Remote Data Transmission And Retrodirective Array Of Wireless Sensor Network

With the development of sensor techniques,wireless communication techniques,nested computation techniques,distributed computation techniques,Wireless Sensor Network(WSN) has emerged in industry,agriculture,transportation,military,security,medical,environmental monitoring and so on,and it is from laboratory research to the practical application of large-scale gradually.In this process,there are many problems,and this paper mainly resolves the practical remote data transmission of the WSN.Combined with development status of WSN and national conditions of China,TCP/IP mode of the GPRS transmission is selected as the main measure.Through analyzing the USART register of ATmega128 and AT command of GPRS module,this article gives the initialization of serial port and the program of data transmission.And the remote transmission from WSN to monitor centre is realized.Nevertheless,since the communication distance between Mobile Base Station and GPRS module is not equation,especially the gain of patch antenna is small,the arrangement of nodes is limited.In order to meet the requirements of large-scale,long distance in field monitoring without increasing the transmission power,the paper researches the design of the Retrodirective Array working in GSM 900 MHz band through the analysis of circuit and simulation.First,the corner-fed dual-polarization element is simulated,and the impact on antenna performance which caused by the thickness and permittivity of dielectric is analyzed.Using the method of slotted patch,the sending and receiving port can work in the uplink and downlink band respectively and this scheme provides an effective method to solve the problem of bandwidth deficiency.Then,a phase-conjugation circuit is designed.As is shown in the results of the analysis and simulation of parallel coupled microstrip line band-pass filter and power-divider,the design can successfully achieves the predicted indexes.Furthermore,considering that the electricity consumption of GPRS module is larger and there is no installation in the field environment,the photovoltaic generation system is designed for the convergent node and the GPRS module using solar panel for the sustainability electricity supply.In a word,under the premise of the full use of existing technology and resources,TCP/IP mode of GPRS transmission is selected to realize the long-distance data transmission.It is an important step for WSN from theory to practical application.The Retrodirective Array systems can track the direction of arrival automatically without the priori knowledge and complex digital signal processing algorithms.So it reduces the capability requirement and the burden of convergent nodes.Without increasing the transmission power of GPRS module,not only does it increase the communication distance between convergent node and Mobile Base Station,but also it ensures the reliability and stability of data transmission.Moreover,it reduces the probability of information interception by an unknown third party to increase the security of data transmission.