Computing Coding Solutions for Opportunistic Network Coding Used in Wireless Mesh Networks

Wireless Personal Communications - Wireless mesh networks represent a key architecture on which several communication systems are relaying. Implementations of these networks which apply...     

无线Mesh网中基于网络编码的多路径TCP研究

在无线多跳网络中,本地重传和网络编码已经被成功地应用到多路径技术上以增加吞吐量并减少丢包。然而,在提高UDP传输性能的同时,也产生了数据包重排序和延迟等副作用,严重影响了TCP性能。针对此问题,主要提出一种基于网络编码的多路径传输方案NC-MPTCP,即在无线mesh网络的多条路径中引入网络编码、执行拥塞控制以及使用一个基于信用的方法控制节点的传输速率,提高网络的吞吐量以及增加网络传输的可靠性。该方案使用一个简单的算法,评估丢包率以及发送线性组合数据包的速率,用来降低目的节点的数据包解码延迟和防止TCP的超时重传。仿真结果表明设计的NC-MPTCP有效。     

Cross-Layer Design of Wireless Mesh Networks with Network Coding

We investigate the optimal design of a multihop wireless mesh network equipped with multiple orthogonal wireless channels and multiple radios. Specifically, we focus on solutions that can efficiently utilize the limited resource to support multiple unicast applications by routing and network coding. We propose a cross-layer optimization framework where the broadcasting feature of the wireless environment, which plays an important role in realizing the achievable gain of network coding, is taken into account. Moreover, we propose a network code construction scheme based on linear programming, with which the possible achievable Coding+MAC gain could be significantly increased. Delay constraints are also included in the network code construction formulation so that the possible impact of the extra decoding delay to the TCP/IP performance can be reduced without changing the upper-layer protocols. The proposed network design based on cross-layer optimization results in significant increase in network throughput.     

丢包感知的线性编码在无线Mesh网络中的应用

采用网络编码提高无线Mesh网络的吞吐量己成为目前研究的热点.文献[1]中,作者提出了一种在无线Mesh网络中采用网络编码的MAC层先验式混合协议,它采用异或编码的算法,这种算法在低丢包环境下性能较好,但不适合高丢包率环境.文章提出了一种适用于无线Mesh网络的线性网络编码方法,并采用复合解码策略,能确保在高丢包的环境...     

基于流的无线网络编码

针对无线链路的不可靠性和物理层的广播特性,将网络编码与无线网络相结合,提出一种基于流的无线网络编码算法——FNC。该算法在先验参考路径的基础上,充分利用每个节点处的路由表项,探测编码机会,在有编码机会的节点对满足编码条件的数据流进行网络编码,达到提高网络吞吐量的目的。仿真结果表明：FNC有效提高了整个网络的吞吐量,改善了网络性能。     

无线中继网络中的物理层网络编码

针对无线中继网络中物理层网络编码技术的应用,分析验证了其所带来可观的吞吐量性能提升。总结了当前物理层网络编码技术的相关研究方向,归纳了通信理论研究、信息理论研究和网络理论研究三个方面。介绍了物理层网络编码的关键技术,对物理层网络编码技术在实际信道条件下的性能分析及改进、采用高阶调制时的检测模糊及改进、基于嵌套格码的计算-转发策略和结合缓冲中继协议设计进行了深入探讨。以期放宽物理层网络编码对信道模型的限制,拓展其适用条件,同时在保障通信过程可靠性的前提下充分发挥该技术对通信有效性的提升,从而推进物理层网络编码技术在实际无线中继通信系统中的应用。     

在多天线多信道无线Mesh网络中基于利用率最大化来融合网络编码和TCP协议

A new approach, named TCP-I2 NC, is proposed to improve the interaction between network coding and TCP and to maximize the network utility in interference-free multi-radio multi-channel wireless mesh networks. It is grounded on a Network Utility Maxmization ( NUM ) formulation which can be decomposed into a rate control problem and a packet scheduling problem. The solutions to these two problems perform resource allocation among different flows. Simulations demonstrate that TCP-I2NC results in a significant throughput gain and a small delay jitter. Network resource is fairly allocated via the solution to the NUM problem and the whole system also runs stably. Moreover, TCP-I2NC is compatible with traditional TCP variants.     

无线Mesh网中基于网络编码感知的分组公平调度机制

 利用竞争无线媒介的用户的传输代价不同,本文提出了一种基于网络编码感知的分组公平调 度机制FSNC.FSNC机制的基本调度单位是编码集,编码集中的用户将依据自身在编码集中的 权重,公平地获取统计上的长期和短期系统服务时间.FSNC机制是通过用户的ARQ反馈消息, 感知用户的解码能力从而做出调度决策的.理论和仿真实验证明,FSNC机制在改善多用户分 集系统的用户的吞吐率的同时,能够为多用户提供公平的服务时间.     

