| Wireless communication is the consequential tendency of future informationtechnology and network technology. WLAN features mobility, low cost and freedomof wire line failure because of no limit of wire line entity. With the gradual emergenceof WLAN advantages and the increasing attention to consumer electronic products,Wi-Fi manufacturers have taken up rigorous competition in the market of HomeWLAN. The household application of WLAN technology will mainly focus onwireless audio-visual transmission of various household amusement products.Session Initiation Protocol (SIP) is a signaling protocol for creating sessions in IPnetwork and is a specification sponsored by Internet Engineering Task Force (IETF).SIP interoperates with a number of other IETF protocols and enables disparatecomputers, phones, televisions and software to communicate.Based on the in-depth study and analysis of the SIP protocol, this paper proposesa practical way to realize the creation of multimedia sessions between SIP UserAgents (UAs). Much effort also focuses on the research of retransmission mechanismof SIP messages in case of network jam. Then a method is brought forward toimplement the retransmission of 200ok response and ACK for it. The resultsgenerated by the program prove that the implementation of the retransmission of200ok response and ACK for it satisfies the retransmission mechanism stipulated bySIP and also validates the correctness of the method and the program. What's more,this paper makes some explorations into the realization of porting SIP protocol andSIP UA application to uClinux system.Implementation of creating multimedia sessions between SIP UAs is based onOpen Source SIP protocol stacks. After comparing and evaluating functions of severalrepresentative open source SIP protocol stacks, we chose an appropriate one which isin accord with the requirements of our task. Then we port the stack and theapplication program to the uClinux system of Motorola M5249C3 platform andrealize a whole process of the session creation and termination between SIP UAs. |
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