| 摘要 |
<p>3GPP IMS platform is upgraded by the introduction of a new network element NE appositely dedicated to implement Push to Watch (PTW) service via IP. It includes a Session Manager (PTW SM) interfaced to a multimedia control and duplication function (MCDF) via an internal interface Mint. Considering the interfacing of the NE to the external environment, PTW SM is interfaced to the IMS's CSCF function via Mr interface, while MCDF is interfaced to the UMTS's GGSN node through the Gi interface. In operation, PTW SM converts the incoming SIP signalling messages into corresponding session-related commands of an internal protocol conveyed by TCP on an internal interface Mint. The MCDF, besides executing commands coming from PTW SM, autonomously interacts with the participants of the PTW session by means of a floor control procedure at User Plane for scheduling the transmissions from a granted user at a time of Audio-Video contents, which are immediately duplicated to other participants. The new NE is managed by a modular software architecture including a master process (MCDFm) and as many parallel slave processes (MCDFs) as the number of running sessions. Each slave being in its turn split into three subcomponent processes: a first one dedicated to execute the master commands aimed to: create, update, or delete sessions; a second one dedicated to manage the RTCP floor control signalling, and a third one dedicated to the duplication of RTP data of the multimedia payload. Both RTP and RTCP are conveyed by UDP (fig.14).</p> |
