The Research Of Zigbee Wireless Transmission Network In Wearable Devices

With the coming of the aging society, the demand is increasing on convenient, economical and real-time monitoring equipment for the old and chronic patients. Under the situation, In this paper, the reliability of the ZigBee network has been studied, which is the wireless transmission network part of the wearable devices monitoring system.Firstly, based on the standard of IEEE 802.15.4 standard, ZigBee data transmission system is simulated, appling the m functions and Simulink of the MATLAB. The DSSS spread spectrum, OQPSK modulation and baseband shaping filters of ZigBee system has been analyzed and researched.Secondly, according to the application environment characters of the wearable devices monitoring system, the paper has analyzed and studied the mainly interferences effect on ZigBee system by simulation. In hospital environment,there are two main interferences, thermal noise interference and co-channel interference (CCI). According to the different sources, CCI can divided into the ZigBee signal interference coming from the other ZigBee network and other wireless communication signal interference using 2.4 GHz communication band. Then, the paper proposes the optimization methods of enhancing anti-jamming ability. For thermal noise interference, it suggests to select raised shaping filter to replace the original shaper to improve system anti-jamming ability for it has little pass band. The result shows that, under the same BER conditions, the SNR of improved system has reduced 3dB than the original system, and the system anti-jamming ability has been improved. For the main interference is CCI in the system, it suggests to adding LMS adaptive filter in system receiver to improve system anti-jamming ability. The results show that, under the influence of the same interference amplitude, the BER of improved system has smaller BER than the original system, and the system anti-jamming ability has been improved.