Relay UE Reflective QoS Indicator Mapping
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Solution Overview
Problem
Existing solutions for reflective quality-of-service (QoS) in Layer-3 UE-to-Network relays face challenges in supporting end-to-end QoS requirements, particularly in deriving the 5QI value for PC5 QoS flows and lack support for UE-to-UE relays, leading to inefficiencies in QoS management across multiple hops.
Innovation Solution
The method involves a relay UE adding reflective QoS indicators to downlink packets to configure corresponding PC5 QoS flows, using UE capability indicators to determine QoS support, and applying derived mapping relations to uplink packets, enabling dynamic QoS handling without explicit SMF intervention, and maintaining mapping tables between QoS Flow Identifiers and data radio bearers to ensure consistent QoS across links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If reflective QoS indicators are added to downlink packets to configure PC5 QoS flows, then dynamic QoS handling is improved, but device complexity increases due to the need to derive and apply QoS rules
Solution Approach 1:
The relay UE autonomously derives QoS rules from reflective QoS indicators contained in downlink packets without requiring explicit configuration from the network. The relay UE extracts QoS parameters from the received packets and automatically applies them to configure PC5 QoS flows, enabling self-service QoS management that reduces signaling overhead while maintaining dynamic adaptability
Solution Approach 2:
The system implements feedback mechanisms where the relay UE monitors downlink packet characteristics and uses this information to dynamically adjust QoS rules for uplink traffic. The reflective QoS indicators provide feedback about network conditions and requirements, allowing the relay UE to adaptively configure PC5 flows based on actual traffic patterns and network state
2Reliability
If QoS requirements are split and satisfied over two legs (PC5 and Uu), then end-to-end QoS is improved, but loss of time increases due to the need to coordinate QoS across multiple links
Solution Approach 1:
The relay UE performs preliminary QoS rule derivation from downlink packets before uplink traffic needs to be transmitted. By pre-configuring PC5 QoS flows based on reflective indicators received in downlink direction, the system prepares QoS parameters in advance, avoiding time-consuming coordination delays when uplink traffic arrives
Solution Approach 2:
The end-to-end QoS management is segmented into independent manageable parts: downlink QoS indicator reception, QoS rule derivation, PC5 flow configuration, and Uu link coordination. This segmentation allows parallel processing of QoS setup tasks and reduces sequential coordination overhead between the two legs
3Stability of the object's composition
If mapping tables between QoS Flow Identifiers and data radio bearers are maintained, then QoS consistency is improved, but device complexity increases due to table management overhead
Solution Approach 1:
The mapping tables for QoS Flow Identifier to data radio bearer relationships are merged and maintained centrally at the relay UE rather than distributed across multiple nodes. This consolidation ensures consistent QoS mapping across PC5 and Uu links while centralizing management responsibilities, reducing the overall system complexity despite the detailed tracking required
Data Source
AI summary
A relay UE (502) having a PC5 link with a remote UE (501) creates a modified downlink (DL) packet by adding one or more reflective quality-of-service (QoS) indicators to the DL packet and transmits the modified DL packet on the PC5 link in a PC5 QoS flow to the remote UE. The remote UE receives the modified DL packet, uses the one or more reflective QoS indicators to derive one or more mapping relations, and applies the one or more derived mapping relations to map an uplink (UL) packet to the QoS flow and transmit the UL packet on the PC5 link. The relay UE receives the UL packet and transmits the UL packet to a network node (504) or a second relay UE.