Sidelink Relay UE Inter-RAT Reselection for Continuous Relay Support
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Solution Overview
Problem
In sidelink communication, a relay UE moving to an LTE cell from new radio (NR) may lose its relay function due to unsupported inter-RAT reselection, especially when the remote UE is in an IDLE state, leading to communication disruptions.
Innovation Solution
Implementing a mechanism for UE-to-Network relay support in both NR and LTE radio access technologies, allowing seamless inter-RAT reselection and maintaining relay functionality even when the remote UE is in an IDLE state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a relay UE performs inter-RAT reselection to an LTE cell, then the relay UE can access LTE network, but the relay UE cannot support relay function to remote UE
Solution Approach 1:
The patent applies dynamics by enabling the relay UE to dynamically switch between NR and LTE RATs based on network conditions. The relay UE can perform inter-RAT reselection to access LTE network when needed, while the system dynamically manages the relay function to ensure continuity. This dynamic adaptation resolves the contradiction by making the system flexible rather than static.
Solution Approach 2:
The patent implements universality by enabling the relay UE to support relay functions across multiple RATs (both NR and LTE). Instead of being limited to a single RAT, the relay UE can maintain relay functionality regardless of whether it is camped on NR or LTE cells. This multi-RAT capability ensures that the relay function remains reliable even during inter-RAT reselection.
2Use of energy by moving object
If the remote UE is in IDLE state during inter-RAT reselection, then the remote UE conserves energy, but the relay UE cannot provide relay function
Solution Approach 1:
The patent applies preliminary action by having the relay UE proactively notify the remote UE about upcoming inter-RAT reselection before it occurs. This advance notification allows the system to prepare for the transition, ensuring that the relay function can be quickly reestablished after reselection. The remote UE can remain in IDLE state conserving energy, while the relay UE prepares the relay function in advance.
Solution Approach 2:
The patent implements feedback by establishing a notification mechanism where the relay UE informs the remote UE about its reselection status and relay function availability. This feedback loop allows the remote UE to understand when the relay function is unavailable due to reselection, while still maintaining energy efficiency by staying in IDLE state when appropriate.
3Use of energy by moving object
If the remote UE is in IDLE state, then the remote UE saves power, but the remote UE does not know whether the relay UE has selected LTE cell
Solution Approach 1:
The patent applies the intermediary principle by using a notification message as a mediator to transmit information from the relay UE to the remote UE. Even when the remote UE is in IDLE state, it can receive this intermediary notification about the relay UE's cell selection status. This intermediary mechanism bridges the information gap without requiring the remote UE to be in an active state, thus preserving energy while maintaining information flow.
Solution Approach 2:
The patent implements self-service by enabling the relay UE to autonomously notify the remote UE about its reselection status. The relay UE independently manages the information exchange, informing the remote UE about whether it has selected an LTE cell or NR cell. This self-service approach eliminates the need for the remote UE to actively query or maintain continuous connection, allowing it to remain in IDLE state while still receiving critical information.
Data Source
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AI summary
Proposed is a method for a first device to perform wireless communication. The method may comprise the steps of: establishing a connection with a second device; and reselecting a cell on the basis that the first device is in a radio resource control (RRC) IDLE state or an RRC INACTIVE state. For example, a priority related to cell reselection can be set such that a cell related to a new radio (NR) has a high priority. For example, cell reselection can be performed first on the cell related to the NR on the basis of the priority related to cell reselection.