Split Bearer Switching via PDCP Extraction and Switch Counter
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Solution Overview
Problem
In the context of LTE-NR tight interworking, split bearers face challenges with excessive buffering requirements and Hyper Frame Number (HFN) de-synchronization due to high data rates and volatile radio conditions, particularly when switching between LTE and NR data paths.
Innovation Solution
The proposed solution involves configuring a split bearer with a first and second data path between user equipment and network nodes, allowing data transmission to be restricted to one path at a time, and using legacy data-reception procedures instead of PDCP reordering, along with retransmitting protocol data units on the newly-selected path and incrementing a switch counter to manage buffer requirements and prevent HFN de-synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCP reordering is used during switching operations on split bearers, then data transmission continuity is improved, but buffering requirements increase excessively
Solution Approach 1:
The patent extracts the reordering function from the PDCP layer and implements it at a different layer (using legacy data-reception procedures), thereby eliminating the need for excessive buffering while maintaining data transmission continuity during switching operations
Solution Approach 2:
The patent introduces a switch counter as an intermediary mechanism to track and manage switching operations between data paths, enabling efficient buffer management and preventing HFN de-synchronization without requiring PDCP reordering
2Adaptability or versatility
If switching between LTE and NR data paths is performed frequently, then adaptability to volatile radio conditions is improved, but HFN de-synchronization occurs
Solution Approach 1:
The patent implements a feedback mechanism through the switch counter that tracks the number of switching operations and provides this information to the receiving end, enabling both sides to maintain HFN synchronization even during frequent switching between LTE and NR data paths
Solution Approach 2:
The patent performs preliminary actions by incrementing the switch counter before actual data transmission on a new path, ensuring that HFN values are properly synchronized in advance, preventing de-synchronization issues during frequent switching operations
3Ease of operation
If RRC message exchange is used for switching operations, then switching control is improved, but switching speed decreases
Solution Approach 1:
The patent extracts the switching control functionality from the RRC layer and implements it directly at the PDCP layer using MAC control elements, eliminating the need for slow RRC message exchange and enabling faster in-band switching operations
Solution Approach 2:
The patent replaces the mechanical RRC message exchange system with a more efficient in-band signaling mechanism using MAC control elements, allowing switching operations to be performed faster without requiring external control messages
Data Source
AI summary
A method and apparatus may include configuring a split bearer. The split bearer is configured with a first data path between a user equipment and a first network node, and the split bearer is also configured with a second data path between the user equipment and a second network node. The split bearer is configured for a switching operation. The switching operation includes an operation where data transmission is restricted to be towards only one of the first data path and the second data path. The method also includes first transmitting on the split bearer towards the first data path. The method also includes performing the switching operation. The transmitting towards the first data path is switched to transmitting towards the second data path. The method also includes second transmitting on the split bearer towards the second data path.