IPTV Service Control

The FOKUS IPTV Session Management Solution

The FOKUS IPTV Service Control (SC) is an implementation of the TISPAN IPTV Service Control Function (ETSI TS 182 027), OIPF Authentication and Session Management (ASM), and the IPTV Control Entity (OIPF Functional Architecture V1.2). The IPTV SC is responsible for service accessibility and managing incoming user requests for Live TV and Content on Demand (CoD), forwarding requests to the appropriate IPTV application server and the media servers represented by FOKUS IPTV MCD. The IPTV SC’s session repository interfaces third-party application servers, while ongoing IPTV session information is used for targeted advertisement, charging and billing, user tracking or interactive services. The IPTV SC is implemented as a converged SIP/HTTP Servlet (JSR289) and has already deployed on Oracle OCCAS, Sun’s Sailfin and the FOKUS SIPSEE. Future releases of the IPTV SC will support both managed telco networks using the SIP/IMS signaling as well as unmanaged HTTP networks and Web services.

Key Functionalities:

• User Tracking & Monitoring
• Third-party Interface throughout Session Repository
• IPTV Session Management
• Charging & Billing

The need for Session Management

Within a Triple Play or Quadruple Play environment, consumers demand certain content which is delivered then by a dedicated infrastructure. Thus, a user-to-content relationship – a Media Session – describes this temporary provisioning. Such a Media Session is always involved if certain interactions (from user’s side, from content provider’s side as well as from delivery system’s side) with the infrastructure occurs. This interaction can be switching between different content, reacting on incoming or outgoing calls, processing trick functions, notification of a subscribed content, etc. Hence, a dedicated entity needs to be introduced to the converged media architecture to keep track of the activities of Media Sessions.
According to ongoing standardization work in ETSI TISPAN and the Open IPTV Forum, FOKUS has implemented the Service Control Function (IPTV SC) for a convenient management and control of media sessions on top of the managed IPTV infrastructures.

In general the Service Control Function is a stateful entity which manages all user-to-content and content-to-user relationships. It is aware which user consumes which content and which content is consumed by which user. Furthermore the SCF manages the transmission of multimedia streaming sessions (live and on-demand) triggered through different IP-based access networks (LAN, WLAN, DVB-H, x-DSL) via different transmission schemes like unicast, multicast and broadcast.

Design and Interfaces

The SCF is the key entity of the Session Management in converged media environments. Regarding the design issues of an IP Multimedia Subsystem powered infrastructure, the SCF is logical integrated as a SIP servlet running on the Application Server (SIPSEE). On the other hand a Session Control Function is a single component, triggered via SIP servlet. This means the entire design is constructed a way, that once, the entire component can be built upon s single SIP stack and deployed as a single component. The AS provides the SIP functionality for the SCF processes all IPTV-related messages, signaling and relays them to the SCF component via the SIP servlet.
The SCF provides two interfaces for service access:

• One interface to the application layer (the application interface) and
• one interface to the servlet (control interface) - respectively to a single SIP stack –

which triggers the SCF component. As a result the SCF provides a single simplified interface to the more general facilities of the complex subsystem and is potent enough to realize powerful applications.
The figure below illustrates a simplified architecture of the SCF consisting of five core elements:

1. Session Management Function
   Proverbial the brain of the SCF. It is the first contact point within the SCF. Creates, controls and deletes media sessions. It furthermore handles the communication with the SIP servlet.
2. Bearer Manager
   Optimization of all active media sessions regarding the transmission scheme and the access network. The Bearer Manager is deeply involved in the monitoring.
3. TV Session Controller
   Drives controlling of all active media / TV sessions.
4. Session Repository
   This entity stores all active sessions. It furthermore provides all statistical information about active sessions.
5. Thread Repository
   Stores all active content threads. Due to the existence of a single content thread per Content Reference Identifier (CRID), simultaneously request processing for different CRIDs is possible.

Features of SCF

As already announced in sections above, the SCF processes robust IPTV and Converged Media Session Handling with all the mentioned fancy features. It provides managing and forwarding of incoming user request. This implies various kinds of multimedia content like linear TV, on-demand media with trick functions, live TV as well as user generated content in terms of requests for pushing the media to the infrastructure.
The SCF provides an IPTV / Media subscription handling for the delivery of premium content and charging purposes.
Based on the bearer and access technology information given by the requesting IMS enabled IPTV and Media Clients, the SCF is able to optimize network infrastructures, acquire and keep bandwidth for high quality streaming in terms of re-organization and re-invitations of media sessions and used transmission schemes. As an example, the SCF is able to call on all connected clients to change their transmission from unicast to multicast if the group of recipients has reached a sensible threshold from the network point of view.