Group Sidelink HARQ Feedback When UE Location Is Unavailable
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Solution Overview
Problem
In wireless communication systems, when location information is unavailable to a receiving UE device, configuring distance-based HARQ feedback can lead to inefficient use of PSFCH resources and unnecessary retransmissions, or conversely, restricting HARQ feedback can degrade service performance.
Innovation Solution
The receiving UE device informs the transmitting UE device about the unavailability of location information, allowing for alternative HARQ feedback mechanisms such as broadcasting a message or establishing a unicast connection to manage HARQ feedback effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If distance-based HARQ feedback is configured when location information is unavailable, then HARQ feedback resources are wasted and unnecessary retransmissions occur, but if HARQ feedback is restricted, then service performance degrades
Solution Approach 1:
The patent changes the feedback mechanism parameter from distance-based HARQ feedback to signal quality-based HARQ feedback. When location information is unavailable, the receiving UE device sends HARQ feedback based on signal quality measurements (e.g., RSRP, SINR) instead of distance calculations, maintaining service reliability while avoiding wasted PSFCH resources
Solution Approach 2:
The patent introduces an intermediary mechanism where the receiving UE device autonomously determines feedback availability and selects appropriate feedback modes. The UE acts as a mediator between the transmitting UE and the HARQ feedback system, deciding whether to send feedback based on location information availability and signal quality, thus optimizing resource usage without degrading service performance
2Loss of information
If location unavailable notification is sent via broadcast, then all UEs receive the notification but unnecessary broadcasting overhead occurs, if sent via unicast, then only the transmitting UE receives it but connection establishment complexity increases
Solution Approach 1:
The patent implements a dynamic notification mechanism where the receiving UE device selects between broadcast and unicast modes based on real-time conditions. If the receiving UE is in RRC connected state with the transmitting UE, it uses unicast notification to save resources. If not connected or for groupcast scenarios, it uses broadcast to ensure all relevant UEs receive the notification. This dynamic selection optimizes both information delivery and resource efficiency
Data Source
AI summary
A receiving user equipment (UE) device sends a location unavailable notification to a transmitting UE device indicating that location information is unavailable. The receiving UE device is one of a group of UE devices receiving a groupcast data transmission from the transmitting UE device where the groupcast data transmission comprises a distance-based hybrid automatic repeat request (HARQ) feedback configuration. The receiving UE determines that location information is unavailable and sends the location unavailable notification. The location unavailable notification may be a broadcast message or message send over unicast communication link.