Session Continuity Server Media Flow Synchronization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In IP multimedia subsystems, synchronizing media flows between wireless transmit/receive units (WTRUs) during collaborative sessions is challenging due to variations in time synchronization, leading to potential playback discrepancies and buffering issues.
Innovation Solution
A method and apparatus that utilize session continuity control application servers to exchange messages containing session description protocol (SDP) attributes with time synchronization information, such as presentation time offset (PTO) and synchronization tolerance, to ensure synchronized media flows across WTRUs, allowing for real-time updates and adjustments to maintain synchronized playback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If media flows are transmitted between multiple WTRUs during collaborative sessions, then multimedia service delivery is enabled, but time synchronization variations cause playback discrepancies and buffering issues
Solution Approach 1:
The patent introduces a session continuity control application server as an intermediary that coordinates time synchronization across multiple WTRUs. The server collects timing information from each WTRU, calculates appropriate presentation time offsets, and distributes synchronized timing parameters back to all participants, thereby mediating the synchronization problem in collaborative media sessions
Solution Approach 2:
The system implements feedback mechanisms where WTRUs report their local timing information and playback status to the session continuity control server. The server uses this feedback to calculate updated presentation time offsets and sends corrections back to WTRUs, creating a closed-loop control system that continuously maintains time synchronization across the collaborative session
2Reliability
If real-time updates to time synchronization information are implemented, then playback synchronization is maintained, but message exchange complexity and signaling overhead increase
Solution Approach 1:
The session continuity control server performs multiple functions within a single entity: it manages session setup, coordinates time synchronization, calculates presentation time offsets, and distributes timing parameters. This multi-functionality consolidates what would otherwise require multiple separate signaling mechanisms into a unified control plane, reducing overall system complexity while maintaining reliable synchronization
Data Source
AI summary
A method and apparatus are described for synchronizing mobile station (i.e., wireless transmit/receive unit (WTRU)) media flows during a collaboration session. Inter-WTRU transfer request messages, flow addition request messages and session update request messages may be exchanged between a plurality of WTRUs and a session continuity control application server (SCC-AS). Each of the messages may include a session description protocol (SDP) attribute line containing time synchronization information (e.g., a presentation time offset (PTO) information element (IE), a media flow group identity (ID) and a synchronization tolerance IE). The SCC-AS may update the time synchronization information and include the updated information in messages it sends to the WTRUs, which may re-synchronize their respective media flows based on the updated time synchronization information.