Research On Group Call And Equipment Control Of VoIP Voice Communication Terminal Based On WLAN

With the rapid development of computer network technology and the arrival era of big data, public pay more attention to promptly and localized information exchange. And the Internet as the carrier of multimedia voice communication service is becoming a research hotspot. VoWLAN (Voice over WLAN) is a new development direction which combines VoIP (Voice over IP) and WLAN (wireless local area network). It contains wireless communication technology, computer network technology, embedded systematic development and other fields of advanced science. VoIP transmits voice signals through the network, WLAN enables terminal equipment to access the Internet through wireless access points.The combination of the two technologies could be used to achieve wireless VoIP communication capabilities, which not only enhance the utilization of network resources but also reduce the cost of communication.The main goal is to design a VoIP voice communication terminal equipment which based on WLAN.It uses the existing WLAN network to achieve VoIP voice wireless communication, which means users could use VoIP voice terminal equipment in the coverage of WLAN network at any time to carry out voice service such as registration, call, hang up, answering and other basic operations.Also, it may be used in industrial application possibility, so I developed special features including group calling and equipment control. Then, give research on MAC layer random access mechanism for this VoIP equipment through the NS2 simulation experiment in order to assure voice service quality with WLAN data, voiceand video business. Finally, verify the effectiveness and reliability of VoIP terminal basic function, group call and device control function through simulation and real test.Firstly, this paper introduces the researchbackgroundand research objective, describes the basic situation of VoIP and WLAN, and compares the difference between H.323 and SIP, and then states the SIP protocol systematically. Secondly, the paper shows the overall design of VoIP voice terminal including system design goals and principles, environment of the software and hardware platform. The hardware design of VoIP voice terminal includes core processor module, memory module, power, audio, JTAG and other peripheral modules. The software design includes function module of SIP protocol stack oSIP such as the parser module, the state machine module and the tool module, the core module of VoIP voice terminal, voice processing module, data transmission module, group call module, device control module, user interface module, code analysis and implementation method of application program. Thirdly, establish MAC layer access mechanism DCF EDCF and accomplish the simulation of QoS performance, which provides itself a good performance with increasing network capacity under EDCF mechanism. At last, build a basic test environment and test core function effectiveness and stability of VoIP voice communication terminal such as register, call, hang up, answer, group call, and equipment control.