PDCP Reordering for Multi-Bearer Wireless Systems
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Solution Overview
Problem
Wireless communication systems face complexity and increased processing overhead due to redundant functions in the radio link control (RLC) layer, particularly in managing packet data convergence protocol (PDCP) service data units (SDUs) for radio bearers with different reliability and delay targets.
Innovation Solution
A method and apparatus that support communication without an RLC layer by managing PDCP SDUs at the PDCP layer, using a common reordering procedure with adjustable parameters based on reliability and delay targets for each radio bearer, including configuring reordering windows and timers to sequence and discard SDUs accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a radio link control (RLC) layer is included in the protocol stack, then error correction and segmentation functions are provided, but processing complexity and signaling overhead increase
Solution Approach 1:
The patent extracts the error correction function from the RLC layer and implements it directly at the PDCP layer using CRC checks and retransmission mechanisms. This removes the redundant RLC layer while preserving the essential error correction capability, thereby reducing protocol complexity without sacrificing reliability.
Solution Approach 2:
The patent merges the error correction functions traditionally performed by the RLC layer with the PDCP layer's existing retransmission mechanisms. By combining these functions at a single layer, the patent eliminates the need for a separate RLC layer, reducing overall protocol stack complexity while maintaining error correction capabilities.
2Reliability
If separate reordering procedures are implemented for each radio bearer to meet different reliability and delay targets, then service quality is improved, but processing complexity increases
Solution Approach 1:
The patent implements a universal reordering procedure at the PDCP layer that can serve multiple radio bearers with different QoS requirements. By making the reordering mechanism bearer-agnostic and configurable through parameters like reordering window size and timer values, the system achieves differentiated service quality without requiring separate complex procedures for each bearer.
Solution Approach 2:
The patent adjusts reordering parameters (window size, timer durations, discard thresholds) based on the specific reliability and delay targets of each radio bearer. This allows a single reordering procedure to adapt to different QoS requirements through parameter configuration rather than requiring structurally different procedures for each bearer.
3Manufacturing precision
If the reordering window size is increased to improve SDU reordering accuracy, then sequencing precision is improved, but delay increases
Solution Approach 1:
The patent implements a dynamic reordering window mechanism that adjusts the window size and timer values based on the specific requirements of each radio bearer and current network conditions. For bearers requiring high sequencing accuracy, the window is enlarged; for delay-sensitive bearers, the window is reduced with corresponding timer adjustments, allowing the system to optimize the precision-delay tradeoff dynamically.
Data Source
AI summary
A device may support communication without a radio link control (RLC) layer, which may include receiving a packet data convergence protocol (PDCP) service data units (SDUs) for multiple radio bearers at a PDCP layer. The multiple radio bearers may have different reliability or delay targets, and a reordering procedure at the PDCP layer may be conducted on the different radio bearers. The reordering procedure may be a same reordering procedure for each of the radio bearers, with one or more parameters that may be adjusted based on one or both of the reliability target or delay target of the radio bearer.