【作者】 奎晓燕；

【导师】 王建新；

【作者基本信息】 中南大学 ， 计算机应用技术， 2012， 博士

【摘要】 无线传感器网络(Wireless sensor networks,简称WSNs)是由大量部署在目标区域的传感器节点构成,作为信息领域的新兴技术,WSN在环境监测、军事侦察、交通管理、医疗监护、智能家居等方面具有广泛的应用前景。传感器节点的存储能力、通信能力和处理能力相对较弱,通过能量有限的电池供电,且节点通常部署在环境条件恶劣或人类很难进入的区域,因此对节点进行更换非常困难。数据收集作为WSN中极为重要的操作之一,其作用是将节点感知到的数据传送到Sink节点以供用户分析和处理。电能是WSN中非常重要的资源。在数据收集过程中,有效降低节点的能量耗费是节点长时间工作延长网络寿命的关键所在。本文对不同环境下无线传感器网络的数据收集技术进行了深入研究,旨在寻找能有效降低节点能量耗费、延长网络生命周期和提高网络可扩展性的方法,本文的研究工作主要包括以下几个方面：(1)针对集中式数据收集存在的问题,在无线传感器网络中提出利用分簇技术来进行分布式数据收集。针对典型的分簇协议存在节点能量消耗不均衡,易导致节点过早死亡和网络生命周期缩短的缺点,提出一种能量均衡的分布式方法EBDSC来进行分簇数据收集。在EBDSC中,如果节点发现自己成为簇头后能承担的数据收集轮数比所有邻居都高,则该节点成为候选簇头。对于每个候选簇头,将根据自己邻居被其他候选簇头覆盖的情况,以反比概率成为正式簇头。理论分析表明,在EBDSC算法中,所有节点在O(logn/loge)个时间步内均能加入簇,算法总的消息复杂度是O(nlogn/loge)。仿真实验表明,与目前已有算法相比,EBDSC在分簇阶段有效减小了节点的能量消耗,最终有效延长了网络生命周期。(2)针对构造连通支配集作为网络虚拟主干来进行数据收集时,已有算法构造的最小连通支配集不能有效均衡节点的能量耗费,导致网络生命周期较短的问题,提出了一种能量有效的基于连通支配集的算法DGA-EBCDS来进行数据收集,通过选择能量水平和度均比较大的节点组成连通支配集,使得支配集中的节点组成一个规模不大但具有较高能量水平的网络骨干。DGA-EBCDS算法使得网络中的所有数据沿虚拟骨干在数量较少的节点中转发,能够节省节点能量,使骨干节点不会因为能量不足而过早死亡。理论分析表明DGA-EBCDS能以O(nlogn)的消息复杂度构造连通支配集。仿真实验表明,与目前已有算法相比,DGA-EBCDS在构造连通支配集时有效减少了节点的能量耗费,从而有效延长了网络生命周期。(3)针对已有数据收集算法普遍只考虑网络中节点产生的数据量是相同的情况下数据收集算法存在的问题,研究当各节点产生的数据量非均衡情况下适合多跳无线传感器网络环境的数据收集算法。首先,提出了一种基于支配集的分簇数据收集算法DSCAU。在DSCAU中,每个节点对自身剩余能量、节点邻居数量、自身和邻居产生的数据量等情况进行综合考虑来选举候选簇头。为避免正式簇头过多,候选簇头根据自身邻居被其他候选簇头覆盖的数量,以反比概率成为正式簇头。算法为了均衡簇头的能量开销,对簇的规模进行了限制。理论分析和仿真实验表明,DSCAU在多跳情况下能有效延长网络生命周期,并且能保证所有节点均能加入簇。然后,为了提高算法的适用性,本文对DSCAU算法进行了改进,提出了一种在更广范围内适用的通过移动Sink来进行数据收集的DSCP算法。理论分析表明,在DSCP算法中,所有节点在O(n/logn)个时间步内均能加入簇,算法总的消息复杂度是O(n2/logn)。仿真实验表明,DSCP与目前已有算法相比,网络生命周期得到有效延长。综上所述,本文对无线传感器网络中的数据收集技术及关键问题进行了深入研究,提出了多个性能更好的协议,能够较好地解决WSN数据收集中存在的问题,具有较高的理论意义及应用价值。更多还原