网络编码在无线Mesh网络中的研究与实现

Mesh网络沿用了Ad Hoc网络中的路由协议,但Mesh网络节点移动性高,路径的生存周期短,根据无线Mesh网络自身的动态特点进行路由协议的优化成为了研究的热点。COPE编码方案是针对Mesh网络中的单播特性提出的一种新的机会网络编码机制,能够提高网络的吞吐量。通过NS2仿真平台对AODV路由协议添加COPE网络编码方案,仿真结果表明在不同网络条件下,AODV和COPE的结合增加了无线节点的编码机会,使网络的吞吐量得到了有效的提高。     

Cooperative Diverse Opportunistic Network Coding for Wireless Networks

Wireless Personal Communications - Opportunistic network coding (ONC) increases communication networks’ throughput by XORing two or more packets together. However, it has shown that ONC...     

大型无线网络中的多跳网络编码

基于网络编码的协作分集技术是目前的无线网络的研究热点.许多研究从理论上证明了它的有效性,但是对于大型网络中网络编码技术的应用的研究涉及较少.采用LDPC码的结构研究了协作分集网络中的网络编码构造,并把它拓展到多跳网络中.这种方法可以根据瞬时的网络拓扑结构形成网络编码,从而适应移动环境下多节点的随机接入,通过获得的网络编码增益提高网络可靠性.     

Network Coding for the Internet and Wireless Networks

In today's practical communication networks such as the Internet, information delivery is performed by routing. A promising generalization of routing is network coding. The potential advantages of network coding over routing include resource (e.g., bandwidth and power) efficiency, computational efficiency, and robustness to network dynamics. This tutorial article provides an overview of the theory, practice, and applications of network coding.     

效率感知的无线网络编码机制

网络编码在无线网络中的应用可以显著提高无线网络的吞吐量和容量。然而,当前大多数的无线网络编码机制在进行编码操作时,都没有考虑将不同长度的报文编码在一起时的效率问题。该文研究了在进行网络编码操作时如何获得最优的每字节编码效率,并设计了编码效率感知的无线网络编码机制(coDing Efficiency awarE Network coding, DEEN),以提升每字节的编码效率。模拟结果表明,DEEN协议能够有效地提升无线网络的容量。     

Random Network Coding Based Schemes for Perfect Wireless Packet Retransmission Problems in Multiple Channel Networks

Solving WPRTPs (wireless packet retransmission problems) using NC (network coding) is increasingly attracting research efforts. However, no work on NC based schemes for WPRTPs in MCNs (multiple channel networks) has been found. In this paper, RNC (random network coding) based schemes for P-WPRTPs (perfect WPRTPs) in MCNs, denoted as MC-P-WPRTPs (multiple channel perfect WPRTPs), are studied by transforming MC-P-WPRTPs into ILP (integer linear programming) problems. The ILP problems corresponding to MC-P-WPRTPs with four typical configurations are derived. Then the corresponding packet retransmission schedule schemes for MC-P-WPRTPs are proposed based on the solutions to the ILP problems and random network coding. To solve the ILP problems efficiently, an algorithm named as progressively fixing algorithm is proposed which recursively reduce the size of the ILP problem by fixing some of the variables according to some criteria. The criteria are related to the solution to the LP problem obtained by relaxing the integral constraints on the variables in the original ILP problem. Simulation results show that the NC based schemes for MC-P-WPRTPs are effective in saving packet retransmissions. In some situations, NC based schemes can save about 50 % packet retransmissions.     

无线Mesh网络中网络编码的文件共享模型

网络编码的基本思想是网络节点不仅参与数据转发,还参与数据处理,可大幅提高网络性能。传统文件传输系统存在文件分发时间的"瓶颈"问题,为此,提出一种在无线Mesh网络中网络编码的简化文件共享模型,采用理论分析和实验仿真的方法,研究节点间的4种合作机制。结果表明,在总分发时间上,基于网络编码转发机制比无网络编码的转发机制平均减少11.67%,显著地降低了文件传输系统的分发时间,从而提高了网络的吞吐量。     

无线Mesh网络视频流媒体自适应编码与传输控制研究

讨论了无线Mesh网络（WMN）中视频流媒体自适应编码与传输控制的问题,包括视频流媒体可分级编码的必要性和实现原理,传输过程中的主动丢包策略,并讨论了对其进一步改进的方法。使读者对WMN中视频流媒体的自适应编码和传输控制有概括性的了解。