For long, it has been envisioned that IPTV services can be delivered over the IMS core network.
TISPAN has done a good job in trying to standardize an architecture for this purpose. With IMS gaining traction globally, it is a good time to review the architecture for IPTV service delivery.
This post describes the architecture for delivering IPTV services over an IMS network. Traditional IPTV services include the following offerings:
1. Video on Demand – VoD
2. Broadcast Television-BCAST
3. Network Personal Video Recording – nPVR
To successfully provide IPTV services, we need an architecture to deliver these three basic services. On top of these services, we can use IMS service enablers to enrich the user experience such as Presence and Instant Messaging (IM).
Moreover, with IPTV over the IMS core we have an opportunity for providing video-interactive services for the first time.
As expected, any application server providing IPTV services will reside on the IMS services layer. This means that this application server will need to support the ISC reference point. (IMS Services Control).
As per the TISPAN architecture, we have the following major servers:
1. Service Discovery Function (SDF).
2. Service Selection Function (SSF).
3. Service Control Function (SCF).
4. Media Control Function (MCF).
5. Media Delivery Function (MDF).
6. User Profile Server Function (UPSF).
7. XML Document Management Server (XDMS).
In addition to these TISPAN entities we also have the following network entities which are required for an end to end deployment:
1. Streaming Servers for TV channels.
2. Head Ends for VoD.
3. AD Injection Servers
4. Content Management System (CMS).
5. Operation Support Subsystem (OSS)
6. Business Support Subsystem (BSS).
B. TISPAN Network Elements:
The network architecture for IPTV service delivery looks like the one shown below:
The Service Discovery Function provides attachment information to the UE and also the addresses of the Service Selection Functions. The SDF functions in two modes:
1. Push Mode, wherein the SDF receives the 3rd party REGISTER request from the S-CSCF and sends a MESSAGE request with the XML payload containing the attachment information.
2. Pull Mode, wherein the UE subscribes to the “ua-profile” event package and the service attachment information is sent in the XML payload of the NOTIFY request.
Based on the attachment information received from the SDF, the UE contacts the Service Selection Function (SSF). The SSF provides the UE with a list of services available. This can be done by providing the UE with the electronic program guide (EPG).
The Service Control Function is divided into three logical sub-functions – one for Broadcast television, another for content on demand and the third for personal video recording.
The SCF is responsible for IMS session control and acts as a SIP-AS. The SCF also generates charging information on DIAMETER protocol for charging these sessions. The SCF refers to the IPTV UE profile stored in the UPSF or in the XDMS for delivering video services.
The Media Control and Delivery functions act as a split architecture similar to the IMS MRFC-P. The MCF is the control plane entity while the MDF is the data plane entity responsible for streaming video. However, in practical deployments, there are dedicated streaming servers available and Head-ends for delivering IPTV content.
In addition to content, there are dedicated servers to inject advertisements in the video streams.
The UPSF is the Tispan counterpart of the HSS. It stores use profile data. The SCF and the SSF can both store the IPTV user profile in the UPSF over the Sh interface.
However, apart from the UPSF there is another storage alternative in the form of XDMS. The XDM operates over the XCAP/HTTP protocol. The XDMS needs to support the “org.etsi.ngn.iptv” application usage for this purpose.
The choice of user profile between the HSS and the XDMS is implementation dependent.
C. The Role of OSS and BSS:
Traditional IPTV middleware solutions consisted of an OSS/BSS along with the functionality defined above. After standardization directions in the OSS/BSS space, and with the advent of the NGOSS architecture, there is a technology neutral approach in the OSS/BSS space. Irrespective of the line of business – IPTV, voice or video, the OSS/BSS remains common.
Hence, legacy IPTV middleware has been broken into two components:
— The realtime components have been standardized by Tispan as described in the previous section.
— The non-realtime components such as OSS/BSS have merged with the NGOSS architecture.
OSS is required for inventory management of the STBs, provisioning of users, provisioning of IPTV services and content, service activation/deactivation and service assurance/SLA management. The Content for IPTV is stored in dedicated Content Management Systems (CMS). However, the content is provisioned from the OSS infrastructure.
BSS is required to carry out traditional billing, rating, mediation and charging responsibilities for the service provider. BSS is also used for partner management for 3rd party IPTV content, executing settlements with content partners as well as generating business intelligence reports.
D. Possible IPTV Applications using IMS:
1. Interactive voice/video: With IMS integration, it will be made possible for integrating voice/video capabilities in IMS. For example, Celebrities can be interviewed by the media without actually needing to travel with the crew to their residence. Using IPTV, the TV studio can directly initiate a video communication with the celebrity and take their interview which can then be broadcast to millions of fans.
2. Messaging: Instant Messaging over IMS can be used as another important application for IPTV…especially amongst teenagers. Instant Messaging can also be used as an avenue for televoting in LIVE programs on TV.
3. Nomadic IPTV: As IMS is access independent, the IPTV program guide can be made nomadic. The user can access their favorite TV programs even when they are on the move and when they are roaming.
4. Video Conference: This can be a very useful application for corporates/educational institutions engaged in distance learning and training. Students can join into an educational broadcast channel or a group discussion from their homes using their IPTV set top box.
5. Video/Photo Share with Web 2.0: Users can record and upload videos from their IPTV set top boxes directly to web based applications such as YouTube. Similarly, set top boxes can also be used for uploading photos to popular services such as Flickr.
6. Security Services: Set top boxes with cameras can be used as home surveillance equipment. A series of cameras can be connected to the STB over WiFi that cover the entire house and its compounds. These live video streams can be sent from the Set top box to the user’s mobile handset.
These applications can be made possible only with IMS integration. IMS helps in bringing voice/video and messaging services to IPTV in a standardized and seamless manner.
It will not be wrong to say that “video” is the next killer application and a replacement for voice !
It will be interesting to invite feedback from visitors/regular readers of this blog on their thoughts on the Tispan IPTV over IMS architecture.
Some questions that beg to be answered are:
— What are the hurdles for its widespread adoption?
— How important is the acceptance of 3GPP MBMS in the adoption of IPTV over IMS ?
— Will IPTV over IMS be a success only with LTE Advanced (where multicast is supported) ?
— What about the devices ?
— Will NGOSS act as an enabler for a smooth rollout of IPTV services? (No need for proprietary IPTV middleware).
Your feedback is appreciated and invited.