UE-to-UE Relay Connection Setup with Sidelink RRC Forwarding
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Solution Overview
Problem
There is a need for a method and device to establish a connection between a source remote user equipment (UE) and a target remote UE for a UE-to-UE relay operation in wireless communication systems, particularly in scenarios requiring enhanced mobile broadband, massive machine type communication, and ultra-reliable low latency communications.
Innovation Solution
The method involves a relay UE receiving a first sidelink radio resource control (SL RRC) message from a source remote UE, establishing a sidelink connection, transmitting a second SL RRC message to a target remote UE, and forwarding messages between them, utilizing Layer-2 IDs for UE-to-UE relay operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct connection establishment between source remote UE and target remote UE is attempted, then connection reliability may be improved, but coverage area is limited and connection cannot be established when UEs are out of direct range
Solution Approach 1:
A relay UE is introduced as an intermediary node between the source remote UE and target remote UE. The relay UE receives messages from the source remote UE and forwards them to the target remote UE, enabling indirect communication when direct connection is not feasible. This extends the effective coverage area while maintaining connection reliability through the relay path.
2Area of stationary object
If multi-hop relay operation is implemented to extend coverage, then coverage area is improved, but message forwarding complexity and latency increase
Solution Approach 1:
The communication path is segmented into distinct hops: source remote UE to relay UE, and relay UE to target remote UE. Each hop is managed independently with separate message forwarding procedures. This segmentation allows for systematic handling of relay operations while keeping each individual hop's latency manageable, though cumulative latency increases with more hops.
3Area of stationary object
If relay UE configuration messages are transmitted through multiple hops, then coverage extension is achieved, but message transmission time and processing complexity increase
Solution Approach 1:
The relay UE acts as a message forwarding intermediary that receives configuration messages from the source remote UE and relays them to the target remote UE. The relay UE maintains message queues and manages forwarding timing, which adds processing complexity but enables coverage extension beyond direct communication range.
4Area of stationary object
If UE-to-UE relay operation is established, then coverage area is extended, but connection establishment steps and signaling overhead increase
Solution Approach 1:
The connection establishment process is segmented into distinct phases: source remote UE selects and connects to relay UE, then relay UE establishes connection with target remote UE. Each phase has specific signaling messages and procedures. This segmentation makes the complex multi-step process more manageable but increases overall signaling overhead compared to direct connection.
Data Source
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AI summary
According to an embodiment, a method for operating a relay UE related to the configuration of a user equipment (UE)-to-UE relay connection in a wireless communication system comprises the steps in which the relay UE: receives a first sidelink radio resource control (SL RRC) message from a source remote UE; establishes an SL connection with the source remote UE; transmits a second SL RRC message to a target remote UE after establishing the SL connection with the source remote UE; establishes an SL connection with the target remote UE; and after establishing the SL connection with the target remote UE, transfers, to the target remote UE, a message for SL connection transmitted by the source remote UE.