基于网络编码的多径路由策略

针对无线传感器网络节点能量受限制的特点,提出基于网络编码的多径路由策略.该策略在数据传输过程当中通过增加跨层协作机制,减少对单个数据包的依赖,降低数据包重传次数,使得网络带宽得到优化,同时数据在传输路径中进行随机编码使得数据包安全传输.分析表明,该策略可以保证数据传输的有效性和安全性.     

An optimal network coding based backpressure routing approach for massive IoT network

Wireless Networks - In order to mitigate the power consumption issue for the sensor’s nodes, an efficient power optimized routing protocol is needed. Therefore, this paper proposes a network...     

A unification of network coding and tree-packing (routing) theorems

Given a network of lossless links with rate constraints, a source node, and a set of destination nodes, the multicast capacity is the maximum rate at which the source can transfer common information to the destinations. The multicast capacity cannot exceed the capacity of any cut separating the source from a destination; the minimum of the cut capacities is called the cut bound. A fundamental theorem in graph theory by Edmonds established that if all nodes other than the source are destinations, the cut bound can be achieved by routing. In general, however, the cut bound cannot be achieved by routing. Ahlswede et al. established that the cut bound can be achieved by performing network coding, which generalizes routing by allowing information to be mixed. This paper presents a unifying theorem that includes Edmonds' theorem and Ahlswede et al.'s theorem as special cases. Specifically, it shows that the multicast capacity can still be achieved even if information mixing is only allowed on edges entering relay nodes. This unifying theorem is established via a graph theoretic hardwiring theorem, together with the network coding theorems for multicasting. The proof of the hardwiring theorem implies a new proof of Edmonds' theorem.     

网络多播路由的改进编码软件设计与实现

传统网络多播路由编码方法采用多播分布树进行编码,但链路容量遭遇瓶颈,致使编码节点较多,导致浪费带宽资源的问题。在此提出基于Koetter指数时间的网络多播路由改进编码算法对编码软件进行设计,分析多播路由的总体设计,通过数据包编码转发模块在多播拓扑不相交路径上进行编码和转发多播数据包,利用输入模块实现网络多播路由和上游节点的信息交换,通过开关仲裁模块判断能够向特定输出端口传输信息的输入端口,利用死锁控制模块对出现死锁现象的路由节点进行检测,一段时间后使多播路由恢复正常的数据交换,通过输出模块对数据的输出进行管理。以降低带宽资源为目的,采用Koetter指数时间算法实现网络多播路由编码,并给出编码的详细代码。实验结果表明,所提方法不仅节省网络资源,而且显著降低多播路由时延,增强网络吞吐量。     

基于网络编码的配电网络下行数据路由算法

文中讨论了利用网络编码技术和使用冗余链路来提高配电网络下行监控网络端对端吞吐量的算法,并通过仿真结果说明了建立多条链路的方法能以较小的网络延迟代价,显著地增强监控网络下行链路的吞吐量,可以提高网络链路的使用。     

Stochastic analysis of computer based communication network systems

This paper represents the reliability analysis of different operating system models i.e. computer, computer based communication network and solar energy systems. All of these models are based on some specific set of assumptions. Failure time distributions are assumed to be negative exponential while the repair, replacement and recovery time distributions are followed to be general for proposed system models. Using regenerative point technique several important cost effective reliability characteristics are obtained. To gain the high reliability targets graphical representations are also provided.     

Stochastic analysis of a fault tolerant network system

This paper deals with a stochastic model related to a converter-based communication network system. In this model two converters are connected in parallel with a network system. Each converter has two failure modes—transient failure and latent failure. Transient failures occur due to minor faults in converters. Further the converter may enter into the latent failure mode if major hardware problems arise in the transient failure mode. The converter may recover automatically when it is in a transient failure mode and needs repair when it is in a latent failure mode. The system also enters preventive maintenance at random epochs when both converters are normal. System failure occurs when both the converters are in a latent failure mode. Using the regenerative point technique, various reliability measures are obtained.     

