基于分块码的无线网络传输性能优化技术研究

发布时间：2018-06-19 07:57

本文选题：网络编码 + 分块码　；参考：《南京大学》2017年硕士论文

【摘要】：近年来,随着无线通信技术和计算机技术的发展,无线网络成为当前最为广泛使用的互联网基础支撑设施之一。但由于现有无线网络通常采用传统面向有线网络架构的路由方式和存储-转发模式进行数据传输,使得无线网络传输性能亟待提高。相比于传统的路由方式,机会路由可以充分利用无线网络中广播通信的特点,从而有效的提升网络的传输性能。但由于缺少全局控制信息,参与机会路由的节点无法知道其他节点已接收报文情况,因此不可避免地会出现不同节点传输相同报文的问题,从而浪费网络资源。为此,业界提出基于网络编码的报文传输机制,将接收到的报文进行编码后在再送出去,从而有效解决冗余报文问题。与此同时,网络编码还可以通过有效利用无线网络中冗余的广播信道,从而更进一步优化网络性能。但无线网络中节点计算能力有限,且具有移动性(如在延迟容忍网络中),因此,如何结合无线网络特征,建立高效、可靠的、基于网络编码的无线网络传输优化机制,是目前相关技术研究的热点问题之一。围绕上述问题,本文利用分块码低复杂度、高可用性特点,对静态无线网络和延迟容忍网络中基于网络编码的网络传输性能优化技术进行了研究,本文的主要工作包含以下两个方向:●针对随机线性网络编码在无线网络中复杂度高、不太适用的问题,本文将分块码应用到基于机会路由的静态无线网络中,采取基于前向纠错的两段优化措施,设计了一个简单但具有一些显著特性的块传输方案,并在此基础上分析了目的节点传输矩阵的经验秩分布,随后利用该分布,对该传输方案的性能使用线性规划进行了优化,并更进一步的为该线性规划提出了一个基于比例近似的优化方案。最后,通过模拟实验对该块传输方案的传输性能进行了比较和验证。●针对延迟容忍网络中由于节点移动导致间断连接的问题,借助中继节点构成两跳路由,采用存储-携带-转发的方式将源节点的报文中继给目的节点,并且利用分块码无率以及块与块之间帮助解码的特点,在延迟容忍网络中提出了一个简单的块传输方案,随后采用M/M/1队列模型分析了中继节点在该传输方案下缓存的状态,以及目的节点的传输矩阵经验秩分布,并在此基础上对端到端的传输延迟进行了分析和优化,最后,我们通过实验对该传输方案的性能进行了评估。
[Abstract]:In recent years, with the development of wireless communication technology and computer technology, wireless network has become one of the most widely used Internet infrastructure. However, the existing wireless networks usually use the traditional routing mode oriented to wired network architecture and storage-forward mode for data transmission, so the wireless network transmission performance needs to be improved urgently. Compared with the traditional routing mode, opportunistic routing can make full use of the characteristics of broadcast communication in wireless networks, thus effectively improve the transmission performance of the network. However, due to the lack of global control information, the nodes participating in opportunistic routing can not know that other nodes have received packets, so it is inevitable that different nodes will transmit the same packets, thus wasting network resources. In order to solve the problem of redundant packets, the network coding mechanism is proposed, which encodes the received packets and sends them out again. At the same time, network coding can further optimize network performance by utilizing redundant broadcast channels in wireless networks. However, nodes in wireless networks have limited computing power and mobility (such as in delay-tolerant networks). Therefore, how to combine the characteristics of wireless networks to establish an efficient, reliable, network-based wireless network transmission optimization mechanism, At present, it is one of the hot issues in related technology research. Based on the above problems, this paper studies the network performance optimization techniques based on network coding in static wireless networks and delay tolerant networks by using the characteristics of low complexity and high availability of block codes. The main work of this paper includes the following two directions: to solve the problem of high complexity and inapplicability of random linear network coding in wireless networks, this paper applies block codes to static wireless networks based on opportunistic routing. A simple block transmission scheme based on forward error correction is designed, and the empirical rank distribution of the destination node transmission matrix is analyzed. The performance of the transmission scheme is optimized by linear programming, and a proportional approximate optimization scheme is proposed for the linear programming. Finally, the transmission performance of the block transmission scheme is compared and verified by simulation experiments. Aiming at the problem of intermittent connection caused by node movement in delay tolerant networks, two-hop routing is constructed by means of relay nodes. In this paper, a simple block transmission scheme is proposed in the delay tolerance network by relaying the packets of the source node to the destination node by means of storage, portability and forwarding, and taking advantage of the characteristics of block code no-rate and block to block decoding, a simple block transmission scheme is proposed in the delay tolerance network. Then we analyze the buffer state of relay node under the transmission scheme and the empirical rank distribution of the destination node's transfer matrix by using the M / M / 1 queue model, and then analyze and optimize the end-to-end transmission delay on this basis. Finally, The performance of the transmission scheme is evaluated experimentally.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN92

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