【作者】 王琳；

【导师】 余震虹；

【作者基本信息】 江南大学 ， 信号与信息处理， 2009， 硕士

【摘要】 随着现在高科技的进步,人们的生活水平有了很大提高,对环境的要求也越来越高,环境问题开始得到社会的重视,尤其是自己所处的环境空气质量。目前,环境监测发展的一个重要方向是开发适合我国国情、价格低廉的远程无线监控系统,而环境空气质量监控系统中极为重要的一部分就是如何获得环境中的有用参数,之后才能进行后面的分析、决策控制工作。无线传感器网络(WSN)能够通过各类集成化的微型传感器协作地实时监测、感知和采集各种监测对象的信息,并传达给控制中心,具有可快速部署、无人值守、功耗低、成本低等优点,十分适合于环境监控系统。传感器、嵌入式系统、计算机网络和无线通信四大技术孕育了无线传感器网络。无线传感器网络可以被广泛应用于军事,商业,医疗和环境监测等多方面。本文即采用无线传感器网络构建一个基于嵌入式无线监控环境空气质量的系统。无线传感器网络由大量密集的传感器节点构成,每个节点相当于一个小型的嵌入式系统,由数据采集模块、数据处理模块、无线收发模块和电源构成。节点由两节五号电池供电,所以各个节点的能源、计算能力都非常有限,本文对这小型嵌入式系统所需的关键芯片做了正确评估和选择,采用超低功耗的MSP430和CC2420 2.4GHz射频芯片,设计了一种低功耗的系统结构。对于WSN来说,传统的无线路由协议已不再适合无线传感器网络,已有的路由协议都是基于特定的应用环境而设计的,所以根据本论文的环境要求,设计能够有效节约能源,延长网络生命周期的路由协议成为了本论文的研究重点。本文对现有的无线传感器网络路由协议进行了分析研究,尤其重点分析了LEACH协议,针对其存在的整体能耗高、网络生命周期短等不足,在LEACH协议的基础上进行了改进,我们把改进后的路由协议简称为LEACH-IMP。在LEACH-IMP中,分别在网络中最优簇数的确定、簇头选择算法和簇间路由机制方面对LEACH进行了改进。LEACH-IMP充分考虑了节点剩余能量与其成为簇头的概率关系,对阈值T(n)重新加以定义;簇头节点与Sink节点间的通信采用多跳路由方式。改进后的路由协议LEACH-IMP保证簇头个数最优且在区域内分布比较均匀,同时均衡了各个节点的能量消耗,从而大大延长了网络的生命周期。经过仿真测试,采用LEACH-IMP算法比采用LEACH算法具有较好的能量优化特性,使整个网络生命周期延长了将近60%。更多还原

【Abstract】 With the modern high-tech progress, people’s living standard has been greatly improved. At the same time, the demands on the environment are more and more strict and the society has been paying attention to environmental issues, especially on air quality of our own environment. At present, developing a low-cost remote monitoring system to suit China’s national conditions is an important direction in the development of environmental monitoring. How to obtain useful parameters in the environment is an important part in the environmental air quality monitoring system. Only by obtain the environment parameters, the analysis and the decision-control work can be carried on. Wireless sensor network (WSN) could monitor real-time, detect and gather cooperatively all kinds of information about monitored objects through various integrated sensors. And then it transmits the information to remote control center. WSN can be a rapidly developed, automatic, low power consumption and low cost system. Therefore, the WSN is very suitable for the environmental monitoring system.Wireless sensor network was formed by the combination of sensor, embedded system, computer network and wireless communication technologies. WSN can be widely applied in military, commercial, medical and environmental monitoring fields. This paper will design an embedded environmental air quality monitoring system based on WSN.WSN consists of a large quantity of sensor nodes, each one equivalent to a small embedded system, which consists of data acquisition module, data process module, wireless transceiver modules and power supply module. Every node’s power is supplied by tow v-type battery, so their power and calculation ability is very limited. Therefore, this paper makes an assessment and selection on the key chip required for this small-scale embedded system. And adopt ultra-low power consumption MSP430 and CC2420 2.4GHz RF chip to design a low-power system architecture.Traditional wireless routing protocol is not suitable for wireless sensor network, the design of existing routing protocols are based on the specific application environment. In accordance with the environmental requirements of this thesis, the key point for researching is to design a valid routing protocol which can save power and prolong the lifetime effectively.This paper firstly analysis current routing protocols of wireless sensor network, especially focus on the analysis of LEACH routing protocol. Then aiming at the disadvantage that this protocol has high power dissipation and short lifetime. Based on the LEACH routing protocol, we improve the LEACH routing protocol, named the advanced routing protocol LEACH-IMP. In this new protocol, we calculate the optimal number of cluster head, improve cluster head selection algorithm and inter-cluster routing mechanism. LEACH-IMP fully takes into account the residual energy of nodes as a cluster head to redefine the threshold value of T(n); and adopt multi-hop routing for the communication between Sink node and cluster node.Improved routing protocol LEACH-IMP to ensure the optimal number of head clusters and more evenly distributed in the region ,at the same time balance the energy consumption of every node, which greatly extend the life cycle of the network. After simulation testing, the LEACH-IMP algorithm has better optimization of energy characteristics to extend the lifetime of the entire network nearly 60%.更多还原