Zigbee無線傳感器網(wǎng)絡(luò)英文文獻.doc

蘭州交通大學(xué)畢業(yè)設(shè)計(英文文獻)Zigbee Wireless Sensor Network in Environmental Monitoring ApplicationsI.ZIGBEE TECHNOLOGY Zigbee is a wireless standard based on IEEE802.15.4 that was developed to address the unique needs of most wireless sensing and control applications. Technology is low cost, low power, a low data rate, highly reliable, highly secure wireless networking protocol targeted towards automation and remote control applications. Its depicts two key performance characteristics wireless radio range and data transmission rate of the wireless spectrum. Comparing to other wireless networking protocols such as Bluetooth, Wi-Fi, UWB and so on, shows excellent transmission ability in lower transmission rate and highly capacity of network.A. Zigbee Framework Framework is made up of a set of blocks called layers. Each layer performs a specific set of services for the layer above. As shown in Fig.1. The IEEE 802.15.4 standard defines the two lower layers: the physical (PHY) layer and the medium access control (MAC) layer. The Alliance builds on this foundation by providing the network and security layer and the framework for the application layer.Fig.1 Framework The IEEE 802.15.4 has two PHY layers that operate in two separate frequency ranges: 868/915 MHz and 2.4GHz. Moreover, MAC sub-layer controls access to the radio channel using a CSMA-CA mechanism. Its responsibilities may also include transmitting beacon frames, synchronization, and providing a reliable transmission mechanism.B. Zigbees Topology The network layer supports star, tree, and mesh topologies, as shown in Fig.2. In a star topology, the network is controlled by one single device called coordinator. The coordinator is responsible for initiating and maintaining the devices on the network. All other devices, known as end devices, directly communicate with the coordinator. In mesh and tree topologies, the coordinator is responsible for starting the network and for choosing certain key network parameters, but the network may be extended through the use of routers. In tree networks, routers move data and control messages through the network using a hierarchical routing strategy. Mesh networks allow full peer-to-peer communication.Fig.2 Mesh topologies Fig.3 is a network model, it shows that supports both single-hop star topology constructed with one coordinator in the center and the end devices, and mesh topology. In the network, the intelligent nodes are composed by Full Function Device (FFD) and Reduced Function Device (RFD). Only the FFN defines the full functionality and can become a network coordinator. Coordinator manages the network, it is to say that coordinator can start a network and allow other devices to join or leave it. Moreover, it can provide binding and address-table services, and save messages until they can be delivered.Fig.3 Zigbee network modelII.THE GREENHOUSE ENVIRONMENTAL MONITORINGSYSTEM DESIGN Traditional agriculture only use machinery and equipment which isolating and no communicating ability. And farmers have to monitor crops growth by themselves. Even if some people use electrical devices, but most of them were restricted to simple communication between control computer and end devices like sensors instead of wire connection, which couldnt be strictly defined as wireless sensor network. Therefore, by through using sensor networks and, agriculture could become more automation, more networking and smarter. In this project, we should deploy five kinds of sensors in the greenhouse basement. By through these deployed sensors, the parameters such as temperature in the greenhouse, soil temperature, dew point, humidity and light intensity can be detected real time. It is key to collect different parameters from all kinds of sensors. And in the greenhouse, monitoring the vegetables growing conditions is the top issue. Therefore, longer battery life and lower data rate and less complexity are very important. From the introduction about above, we know that meet the requirements for reliability, security, low costs and low