The Research On Key Technology Of High Enery-efficient Communication In Wireless Sensor Network

Wireless Sensor Networks is a self-organized network composed by large amount of tiny sensor nodes in the monitor area.WSN is widely applied in monitoring, tracking, medical treatment and controlling.The sensor nodes are usually battery-powered, for which the energy consumption must be minimized in order to make their working time longer. So that, as to the Wireless Sensor Network technology, high energy efficiency is one of the most significant key problems. In the communication system composed by the nodes of WSN, the energy cost of RF frontend is much higher than that of digital baseband part.Therefore, the energy cost of RF frontend must be reduced as much as possible. Meanwhile, as to the electronic circuit and hardware device in WSN, RF Power Amplifier'energy cost has taken a large proportion in the whole communication system, and the nonlinear effect of the RF PA could bring negative effect to the communication quality, so enhancing the linear characteristic and improving the energy efficiency of PA by Digital Pre-Distortion is absolutely necessary.The thesis has reseached the high energy efficiency communication technology of WSN, and the abstract of our work is below:(1) In this paper, we finished our work on RF frontend energy model and minimize the energy consumption in RF circuit by adjusting the base-band parameters, such as modulation level, data rate and signal peak-to-average ratio (PAR) etc. In the mean while, we consider the impacts of circuit thermal noise,1/f noise, the third-order harmonic distortion and the channel flat fading, on the communication quality. Thus, the most energy efficient system parameters under certain bit error rate (BER) are determined. We propose four kinds of RF front-end architectures; energy model of each architecture and the corresponding modulation scheme are analyzed in detail; the design method for low power RF front-end architecture is given for different transmission distances and data rates with the consideration of both the energy consumption of transmission and energy consumption of circuit.(2)Based on the RF frontend energy model in wireless communication systems, this thesis has reseached the adaptive modulation and power control method from the angel of the highest enery efficiency. And has presented an adptive modulation and power control algorithm of Quadrature Amplitude Modulation.(3) The thesis has reseached the digital pre-distortion system with QAM input signal. The equation solution secant method in mathematics is ultilized in adaptive pre-distortion signal processing. And the result of the simulation has proved this method useful. The thesis has also proposed a new method based on the new adptive algorithm, which is based on the discrete Newton method in mathematics. Its core considers is to transform a one dimension equation to two dimension equations, which are composed by one equation of amplify and one equation of phase. And through the adaptive iterations, it has better effect of linear characteristic and faster computing rate by ultilizing Discrete Newton method.