【作者】 张剑；

【导师】 黄本雄；

【作者基本信息】 华中科技大学 ， 信息与通信工程， 2007， 博士

【摘要】 无线传感器网络在民用和军事领域有着广阔的应用前景,因此得到了国内外的高度重视。随着人们对辽阔海洋探索的迫切渴望和沿海地区军事防御、商业开发等需求的日益增加,以无线传感器网络为基础的水下传感器网络,也同样已经引起了学术界和工业界的密切关注,它将在未来的水下监视预警系统中发挥重要作用,因此对水下传感器网络的研究是一项具有重大意义的研究课题。高效的网络拓扑结构和通信协议对于无线传感器网络至关重要。而水下声信道极为特殊,时延大且易变、多径效应和多普勒频率偏移严重,使得陆基无线通信网络的技术不能直接应用于水下。因此水下传感器网络存在能量消耗均衡、高效的拓扑结构、能量有效的通信协议等方面的诸多挑战。基于此,本文在组网相关技术难点方面展开研究。首先针对网络拓扑结构进行理论研究,并设计能量消耗均衡的拓扑结构模型。然后分别研究和设计了适应于水下高传输延迟和高能耗特性的路由协议和MAC协议。最后通过仿真(实验)结果论证这些协议和拓扑结构的良好性能和可行性。本文所做的工作主要有以下几个方面:(1)建立了网络拓扑结构与能量消耗分析模型:针对水下传感器网络的网络结构进行分析。利用能耗模型,分析水下信道多跳传输的能量消耗,水下环境分簇网络结构的优势及其网络能量消耗最优的簇头数目。以此为基础,给出水下环境下的分簇多跳网络拓扑结构,并指出了后续章节的研究重点和思路。(2)提出了适合多跳结构的传感器网络非均等分簇算法:通过网络结构分析模型和水下声信道能耗模型,以几何规划理论推导为基础,提出了一种能量消耗均衡的分簇策略BECS。该策略通过距离向量和能量水平智能地改变节点成为簇头的概率,并使簇头自适应的确定其“管辖”范围大小。同时还引入簇头协商机制,使得簇头分布均匀,较好地均衡了网络负载,有效的延长网络的生命周期。(3)提出了水下传感器网络中基于前向簇头和前向网关的路由算法:针对水下的高传输延迟和高能耗问题,以分簇结构为基础,提出了以前向簇头和前向网关为基础的路由协议FFBR。此协议充分利用节点的地理位置信息,使得网络在拓扑结构初始化的过程中就能够基本形成方向性节能路由,同时通过前向簇头和前向网关的选择策略,保证网络能量消耗均衡,并减小了路由建立造成的开销和时延。(4)提出水下网络中基于预约的能量有效的MAC协议:针对水下声信道传输时延长、多变、同步难等特点,结合分簇结构提出了一种基于预约的能量有效MAC协议。此协议运用时间标记的方法,解决水下传感器网络中数据传送接收同步的问题,同时运用“保护时间”的方法,尽量减少和避免水下传感器网络中,由于信道变化而引起的数据传输冲突,提高通信效率。本文的研究工作对水下传感器网络提出了一种较优的网络结构组织方法,并针对水下传感器网络特点提出了切实可行的通信协议,有一定的理论意义和实际应用前景。更多还原

【Abstract】 With the wide application in both civilian and military domains, wireless sensor network (WSN) has been highly focused on in the world. Furthermore, along with the urgent requirement for exploring wide ocean area and the constant growing developments of military defense and business exploiture, underwater acoustic wireless sensor network (UAWSN) based on WSN is also being concerned and expected to play a very important role in future underwater monitoring system. Therefore, UAWSN are becoming those research topics with great significances.As known, an efficient design of network topology and communication protocol is very important for UAWSN. Besides that, long transmission delay, serious multi-path reflection and Doppler frequency spread are also very serious in the underwater acoustic channel. These problems prevent many techniques used in the land wireless sensor network transplanting into UAWSN directly. So the UAWSN confronts several challenges such as balanced energy consumption, network topology and energy efficient communication protocol.Based on above discussion, this thesis addresses those problems relative to the network organization. First of all, theoretical researches are developed on the network topology, and the topology model of balanced energy consumption is also designed. After that, deep researches on the routing and MAC protocols of UAWSN are developed and designed to be able to avoid long transmission delay and heavy energy consumption. Finally, sufficient simulations are made and experimental results demonstrate the better performance and feasibility of those proposed protocols.Main works in this thesis fall into following aspects:(1) Network topology and energy consumption analysis. By the usage of energy consumption model for the underwater acoustic channel, the energy consumption of node on multi-hop path, the advantage of underwater clustered network and the optimal number of cluster head for energy consumption are analyzed in detail, which become the theoretical basis for the next research on the selection of network topology.(2) Propose adaptive clustering algorithm in underwater multi-hop sensor network. By using the network analysis model and the underwater energy consumption model, an efficient balanced energy consumption strategy (BECS) is proposed based on the geometrical programming theory. BECS makes use of the distance vector and node energy level to adaptively dynamically change the probability for a node becoming the cluster head, and enables the cluster head to adaptively determine its managing radii. As expected, BECS balances the network burden very well and prolongs the life time of network.(3) Propose routing algorithm based on the forward cluster head and forward gateway in the UAWSN. A routing protocol based on the forward cluster head and forward gateway is proposed to solve the long delay and heavy energy consumption problems in acoustic transmission.(4) Propose energy efficient MAC protocol in the acoustic network. An energy efficient MAC protocol based on the real-time delay estimation is proposed to overcome the problems such as long delay, synchronization difficulty and uncertain variation in the UAWSN.The research of this thesis optimized the topology of the underwater sensor networks to certain extend, especially, propose feasible communication protocol for the UAWSN, it can expedite the ocean explore and research.更多还原