Research And Realization Of Interior Node RSSI-based Location Method

With the rapid development of Internet and intelligent terminal, indoor target localization based on wireless sensor net work has a wide range of application requirements, such as the mobile track positioning on firefighters in shopping mall etc.The node localization technology based on the received signal strength indicator(RSSI) of wireless sensor network because of its l ow cost, low power consumption, low hardware requirements is widely used for the indoor localization. However the complicated indoor environment, such as the node transmission power, long distance communication, sudden interference, environmental factor, c an influence the measurements of the RSSI to affect the positioning. So how to suppress the interference of indoor environmental factors, improve the indoor positioning accuracy of wireless sensor networks has a great significance on the RSSI indoor locat ion.Based on these factors affected by environment in RISS indoor location, and through the experiment, the paper analyzed the influence of various environmental factors on the RSSI characteristics and puts forward the strategy.Through the node point to point communication experiment, to get the RSSI values with the characteristic curve of the distance, to decorate in the node to determine the maximum communication distance between nodes, thus reducing the influence of long distance communication for RSSI measurement;Through the experiment of node transmission power,that can prove the influence of different transmission power in one meter to receive power; By the sudden disturbance experiment of the wave characteristics of RSSI values, RSSI back to be normal soon after to prove the abrupt interference, by using the filter to eliminate the abnormal data, reduce the abrupt interference effects on RSSI; Through the indoor test of environmental factors in different regions of the world, to prove that the dynamic changes of the indoor environment factor, thus using the minimum zone dynamic environment factor to replace the entire indoor fixed environment factor, thus reducing the RSSI measurement errors caused by environmental factors change.After the experimental analysis of various environmental factors and the corresponding solutions, to improve the minimum zone dynamic range model, this paper puts forward the distance model of node location accuracy unchanged under the condition of different transmission power, to eliminate the influence of emission power of RSSI ranging.From the matlab simulation experiment, we know that the improved scheme improved a lot for the RSSI ranging precision under different transmission power. In order to reduce the amount of calculation of the positioning scheme, the optimization RSSI value filtering can improve the average filtering algorithm to achieve the Gaussian filtering in the case of sudden disturbance filtering effect; On the software implementation, in order to reduce the computational complexity of complex formula, such as index formula, the author adopts least square algorithm to carry straight line fitting for complex formula. and analysis the section fitting effect through matlab simulation. Finally, the algorithm is written to the IT company's CC2430 sensor node, which respectively to prove the feasibility of ranging scheme and trilateral localization algorithm in the indoor localization.