Relay Cell Reselection During 5G Path Switching
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Solution Overview
Problem
Path switching failures occur when a relay UE in RRC_IDLE/INACTIVE state changes cells during the path switching preparation phase, leading to incorrect relay UE selection and failed indirect path switching in 5G networks.
Innovation Solution
Incorporating a mechanism where the remote UE provides a second cell ID in the path switching command to the relay UE, allowing it to identify the target cell for indirect path switching, and triggering an RRC re-establishment procedure if the relay UE has changed cells, ensuring correct path switching configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If path switching is performed using relay UE in RRC_IDLE/INACTIVE state, then device complexity is reduced and battery consumption is lowered, but path switching reliability deteriorates when relay UE changes cells during preparation phase
Solution Approach 1:
The patent applies preliminary action by having the remote UE provide the second cell ID (target cell identifier) in advance during the path switching preparation phase. This allows the network to prepare the correct path switching configuration before the relay UE potentially changes cells, ensuring that when the relay UE does change cells, the network already has the correct target cell information to establish the indirect path successfully.
Solution Approach 2:
The patent implements feedback by having the remote UE continuously provide cell identifier information to the network during path switching preparation. This feedback mechanism ensures that the network has up-to-date information about the target cell, allowing it to adjust and correct the path switching configuration if the relay UE changes cells during the preparation phase, thereby maintaining path switching reliability.
2Reliability
If relay UE changes cells during path switching preparation, then relay UE can maintain better connection quality, but path switching configuration becomes incorrect leading to switching failure
Solution Approach 1:
The network performs preliminary path switching configuration preparation using the second cell ID provided by the remote UE before the relay UE actually changes cells. This preliminary configuration is then updated or corrected based on the relay UE's actual cell change, ensuring that the final path switching configuration is accurate even though the relay UE moved to a different cell during preparation.
Solution Approach 2:
The patent applies dynamics by making the path switching configuration adaptive to the relay UE's cell changes. Instead of using a static configuration based on initial cell information, the system dynamically updates the path switching configuration to reflect the relay UE's actual cell location at the time of switching execution, ensuring configuration accuracy matches the dynamic mobile environment.
3Ease of operation
If traditional path switching procedure is used without cell ID verification, then procedure simplicity is maintained, but path switching failures occur due to relay UE cell changes
Solution Approach 1:
The patent incorporates preliminary cell ID verification into the existing path switching procedure. The remote UE provides the second cell ID in advance during the preparation phase, and the network uses this information to verify and correct the path switching configuration. This preliminary verification step is integrated seamlessly into the existing procedure, maintaining simplicity while adding the necessary reliability check to prevent failures due to relay UE cell changes.
Data Source
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AI summary
There is provided a method, comprising: obtaining, by a user equipment in a first cell, information of at least one candidate relay device, the information including at least a first cell identifier associated with the at least one candidate relay device; transmitting the information to a radio access node of the first cell; receiving, from the radio access node, a path switching command comprising an indication of a relay device among the at least one candidate relay device and a second cell identifier; transmitting, to the relay device, a request to act as a relay for the user equipment, the request comprising an indication of the second cell identifier associated with the path switching command.