基于网络编码的多信源组播通信系统

本文首先介绍网络编码理论的基本概念,回顾了近年来网络编码的研究动态。接着在使用NetFPGA开发平台的基础上,提出网络编码组播通信系统及其整体设计方案。由于本系统的主要功能是由硬件实现,所以和传统组播通信网络相比,具有时延小,没有了调度和排队时间,使得网络中链路负载更均衡,体现出了网络编码的优势。     

用FPGA在卫星通信系统中实现级联编码

利用卫星信道传输数据,要求有很高的可靠性,但卫星信道与其它所有信道一样都存在缺陷:如信道中存在各种干扰噪声等,因而传输效果不理想。一般情况下,卫星信道基本可看作是加性高斯白噪声恒参信道,要完全消除这种噪声是不可能的。因此,卫星信道传输数据时,不可避免地会在接收数据中出现差错。在某些情况下,可采取一些措施(如增大系统增益和选择性能好的调制解调器等)改进整个信道性能,但有时信道的改进可能不切实际或不经济。实践证明,在卫星通信中,可采用提高系统增益等手段来降低差错率,使信噪比增加1dB所需的费用比采用纠错编码所需的费…     

新型编解码两用器件

ＵＭ３７５８１０８Ａ／ＡＭ是具有编码发送和接收解码双重功能的编译码ＩＣ，广泛用于各种遥控系统，具有电路简单、功耗低等特点。本文介绍了该器件的主要特性及典型应用     

立体声编解码电路AD1843

立体声编解码电路ＡＤ１８４３邵振付ＡＤ１８４３是电话和音频通信应用中基于数字信号处理技术的一种高性能ＩＯ模拟接口电路。它的功能很多，主要有：１全双工Ｖ．３４（或后向兼容）数据ＭＯＤＥＭ（包括ＰＳＴＮ公用电话网回波抵消相位频率再抽样）和同时ＣＤ音质立...     

无线网络中基于网络编码的路由算法

网络编码为无线网络带来了更高的可靠性,二者的结合已经引起了很多研究学者的关注,无线网络中基于网络编码的路由算法更是值得探讨和研究的问题,本文在网络编码的基础上分别对网络编码的多路径路由算法和编码感知的路由算法进行了分析和研究,以期实现提高无线传输效率的目标。     

基于网络编码的机会网络高效路由算法

针对采用Epidemic机制的机会网络路由算法在数据分组传送阶段存在通信冗余的问题,提出了一种基于网络编码的高效路由算法--NCBER(network-coding-based epidemic routing）。NCBER在传送数据分组的过程中使用主动异或网络编码和多播,并取消了 Request（请求）控制分组,从而减少数据分组的转发次数和控制分组数量,降低网络开销,缩短分组传输时延。理论分析和仿真结果表明,NCBER 算法在网络开销和数据分组端到端时延性能方面优于经典的Epidemic路由算法及其改进算法MRRMR（message redundancy removal of multi-copy routing）,并且使数据传送成功率保持在100%。     

网络编码构造算法研究

网络编码是通信网络中信息传输技术的一个重大突破,其核心思想就是利用路由器的智能化功能,允许网络中间节点对传输信息进行编码,从而提高网络传输效率。该文通过＂蝶形网络＂来分析网络编码的基本原理,并归纳现有网络编码的基本构造算法及其优缺点,最后讨论网络编码构造算法的进一步发展方向。     

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。     

广东广电数字微波网编解码系统介绍

本文主要介绍了广东省广播电视数字微波传输网的编解码系统,文章从编解码设备的类型、系统的传输结构和网管结构等几个方面进行了详细说明.     

基于机会式网络编码的高效广播传输算法

为了提高无线网络广播传输的效率,针对单跳无线网络提出了采用编码方法的广播传输算法。在传统的无线广播传输模型的基础上,分别实现了基于机会式网络编码的单组合分组广播传输算法和多组合分组广播传输算法。它们采用不同的策略选择多个丢失分组编码组合成重传分组,并通过从编码组合数据分组中恢复丢失分组的方式来提高广播传输的吞吐量。仿真结果表明,新算法在不同无线信道传输模型下相比已有的算法有效地降低了广播传输所需的传输带宽。     

易于硬件实现的内嵌图像编码算法

EZBC算法综合利用了子带内和子带间系数的相关性．把零树／零块结构和基于上下文编码的优点有机结合在一起,获得了比SPHIT算法更好的压缩性能,比EBCOT更高的压缩效率。但是EZBC算法编码中的两个排序链表需要很大且非固定的存储空间,这使得EZBC算法的硬件实现非常困难。在EZBC算法的基础上提出了一种易于硬件实现、低存储量、高压缩性能的内嵌零块图像编码算法。该算法利用比特平面节点重要性状态表和上下文查找表来完成整个编码过程和形成上下文。实验结果表明,所提出的算法具有与EZBC算法基本相同的高压缩性能,但所需存储空间约为EZBC算法的四分之一,所以该算法更易于硬件实现。     

一种基于网络编码的重传算法研究

无线网络中,节点发送的数据分组传输失败后,执行重传机制。传统的重传机制ARQ由于在一次重传中只能发送一个丢失的数据分组,因此传输效率比较低。利用网络编码技术和AQR重传机制,我们可以在重传中使用网络编码,广播发送由多个丢失数据分组编码得到的编码分组,从而提高重传效率。本文中我们提出一种将网络编码应用于多个发送方多个接收方(MSMR)无线网络中的算法RMBNC。理论推导和仿真分析验证了我们提出的算法的有效性。     

