PDCP Packet-Based DDDS Frame Transmission for QoS Remapping
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Solution Overview
Problem
In next-generation (NG) radio access networks, particularly in 5G New Radio (NR) deployments, the remapping of quality of service (QoS) flows across data radio bearers (DRBs) can lead to significant delays due to the separation of control and user planes, resulting in potential service interruptions and challenges in ensuring in-order delivery of packets during handovers or changes in radio environments.
Innovation Solution
Implementing enhanced flow control mechanisms that trigger Downlink Data Delivery Status (DDDS) feedback immediately upon successful delivery of specific PDCP packets, and buffering PDCP packets in both source and target DRBs during QoS flow remapping, to minimize remapping delays and ensure in-order delivery without impacting other QoS flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If QoS flows are remapped across data radio bearers in separated protocol layer deployments, then network flexibility and scalability are improved, but remapping delays occur causing service interruptions
Solution Approach 1:
The patent applies preliminary action by having the source gNB buffer PDCP packets and prepare remapping in advance before the actual handover or QoS flow remapping occurs. This allows the network to pre-process the remapping operations and trigger DDDS feedback mechanisms proactively, thereby reducing the actual remapping delay and minimizing service interruptions while maintaining network flexibility.
2Reliability
If PDCP packets are buffered during QoS flow remapping, then in-order delivery is ensured, but transmission delay increases
Solution Approach 1:
The patent implements feedback mechanisms where the source gNB monitors PDCP packet delivery status and triggers Downlink Data Delivery Status (DDDS) feedback to the target gNB. This feedback-driven approach allows the system to maintain packet buffering only when necessary for in-order delivery, dynamically adjusting the buffering duration based on actual delivery status, thereby ensuring reliability while minimizing unnecessary transmission delays.
3Adaptability or versatility
If control and user planes are separated in NR deployments, then network architecture scalability is improved, but coordination complexity between gNBs increases
Solution Approach 1:
The patent introduces an intermediary coordination mechanism where the source gNB acts as a mediator that buffers PDCP packets, manages the remapping process, and coordinates with the target gNB through structured DDDS feedback messages. This intermediary approach simplifies the overall coordination complexity by centralizing the remapping management at the source gNB while maintaining the scalable separated control-user plane architecture, as the target gNB only needs to receive and forward packets without complex remapping logic.
Data Source
AI summary
Systems and methods of providing feedback when a specific PDU is successfully delivered or transmitted are described. The node hosting PDCP entity indicates triggering of a DDDS frame from the remote corresponding node. Rather than immediately triggering transmission of a DDDS frame, the node hosting PDCP entity indicates triggering based on successful delivery of a PDU having a specific SN, as long as in-sequence delivery or transmission of PDUs up to the specific SN was successful. The DDDS frame is transmitted once the corresponding node determines that the PDU having the SN was successfully delivered or transmitted. After reporting by the DDDS frame, the QoS flow associated with the PDUs is remapped from a source DRB to a target DRB.