Running Status Table

Description

The Running Status Table (RST) is a specific component within the 3GPP Multimedia Broadcast Multicast Service (MBMS) architecture, standardized primarily in TS 26.347 for the File Delivery over Unidirectional Transport (FLUTE) protocol. FLUTE is used for reliable file delivery over broadcast/multicast networks. The RST is an in-band signaling table that is periodically transmitted within the FLUTE session alongside the actual file data. Its primary function is to convey the real-time transmission status of files within the session to all receiving clients. The table contains entries for each file being delivered, including crucial metadata such as the file's Transport Object Identifier (TOI), its current delivery status (e.g., 'active', 'completed', 'cancelled'), and relevant timing information. Architecturally, the RST is generated and managed by the Broadcast Multicast Service Center (BM-SC), which is the core network entity responsible for MBMS service provisioning and delivery. The BM-SC encapsulates the RST into FLUTE packets and schedules its transmission within the broadcast carousel. On the receiver side (the UE), the MBMS client parses the incoming FLUTE data, extracts the RST, and uses it to manage the file reception process. The RST enables the receiver to determine which files are currently being transmitted, which have finished, and whether any scheduled files have been removed. This allows the client to make intelligent decisions, such as ignoring completed files, starting reception for newly announced files, or releasing resources for cancelled files. It is a key mechanism for achieving efficient and reliable file delivery in a unidirectional environment where explicit feedback from receivers to the sender is not possible or scalable.

Purpose & Motivation

The RST was created to solve the problem of dynamic session management in unidirectional broadcast/multicast file delivery systems, specifically within 3GPP's MBMS framework. In traditional unicast file download, a two-way handshake and control protocol (like TCP) manages session status. However, in broadcast, where a single transmitter serves potentially millions of passive receivers, such feedback is impossible. Prior approaches might have relied solely on static session description (e.g., the File Delivery Table - FDT), which only describes the initial plan, not the live progress. The RST addresses the limitation of static descriptions by providing a real-time, in-band 'heartbeat' of the delivery session. It informs receivers about changes that occur after the session begins, such as files being added, removed, or their transmission completing. This is critical for services like software updates over-the-air (FOTA), where the content lineup might change dynamically, or for efficient carousel-based delivery of repetitive content. The RST ensures all receivers have a synchronized and accurate view of the transmission state, enabling efficient use of receiver battery and processing resources, and preventing clients from waiting indefinitely for files that are no longer scheduled.

Key Features

• In-band signaling transmitted periodically within the FLUTE session data stream
• Provides real-time status (active, completed, cancelled) for each file being delivered
• Identifies files using the FLUTE Transport Object Identifier (TOI)
• Generated and managed by the Broadcast Multicast Service Center (BM-SC)
• Enables efficient receiver resource management in unidirectional broadcast scenarios
• Essential for dynamic MBMS session management where the file lineup can change

Evolution Across Releases

Defining Specifications