5G UM RLC SDU Forwarding Without Reordering Delay
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Solution Overview
Problem
In 5G networks, the functions of reordering and duplicate detection are no longer performed at the RLC layer in the unacknowledged mode (UM), necessitating efficient data transmission methods at this layer to avoid processing delays.
Innovation Solution
The method involves determining whether an RLC PDU includes a complete SDU or an SDU segment, and transmitting the complete SDU or assembled SDU segments to the PDCP layer using buffer windows, timers, or indicator fields to ensure timely delivery, thereby avoiding buffer occupation and reducing transmission overheads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reordering and duplicate detection are performed at the RLC layer in UM mode, then data transmission reliability is improved, but processing delay increases
Solution Approach 1:
The patent extracts the reordering and duplicate detection functions from the RLC layer and relocates them to the PDCP layer. This allows the RLC layer in UM mode to operate without these processing functions, thereby reducing processing delay while the PDCP layer handles reordering and duplicate detection to maintain data transmission reliability.
2Reliability
If SDU segments are buffered at the RLC layer for assembly, then complete SDUs are delivered to PDCP layer, but buffer occupancy increases
Solution Approach 1:
The patent transfers the SDU assembly function from the RLC layer to the PDCP layer. The RLC layer in UM mode no longer buffers SDU segments for assembly, which reduces buffer occupancy. The PDCP layer receives RLC PDUs and performs the assembly of SDU segments into complete SDUs, ensuring reliable delivery while minimizing buffer usage at the RLC layer.
3Adaptability or versatility
If RLC layer performs segmentation and concatenation, then data adaptation to MAC layer is improved, but processing complexity increases
Solution Approach 1:
The patent extracts the segmentation and concatenation functions from the RLC layer and relocates them to the PDCP layer. This reduces the processing complexity of the RLC layer in UM mode, as it no longer needs to perform these operations. The PDCP layer handles segmentation and concatenation to adapt data to MAC layer requirements, maintaining adaptability while simplifying RLC layer processing.
Data Source
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AI summary
This application provides a data transmission method, apparatus, and system, and a device. The method includes: receiving, by a receive end, a Radio Link Control protocol data unit (RLC PDU); determining, by the receive end, whether the RLC PDU includes a complete service data unit (SDU) or an SDU segment, where the RLC PDU is transmitted in unacknowledged mode (LTM); and transmitting, by the receive end to a Packet Data Convergence Protocol (PDCP) layer based on a result of the determining, the complete SDU or a complete SDU assembled by using the SDU segment. The data transmission method, apparatus, and system, and the device provided in this application implement data transmission in UM at an RLC layer in 5G.