RRC Connection Resumption Using Stored RAT Type Information
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Solution Overview
Problem
In wireless communications, user equipment (UE) often faces issues transitioning from the RRC_INACTIVE state to the RRC_CONNECTED state, resulting in an inability to transmit or receive data due to anomalies in the RRC resume procedure, particularly when the PDCP entity used for connection release differs from the RAT used by the base station.
Innovation Solution
The UE and base station employ techniques to properly decode RRC resume messages by using the same protocol format for resuming the connection as before the release, ensuring that the RRCConnectionSetupComplete message is transmitted and decoded correctly, regardless of the previous PDCP entity's RAT, allowing subsequent procedures to be performed using either the original or new PDCP entities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the UE uses a different RAT's PDCP entity format for connection resumption, then the connection can be resumed faster, but the base station cannot properly decode the RRC resume messages
Solution Approach 1:
The base station performs preliminary action by storing the RAT type information before the UE transitions to inactive state. When the UE sends the resume request, the base station already has the necessary information to correctly decode the message using the appropriate PDCP entity format, eliminating the need for the UE to switch formats while ensuring reliable decoding.
Solution Approach 2:
The stored RAT type information acts as an intermediary that bridges the gap between the UE's current format and the base station's expected format. This intermediary information allows the base station to correctly interpret messages regardless of which RAT's PDCP entity the UE is using, resolving the contradiction between speed and reliability.
2Quantity of substance
If the UE releases all radio resources including the original PDCP entity during state transition, then memory is freed for other uses, but the original connection format information is lost
Solution Approach 1:
The base station extracts and stores only the essential RAT type information before the UE releases its resources. This extraction approach allows the base station to retain the critical format information needed for future message decoding without requiring the UE to maintain additional resources, thus freeing UE memory while preserving necessary connection information.
Solution Approach 2:
The base station creates a copy of the RAT type information and stores it locally. This copying mechanism ensures that the original connection format information is preserved in the base station's memory, allowing the UE to safely release its resources without losing the format information needed for connection resumption.
3Stability of the object's composition
If the base station expects messages in the original RAT's format, then protocol consistency is maintained, but the UE cannot transmit data using the current RAT's PDCP entity
Solution Approach 1:
The system dynamically adapts to the UE's current RAT state. When the UE sends a resume request using the current RAT's PDCP entity format, the base station uses the stored RAT type information to dynamically adjust its decoding expectations, maintaining protocol consistency while allowing the UE to transmit data in its current format without interruption.
Solution Approach 2:
The base station changes its expected message format parameters based on the stored RAT type information. This parameter adjustment allows the base station to correctly decode messages in whichever RAT's format the UE is currently using, maintaining both protocol consistency and data transmission productivity by adapting to the UE's state rather than requiring the UE to match a fixed format.
Data Source
AI summary
To resume a connection with a base station, a user equipment (UE) communicates messages with the base station in accordance with a format that corresponds to a first radio access technology (RAT), using a radio connection over a radio interface that conforms to a second RAT (702). The UE suspends the radio connection (704) and, subsequently to the suspending, transmits to the base station an indication that the radio connection has been resumed, in accordance with the format that corresponds to the first RAT (708).