Optimization of layered multicast with network coding and genetic algorithm

This article studies the problem of constructing optimal layered multicast with network coding for heterogeneous networks.Based on the flexibility of layered source coding, a global-favorable optimization scheme is proposed, which maximizes the aggregate throughput of heterogeneous sink nodes for layered multicast with network coding by determining the optimal bit rates of the layers. To solve this global-favorable optimization scheme, especially in the large-scale heterogeneous networks, a new problem-specific genetic algorithm (GA) is further proposed. It not only searches efficiently for the optimal allocation of layer bit rates, but also guarantees the validity of candidate solutions in the whole evolutionary process. Simulation results demonstrate that this new GA-based optimization scheme could obtain efficiently the optimal or satisfactorily near-optimal bit rates for layered multicast with network coding, even in the large-scale heterogeneous networks.     

Relay algorithm based on network coding in wireless local network

The network coding is a new technology in the field of information in 21st century. It could enhance the network throughput and save the energy consumption, and is mainly based on the single transmission rate. However, with the development of wireless network and equipment, wireless local network MAC protocols have already supported the multi-rate transmission. This paper investigates the optimal relay selection problem based on network coding. Firstly, the problem is formulated as an optimization problem. Moreover, a relay algorithm based on network coding is proposed and the transmission time gain of our algorithm over the traditional relay algorithm is analyzed. Lastly, we compare total transmission time and the energy consumption of our proposed algorithm, Network Coding with Relay Assistance (NCRA), Transmission Request (TR), and the Direct Transmission (DT) without relay algorithm by adopting IEEE 802.11b. The simulation results demonstrate that our algorithm that improves the coding opportunity by the cooperation of the relay nodes leads to the transmission time decrease of up to 17% over the traditional relay algorithms.     

一种适于硬件实现的算术编码算法

本文提出了一种改进的Q-coder算术编码算法。这种算法的主要特点包括：使用Q表进行概率估计;采用Witten等人提出的重整化方法;用移位加来代替原算法中的乘法。采用移位中加方法,可以在硬件花费较少的情况下显著提高算法的编码效率;重整化方法可以用解决硬件实现中的进行翻转问题,本文还对算法的编码效率提高情况作了定量分析,同时对Q解码器进行了逻辑综合,结果表明了算法硬件实现的复杂度。     

一种新的基于网络编码的碰撞解决算法

文中提出一种叫做网络编码树算法的新的碰撞解决算法,该算法在树算法的基础上结合了网络编码技术.树算法没有充分利用碰撞的数据包,对于碰撞数据包的处理往往采用丢弃的方式.通过引入网络编码技术,可以利用碰撞的数据包带来的信息,从而提高树算法的效率和性能.通过仿真,将网络编码分裂树算法与现有的其他碰撞解决算法进行了性能比较,证实网络编码树算法大幅度地提高网络的吞吐量并降低了平均延时.     

Scalable broadcast with network coding in heterogeneous networks

This article studies the scalable broadcast scheme realized with the joint application of layered source coding,unequal error protection(UEP)and random network coding from the theoretical point of view.The success probability for any non-source node in a heterogeneous network to recover the most important layers of the source data is deduced.This probability proves that in this broadcast scheme every non-source node with enough capacity can always recover the source data partially or entirely as long as the finite field size is sufficiently large.Furthermore,a special construction for the local encoding kernel at the source node is proposed.With this special construction,an increased success probability for partial decoding at any non-source node is achieved,i.e.,the partial decodability offered by the scalable broadcast scheme is improved.     

联合网络编码和叠加编码的协作发射策略

提出一种联合网络编码和叠加编码的协作发射策略。对传统的解码转发中继采用网络编码可以提高频谱效率,这是因为放宽了不同数据流之间的正交约束并且可通过预编码/波束形成技术减轻由此带来的干扰。与基于信道状态信息获得近似最优性能但计算繁重的波束形成策略相比,提出利用叠加编码思想确定网络预编码处理向量,该方法无需发射端预知CSI因而大大减小了计算复杂度。理论分析和仿真结果同时表明,所提策略可获得与基于CSI近似最优的线性网络预编码和脏纸网络预编码策略极为相近的性能。     

Time and power scheduling in an ad hoc network with bidirectional relaying and network coding

Network coding (NC) is a technique that allows intermediate nodes to combine the received packets from multiple links and forwarded to subsequent nodes. Compared with pure relaying, using NC in a wireless network, one can potentially improve the network throughput, but it increases the complexity of resource allocations as the quality of one transmission is often affected by the transmission conditions of multiple links. In this paper, we consider an ad hoc network, where all the links have bidirectional communications, and a relay node forwards traffic between the source and the destination nodes using NC. All transmissions share the same frequency channel, and simultaneous transmissions cause interference to each other. We consider both digital NC and analog NC strategies, referred to as DNC and ANC, respectively, and schedule transmission time and power of the nodes in order to maximize the overall network throughput. For DNC, an optimum scheduling is formulated and solved by assuming that a central controller is available to collect all the link gain information and make the scheduling decisions. Distributed scheduling schemes are proposed for networks using DNC and ANC. Our results indicate that the proposed scheduling scheme for DNC achieves higher throughput than pure relaying, and the scheduling scheme for ANC can achieve higher throughput than both DNC and pure relaying under certain conditions. Copyright © 2013 John Wiley & Sons, Ltd.