Constructing Wireless Embedded Web Server Based On T/tcp Protocol

With the development of embedded technology, the combination of embedded system, Web technology and wireless network has become a new development trend in embedded technology. However, at the beginning of designing TCP, it did not make full consideration to the features of wireless network and embedded system, so TCP does not provide satisfactory performance in wireless embedded Webserver application. Firstly, most TCP implementations have made some optimizations based on assumption of wired networks. However, such optimizations do not work out in wireless environment. Ignoring characteristics of wireless transmission will lead to a logically correct TCP implementation but worse in performance. Secondly, due to the inherent features of TCP such as 3-way handshake process and TIME_WAIT state, there are some defects and limitations of TCP application in embedded environment. Further more, most data transmitting between embedded Webserver and client is small data, and with connection featrues of short duration and frequent connecting times. TCP using in such application will cause a waste of system resource. Thus, this paper proposes to port T/TCP in VxWorks to compensate the defects of TCP in wireless embedded Webserver application, and then constructs a wireless embedded Webserver based on T/TCP.This paper will first disscuss the mechanism of T/TCP, analyze the process of bypassing 3-way handshake and truncating TIME_WAIT state, and then illuminate T/TCP's advances in embedded appliaction by comparing T/TCP with UDP and TCP. It will also present the porting process of T/TCP in VxWorks, and design test programs to verify whether T/TCP has been successfully ported.Based on T/TCP having been sucessfully integrated in VxWorks, it will construct a simple Webserver. According to data characteristics of embedded system, we optimize the data tramsmiting operation of Webserver, implemente a data cache mechanism to reduce the number of segments in one transaction, which will also reduce overhead of network and system. Futher more, we will design test programs to analyze the data transmitting performance of our Webserver.The last part of the paper will analyze the network struct of GPRS. A GPRS module will be integrated in system and drivers will be designed to implement function of accessing wireless nework. In order to solve the problem of dynamic Ip assignment in GPRS network, it proposes an IP acquiring system module for GPRS network.