UE RRC-Inactive State Management for Faster NR Paging
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Solution Overview
Problem
Inconsistent UE states between the network and the actual UE state lead to slow paging responses, resulting in poor user experience in NR systems due to RAN paging failures and subsequent CN paging initiation after timeouts or retries.
Innovation Solution
The method involves UE camping on a first cell in an RRC connected state and entering an RRC inactive state upon receiving a message from the access network, maintaining this state consistently across cell changes, and responding rapidly to RAN paging without automatically transitioning to RRC idle state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the network side delivers RAN paging to search for the UE in RNA when the UE is in RRC_INACTIVE state, then the paging response speed is improved, but the UE may not respond if it has actually switched to RRC_IDLE state, causing inconsistency between network-recorded state and actual UE state
Solution Approach 1:
The UE feeds back its actual RRC state (IDLE or INACTIVE) to the network through registration requests or other signaling messages. This feedback mechanism allows the network to update its records and ensure state consistency, resolving the contradiction between fast paging response and reliable state tracking.
Solution Approach 2:
The UE performs preliminary state management by maintaining its RRC state (IDLE or INACTIVE) even when moving between cells, rather than automatically transitioning to IDLE upon cell reselection. This preliminary action ensures that when the network sends RAN paging, the UE is still in the expected state and can respond promptly.
2Use of energy by moving object
If the UE automatically switches to RRC_IDLE state after detaching or reselecting, then power consumption is reduced, but the paging response speed deteriorates due to state inconsistency with network records
Solution Approach 1:
The UE dynamically maintains its RRC state (IDLE or INACTIVE) based on network configuration and actual conditions, rather than following a fixed automatic transition rule. This dynamic state management allows the UE to remain in INACTIVE state when appropriate, enabling fast paging response while still managing power consumption efficiently through conditional state transitions.
3Reliability
If the network side sends CN paging after RAN paging timeout or retries, then the UE can be reached, but the overall paging response time increases due to the timeout and retry delays
Solution Approach 1:
The UE acts as an intermediary by proactively providing its actual state information to the network through registration requests or state indication messages. This intermediary action allows the network to avoid unnecessary RAN paging timeouts and retries, directly initiating appropriate paging procedures based on the UE's actual state, thereby reducing overall paging response time while maintaining reliable delivery.
Data Source
AI summary
A method for improving a paging response speed of a user equipment (UE), includes: camping, by the UE on a first cell of a first network, the UE being in an RRC connected state; when a first preset condition is met, sending, by an access network device, a first message to the UE, the first message being used to indicate the UE to enter an RRC inactive state; recording, by the access network device, that the UE is in an RRC inactive state; and in response to the first message that is received, entering, by the UE, the RRC inactive state; and when a second preset condition is met, camping, by the UE, on a second cell of the first network, where the UE is in an RRC inactive state, and the first cell and the second cell are the same or different.