PDCP Entity Reconfiguration for Bearer Type Changes
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Solution Overview
Problem
The handling of bearer type changes for radio bearers during handovers from New Radio (NR) to Long-Term Evolution (LTE) is unclear, particularly regarding the operations of the Packet Data Convergence Protocol (PDCP) after the change.
Innovation Solution
A method and device for handling bearer type changes by receiving RRC messages on a Signaling Radio Bearer (SRB) to configure and reconfigure PDCP entities for Data Radio Bearers (DRBs), transitioning between Secondary Cell Group (SCG) and Master Cell Group (MCG) bearer types, and managing PDCP Service Data Units (SDUs) accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the bearer type changes during handover from NR to LTE, then the radio bearer can be reconfigured to adapt to different network conditions, but the PDCP entity operations become unclear and may cause data transmission interruptions
Solution Approach 1:
The patent applies preliminary action by establishing the first PDCP entity before the bearer type change occurs. The network device configures the PDCP entity in advance with appropriate parameters (such as sequence number length) based on the upcoming bearer type, ensuring that when the handover occurs, the PDCP entity is already ready to operate without interruption or uncertainty.
Solution Approach 2:
The patent implements dynamics by allowing the PDCP entity to be reconfigured during the bearer type change process. The network device can dynamically adjust PDCP parameters (like sequence number length) based on the target bearer type, and the terminal device adapts its operations accordingly. This dynamic reconfiguration ensures continuous reliable operation through the transition.
2Adaptability or versatility
If the PDCP entity is reconfigured during bearer type change, then the system can adapt to new transmission requirements, but data transmission may be interrupted during the reconfiguration process
Solution Approach 1:
The patent ensures continuity of useful action by maintaining the PDCP entity throughout the bearer type change process. Instead of releasing and recreating the PDCP entity, the patent reconfigures existing parameters while keeping the entity active. This allows data transmission to continue without interruption, as the PDCP layer remains operational throughout the transition.
Solution Approach 2:
The patent applies parameter changes by modifying specific PDCP parameters (such as sequence number length, header format) while keeping the PDCP entity structure intact. The network device sends reconfiguration messages with updated parameters, and the terminal device applies these changes without releasing the existing PDCP entity, thereby maintaining continuous data transmission with updated configuration.
3Adaptability or versatility
If the PDCP entity is released and reestablished during bearer type change, then the new configuration can be applied, but the process becomes complex and time-consuming
Solution Approach 1:
The patent applies preliminary action by pre-establishing the PDCP entity with initial configuration parameters before the bearer type change is triggered. The network device prepares the PDCP configuration in advance, so when the handover occurs, the entity is already in place and only needs parameter adjustments rather than complete recreation, simplifying the overall process.
4Ease of manufacture
If the PDCP sequence number length is not properly configured during bearer type change, then configuration simplicity is maintained, but data transmission errors may occur
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the PDCP sequence number length parameter based on the bearer type. When the bearer type changes from NR to LTE or vice versa, the network device calculates and configures the appropriate sequence number length (12 bits or 18 bits) and informs the terminal device through RRC messages, ensuring correct configuration without manual intervention.
Data Source
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AI summary
A method for handling a bearer type change comprises receiving a first RRC message from a first BS; transmitting a first RRC response message to the first BS; establishing a first PDCP entity; transmitting a first plurality of PDCP SDUs to a second BS according to the first PDCP entity; receiving a second RRC message from the first BS, wherein the second message configures the DRB from the SCG bearer type or the split bearer type to a MCG bearer type; transmitting a second RRC response message to the first BS; releasing the first PDCP entity, and establishing a second PDCP entity; and transmitting a second plurality of PDCP SDUs to the first BS according to the second PDCP entity.