The Design And Implementation Of WLAN And VoIP In The Embedded Mobile Terminal

As technology advances, mobile communication terminals have come a long way. Not only is the size, appearance, and more importantly mobile terminal has evolved from a single communication tools, developed into a communications, multimedia, entertainment and other all-in-one. In addition, NGN is getting closer, it was necessary to change the mobile terminal single access methods (GSM, CDMA, and other cellular mobile communication network access).Based on these considerations, this article proposes a way to increase mobile terminal access and greater play communication terminal hardware capability; enables mobile communication terminal became more comprehensive, portable communications, entertainment, Office tool design. To achieve this goal, this article has chosen the subject IEEE802.11 series Protocol WLAN access as a computer network. Its main causes:1) to comply with the agreement of WLAN IEEE802.11 has widespread application, easy to implement interoperability; 2) to the other WLAN access mode can support terminal mobility characteristics. And then this article use WLAN as access way design an application - VoIP. In an in-depth study on the fundamentals of VoIP, related technologies and protocols, on the h.323 and SIP protocols do analysis and comparison. SIP call process is relatively simple and flexible, system scalability. Eventually I selected SIP as the control protocol, in the original design on the GSM mobile terminal and the realization of VoIP applications. Next, I examined the software architecture of embedded mobile communications terminal. That the software of embedded mobile terminal was divided into three layers:Driver layer, Protocol, service layer and Application layer. In order to conform to this schema design, the software architecture of WLAN and VoIP (Terminal) was also designed as a three-layer structure. Which driver layer includes WLAN chip driver and speech processing related hardware drivers, and then put the WLAN management, protocol stacks, call management and VoIP related protocol in the Protocol, the service layer. Finally in NXP7208 mobile terminal solution, choose to integrate a high level of Sychip7101 chip (integrated WLAN chip and voice codec, and other functions) as hardware environment, on WLAN and VoIP Terminal software to do the specific design and implementation.After the test, embedded mobile terminal can access Internet via WLAN stably, VoIP functionality already implements the parties call, voice quality is good, and there has no significant delay.