PDCP Split Bearer Allocation for 5G Reliability
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Solution Overview
Problem
The 5G new radio (NR) technology faces reliability issues in transmitting PDCP packets due to poor signal quality, as the PDCP layer is at the top of the wireless user plane protocol stack, leading to low successful transmission probabilities, which is exacerbated by the inability of two lower-layer carriers to fully transmit PDCP packets.
Innovation Solution
A method is proposed that allocates two RLC entities with either replication or distribution functions for PDCP packets, allowing them to be mapped to different physical carriers, and includes re-transmitting unsuccessfully transmitted packets based on feedback and predefined conditions to improve reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCP packets are transmitted through two carriers at the lower layer, then transmission diversity is provided, but the successful transmission probability remains low when signal quality is poor
Solution Approach 1:
The patent segments the transmission function by separating PDCP packet transmission into two independent bearers (split bearer), where each bearer can be transmitted through different carriers. This segmentation allows the system to overcome the limitation of single-carrier transmission and improve reliability by distributing packets across multiple transmission paths with different signal qualities.
Solution Approach 2:
The patent introduces a new dimension in the protocol stack by implementing split bearer that spans multiple radio link control (RLC) entities and logical channels. This dimensional expansion from single-path to multi-path transmission enables packets to be routed through different carriers simultaneously, thereby improving transmission reliability without increasing base protocol complexity.
2Reliability
If split bearer is used to map PDCP packets to different logical channels, then transmission reliability is improved, but processing complexity increases
Solution Approach 1:
The patent implements dynamic function allocation where the replication or distribution function can be flexibly assigned to either the master node or secondary node based on real-time network conditions and signal quality. This dynamic approach allows the system to adapt to changing environments, maintaining high reliability while optimizing processing complexity by placing the intelligent decision-making function at the appropriate network node.
Solution Approach 2:
The patent employs preliminary action by pre-configuring the split bearer structure and function allocation through RRC signaling before actual data transmission begins. This preliminary setup includes defining the replication/distribution function assignment and carrier mappings in advance, which simplifies real-time processing during data transmission and reduces runtime complexity.
3Reliability
If PDCP replication packets are transmitted through multiple carriers, then transmission robustness is enhanced, but wireless resource consumption increases
Solution Approach 1:
The patent utilizes parameter changes by dynamically adjusting the replication factor and carrier selection based on signal quality metrics and channel conditions. When signal quality is good, the system can reduce replication or concentrate transmission on a single carrier, thereby saving wireless resources. When signal quality deteriorates, the system increases replication across multiple carriers to maintain robustness, optimizing the trade-off between reliability and resource consumption.
Data Source
AI summary
A function allocating method includes receiving a radio resource control (RRC) message carrying allocation information transmitted by a base station, wherein the allocation information is used to allocate two radio link control (RLC) entities and one of a replication function and a distribution function of packet data convergence protocol (PDCP) packets to a data radio bearer (DRB) or a signaling radio bearer (SRB); and allocating, in response to the RRC message, the two RLC entities, and one of the replication function and the distribution function of the PDCP packets for the DRB or the SRB.