A Zigbee-based localization algorithm for indoor environments

To improve the accuracy of CC2431-based Zigbee locating system in the indoor environment, a localization algorithm is proposed. Multipath propagation and Corrected multipath fading coefficient is investigated for the relationship of received signal strength (RSS) and distance. Window Mean Exponentially Weighted Moving Average (WMEWMA) is adopted to smooth the signal propagation exponent (SSPE) and averaged RSSI is used to soften fluctuations. We also incorporate preprocess methods to minimize the effect of multipath propagation, such as arranging reference nodes' position, calibrate RSSI value for location engine in CC2431, lower the output power level and shut down irrelevant wireless nodes. Experimental results show that the precision of the indoor location system is improved and the proposed algorithm is stable. Combining preprocess methods and SSPE successfully reduce the influences of unpredictable multipath propagation when indoor localization system is working.