联合无线网络编码与TCP Vegas的多播协议优化研究

为解决移动自组网中网络编码多播路由协议因业务传输负载增大,而产生的网络拥塞现象,本文提出了一种可靠的基于TCP Vegas窗口拥塞控制的网络编码多播路由协议。该协议的核心思想是发送节点采用发送窗口自调整和反馈消息触发发送窗口调整的机制,综合的调节数据包的发送速率,来改善网络拥塞现象,从而可以降低丢包率。仿真结果表明,当传输负载增大时,基于窗口拥塞控制的网络编码多播路由协议可使得系统的总开销大大降低,分组投递率获得了相对的提升。     

Throughput analysis of two-hop wireless networks with network coding

A Two-hop Wireless Network (TWN) is the basic topology structure that provides network coding opportunity for improving throughput. Network coding on a homogeneous TWN, in which all the data flows have the same packet size and all the links have the same transmission rate, has been extensively investigated. In this paper, network coding on more practical heterogeneous TWNs, featured by various packet sizes and transmission rates, is studied. Based on the Markov model, the throughput of the proposed network coding scheme, together with the throughput gain, is derived, which matches the simulation results very well. Numerical analyses indicate that, encoding the packets with close size and close transmission rate and enlarging buffer size at the relay node help in improving the throughput gain.     

一种机会空时协作网络编码及其性能分析

本文提出了一种机会空时协作网络编码(OST-CNC,opportunistic space-time-coded cooperative network coding),该技术将协作分集技术和网络编码技术有机结合,能够克服无线信道衰落、提高系统资源利用率和网络吞吐.针对间隔两跳的链状网络中进行端到端信息交换的情形,分析了OST-CNC的中断性能和获取的网络编码增益,结果表明:相对于传统的数据交互策略,机会空时协作网络编码在获得全分集(获得的分集阶数为参与协作的节点数)的同时,也获得了4/3倍的渐近网络编码增益,由于机会路由的形成,OST-CNC的网络编码增益在中低信噪比(SNR)区域更为突出.     

Saturation routing network limits

Saturation routing means a flooding of a network with messages which search for a particular subscriber's number without regard to where that subscriber is located in the network. Saturation routing, often thought of as inappropriate in a communication network, can be a useful routing scheme with the use of state-of-the-art design. In this paper, consideration will be spent on the kinds of networks in which saturation routing is applicable, and how it compares with other routing systems. The functional designs of saturation routing will be combined with the appropriate variables to create a mathematical model for performing of saturation routing in a network. The following are some of the variables: i) processor rate; ii) transmission data rate; iii) hierarchy; iv) queuing delays; v) traffic; vi) message size. The paper will be concluded with an example of a realistic network using saturation routing.     

Research on adaptive compression coding for network coding in wireless sensor network

Based on the sequence entropy of Shannon information theory, we work on the network coding technology in Wireless Sensor Network (WSN). In this paper, we take into account the similarity of the transmission sequences at the network coding node in the multi-sources and multi-receivers network in order to compress the data redundancy. Theoretical analysis and computer simulation results show that this proposed scheme not only further improves the efficiency of network transmission and enhances the throughput of the network, but also reduces the energy consumption of sensor nodes and extends the network life cycle.     

Linear network coding

Consider a communication network in which certain source nodes multicast information to other nodes on the network in the multihop fashion where every node can pass on any of its received data to others. We are interested in how fast each node can receive the complete information, or equivalently, what the information rate arriving at each node is. Allowing a node to encode its received data before passing it on, the question involves optimization of the multicast mechanisms at the nodes. Among the simplest coding schemes is linear coding, which regards a block of data as a vector over a certain base field and allows a node to apply a linear transformation to a vector before passing it on. We formulate this multicast problem and prove that linear coding suffices to achieve the optimum, which is the max-flow from the source to each receiving node.     

