Multicast Session Restoration Through RAN Reachability Feedback
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Solution Overview
Problem
Current broadcast systems in 5G networks face challenges in providing service to moving users or users in areas with complex orography and poor signal quality, lacking a mechanism for the Access and Mobility Management Function (AMF) to report 'not-reachable' failures in Next Generation Radio Access Networks (NG-RAN) during multicast/broadcast service sessions.
Innovation Solution
A method is provided for an AMF to detect failure in contacting RAN nodes for multicast or broadcast sessions and transmit a message to the Multicast/Broadcast Session Management Function (MB-SMF) indicating the failed RAN nodes, enabling the MB-SMF to take remedial actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If broadcast or multicast transmission is used to deliver the same content to multiple users, then network capacity requirements and energy consumption are reduced, but there is no mechanism for AMF to report 'not-reachable' failures in NG-RAN during MBS session procedures
Solution Approach 1:
The patent implements a feedback mechanism where the AMF sends a notification message to the MB-SMF when it fails to contact one or more RAN nodes during MBS session start, release, update, activation, or deactivation procedures. This feedback enables the MB-SMF to detect the failure and initiate appropriate remedial actions, ensuring session continuity while maintaining energy-efficient broadcast/multicast transmission.
Solution Approach 2:
The patent performs preliminary failure detection by having the AMF proactively notify the MB-SMF about unreachable RAN nodes before the session completely fails. This preliminary action allows the MB-SMF to take remedial measures in advance, such as selecting alternative RAN nodes or reconfiguring the session, thereby maintaining service continuity.
2Reliability
If the AMF attempts to contact all RAN nodes for MBS session procedures, then complete session management is achieved, but service delivery to moving users or users in areas with complex orography and poor signal quality is disrupted
Solution Approach 1:
The patent extracts the failure detection and notification function from the general session management process. When the AMF encounters unreachable RAN nodes, it separates this failure information and notifies the MB-SMF specifically, allowing the session management to continue with reachable nodes while handling the failure case independently. This enables service delivery to continue in areas with partial RAN availability.
3Device complexity
If no failure reporting mechanism is implemented, then the system architecture remains simple, but remedial actions cannot be taken when RAN nodes are unreachable
Solution Approach 1:
The patent introduces a lightweight intermediary notification mechanism where the AMF acts as a mediator that detects RAN reachability issues and communicates them to the MB-SMF. This intermediary function adds minimal complexity to the existing architecture while enabling comprehensive failure detection and remedial actions. The notification message contains only essential failure information, keeping the added complexity low.
Data Source
AI summary
The present disclosure is related to network nodes and methods for restoration of a multicast or broadcast session. A method at an AMF for facilitating an MB-SMF in attempting a multicast session signaling for a multicast session or a broadcast session signaling for a broadcast session includes: determining whether the AMF fails to contact one or more RAN nodes for the multicast or broadcast session or not; and transmitting, to the MB-SMF, a first message indicating at least one first RAN node of the one or more RAN nodes in response to determining that the AMF fails to contact the at least one first RAN node for the multicast or broadcast session.