PDCP Handling in Serving Cell Change Without Reestablishment
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Solution Overview
Problem
Existing serving cell change procedures in wireless communication systems involve lengthy latency and high overhead due to complete L2 and L1 resets, which hinder efficient handovers between cells.
Innovation Solution
A method is implemented where a UE refrains from performing PDCP reestablishment during a serving cell change, based on an activation command from the RAN, allowing for a seamless transition without reconfiguring the PDCP entity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complete L2 and L1 resets are performed during serving cell change, then network reliability is maintained, but latency increases and overhead increases
Solution Approach 1:
The patent extracts the PDCP reestablishment step from the mandatory serving cell change procedure. By conditionally omitting this step based on the reconfigurationWithSync flag, the system maintains network reliability through L2/L1 resets while eliminating unnecessary PDCP reestablishment overhead and latency in synchronized scenarios.
Solution Approach 2:
The patent introduces dynamic behavior by making the PDCP reestablishment action conditional rather than fixed. The UE dynamically decides whether to perform PDCP reestablishment based on the reconfigurationWithSync indication received from the network, allowing the procedure to adapt between full reset (asynchronous) and partial reset (synchronized) modes.
2Reliability
If complete L2 and L1 resets are performed during serving cell change, then network reliability is maintained, but overhead increases
Solution Approach 1:
The patent removes the PDCP reestablishment step from the standard serving cell change procedure when synchronization is present. This extraction reduces procedural overhead and simplifies the handover process while maintaining network reliability through the retained L2 and L1 reset operations.
Solution Approach 2:
Instead of always performing complete PDCP reestablishment, the patent applies partial action by skipping this step when the reconfigurationWithSync flag is set. This partial approach (omitting unnecessary reestablishment) reduces overhead while the L2/L1 resets provide sufficient reliability assurance.
3Reliability
If PDCP reestablishment is performed during serving cell change, then data integrity is ensured, but latency increases
Solution Approach 1:
The patent extracts the PDCP reestablishment operation from the serving cell change procedure. By conditionally omitting this step based on synchronization status, the system reduces handover latency while maintaining data integrity through the L2 and L1 reset mechanisms that preserve critical connection state.
Solution Approach 2:
The patent applies preliminary action by having the network prepare and indicate the reconfigurationWithSync status before the actual cell change occurs. This advance information allows the UE to pre-determine whether PDCP reestablishment is necessary, avoiding unnecessary latency while ensuring data integrity when needed.
Data Source
AI summary
A node of a radio access network (RAN) transmits, to a user equipment (UE) communicating with the RAN in a first cell and using a radio bearer, a message including a configuration for performing a serving cell change to a second cell subsequent to an activation command, including refraining from including a Packet Data Convergence Protocol (PDCP) reestablishment indication in the message; and transmits, to the UE and subsequent to the transmitting of the message including the configuration, an activation command for performing the serving cell change to the second cell in accordance with the configuration and without reestablishing a PDCP entity of the UE for the radio bearer.