RRC Inactive Mode PLMN Selection State Synchronization
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Solution Overview
Problem
In 5G wireless communication, there is a state mismatch between upper and lower layers of user equipment (UE) when transitioning between different resource control states, leading to unnecessary radio access network-based notification area updates and power wastage, as the RRC layer remains in an inactive state despite the NAS layer entering idle mode.
Innovation Solution
A resource control module is implemented to manage PLMN selection and transition between states, performing cell-selection and cell-reselection procedures to determine if the new PLMN is equivalent, and sending indications to lower layers to enter idle mode when necessary, thereby reducing unnecessary updates and conserving power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UE performs cell reselection and selects a new PLMN while in RRC inactive mode, then the UE can maintain connectivity and mobility, but the RRC layer remains in inactive state causing state mismatch with upper layers and triggering unnecessary RNA update procedures
Solution Approach 1:
The patent implements a feedback mechanism where the RRC layer monitors the state of upper layers (NAS layer) and detects when they have transitioned to idle mode. Based on this feedback, the RRC layer adjusts its own state accordingly, preventing the state mismatch that would otherwise trigger unnecessary RNA update procedures and associated power consumption.
Solution Approach 2:
The patent applies preliminary action by having the RRC layer proactively check whether upper layers have transitioned to idle mode before performing RNA update procedures. This preliminary state verification prevents the execution of unnecessary update procedures, thereby conserving power and network resources.
2Reliability
If the RRC layer performs RNA update procedure while upper layers are in idle mode, then the RRC layer maintains its inactive state operations, but unnecessary network resources are consumed and power is wasted
Solution Approach 1:
The RRC layer implements feedback monitoring to detect when upper layers transition to idle mode. This feedback mechanism ensures that the RRC layer does not perform RNA update procedures when they are unnecessary, thereby maintaining state consistency while improving network efficiency by avoiding redundant operations.
Solution Approach 2:
The patent makes the RRC layer's behavior dynamic by allowing it to adapt its state and operations based on the state of upper layers. When upper layers are in idle mode, the RRC layer recognizes this and adjusts its behavior accordingly, preventing unnecessary RNA updates and improving overall system efficiency.
3Ease of operation
If the NAS layer transitions to idle mode while RRC layer remains in inactive mode, then the upper layer can manage PLMN selection independently, but a state mismatch occurs causing the RRC layer to ignore connection requests and perform unnecessary updates
Solution Approach 1:
The patent establishes a feedback channel between upper layers and the RRC layer, allowing the RRC layer to detect when upper layers have transitioned to idle mode. This feedback mechanism maintains state synchronization without compromising layer independence, as each layer can operate autonomously while remaining aware of the other's state through controlled information exchange.
Solution Approach 2:
The patent introduces an intermediary mechanism (the state indication message) that facilitates communication between the NAS layer and RRC layer. This intermediary allows the layers to maintain independence while synchronizing their states, preventing the RRC layer from ignoring connection requests or performing unnecessary updates due to state mismatch.
Data Source
AI summary
This document describes techniques and apparatuses for handling Public Land Mobile Network (PLMN) selection while user equipment is in an inactive mode at a radio resource control layer. In aspects, the UE performs a cell-selection procedure that selects a first cell that serves a first Public Land Mobile Network (PLMN). The UE establishes a radio connection to the first PLMN. The UE transitions from a connected mode at a radio resource control layer to an inactive mode at a radio resource control layer. After a period of time, the UE performs a cell-reselection procedure that selects a second cell that serves a second PLMN. The UE determines if the second PLMN is an equivalent PLMN to the first PLMN. If the second PLMN is an equivalent PLMN to the first PLMN, the UE sends an indication to a lower layer that triggers an action.