Using an RTSP proxy to implement the IPTV Media Function via a streaming server

Multimedia in IMS, including IPTV, is handled by a separate unit, the Media Function (MF), which is made up of Media Control and Media Delivery Functions (MCF & MDF). According to the different specifications of an IMS based IPTV architecture, the User Equipment (UE) is expected to use the RTSP protocol as a media control protocol to interact with the MCF, and gets delivery of media from the MDF using the RTP protocol. This generally means that the streaming session is initiated from the media controller on behalf of the user but the delivery of media is sent to the UE from the media deliverer (media server). Due to lack of free and open source Media Servers and on the contrary, the availability of free and open source Streaming Servers, the ideal choice for the delivery of media in multimedia services, including IPTV, by the research community are Streaming Servers. Nevertheless, because of denial of service attack and other issues, most streaming servers do not allow different locations for the session setup request and the delivery of media of the streaming session. This makes it difficult to have a separate media control unit for IPTV service in IMS, if one wants to use a streaming server as an MDF unit. For this purpose we propose another component (an RTSP proxy and relay unit) to be part of the IPTV Media Function (MF). The unit will be used to mediate between the MFC and MDF and will properly relay media control (RTSP) commands from the UE and MFC to the MDF and RTP packets from the MDF to the UE. This, we believe, will facilitate the development of an IPTV service using readily available open source streaming servers. In this paper we show how this RTSP proxy and relay unit can be integrated into the Media Function of the IPTV architecture to ease the media delivery process of IMS based IPTV service.