【Abstract】 Wireless sensor network (WSN) is a new hot-spot in current research, and it has broad application foreground. A wireless sensor network consists of a large number of nodes that collaborate together to monitor various phenomenons. WSN.can be used in various fields, such as military, environment, disaster forecast and relief, business, health, etc. The sensor nodes have only limited communication ability, computational ability, storage space, and energy, etc. Moreover, the nodes are difficult to be replaced because they are often deployed in remote or inaccessible environments.Wireless sensor networks are data-oriented and are usually densely deployed in a monitor environment to process a great deal of data. Data collection is one of the most important operations in the network, which means that the data sensed by nodes should be transmitted to the sink for further processing. How to conserve the limited energy of nodes and extend the lifetime of the network is an important issue in data collection. This dissertation focuses on the problem that how to find some ways to effectively decrease energy consumption of the nodes and maximize the network lifetime and improve the scalability of the network. The main contributions of this dissertation are showed as follows.(1) Aiming at the problem of existing clustering protocols usually randomly choose cluster heads or use the node with the highest remaining energy in a cluster as the head, which may lead to unbalanced energy consumption among different nodes and shorten the network lifetime, we propose a distributed energy-balanced dominating set based clustering scheme named EBDSC, which effectively prolongs the network lifetime by balancing energy consumption among nodes. In EBDSC, each node calculates the number of rounds it can afford if it was selected as the cluster head. A node becomes a candidate cluster head if it affords most number of rounds among its neighbors. A candidate cluster head becomes a final cluster head with a probability determined by its uncovered neighbors. The protocol can terminate in O(logn/loge) steps, and its total message complexity is O(nlogn/loge). Simulation results show that EBDSC can balance energy consumption among nodes well. The average energy consumption of EBDSC is reduced in the clustering phase, and the network lifetime is prolonged compared with another clustering algorithm ECDS.(2) Aiming at the problem of exsiting researches construct virtual backbone of network by using minimum connected dominating sets, and each node in the network can transmit its data to the sink by the virtual backbone. But, the minimum connected dominating sets cannot balance the energy consumptions among nodes. Therefore, the network lifetime is hard to be extended. We propose a novel algorithm named DGA-EBCDS to construct an energy-balanced connected dominating set. In DGA-EBCDS, each node in the connected dominating set has high energy and large degree, and these nodes form a virtual backbone in the network. By transmitting data through the backbone with small numbers of sensor nodes, each node can preserve its energy effectively. Moreover, the nodes in the backbone can live longer. Theoretical analyses show that DGA-EBCDS can construct a connected dominating set with O(nlogn) message complexity, and simulations show that the average energy consumption of DGA-EBCDS is reduced, and the network lifetime is prolonged compared with another algorithm mr-CDS.(3) Aiming at the problem of existing data collection protocols mainly assume that every node in the network produces the same amount of data, we propose a novel dominating set based algorithm DSCAU to solve the problem. In DSCAU, when electing the tentative cluster head, each node takes its remainder energy, its traffic load, the number of its neighbors, and the traffic loads of its neighbors into consideration. The tentative cluster head will become final cluster head with a probability inversely proportional to the numbers of other tentative cluster heads that cover its neighbors. Furthermore, the size of clusters is restricted to balance the energy consumption among different cluster heads. Theoretical analyses and simulation results show that DSCAU can effectively prolong the network lifetime in multi-hop WSNs, meanwhile guaranteeing that all the nodes in the network can join a cluster.Moreover, in order to expand the applicability of the algorithm, we futher propose a new algorithm named DSCP to improve DSCAU. In DSCP, a node evaluates the potential lifetime of the network (from its local point of view) assuming that it acts as the cluster head, and claims to be a tentative cluster head if it maximizes the potential lifetime. When evaluating the potential lifetime of the network, a node considers not only its remaining energy, but also other factors including its traffic load, the number of its neighbors, and the traffic loads of its neighbors. The protocol can terminate in O(n/logn) steps, and its total message complexity is O(n2/logn). Simulation results show that DSCP can effectively prolong the lifetime of the network in multi-hop networks with unbalanced traffic load.In a word, the dissertation performs an in-depth study on the data collection of wireless sensor networks. Moreover, several energy-efficient data collection protocols with higher performance are proposed. Therefore, the research of the dissertation has strong theoretical and practical significances.更多还原