Research And Design Of Remote Data Transmission System Based On GPRS

This thesis discribles a remote data transmission system under the demand of automatic control on electrical power system and remote Meter Reading, integrating the need of the other domain, relying on the GPRS network of mobile corporation and Internet network. The research and design of the thesis to the character of remote data transmission are as follows:First, the total design of hardware and software has been realized. Some common connect schemes of GPRS have been comparing with by GPRS's character.According to the requirements of most business, a connect scheme of network host computer is picked up. As the world's IP address is costful and general corporations visit internet by the proxy server in their local network, IP address mapping can be realized by NAT technology in using this scheme.By mapping the outer network's port numbers of router which is offered by ISP corporation into the inner network's IP address of center data server, Data transmission between the GPRS data transmission unit and the center data server can be completed.Second,the GPRS data transmission unit has been designed,including hardware design and software design.Some advanced technology such as MC39i which is a Simens'GPRS transmission module,S3C44B0X which is an embedded chip,μClinux which is an embedded operating system,etc.AsμClinux is stable,its network's functions is strong and TCP/IP protocol has been installed inside,software developing can be used by PPP package directly.Finally,aiming at the characteristics of the current GPRS traffic,a control strategy has been analysed and proposed.Third,the local network based on ARM and embedded Linux has been designed.Althrough GPRS charges by follow rather than by time, If a certain period of time without data transmission, the link will be interrupted by mobile corporation. In order to maintain the smooth flow of links, in the design of GPRS data transmission unit, it is necessary to design a "heartbeat packet". If no data is transfered in a specified time, the "heartbeat packet" will be issued. But this way will increase the user's cost. In order to reduce the "heartbeat packet" issue, the paper design of the embedded LAN which first unifies the distribution point's data, then sends.Fourth, Because of the data transmission in the Internet, security risks exist. It is necessary to encrypt the transmission data. In this paper, AES encryption algorithm for data transmission has been used.