User Equipment RLC and PDCP Re-establishment for Split Bearer
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Solution Overview
Problem
In dual connectivity scenarios of LTE-Advanced systems, the deletion of a split bearer leads to inefficient uplink packet transmission due to lack of re-establishment on the PDCP and RLC layers, resulting in discarded packets and reduced throughput, and the change in uplink transmission direction causes unnecessary data transmission and reception issues.
Innovation Solution
The user equipment performs re-establishment on the s-RLC and PDCP layers before deleting the split bearer, assembling and transmitting waiting RLC SDUs to the PDCP layer, and re-establishes the RLC and PDCP layers when the uplink transmission direction changes, ensuring sequential transmission to the correct base station.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the split bearer is deleted without re-establishment on PDCP and RLC layers, then the device complexity is reduced, but packet loss occurs and throughput is reduced
Solution Approach 1:
The patent applies preliminary action by performing re-establishment on the PDCP and RLC layers before deleting the split bearer. This ensures that all packets are properly transmitted and acknowledged before the bearer is removed, preventing packet loss while maintaining a relatively simple deletion procedure.
Solution Approach 2:
The patent uses feedback mechanisms where the PDCP layer monitors packet acknowledgments and the RLC layer tracks packet delivery status. This feedback enables the system to determine when re-establishment is complete and the split bearer can be safely deleted without losing packets.
2Reliability
If re-establishment is performed on PDCP and RLC layers before deleting split bearer, then packet loss is prevented, but transmission time is increased
Solution Approach 1:
The patent applies partial action by performing re-establishment only on the necessary PDCP and RLC layers involved in the split bearer deletion, rather than re-establishing the entire protocol stack. This minimizes the time overhead while ensuring reliable packet transmission for the affected bearer.
3Ease of operation
If uplink transmission direction changes without re-establishment, then the ease of operation is improved, but data is transmitted to wrong base station causing throughput reduction
Solution Approach 1:
The patent applies preliminary action by performing re-establishment on the RLC layer before changing the uplink transmission direction. This ensures that the transmitting side clears its buffer and the receiving side is prepared, preventing data from being sent to the wrong base station while keeping the direction change procedure straightforward.
4Reliability
If RLC layer re-establishment is performed, then packet reordering is achieved, but the loss of time occurs due to timer stopping and resetting
Solution Approach 1:
The patent applies parameter changes by resetting timer values and buffer states during RLC layer re-establishment. This standardizes the system state after direction changes or bearer deletions, ensuring reliable packet delivery while minimizing the time impact through efficient parameter reset operations.
Data Source
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AI summary
Techniques are disclosed for implementing efficient transmission of uplink packets when the uplink transmission direction is changed in a split bearer. One aspect of the present invention relates to user equipment, comprising: a transmission and reception unit configured to communicate with a master base station and a secondary base station simultaneously in dual connectivity; an RLC (Radio Link Control) layer processing unit configured to have an RLC layer for the master base station and an RLC layer for the secondary base station; and a PDCP (Packet Data Convergence Protocol) layer processing unit configured to have a PDCP layer transmitting and receiving data to/from the RLC layer for the master base station and the RLC layer for the secondary base station, wherein when a transmission direction of uplink data packets is changed in the split bearer configured for the master base station and the secondary base station, the RLC layer processing unit performs re-establishment on the RLC layer for the master base station and the RLC layer for the secondary base station, and the PDCP layer processing unit performs re-establishment on the PDCP layer.