【作者】 李文霁；

【导师】 郭世泽；

【作者基本信息】 北京邮电大学 ， 信息安全， 2013， 博士

【摘要】 无线传感器网络作为二十一世纪公认的最重要技术之一,已经成为学术界中的热门研究方向,在偏远地区、应急性、条件恶劣等传统网络无法覆盖的通信环境中有着很好的适用性。随着应用需求的不断扩展,传感器节点常常被部署在较大的监视区域内,并依附在运动物体上,以及由于节点自身的资源有限性,导致了整个网络具有节点随机运动、部署相对稀疏和通信范围较小的特点,因此这类网络很难和传统网络一样提供稳定的端对端通信连接。为了解决在该类网络中有效数据传输问题,延迟容忍移动传感器网络(Delay Tolerant Mobile Sensor Network, DTMSN)的概念应运而生。DTMSN是对具有节点随机运动和间歇性连通特点的无线传感器网络的统称。作为一种面向非连接的网络类型,DTMSN有着非常广泛的应用领域,如环境数据获取、病毒扩散信息监测、战场信息收集等,已经成为无线传感器网络研究的新热点。目前,已有DTMSN研究还主要集中在数据传输路由技术方面,主要目标是以更低的传输延迟和传输能耗来实现更高的数据传输成功率,并取得了一定的研究成果。针对DTMSN网络特性,本文在对已有研究的深入分析和总结的基础上,对]DTMSN的数据传输进行了更为全面、细致的研究,主要探讨了以下问题：(1)如何在低能耗开销需求下实现更高效的邻居节点异步连接探测；(2)如何实现有效的数据传输路由,以完成数据传输成功率、传输延迟和传输能耗的更有效平衡；(3)如何在低运算开销下有效实现数据的安全传输。本文主要取得如下创新性研究成果：1.针对DTMSN邻居节点连接探测问题,提出了一种基于互质周期对的节点异步连接探测机制EAPS(Efficient Asynchronous Probing Scheme)。其基本思想是将传感器节点状态划分为唤醒、睡眠两类,利用基于互质周期对的时隙睡眠方法,来保证在没有预先连接信息条件下节点异步探测以低探测能耗实现较高探测成功率和较低探测延迟；此外,在分析RWP运功模型的统计特性基础上,研究了不同网络区域内的节点出现概率分布和相遇概率分布,将整个网络划分为不同区域,并通过在不同区域内合理选择探测占空比,进一步提高探测性能。2.针对DTMSN数据传输路由问题,提出了一种基于节点运动状态感知的数据传输策略MSAD (Motive State-Aware data Delivery scheme)。其基本思想是使用两个通信频率f1和f2分别进行节点运动状态获取和数据传输。其中,在频率f1上采用基于TDOA(Time Difference of Arrival)技术的定位方法来降低采用GPS带来的成本问题,并利用节点周期性定位获得节点的当前位置、运动速度大小和方向等运动状态参数,通过预测节点在下一时刻的位置,来估算节点传输概率；在频率f2上,节点之间通过比较传输概率来决定数据转发路由。此外,MSAD结合“自私性”原则(selfish,SF)和消息生存时间(survival time, ST)进行消息队列管理,以避免仅采用生存时间而导致的消息转发不均衡的问题以及仅采用“自私性”原则而产生的传输延迟较大情况。3.针对DTMSN安全数据传输问题,分析了身份密码学IBC(Identity-based Cryptography)在DTMSN中的适用性,并提出了一种低运算开销的IBC签名和批量认证机制ISBA(Identity-based Signature scheme with Batch Authentication)。其基本思想是采用在线／离线签名技术来降低IBC签名在线阶段的运算开销,而利用批量认证技术来实现一次性认证多个消息,从而降低认证消息签名的运算开销；此外,通过引入接收节点建立连接的最小剩余空间,对MSAD策略的数据转发算法进行了改进,增加了每次批量认证的消息数量,进一步降低了运算开销,仿真实验表明,改进的MSAD并没有对传输性能造成明显影响。更多还原

