Design And Implementation Of Wireless Sensor Network Based On Contiki OS

In recent years, along with the advances of sensor technology, wireless communication technology and embedded technology, the development of wireless sensor network(WSN) also has been greatly promoted. At present, WSNs is widely used in smart home, agriculture, medical, industrial control, military and other fields, which have very broad application prospects.Firstly, this paper introduces the current domestic and international situation of wireless sensor networks,expounding the development of bottlenecks. Then, on the basis of the existing issues in WSN such as many nodes, high cost, low safety and poor system compatibility, according to the actual needs of application scenarios in agricultural greenhouses, this paper builds uIP protocol stack based on Contiki operating system, and implements networking through the RPL routing protocol in reference to IPv6,6LoWPAN, CCM-AES encryption and other related protocol standard.The main contents of this study are as follows:1.Elaborating the key technology about IEEE802.15.4, IPv6,6LoWPAN, CCM-AES encryption and RPL routing protocol standards.2.Deeply studying of the Contiki embedded operating system--ContikiOS-2.7, emphatically analyzing the process management, event and timer of Contiki kernel, network communication protocol stack of Contiki uIP and packetbuf buffer management in details.3.Designing nodes and gateway hardware circuit based on CC2530, and porting Contiki OS to the hardware. Then, building the uIP protocol stack based on Contiki operating system,and achieves the underlying driver. Designing unified instructions format for transmission data, completing the UDP communication between sensor nodes, finally realizing the acquisition and forwarding of sensor data.4.In order to improve the safety of data in the network transmission, this paper designs a new application protocol of data security transmission based on the Contiki operating system and CCM-AES encryption algorithm, to ensure the confidentiality, integrity, and authentication function in the process of WSN data transmission, preventing eavesdropping, tampering, forging, etc..5. Building the client program based on Android OS, through communicating with gateway, implements monitoring including the environmental temperature, humidity, light intensity and CO2 concentration.In addition, in order to better management of wireless sensor network node, adding the display of network topology, so as to know the network topology of WSN.6.Structuring the actual test environment to test the communication distance between nodes, RSSI values and packet loss rate, and through the Android mobile phone displaying the all kinds of sensors data. The test results show that the design of wireless sensor network has great practicability, and have reached the expected requirement.