, is a major problem in geographic routing. This phenomenon is attributed to an area called a hole that lacks active sensors, which either prevents the packet from being forwarded to a destination node or produces a long detour path. In order to solve the hole problem, mechanisms to detect holes and determine landmark nodes have been proposed. Based on the proposed mechanisms, landmark-based routing was developed in which the source node first sends a packet to the landmark node, and the landmark node then sends the packet to the destination. However, this approach often creates a constant node sequence, causing nodes that perform routing tasks to quickly run out of energy, thus producing larger holes. In this paper, a new approach is proposed in which two virtual ellipses are created with the source, landmark, and destination nodes. Then guide the forwarding along the virtual ellipses. Furthermore, a recursive algorithm is designed to ensure a shortcut even if there are multiple holes or a hole has multiple landmarks. Thus, the proposed approach improves both geographic routing and energy efficiency routing. Simulation experiments show that the proposed approach increases the battery life of sensor nodes, lowers the end-to-end delay, and generates a short path.     

An enhanced performance through agent-based secure approach for mobile ad hoc networks

This paper proposes an agent-based secure enhanced performance approach (AB-SEP) for mobile ad hoc network. In this approach, agent nodes are selected through optimal node reliability as a factor. This factor is calculated on the basis of node performance features such as degree difference, normalised distance value, energy level, mobility and optimal hello interval of node. After selection of agent nodes, a procedure of malicious behaviour detection is performed using fuzzy-based secure architecture (FBSA). To evaluate the performance of the proposed approach, comparative analysis is done with conventional schemes using performance parameters such as packet delivery ratio, throughput, total packet forwarding, network overhead, end-to-end delay and percentage of malicious detection.     

Routing optimization based on topology control in satellite network

A new double-layer satellite network model for space networking was established and a routing algorithm based on topology control (TCRA) was proposed considering the advantages of low earth orbit and stationary earth orbit satellite networks.This model used virtual node strategy and satellite grouping idea,which regarded the coverage area of each low earth orbit satellite as a virtual node.The network took into account the influence of the polar area on the division of the satellite footprints,such that the upper management satellites can accurately acquire the topology of the lower satellites.Using the improved virtual node strategy,the time slices were superior to other network models in quantity,length and other aspects.Based on the network topology,stationary earth orbit satellites calculate routing for low earth orbit satellites,while low earth orbit satellites were responsible for forwarding data.The simulation results show that the routing algorithm is superior to other algorithms in average end-to-end delay and packet loss rate.     

无线多媒体传感器网络中一种改进路由算法

随着网络负载增加,经典的TPGF( Two-Phase geographic Greedy Forwarding)算法难以找到节点分离路径,会导致网络吞吐量、投递率以及端到端时延性能下降。此外,当网络拓扑变动不大时, TPGF中每条路径所包含节点要消耗比其他节点更多的能量,会导致其过快死亡,从而影响网络性能。为此,将联合网络编码技术引入 TPGF,提出一种编码与能量感知的 TPGF 路由算法( NE-TPGF)。该算法综合考虑节点的地理位置、编码机会、剩余能量等因素,同时利用联合网络编码技术进一步扩展编码结构,充分利用网络编码优势来建立相对最优的传输路径。仿真结果表明, NE-TPGF能够增加编码机会,提高网络吞吐量和投递率,降低端到端时延,并且还有利于减少和平衡节点的能量消耗。