Multicast PDU Session Joining Without UPF IGMP Identification
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Solution Overview
Problem
In 3GPP networks, some User Plane Functions (UPFs) lack the capability to identify Internet Group Management Protocol (IGMP) messages, preventing terminals from joining multicast groups and receiving multicast data.
Innovation Solution
Terminals use a PDU session establishment procedure to join multicast groups by sending a PDU session establishment request message with multicast group identification information, enabling mobility management and session management network elements to facilitate multicast data reception through context information exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal uses the IGMP message to join the multicast group, then the terminal can join the multicast group, but the UPF must have the capability of identifying the broadcast message, which increases device complexity and not all UPFs have this capability
Solution Approach 1:
The patent introduces a session management network element as an intermediary between the terminal and the UPF. This intermediary handles the multicast group joining process by managing the PDU session establishment and maintaining the correspondence between unicast and multicast sessions, thereby relieving the UPF of the complex task of identifying IGMP messages and reducing device complexity while ensuring reliable multicast group joining
2Reliability
If the UPF forwards the IGMP message to the application server, then the terminal can receive multicast data, but the UPF must identify the message type, which reduces ease of operation
Solution Approach 1:
The session management network element acts as an intermediary that manages the entire multicast session lifecycle. It receives the PDU session establishment request from the terminal, identifies the multicast group joining intent, establishes the multicast session, and manages the correspondence between unicast and multicast sessions. This intermediary approach simplifies the UPF's operation to basic packet forwarding without complex message type identification
Solution Approach 2:
The terminal autonomously initiates the multicast group joining process by sending a PDU session establishment request with specific parameters indicating multicast group identification. The session management network element autonomously processes this request, establishes the appropriate multicast session, and configures the necessary forwarding rules, eliminating the need for manual configuration and simplifying the overall operation
3Device complexity
If the terminal joins the multicast group through the PDU session establishment procedure, then the design complexity is reduced, but the terminal needs to send a specific request message with multicast group identification information
Solution Approach 1:
The patent merges the multicast group joining function with the existing PDU session establishment procedure. The terminal sends a PDU session establishment request that includes both standard session establishment parameters and additional parameters indicating multicast group identification (such as DNN, S-NSSAI, or specific information elements). The session management network element extracts the multicast group identification from these parameters and establishes the corresponding multicast session, thereby combining multiple functions into a single unified procedure that reduces overall system complexity
Data Source
AI summary
Embodiments of this application disclose a communication method of adding a terminal to a multicast group by using a unicast PDU session establishment procedure. The terminal sends, to a mobility management network element, a PDU session establishment request message that includes identification information of a multicast group, where the PDU session establishment request message is used by the terminal to join the multicast group. The mobility management network element receives the PDU session establishment request message, sends the identification information of the multicast group to a session management network element, triggers the session management network element to establish a multicast PDU session, and feeds back the context information of the multicast PDU session to the terminal to allow the terminal to join the multicast group so that the terminal receives multicast data by using the multicast PDU session.