【作者】 李璐；

【导师】 张国印；

【作者基本信息】 哈尔滨工程大学 ， 计算机应用技术， 2013， 博士

【摘要】 随着移动终端设备性能的逐渐提高，移动网络得到快速的发展，MP2P作为对等网络与移动计算的产物，摆脱固定基站的束缚，为移动网络市场开辟了新的发展方向。MP2P网络继承了传统P2P网络的资源负载均衡、无中心化、节点对等、网络框架高分布性和易扩展性等优点，且无需基站支持，为在随时、随地实现信息的交互提供了便利条件。但其多跳、无线、节点频繁加入离开、不断移动的扰动性，给MP2P网络实现高效的内容分发带来了一系列的挑战。本文主要针对无固定基站、自组织的无线网络进行研究，从支撑内容分发技术的网络框架，数据处理，缓存策略，及路由策略入手，以提高MP2P网络内容分发机制为目的进行研究工作。首先，本文对无线移动自组网络拓扑的抗扰动性进行研究。由于移动设备的游走性，使得自组网络普遍存在不易管理和维护的问题，而网络框架是为网内数据处理及传输构建稳定环境的前提条件。因此，本文针对MP2P网络中动态节点特征，提出基于球形簇域的网络结构，将网络划分为多个子网进行分区管理，每个子网域由一个超级节点进行路由信息和分发策略的管理，簇域之间通过交叉区域中的机会节点进行信息传递，以此保障整个网络交互信息的连通性。可以有效提高命中率，减少信息传输延迟，降低动点对下载成功率的影响。其次，基于上述MP2P网络拓扑基础，针对网络中数据下载成功率过分依赖种子节点的在线时间、数据重复传送及易引起网络拥塞等问题，本文提出一种基于网络编码的数据处理策略，对传输数据进行编、解码操作。同时，通过线性判断减少重复数据出现概率，减少通信数据占据空间，缩短数据在传输中的排队时间，降低了信道拥塞情况的发生。因此，可有效提高资源的下载成功率和吞吐量，降低传输时延，提高有限带宽内数据的传输效率。同时，由于节点的动态特性，导致其所携带的资源不稳定，因此需要部分节点协助缓存资源。但移动终端的存储能力有限，在数据存储与数据替换策略上会直接影响网络的内容分发效率。本文提出一种基于部分网络编码的缓存策略，对节点处存储的数据进行编码处理，增大有限存储空间里所存储的信息数量，并及时更替存储空间已满的信息，使得可用性较高的信息得到存储，同时也避免缓存出现溢出而导致节点崩溃的问题。因此，在MP2P网络中，对数据进行部分网络编码的缓存操作可减少查询节点与存储节点的平均连接次数，加快下载进度，提高命中率，减少数据下载延迟。最后，针对减少有限带宽和动点扰动性对数据传输的影响进行路由规划。由于数据发送路径的搭建及选择直接影响着网内资源定位及传输效率，因此，本文基于球形簇域的网络拓扑环境，在数据进行编码的前提下，提出采用语义相似度选择策略加强路由节点间互联关系，在多条可用路径中以向“潜在客户”推送相关数据、减少数据重传为原则进行路由规划。当节点在一定运动速度范围内时，此路由策略可有效提高查全率与查询效率，减少传输延迟，加强节点间协作能力，改善数据分发机制。论文根据MP2P网络内容分发机制研究项目，对网络架构，传输及存储数据处理策略，路由策略等方面开展研究工作，并对关键技术及模块给予详细的研究方案。更多还原

【Abstract】 With the gradual improvement in the performance of mobile terminal equipment, mobilenetwork has been undergoing a rapid development. MP2P as the product of peer-to-peernetwork and mobile computing, is free from fixed base station and provides a newdevelopment direction for the mobile network. MP2P, in line with its predecessor, thetraditional P2P, has the advantage of resource load balancing, no centralization, peer-to-peerequivalence, high distribution of network framework and scalability. Furthermore, MP2Pmakes it convenient to send messages at any time in any place without the base station.However, its other characters such as multi-hop, wirelessness, frequent joining and leaving,and constant leaving perturbation, all pose a series of challenges to achieving the efficiencyMP2P.The paper, concerning on no fix base station, self-organizing wireless networks, is aimedat analyzing the network framework, data processing, caching strategies, routing strategies,with the ultimate objective to enhance the distribution of MP2P network content. The specificcontributions are as follows:Firstly, the study is concerned with the anti-perturbation of wireless mobileself-organized network topology. The rumor of mobile equipment induces such genericproblems as difficulty in manageability and maintenance to self-organized networks. However,network framework is one of the key factors and the first step for the design of MP2P networkcontent distribution mechanism. The paper, considering the dynamic nodes of MP2P, proposesa network architecture based on sphere cluster, which divides the network into multiplesubnets managed by partition. Each subnet is managed by super node for information routingand distribution. The information is then transmitted by the transition node in crossing area toguarantee the connection of the information exchange. The strategy proposed herein canefficiently reduce the transmission delay and the influence of download success rate, andhence the hit rate can be improved.Secondly, based on the aforementioned wireless ad hoc network topology, in terms of theproblems of the over-reliance of data download success rate on the seed online, repeated datatransmission and liability of network congestion, this paper proposes a network strategy to improve the content distribution efficiency of MP2P network. This strategy, in addition tostoring and forwarding information, can encode and decode information in the node. In themeantime, it reduces the rate of repeated data, space occupied by traffic data, shortenstransmission time, and eases channel congestions. Thus the download success rate isimproved, the transmission delay reduced the robustness of the MP2P content distributionenhanced as well.Thirdly, the dynamic feature of nodes would result in the instability of carried resources,and thus a proportion of nodes are required to assist caching. However the limited capacity ofmobile terminals is limited would influence the content distribution efficiency. This paperhereby proposes a new cache strategy to optimize the node storage, make full use of thelimited storage space, update the storage the information in time and prevent the cacheoverflowing. Therefore, caching data by means of encoding a proportion of network canreduce the average connection of inquiring nodes and storage nodes, accelerate downloadspeed, increase hit rate, and reduce data download delay.Last but not least, the present study devises a routing plan to solve to problem ofreducing the influence of limited bandwidth and perturbation on data transmission. Therefore,based on network topology of sphere cluster, this paper proposes a routing plan that enhancesthe connection of routing nodes on basis of semantic similarity, as well as pushing relevantdata and reducing repeated data transmission. When the node moves within a certain speedrange, this routing strategy can effectively improve the recall rate and query efficiency, reducetransmission delay, enhance inter-node collaboration capability, and improve data distributionmechanism.This dissertation, based on the study of MP2P network distribution mechanism, exploresnetworking framework, data transmission and storage strategy, as well as routing strategy, andfurther proposes relevant detailed plans for key technologies and modules.更多还原