Improved RSSI-based localization algorithm for park lighting control and child location tracking

Based on the ZigBee wireless network, a park lighting control and child location tracking system is designed in this paper. Considering that there may be a number of children that needs to be tracked concurrently, distributed localization is needed, so an improved RSSI-based algorithm is introduced in this paper. As a goal of our system, the new method, unlike commercial digital-hardware-block based strategy used in CC2431, can be implemented by using ordinary 8-bit MCU. In the new distributed localization strategy, instead of ‘lognormal’, ‘piecewise linear’ path loss model was established, which needs only linear operation when estimating range from RSSI. Besides, min-max method, other than maximum likelihood estimation method, was used to simplify coordinates calculation. Furthermore, ZigBee compatible node modules were developed as the system hardware platform to carry out the experiments, and results demonstrate the new method has close or even better precision compared with basic algorithm, and therefore meets the demand of child location tracking system in the park.