Interactive service

Description

An interactive service, as defined in 3GPP TS 21.905 and referenced in TS 22.060 and TS 26.953, is a multimedia service delivered via MBMS (Multimedia Broadcast/Multicast Service) or PSS (Packet-switched Streaming Service) that is characterized by the ability of users to interact with the content or program. This interaction can take one or both of two forms: first, the user can change the presented content — for example, by accessing auxiliary information, changing the camera angle, overlaying supplementary media content on the main program, or displaying concurrent text with the main video. Second, the user can return end-user-supplied information or initiate an action back to the service provider or content provider through a unicast channel — for example, to vote for a particular choice, order a product, or participate in an on-screen quiz.

Architecturally, interactive services build on the MBMS and PSS frameworks. MBMS provides a point-to-multipoint bearer service for efficient delivery of popular content to many users simultaneously, using either broadcast or multicast modes. PSS provides on-demand streaming over unicast bearers. An interactive service combines these delivery mechanisms with a return channel — typically a unicast connection such as HTTP, RTSP, or a dedicated interactive protocol — that allows the user to send feedback or requests to the service provider. The service layer may include an application server that manages the interactive session, synchronizes the broadcast/multicast stream with the unicast return channel, and processes user input.

The interaction model can be synchronous or asynchronous. In synchronous interaction, the user's action affects the content in real time — for example, changing the camera angle during a live sports broadcast, or voting in a live poll where results are displayed immediately. This requires low-latency communication between the client and the server, and tight synchronization between the broadcast stream and the unicast return path. In asynchronous interaction, the user's action may be processed with some delay — for example, ordering a product or submitting a quiz answer that is evaluated later. The service may also support time-shifted interaction, where users interact with recorded content.

Key technical challenges for interactive services include synchronization between the broadcast/multicast content and the unicast interaction channel, scalability (handling many simultaneous users interacting with the same content), security (authenticating users and protecting their input), and QoS management (ensuring that the return channel has sufficient bandwidth and low enough latency to support the interaction). 3GPP specifications address these through mechanisms such as MBMS bearer management, PSS session control, and QoS differentiation for interactive traffic.

Interactive services are important for enabling new business models and user experiences in mobile networks. They transform passive broadcast and streaming into participatory experiences, supporting applications such as live sports with multiple camera angles, interactive advertising, audience voting, e-learning, and multiplayer gaming. As networks evolve toward 5G and beyond, interactive services are expected to benefit from lower latency, higher bandwidth, and edge computing, enabling even richer and more responsive interactions.

Purpose & Motivation

Interactive services exist to bridge the gap between passive content consumption and active user participation. Traditional broadcast and streaming services deliver content one-way, offering no opportunity for the user to influence or respond to what they are watching. Interactive services solve this by adding a return channel and interaction logic, enabling users to change the content they see and send information back to the provider.

The motivation for interactive services grew with the convergence of broadcast and broadband networks. Early mobile broadcast services like MBMS (introduced in Rel-6) were designed primarily for efficient one-to-many delivery, but operators and content providers soon recognized the value of combining broadcast efficiency with unicast interactivity. This led to services such as interactive TV, live voting, and on-demand content selection. The definition in 3GPP evolved accordingly: initially, in Rel-4 through Rel-12, the term was defined broadly as a service providing bi-directional exchange of information between users, based on ITU-T I.113. In Rel-13, the definition was revised to specifically address MBMS and PSS interactive services, reflecting the growing importance of these delivery technologies.

Interactive services address several limitations of previous approaches. They allow content providers to monetize engagement through transactions and voting, enable personalized experiences, and provide valuable feedback data. For users, they offer greater control and participation. For operators, they create new revenue opportunities and differentiate services from over-the-top competitors. As mobile networks continue to evolve, interactive services remain a key area of innovation, leveraging lower latency and higher capacity to deliver increasingly immersive experiences.