移动自组网典型路由协议的性能分析与比较

分析了移动自组网的先应式路由协议DSDV和按需路由协议AODV与DSR,并通过网络仿真软件ns2进行了仿真实验,对其分组投递率,端到端平均时延、吞吐量、路由开销等方面的性能进行了分析和比较.实验结果表明,按需路由协议具有更好的性能.     

Code-based all optical routing using two-level coding

Code-based all optical routing employing a two-level-coding scheme is proposed. The first level of coding is employed to establish connections between users within a local area network; a second level of coding provides routing/interconnectivity between networks. The limitations due to physical-layer impairments, such as relative intensity noise (RIN) of the optical source, the signal-dependent shot noise, optical beat interference (OBI), and thermal noise at the receiver, which are some of the fundamental issues in the design of practical optical code division multiple access (CDMA) systems, are analyzed for the two-level scheme. The throughput in terms of "packets/time slot" offered by the scheme is also compared with that of the wavelength division multiple access (WDMA) system. The system capacity in WDMA is limited by the number of available wavelengths; optical CDMA, on the other hand, has many codes (user addresses), but the throughput is limited by multiple user interference, OBI, and RIN. System designs that overcome these effects and thereby improve the throughput are suggested.     

Load balance in hierarchical routing network

In this article, the problem of load balance in hierarchical routing network is studied. Since conventional shortest path first (SPF) algorithm over aggregated topology in hierarchical routing network may result in worse routing performance, a traffic sharing path selection algorithm and a variable weight scheme are put forward for hierarchical routing network, which can equilibrate the utilities of link resources and reduce the blocking probability of connections with the improvement on survivability. Simulations are conducted to evaluate proposed variable weight and traffics balance (VWTB) algorithm, which combines traffic sharing and variable weight. From the simulation results, it can be found that the proposed VWTB algorithm can balance the traffics and equilibrate the utilities of link resources significantly.     

Minimum delay routing in stochastic network

The authors consider the problem of traveling with least expected delay in networks whose link delays change probabilistically according to Markov chains. This is a typical routing problem in dynamic computer communication networks. Several optimization problems, posed on infinite and finite horizons, are formulated, and they are considered with and without using memory in the decision-making process. It is proved that all these problems are, in general, intractable. However, for networks with nodal stochastic delays, a simple polynomial optimal solution is presented. This is typical of high-speed networks, in which the dominant delays are incurred by the nodes. For more general networks, a tractable ∈-optimal solution is presented     

Throughput oriented forwarders selection analysis for opportunistic routing in wireless mesh network

Opportunistic routing explicitly takes advantage of the broadcast nature of wireless communications by using a set of forwarders to opportunistically perform packet forwarding. A key issue in the design of opportunistic routing protocols is the forwarder list selection problem. This paper proposes a novel routing metric which shows the end-to-end throughput and a corresponding throughput oriented opportunistic routing forwarder-selecting algorithm throughput oriented forwarders selection (TOFS) through analyzing forwarding characteristics of forwarders. The algorithm puts forward a constraint mechanism that controls the number of forwarders by constraint of throughput for forwarders selection, achieving a better balance between number of forwarders and effective link stability by introducing the factor of transmission time. Simulation results show that the algorithm can improve the network end-to-end throughput effectively over existing methods.     

Topology matters in network coding

Seeking to understand the potential of network coding in future internet endeavors, we consider the vital role of network topology with respect to the potential benefits of Random Linear Network Coding (RLNC). First, we propose a set of metrics that capture the essential trade-offs between throughput, confidentiality and decoding delay. Using large network simulation, we are able to evaluate the behavior of RLNC for various topological classes based on random graphs. Our results show significant differences between local dissemination of information (typical of wireless networks) and long range connectivity (typical of peer-to-peer environments). We believe that our results can help pave the way for the creation of better overlay topologies for RLNC protocols in future internet applications.