power.A. System Overview The overview of Greenhouse environmental monitoring system, which is made up by one sink node (coordinator), many sensor nodes, workstation and database. Mote node and sensor node together composed of each collecting node. When sensors collect parameters real time, such as temperature in the greenhouse, soil temperature, dew point, humidity and light intensity, these data will be offered to A/D converter, then by through quantizing and encoding become the digital signal that is able to transmit by wireless sensor communicating node. Each wireless sensor communicating node has ability of transmitting, receiving function. In this WSN, sensor nodes deployed in the greenhouse, which can collect real time data and transmit data to sink node (Coordinator) by the way of multi-hop. Sink node complete the task of data analysis and data storage. Meanwhile, sink node is connected with GPRS/CDMA can provide remote control and data download service. In the monitoring and controlling room, by running greenhouse management software, the sink node can periodically receives the data from the wireless sensor nodes and displays them on monitors.B. Node Hardware Design Sensor nodes are the basic units of WSN. The hardware platform is made up sensor nodes closely related to the specific application requirements. Therefore, the most important work is the nodes design which can perfect implement the function of detecting and transmission as a WSN node, and perform its technology characteristics. Fig.4 shows the universal structure of the WSN nodes. Power module provides the necessary energy for the sensor nodes. Data collection module is used to receive and convert signals of sensors. Data processing and control modules functions are node device control, task scheduling, and energy computing and so on. Communication module is used to send data between nodes and frequency chosen and so on.Fig.4 Universal structure of the wsn nodes In the data transfer unit, the module is embedded to match the MAC layer and the NET layer of the protocol. We choose CC2430 as the protocol chips, which integrated the CPU, RF transceiver, net protocol and the RAM together. CC2430 uses an 8 bit MCU (8051), and has 128KB programmable flash memory and 8KB RAM. It also includes A/D converter, some Timers, AES128 Coprocessor, Watchdog Timer, 32K crystal Sleep mode Timer, Power on Reset, Brown out Detection and 21 I/Os. Based on the chips, many modules for the protocol are provided. And the transfer unit could be easily designed based on the modules. As an example of a sensor end device integrated temperature, humidity and light, the design is shown in Fig. 5. Fig.5 The hardware design of a sensor node The SHT11 is a single chip relative humidity and temperature multi sensor module comprising a calibrated digital output. It can test the soil temperature and humidity. The DS18B20 is a digital temperature sensor, which has 3 pins and data pin can link MSP430 directly. It can detect temperature in greenhouse. The TCS320 is a digital light sensor. SHT11, DS18B20 and TCS320 are both digital sensors with small size and low power consumption. Other sensor nodes can be obtained by changing the sensors. The sensor nodes are powered from onboard batteries and the coordinator also allows to be powered from an external power supply determined by a jumper.C. Node Software Design The application system consists of a coordinator and several end devices. The general structure of the code in each is the same, with an initialization followed by a main loop. The software flow of coordinator, upon the coordinator being started, the first action of the application is the initialization of the hardware, liquid crystal, stack and application variables and opening the interrupt. Then a network will be formatted. If this net has been formatted successfully, some network information, such as physical address, net ID, channel number will be shown on the LCD. Then program will step into application layer and monitor signal. If there is end device or router want to join in this net, LCD will shown