The Research On GPRS Data Terminal For Large Amounts Of Data Transmission

With the rapid development of mobile communication technology, the access to Internet services through GPRS has become an important manner to achieve long-distance wireless data communication. In the dissertation which is sponsored by the actual project, according to the specific requirements of the project, a GPRS data terminal has been designed for large amounts of data transmission. The software and hardware design process of GPRS data terminal is introduced, as well as the performance test is implemented.Since the GPRS data terminal is designed based on external protocol stack, more RAM and FLASH resources are needed. In order to reduce the complexity of the hardware design, The 32-bit ARM processor LPC2106 with rich on-chip resources is selected as the system's microprocessor. With the integration of the GPRS radio module MC55, external FLASH memory K9F1G08U0B and efficient power management module, the hardware design of the GPRS data terminal has been completed.The system software is designed on the basis of the embedded real time operating systemμC/OS-Ⅱand embedded TCP/IP protocol stack LwIP. In terms of the actual application requirements, the operating system task partition and design are implemented firstly, then the implementation process of PPP protocol and that of LwIP protocol are described in detail. Next, the UART drivers and storage system are developed. Finally, based on the specific features of GPRS wireless network, the TCP protocol is optimized.The performance of GPRS data terminal is tested in the end of the dissertation. After comparision experiment platform is built, the transmission performance of GPRS data terminal grounded on embedded protocol stack and that grounded on external protocol stack are tested separately. By analyzing the experimental results, it proves that the GPRS data terminal designed by the dissertation has achieved better transmission performance and has met the design target. The TCP protocol founded on NewReno and limited delivery mechanisms is also tested, and it shows that the optimized TCP protocol helps to improve data transmission performance of the GPRS data terminal. Especially in the bad GPRS network environment, the effect will be better.