【作者】 李正宝；

【导师】 郭忠文；

【作者基本信息】 中国海洋大学 ， 计算机应用技术， 2011， 博士

【摘要】 水下传感器网络(Underwater Acoustic Sensor Network,简称UASN)是指将能耗低、低成本、具有通信与计算能力的传感器节点部署到监测海域,节点以无线自组织的方式构成的分布式水下监测网络。水下传感器网络可以被广泛的应用在海洋资源勘探、海洋信息监测、水下目标跟踪和定位等领域,具有重要的应用价值和研究意义,并逐渐成为当前信息科学领域的研究热点之一。本文分析了水声信道特性对水下传感器网络性能的影响,从网络体系结构、数据链路层协议和时间同步机制三方面对基础协议设计进行研究,设计了可扩展的、通用的水下移动传感器网络体系结构,提出了适应于水下传感器网络时空多变性、高误码率和高延迟特点的介质访问控制协议(MAC)和时间同步算法。具体的研究内容和创新之处包括以下几个方面:1、针对水下移动传感器网络中的通信受限和异构互联问题,分析已提出的容迟网络体系结构,指出由于其通用性差,不适用于水下移动传感器网络。进而研究水下移动传感器网络的典型应用场景和基本特征,提出可扩展的、通用的新型容迟网络体系结构,研究体系结构的各层在组网通信中的作用和对协议设计的需求,指出网络协议研究中的关键技术。2、针对水下三维网格拓扑结构,分析三种不同通信模式对数据包的传输方向和传输时延的影响,研究节点坐标和数据发送时间的关系。根据网络节点单位圆干扰模型,推导出节点坐标位置和节点时隙分配的函数关系,提出了基于三维网格结构的集中式MAC协议:USS-TDMA。USS-TDMA算法采用冲突避免机制,由基站管理时间片分配,并通过广播同步消息保持全网络同步运行,能极大地提高水声信道的利用率和网络吞吐量,降低时延。3、研究TDMA算法中节点时隙分配的本质规律,提出一种能量高效的分布式MAC协议:UD-TDMA。UD-TDMA算法将求解并发通信节点个数问题转化为求解极大独立集的理论问题,设计分布式算法获得每轮发送节点的极大独立集,进而确定节点时隙分配和发送周期。算法的时间复杂度为O(n),其中n为2跳邻居节点集的度的最大值。通过理论分析、仿真试验,证明UD-TDMA算法的可行性和有效性,验证UD-TDMA的性能和效率。4、针对水下节点移动导致数据传播时延动态变化的问题,研究水下传感器网络节点移动对传播延迟的影响规律,建立节点移动和传播延迟的关系模型,提出适用于水下传感器网络的高精度时间同步算法:E2DTS。E2DTS通过求解相邻数据包的接收/发送时间差值,采用线性回归方法估计时间漂移率和时间偏移,减少了数据交换过程中各种因素对时间同步精度的影响。模拟实验证明,与已有算法相比,E2DTS的能耗较低,精度至少提高30%。本文的研究工作是在具有时空多变性的水下传感器网络基础协议方面进行的探索,针对水下传感器网络的特点设计出切实可行的解决方案,具有一定的理论意义和应用价值。更多还原

【Abstract】 Underwater acoustic sensor network(referred to as UASN) is a distributed self-organized underwater monitoring network, which formed by low-cost sensor nodes that have the low energy consumption, underwater acoustic communications and computing power, deployed to the designated area. UASN can be widely used in the exploration of marine resources, marine information monitoring, underwater target tracking and positioning, and other civilian and military areas. It has extensive application value and research value, and gradually becomes one of the hotspots in information science research domain.We analyze the influence of the underwater acoustic channel properties on the underwater acoustic sensor network performance. Then we study three issues of the basic network protocols: data link layer protocol, time synchronization mechanisms and network architecture. We design scalable, universal new delay tolerant network architecture for underwater mobile sensor network, propose a medium access control protocol (MAC) and a time synchronization algorithm for underwater sensor networks in order to adapt the characteristics of spatial and temporal variability, high error rate and high latency. The specific research and contributions are as follows:1. Investigate the problem of limited and heterogeneous communication in underwater mobile sensor network. Analyze the capacity of the proposed network architectures, indicate that due to the versatility is poor, and do not apply to underwater mobile sensor network. Further, we study the typical application scenarios and basic characteristics of underwater mobile sensor network. We propose scalable universal underwater mobile sensor network architecture. Finally we point out the key research issues of underwater mobile sensor network protocols.2. Analyze the cube-based underwater acoustic sensor network topology; investigate the effect of three different communication modes in data transmission direction and delay. Study the relationship between nodes coordinates and data transmission. Under the foundation of the unit circle interference model, we derive the function between node coordinates and slot distribution. We propose a centralized MAC protocol for three-dimensional cube-based underwater acoustic sensor network: USS-TDMA. USS-TDMA algorithm uses the collision avoidance mechanism, manages the time slots allocated by the base station and keeps the whole network synchronous through broadcast synchronization message to whole network. It can greatly improve the utilization of underwater acoustic channel and reduce the delay.3. Investigate the nature of the nodes slot allocation rules in TDMA algorithm, propose an energy effiency distributed TDMA algorithm for UASN: UD-TDMA. UD-TDMA algorithm transforms the solution of the number of concurrent communication node into solving the theoretical issues of maximal independent set. It designs a distributed algorithm to obtain a maximal independent set of concurrent node and to determine the node slot distribution and the transmission cycle. UD-TDMA algorithm has a time complexity of O (n), where n is the maximum degree of two hop neighbor node sets. The theoretical analysis and simulation tests show that the UD-TDMA is feasibility and effectiveness, is validated the performance and efficiency.4. Directed towards dynamic changes of data transmission delay caused by underwater nodes mobility, research the impact of nodes mobility on underwater sensor network data propagation delay, establish the model of relationship between propagation delay and nodes mobility, propose an energy efficienct distributed time synchronization algorithm: E2DTS. By solving the time difference of adjacent receive/transmit packets, E2DTS use linear regression methods to estimate the clock skew and offset so as to reduce the influence of various factors on the time synchronization accuracy in the process of data exchange. Simulation experiments show that compared with existing algorithms, E2DTS has the lower energy consumption and better accuracy of at least 30% higher than others. This research work is an exploration in spatial-temporal varying underwater acoustic sensor networks. Several practical solutions are designed directed towards the characteristics of underwater acoustic sensor networks and have some theoretical and practical value.更多还原