| With the rapid development of semiconductor technology, tiny system technology, modern network and wireless communication technology, the wireless sensor network is applied to more and more fields. In order to bring wireless sensor network into full play, the information that the sensor network collects must be transmitted timely, accurately to the external world. Based on this need, this thesis have designed and realized a comparatively perfect wireless function sensor network system, being in charge of the communication of sensor network and external network.With the development of sensor technology, the types of wireless sensor network sensor that is available are more and more. The various physics amounts such as electromagnetism, temperature, humidity, noise, light intensity, pressure, object speed and direction can be detected by making use of these sensors. And they have such advantages such as low-power consumption, low cost, reliable transferring, big network capacity, dynamic organization network, which have given vast prospect of application to the wireless sensor network. The wireless sensor network can now be applied to military affairs, environmental monitoring and forecasting, healthy nursing, intelligence home, building monitors, complicated machinery monitors, city traffic, space exploration, large-scale workshop and storehouse management, and safety monitor of airport, large-scale industrial parks and so on. With the fact that wireless network sensor studying in a deep going way and applying broadly, the sensor network will go deep into each field of human life gradually, and will become an essential part.Wireless sensor network (Wireless Sensor Network, shorter form WSN), being regarded as one of the most important technologies of the 21st century, is that a lot of sensors contact mutually, handle and transfer information in the wireless communicative way. This network which synthetically makes use of the sensor technology, inserted calculating technology, distributed information processing technology and the communication technology, can real time monitor, percept and collect the various environmental or the monitor information within the network distribution areas, and cope with these information then transmit them to the people who need. The wireless sensor network can be applied in such fields as defense industries, traffic safety, medical treatment, and so on. Its research, development and application concern with many significant aspects such as national security and economic development and have aroused broad attention and great investment in recent years.From one research that a distributed sensor network group did about WSN in 1978 donated by USA Ministry of National Defense DARPA, in the past 30 years, WSN has been developed at full speed, and its application field has also expanded to various fields such as environmental monitoring, health and medical community today from the initial military affairs. The various technology related to WSN has been gradually mature; sensor node treatment ability and communication ability have got very big rise, with skyrocketing amounts of WSN transmission information. Aiming to give full scope to wireless sensor network sufficiently, must this information be transmitted accurately, timely to the external world right away. According to wireless sensor network system structure, convergence node is in charge of the sensor network and external network connection; whether the convergence node can work with the function directly affects the entire wireless sensor network ; it may bring about the entire network sensor paralysis if the convergence node loses efficacy regularly. Therefore, realizing a powerful convergence node network application is all-important to the sensor.The wireless sensor network base stand system which is designed in this thesis is just a perfect functional convergence node. It adopts the ARM processor, Windows CE implants OS style, being able to satisfy the great majority of application needs of wireless sensor network, by the fact that it can deliver data by linking Internet with the GSM network. According to the common process of implanting dyadic system development, a comparatively perfect functional sensor network base stand system is designed and realized, and some major jobs have been carried out as following:1. According to the base stand's need for treatment ability, memory ability, and communication ability, a system hardware platform is built;2. According to hardware platform characteristic property, Windows CE process system is planned, board supporting bag step (BSP) is transplanted, and a driver mode for wireless communication module is designed and realized;3. Above custom-built platform, the base stand software function module is developed, which has realized the base stand's communication with wireless sensor network and locality memory of data which is carried out by the linking of Internet and the GSM network.4. Based on the Route algorithm of base stand, do some test to systematic base stand route function.In the following parts, we will introduce design and realization process of WSN system from both the hardware design and the software design.Hardware design aspect:Factors concerned: with the development of wireless sensor technology and gradually growing data amount, it has become a requirement that the base stand needs to have very strong treatment ability, communication ability and data memory ability.Realization ways: The base stand hardware platform chooses S3C2410 of the SAMSUNG Company as central authority processor, and has deployed the main function component as the following around that processor base stand: Memory, Ethernet interface, RS232 string, wireless Modem of GSM, 2.4 wireless GHz communication module, LCD liquid crystal display, SD card interfaces. Among them wireless Modem of GSM and wireless communication module designs are the major parts.Wireless Modem of GSM: Has adopt the FASTRACK M1206 chip that the WaveCom company produces, supports EGSM900/1800MHz and EGSM900/1900 MHz two frequency, applies to the data, fax, short message and implication apply. Since the hardware platform have linked wireless Modem of GSM, the base stand can communicate with the external world by the wireless network of GSM, though there is no wired network.Wireless CC2420 communication module: this module realized the function as wireless communication, which is a most important module to base stand. The radio frequency receiver and dispatching chip CC2420 is the first frequency receiver that the Chipcon company designed to conform to the standard of 2.4 GHz IEEE802.15.4, which needs seldom external component, and its function is stable while the power dissipation is extremely low, thus it may ensure validity and reliability of short distance communication, and realizes the multiple spot fleetness group net to the multiple spot.The software designs aspect:Factors concerned: Since the wireless sensor network adopt wireless communication module to receive and dispatch data, to transmit data by network, while WSN is very easy to be interfered by the external world, the transmission quality and reliability can not be ensured. Aiming to guarantee the transmission quality, especially when should the transmission be in progress under abnormal condition appearing on network, system monitor the network transmission process by increasing monitoring lines; when the network is cut off, data is stored to the locality data base, and so is a queue. When the network is restored to normal status, data will be transmitted again according to memory queue.Realization ways: WinSocket communication module, data memory, short message receive and dispatch module, CDMA short message module and route algorithm are designed. Among them are data memory, base stand route algorithm is the major parts.Data memory module: For ensuring that the data is not to such an extent as to be too big, regular refurbishment to the data is necessary. System adopts the SQLite data base. The reason why we adopt the SQLite data base is very simple. Because SQLite is unlike the other most SQL data base engine, and its first overall design target is simplification, being easy to manage, to use easily, to implant easily other large-scale procedure. Since the base stand does not need complicated data inquiry in system, the most functions concentrate major parts on data memory and management, therefore it's very fit to adopt the SQLite data base; the other comparatively important reason is that data base is open to resources, thus we can transplants WinCE system middle very conveniently.The route agreement accomplishes two missions mainly, one is choosing rightly optimized route, the other is transmitting data correctly along selected route. Due to the concerns of network energy consumption in WSN, we pursue the goal of a minimum delay from one end to the other, a minimum counts of skipping, a maximum utilization ratio of network, as well as the concerns of avoiding problem such as network jam and balance network rate of flow, therefore the wireless sensor network route agreement problem is choosing optimum route. Therefore we adopt the Graph Embedding (be called the GEM route agreement for short hereafter) route as the route upon the base stand system agreement.In short, this system adopts SAMSUNG company's ARM9 S3C2410 chip and CC2420 chip of Chipcon company to design base stand hardware platform, and then plans Windows CE operating system based on this platform, transplants board supporting bag, designs and realizes the driver procedure of wireless CC2420 communication module, develops software functional module of the base stand, including its communication module between WSN and the base stand, this locality data memory module with Internet, the GSM network communication module. By passing the software and hardware testing, the design objective is reached. |
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