【Abstract】 Recognized as one of the most important technologies in the21st century, wireless sensor network(WSN) has been attacked a lot of attentions in academia, and it could work well in many challenging special environments where traditional networks are difficult to be applied, such as remote areas, emergency communications fields and areas with harsh natural conditions. With the continuous expansion of its application requirements, sensor nodes are often deployed in a large monitoring area, and need to be placed on moving objects. In this network, the stable end-to-end communication connect can not be provided as traditional networks, because sensor nodes have the characteristics of the random movements, sparsity and the limited communication range. In order to efficiently transmit data packets in these environments, the concept of delay tolerant mobile sensor network(DTMSN) is proposed to face these challenges.DTMSN is a kind of network which is characterized by node random mobility and intermittent connectivity between nodes. As a non-connection oriented network, DTMSN is suitable for many applications, such as environmental data acquisition, virus spreading informantion monitoring, battlefield information gathering, et al, and has drawn wide attentions. At present, most of exsiting DTMSN research still foucs on improving data delivery routing mechanism, and many research achievements in this field has been obtained. Its main goal is to achieve a higher data delivery radio with the lower delivery delay and energy consumption. Based on the in-depth analysis and systematical summary of relevant works, we do a comprehensive and detailed research on DTMSN data delivery technology based on the characteristics of this network. The main studies foucs on the following issues:(1) How to efficiently discover neighbor nodes with a lower probing energy consumption in an asynchronous case;(2) How to efficiently delivery data to improve the delivery radio, decrease the delivery delay and energy consumptions;(3) How to efficient achieve the secure data delivery with a lower computational cost. The innovative research achievements are shown as following:1. To solve the issue of neighbor discovery, an Efficient Asynchronous Probing Scheme(EAPS) for DTMSN is proposed. EAPS divides the status of sensor nodes into two categories:wakeup and sleeping, and designes a slotted-wakeup schedule based oncoprime cycle pairs to improve the probing accuracy and decrease the discovery delay under the low energy consumption. Additionally, EAPS gives a reasonable regional plan based on the study of stochastic properties of Random Way-Point(RWP) mobility model, and optimal coprime cycle pairs are selected in these different regions to further improve the discovery radio and reduce energy consumption.2. To solve the issue of data delivery routing, a Motive State-Aware data Delivery scheme(MSAD) for DTMSN is proposed. MSAD adopts two communication frequencies f1, f2to obtain motive state of sensor nodes and forward data. On the frequency of f1, MSAD uses a new positioning method based on time different of arrival(TDOA) which has a lower cost than GPS, sensor nodes obtain their own motive state by cyclical positioning and calculate their delivery probability by predicting their position in the next moment. On the frequency of f2, data delivey routing between sensor nodes will be determined by comparing the delivery probability. Additionally, to efficiently manage the message queue, MSAD employs the principle of selfish(SF) and the survival time(ST) to avoid the issue of imbalance number of message copies caused by only adopting ST and the issue of the large delivery delay caused by only adopting SF 3. To solve the issue of secure data delivery, we analyze the applicability of identity-based cryptography in DTMSN, and an Identity-based Signature scheme with Batch Authentication(ISBA) is proposed to reduce the computational cost for DTMSN. ISBA is composed of online/offline signature, batch authentication and message forwarding algorithm improve-ment based on MSAD. Specially, online/offline signature has a very light computational cost at the online signature phase; Batch authentication could reduce the computation cost by validating multiple signatures simultaneously instead of verifying them one by one; Additionally, the minimum remaining space(MRS) is introduced to improve MSAD that new connections can’t be established until the remaining space of the receiver isn’t less than MRS, therefore, average message number in each batch authentication increases and the computational cost reduces. Simulation results show that the improved mechanism of MSAD does not induce negative impact on the delivery performance.更多还原