In RFID system, when multiple tags transmit information in the same wireless channel simultaneously, data collisions usually occur which will reduce the identifying efficiency of RFID systems. To resolve this problem, several Dynamic Frame-Slotted ALOHA (DFSA) methods have been proposed. However, these methods are generally not capable of achieving expected performance when the number of tags is much larger or smaller than the initial frame size. Aiming to this problem, a Rapid DFSAI (RDFSAI) method was put forward based on the DFSA with interrupt (DFSAI) in this paper. Firstly, whether the frame size is adjusted or not is judged by comparing the system efficiency with the reference system efficiency. Secondly, the multiple factor of the frame size is determined by the ratio between the collision and empty slots, which leads to a seriels of different multiple factors or. As a result, the proposed RDFSAI elevates the adjustment speed of frame size and reduces the unnecessary empty and collision slots effectively. Simulation results indicate that the RDFSAI method appears better performance than the conventional methods even the tag number is increased up to 1600.

An elderly people monitoring system based on 3-axis digital accelerometer ADXL345 and digital signal controller TMS320F28335 was designed based on 3-axis digital accelerometer ADXL345 and digital signal controller TMS320F28335. The human posture was collected from ADXL345 by the DSC28335. The FFT filtering algorithm was used to improve the detection accuracy. Then the exercise situation of the elderly people was calculated by using Pedometer algorithm. The fall information was calculated by analyzing the rate of acceleration change. The Beidou Satellite Navigation System was designed for collecting position data to protect the elderly people in different situation.