Relay UE MBS Session Start Notification Sidelink
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Solution Overview
Problem
Current 3GPP technical specifications lack a mechanism to combine multicast broadcast services with sidelink relay in 5G/NR mobile communication systems, preventing remote user equipment outside a base station's coverage from receiving multicast broadcast data effectively.
Innovation Solution
A communication method that involves a relay user equipment receiving an MBS session start notification from a base station and transmitting MBS session start information to a remote user equipment over a sidelink, allowing the remote user equipment to associate with the correct layer-2 identifier for receiving MBS data, thereby enabling the relay user equipment to transfer MBS data from the base station to the remote user equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multicast broadcast services are provided directly from base station to user equipment, then service delivery efficiency is improved, but coverage area is limited to base station range
Solution Approach 1:
The patent introduces relay user equipment as an intermediary node between the base station and remote user equipment. The relay UE receives MBS data from the base station via Uu interface and forwards it to remote UEs via sidelink, thereby extending service coverage beyond the base station's direct coverage area while maintaining a manageable communication mechanism through standardized interface protocols.
2Area of stationary object
If relay user equipment is introduced to extend coverage, then coverage area is improved, but identification and data routing complexity increases
Solution Approach 1:
The patent segments the identification system into two distinct parts: Uu interface identifiers (C-RNTI, G-RNTI) for base station communication and sidelink identifiers (source/destination layer-2 identifiers) for relay communication. This segmentation allows each interface to use its own standardized identification mechanism, preventing complexity from propagating across the entire system while enabling the relay UE to perform identifier translation and mapping between the two domains.
Solution Approach 2:
The relay user equipment acts as an intermediary that performs identifier mapping between the base station's downlink identifiers and the sidelink's layer-2 identifiers. This mediation resolves the identification complexity by translating between different identifier systems rather than requiring a unified complex identification mechanism across both interfaces.
3Reliability
If direct base station to remote user equipment communication is used, then connection simplicity is maintained, but service availability for remote users deteriorates
Solution Approach 1:
The relay user equipment serves as a mediator that enables service availability for remote UEs without direct base station coverage. The relay UE establishes separate communication paths: one from the base station (Uu interface) and another to the remote UE (sidelink), thereby ensuring service continuity and availability while managing path complexity through standardized protocol interfaces at each hop.
Data Source
AI summary
A communication method for transmitting multicast broadcast service (MBS) data belonging to an MBS session from a network node to a remote user equipment via a relay user equipment, the communication method including a step of receiving, by a relay user equipment, an MBS session start notification indicating start of an MBS session from a network node, and a step of transmitting, by the relay user equipment, an MBS session start information based on the MBS session start notification to a remote user equipment over a sidelink.