Research On WSN Nodes Localization In Indoor Environment

Since the21st century, the rapid development of micro-sensor technology, microelectronic technology, wireless communication technology and computer technology, greatly promoted the progress of the wireless sensor networks which can collect, process and transmit information. Wireless sensor networks can realize the functions of information collection, distributed processing, information integration and data transmitting, monitor the region where is hazardous or inaccessible for human. In the process of monitoring, the location information is indispensable for the collected data, monitoring messages without location information are usually meaningless. Therefore, node localization technology is very important for the wireless sensor networks.In this paper, we studied wireless sensor networks node localization in indoor complex environment, by using RSSI(Received Signal Strength Indication).On the basis of the ZigBee protocol, using chip CC2430which offered by Texas Instruments, designed a low-cost, low-power wireless sensor network node, and tested the performance of the node, achieved network building and data transmission.The experiment analyzed the properties of RSSI in indoor complex environment with the reference node upside down on the ceiling and the blind node fixed in the horizontal plane. Experimental results show that:compared to the reference node fixed in a horizontal plane, placing the reference node upside down on the ceiling has better concentration of the RSSI. It is possible to further improve the concentration of the RSSI by adjusting the transmission power of the sensing node according to the size of the three-dimensional indoor space. It can be judged by the standard deviation whether someone or obstacle is around the node. RSSI-based ranging technology is feasible in the indoor three-dimensional space positioning system.Finally, established a RSSI attenuation model with the measured data for indoor environment and used segmentation algorithm to compensate the range error. The coordinates of the reference node placing in a special position to form a three-dimensional coordinate system, can effectively reduce the computational complexity of positioning. According to the position relationship between the reference node and the blinde node proposed RSSI-ranging scheme based on horizontal distance. The linear relationship between the horizontal distance and RSSI can greatly reduce the calculation amount ranging process.