Uplink Switching via Dual RLC Entities for Split Bearer Latency
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Solution Overview
Problem
In wireless communication systems, particularly in 5G NR, user equipment (UE) configured for dual connectivity with a split bearer architecture may experience delays and increased latency when the master cell group (MCG) becomes temporarily unavailable, as uplink data packets build up in buffers, leading to slower recovery and potential communication disruptions.
Innovation Solution
The UE is configured to transmit uplink data packets using both a first and a second radio link control (RLC) entity associated with a master cell group (MCG) and a secondary cell group (SCG), with a transmit buffer threshold, allowing it to switch to the SCG when the MCG is unavailable, thereby preventing buffer buildup and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE transmits uplink data packets only through the MCG, then the transmission path is simple and stable, but the system experiences delays and increased latency when the MCG becomes temporarily unavailable due to buffer buildup
Solution Approach 1:
The patent introduces a secondary cell group (SCG) as an intermediary transmission path when the master cell group (MCG) becomes unavailable. The network configures the UE with both MCG and SCG resources, allowing seamless switching to SCG for uplink transmission when MCG is temporarily unavailable, thus maintaining transmission reliability without significant latency increase
Solution Approach 2:
The patent implements dynamic path selection by configuring the UE with multiple RLC entities (first RLC entity for MCG, second RLC entity for SCG) and enabling conditional switching based on transmission status. The UE can dynamically activate the second RLC entity and switch to SCG when needed, making the transmission path adaptive rather than static
2Loss of time
If the UE switches to SCG when MCG is unavailable, then latency is reduced and transmission continuity is maintained, but the device complexity increases due to dual RLC entity configuration
Solution Approach 1:
The patent segments the uplink transmission function into two independent RLC entities: first RLC entity associated with MCG and second RLC entity associated with SCG. Each RLC entity operates independently with its own transmission path, allowing parallel operation and seamless switching without requiring complex integrated processing
Solution Approach 2:
The UE is configured with universal capabilities to handle both MCG and SCG transmissions through dual RLC entities. The same PDCP entity can route uplink packets to either first or second RLC entity based on transmission needs, making the system multi-functional without requiring separate dedicated systems for each path
3Productivity
If the UE uses both MCG and SCG for uplink transmission, then bandwidth and transmission efficiency are improved, but the buffer management complexity increases
Solution Approach 1:
The network configures the UE with autonomous buffer management capabilities including transmit buffer threshold and uplink switch start/stop indications. The UE independently monitors its own buffer status and automatically activates/deactivates the second RLC entity based on configured thresholds and network indications, without requiring complex centralized buffer management
Data Source
AI summary
A user equipment (UE) configured for dual connectivity with a split bearer configuration may transmit uplink data packets to one or both a master cell group (MCG) and a secondary cell group (SCG). The UE may transmit an uplink transmission from a packet data convergence protocol (PDCP) entity over one or both of a first radio link control (RLC) entity associated with the MCG and a second RLC entity associated with the SCG. The configuration including a transmit buffer threshold. The UE may receive, at the PDCP entity, an uplink switch start indication. The UE may activate the second RLC entity in response to receiving the uplink switch start indication. The UE may transmit a buffer status report according to a current transmit buffer level plus the transmit buffer threshold. Accordingly, the UE may communicate with the SCG based on the uplink switch start indication.