PDCP-RLC Timer Synchronization to Block Outdated User Plane Packets
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Solution Overview
Problem
XR communications face challenging latency and data rate requirements due to independent functioning of PDCP and RLC layers in the user plane, leading to increased latency and resource inefficiencies from discarded and outdated data packets.
Innovation Solution
Implementing a new timer (t-Receive) at the RLC layer to synchronize with the PDCP layer, along with mechanisms to prevent transmission of outdated packets and synchronize reordering and reception windows between entities, enhancing the user plane protocol stack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If PDCP and RLC layers function independently in the user plane, then protocol simplicity is maintained, but latency increases and resource efficiency deteriorates due to discarded and outdated data packets
Solution Approach 1:
The patent merges the PDCP and RLC layer functions by introducing a receive window mechanism at the RLC layer that synchronizes with the PDCP discard timer. This coordination allows the RLC layer to identify and mark outdated packets before transmission, eliminating redundant transmissions and reducing latency while maintaining protocol simplicity through a unified window management approach.
Solution Approach 2:
The patent applies preliminary action by using the PDCP discard timer to pre-identify outdated packets before they are transmitted. The receive window at the RLC layer is advanced in anticipation of packet discards, allowing the system to prepare for and prevent unnecessary transmissions of outdated data, thereby reducing latency and resource waste.
2Device complexity
If PDCP and RLC layers function independently, then implementation simplicity is maintained, but resource efficiency deteriorates due to unnecessary transmissions and discards
Solution Approach 1:
The patent combines the resource management functions of PDCP and RLC layers through the receive window mechanism. By synchronizing the RLC receive window with the PDCP discard timer, the system efficiently identifies outdated packets and prevents their transmission, reducing energy consumption and resource waste while maintaining implementation simplicity through a unified window advancement approach.
Solution Approach 2:
The patent implements feedback by using the PDCP discard timer status to control the RLC receive window advancement. The system continuously monitors whether packets are outdated based on the discard timer and adjusts the receive window accordingly, creating a feedback loop that optimizes resource usage by preventing transmissions of packets that will be discarded, thereby improving energy efficiency.
Data Source
AI summary
Various aspects of the present disclosure relate to enhancing the functionality of a user plane protocol stack, such as by synchronizing or associating certain aspects of a radio link control (RLC) layer and a Packet Data Convergence Protocol (PDCP) layer to one another. For example, the present disclosure introduces a new timer to the RLC layer that starts when the RLC layer triggers a reordering timer in the PDCP layer (e.g., by the RLC later delivering an out of order data packet to the PDCP layer). As another example, the present disclosure enhances user plane transmissions to avoid, mitigate, and/or prevent the transmission/retransmission of outdated packets, such as outdated RLC data units.