The Design And Implementtaion Of The VoIP Gateway Integrated In The Wonu

Recently, fiber to the home (FTTH) based on the Ethernet passive optical network (EPON) technology has been widely used. The object of the dissertation is to design and realize the VoIP voice gateway which integrated in the wireless optical network unit (WONU).This study includes the function design of VoIP voice gateway and the implementation of hardware and software. Main works of this dissertation are summarized as follows:Firstly, the EPON technology was concluded, including the network structure, the important parameters and the advantages of the EPON access network. Moreover the working principle, key technology and development prospects of the VoIP technology were introduced. On the basis of former works, the feasibility and advantage of the VoIP voice gateway applied to the wireless ONU was demonstrated.Secondly, the dissertation was proposed the design scheme of VoIP voice gateway integrated in the WONU and then the printed circuit board (PCB) of the hardware system was performed. The main functions of the system were implemented by the embedded processor chip, digital signal processor (DSP) chip and subscriber line interface circuit (SLIC) chip. The S3C2440 was selected as the embedded processor chip. The AC48802C-C was selected as the DSP chip. And the Le88221 was selected as the SLIC chip. Overall the S3C2440 acted as the core of the whole system, which is in charge of the loading and running of the embedded Linux system, and the functions of management. AC48802C-C was mainly responsible for the compressed encoding of the voice signal and the signaling processing. And the AC48802C-C was used to connect to the S3C2440 by means of the HPI interface.Thirdly, the transplantation of embedded Linux system and the design of the AC48802C-C drivers were implemented. The drivers for AC48802C-C were composed of hardware level drivers, low level drivers and high level drivers. Besides the VoIP call process on the PC platform was performed. The SIP protocols were analyzed by the network protocol analyzer.