Design And Implementation Of PC Client In The PoC System

PoC (Push-to-talk over Cellular) is one kind of IMS (IP Multimedia Subsystem) service, which supports both 1-1 communication and group communication based on half-duplex VoIP.PoC service has been widely considered as a popular mobile service when 3G comes. The development of PoC service needs cooperation of the PoC Client and the PoC server. PoC Client is a very important part of PoC system.With other independent enablers, like XML Document Management (XDM) and Presence, PoC becomes a service system.As the access entity of PoC, PC Client has capabilities including getting contacts list, group list, PoC access policy, watching buddies' presence, initialing a PoC Session, ect.. OMA has defined specifications for PoC, XDM and presence, while IETF (Internet Engineering Task Force) published protocols like XCAP (XML Configuration Access Protocol) and SIP (Session Initiation Protocol) adopted as signaling protocols between servers and clients in PoC System.This thesis focuses on the design and implementation of PC Client in PoC system. On the basis of deeply understanding of related standards published by OMA and IETF, we analyse the service requirements and provide a practicable solution of PC Client in PoC system.The thesis comprises five parts.In the first chapter, we firstly introduce the concepts of PoC; then propose a brief presentation of the researches on stardards and specifications of enablers in PoC system. The objective of our research is described at the end of this chapter. That is to research the related specifications of PoC, XDM, Presence and PTO, etc., and designs and implements the PoC PC Client, and analysises the technical difficulties.In chapter two, we analyse and classify the functions of PC Client in PoC system and demonstrate several key requirements. The detailed procedure is also provided. This chapter talks about the PoC functions including the control plane and the user plane, the XDM functions including the friendlist, the group usage list, the group list, and the access policy, the Presence functions of the presentity and the watcher, and the PTO functions including the ordering, presenting, and subscribing the PTO channel. And detailed the mechanism of the control of the talk burst.In the third chapter, the architecture of PoC PC Client is suggested, which consists of network access layer, middle layer, and services layer. Services layer can be divided into several functional modules. We also analyze each module in the architecture and propose the details of design and implementation.Chapter four specifies several key issues in PC Client designing, including mechanism of subscription and presentation for PTO(Push To Order) envolved from PoC, modeling on how to parse the list contents in the format of XML, problems of GUI and presence..The fifth chapter includes the test results of the client in PoC system.The sixth chapter includes the conclusions of the study and our future work.