this information, and show the physical address of applying node, and the coordinator will allocate a net address to this node. If the node has been joined in this network, the data transmitted by this node will be received by coordinator and shown in the LCD. The software flow of a sensor node, as each sensor node is switched on, it scans all channels and, after seeing any beacons, checks that the coordinator is the one that it is looking for. It then performs a synchronization and association. Once association is complete, the sensor node enters a regular loop of reading its sensors and putting out a frame containing the sensor data. If sending successfully, end device will step into idle state; by contrast, it will collect data once again and send to coordinator until sending successfully.D. Greenhouse Monitoring Software DesignWe use VB language to build an interface for the test and this greenhouse sensor network software can be installed and launched on any Windows-based operating system. It has 4 dialog box selections: setting controlling conditions, setting Timer, setting relevant parameters and showing current status. By setting some parameters, it can perform the functions of communicating with port, data collection and data viewing.Zigbee無線傳感器網(wǎng)絡(luò)在環(huán)境監(jiān)測中的應(yīng)用I. Zigbee技術(shù)Zigbee是一種基于IEEE802.15.4的無線標(biāo)準(zhǔn)上被開發(fā)用來滿足大多數(shù)無線傳感和控制應(yīng)用的獨特需求。Zigbee技術(shù)是低成本，低功耗，低數(shù)據(jù)速率，高可靠性，高度安全的無線網(wǎng)絡(luò)協(xié)議實現(xiàn)自動化和遠程控制應(yīng)用的目標(biāo)。它描述了兩個關(guān)鍵的性能特點無線射頻范圍和無線頻譜的數(shù)據(jù)傳輸速率。相較于其他如藍牙，Wi-Fi技術(shù)，超寬帶等無線網(wǎng)絡(luò)協(xié)議，Zigbee雖然傳輸速率慢但傳輸容量大的特點向我們展示了他出色的傳輸能力。 A、技術(shù)框架Zigbee的框架是由一組層組成的。上述層中每一層都要執(zhí)行一組特定的服務(wù)任務(wù)。圖1所示。在IEEE802.15.4標(biāo)準(zhǔn)定義了兩個較低層：物理層（PHY）和媒體接入控制（MAC）層。Zigbee聯(lián)盟建立在網(wǎng)絡(luò)層和安全層及應(yīng)用層框架提供的基礎(chǔ)上。圖1 技術(shù)框架在IEEE802.15.4有兩個PHY層，它們在兩個不同的頻率范圍操作：868/915兆赫和2.4GHz。此外，MAC子層控制訪問無線電頻道使用的CSMA- CA的機制。它的功能還可以包括信標(biāo)幀傳輸，同步，并提供一個可靠的傳輸機制。B、Zigbee技術(shù)的拓?fù)?Zigbee網(wǎng)絡(luò)層支持星形，樹形和網(wǎng)狀形拓?fù)浣Y(jié)構(gòu)，如圖2所示。在星型拓?fù)浣Y(jié)構(gòu)中，網(wǎng)絡(luò)是由一個叫做Zigbee協(xié)調(diào)器的單一設(shè)備控制的。 Zigbee協(xié)調(diào)器負(fù)責(zé)發(fā)起和維護網(wǎng)絡(luò)上的設(shè)備。所有其他裝置，稱為終端設(shè)備，直接與Zigbee協(xié)調(diào)器相連通。在網(wǎng)狀和樹狀拓?fù)浣Y(jié)構(gòu)中，Zigbee協(xié)調(diào)器的作用是啟動網(wǎng)絡(luò)，并選擇一些重要的網(wǎng)絡(luò)參數(shù)，但網(wǎng)絡(luò)可以通過Zigbee路由器擴展。在樹狀網(wǎng)絡(luò)中，路由器將通過使用分層路由策略移動數(shù)據(jù)和控制消息。網(wǎng)狀網(wǎng)絡(luò)允許完全對等的對等通信。 圖2 技術(shù)的拓?fù)?圖3是一個Zigbee網(wǎng)絡(luò)模型，它表明Zigbee支持協(xié)調(diào)器中心的單跳星形拓?fù)浣Y(jié)構(gòu)和終端設(shè)備，以及網(wǎng)狀拓?fù)錁?gòu)造。在Zigbee網(wǎng)絡(luò)中，智能節(jié)點由全功能設(shè)備（FFD）和精簡功能設(shè)備（RFD）組成。只有FFN定義了完整的Zigbee功能，并且可成為網(wǎng)絡(luò)協(xié)調(diào)器。協(xié)調(diào)器管理網(wǎng)絡(luò)，也就是說，協(xié)調(diào)器可以啟動網(wǎng)絡(luò)，并允許其他設(shè)備加入或離開它。此外，它可以提供綁定和地址表服務(wù)，并保存，直到他們能傳遞信息。圖3 Zigbee網(wǎng)絡(luò)模型II.溫室環(huán)境監(jiān)測的系統(tǒng)設(shè)計 傳統(tǒng)農(nóng)業(yè)只使用孤立和沒有溝通能力的機器和設(shè)備。農(nóng)民們必須自己親自監(jiān)控作物的生長。即使有些人用電氣設(shè)備，但他們中大多只限于控制計算機和終端設(shè)備的簡單通信，此終端設(shè)備像傳感器而不是像線相連接的傳感器，嚴(yán)格上說不能被定義為無線傳感器網(wǎng)絡(luò)。因此，通過使用傳感器網(wǎng)絡(luò)和Zigbee，農(nóng)業(yè)可能變得更加自動化，更加的網(wǎng)絡(luò)化和智能化。在這個項目中，我們要在溫室的地下室部署五種傳感器。通過這些部署的傳感器，如溫室的溫度，土壤溫度，露點，濕度和光照強度的參數(shù)可以實時檢測。它的關(guān)鍵是從各種不同的傳感器來收集不同的參數(shù)。而在溫室，監(jiān)測蔬菜的長勢是首要問題。因此，延長電池的壽命，減小數(shù)據(jù)速率和降低復(fù)雜度是非常重要的。從上述關(guān)于Zigbee的介紹，我們知道Zigbee滿足了可靠性，安全性，低成本，低功耗的要求。A、系統(tǒng)概述 溫室環(huán)境監(jiān)測系統(tǒng)是由一個接收器節(jié)點（協(xié)調(diào)器），許多傳感器節(jié)點，工作站和數(shù)據(jù)庫組成的。莫特節(jié)點和傳感器節(jié)點共同組成了每個收集節(jié)點。當(dāng)傳感器參數(shù)進行實時采集，如溫室溫度，土壤溫度，露點，濕度和光照強度，這些數(shù)據(jù)將提供給的A / D轉(zhuǎn)換器，然后透過量化和編碼成為數(shù)字信號，它能通過無線傳感器通信節(jié)點傳送。每個無線傳感器通信節(jié)點有傳送和接收的能力。在這種傳感器網(wǎng)絡(luò)中，傳感器節(jié)點部署在溫室，它可以采集實時數(shù)據(jù)和通過多跳方式傳送數(shù)據(jù)到接收器節(jié)點（協(xié)調(diào)器）。接收器節(jié)點完成了數(shù)據(jù)分析和貯存的任務(wù)。同時，接收器節(jié)點與GPRS/CDMA連接可以提供遠程控制和數(shù)據(jù)下載服務(wù)。在監(jiān)控室通過運行溫室管理軟件，接收器節(jié)點可以定期收到來自無線傳感器節(jié)點和在監(jiān)視器上顯示這些數(shù)據(jù)。B、節(jié)點的硬件設(shè)計 傳感器節(jié)點是無線傳感器網(wǎng)絡(luò)的基本單位。硬件平臺是由密切相關(guān)的具體應(yīng)用要求的傳感器節(jié)點組成的。因此，最重要的工作是節(jié)點設(shè)計，可以完美執(zhí)行無線傳感器網(wǎng)絡(luò)的傳送和監(jiān)測功能，并體現(xiàn)了Zigbee的技