Research Of Low Power Rf Wake-up Technology Suitable For Wireless Sensor Network

Wireless sensor network is a techonology developing rapidly in recent years which use sensors and wireless communication method to obtain and process information. An important feature of it is low power consumption, but in practical applications, the radio frequency chip which support Zig Bee’s protocol can’t wake up from sleeping mode automatically, the RF chip can only be in full working mode or wake-up periodically mode. Although "listening, sleeping" mode consumes less power consumption than full working mode, it is no doubt that in both operating modes, the RF modules are still with high power consumption and unable to meet the needs of practical application.Firstly, This paper introduced the current development of wireless sensor networks and the existing research results on the quesiton of power consumption, then proposed and analyzed circuit analysis model, which based on Cockcroft-Walton voltage doubler rectifier circuit, this model was not only consider the actual conditions in the environment, but also consider the diode parameters, voltage series, load impedance in the condition of high frequency and low power inputing. This paper analyzed and simplified the model in detail.Secondly, we designed and made a semi-passive module with the model, which was suitable for wireless sensor network with low power RF wake-up technology. we debuged and practical tested the module in detal, including impedance match circuit, power amplifier circuit, and multi-point testing on the wake-up distance and power consumption, as well as the optimization of circuit parameters. The results showed that this module had a wake-up distance about 13 meters in the case of consuming 6.2u W energy by tested under the open conditions.Finally, in order to make the RF wake-up module integration of MAC layer protocol, this paper improved wireless token protocol on the existing MAC layer protocol research results. The improved protocol made full use of the RF wake-up mechanism and wireless ring network mechanism, divided the transmission channel into a data channel and a wake-up channel. Experimental results showed that the improved MAC layer protocol was better than S-MAC protocol in the transmission delay and power consumption, this made the power consumption of the wireless sensor network further reducing.