NR V2X Sidelink HARQ Feedback Control by UE Locality
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Solution Overview
Problem
In wireless communications networks, particularly in New Radio Vehicle to Everything (NR V2X) groupcast sidelink communications, Hybrid Automatic Repeat Request (HARQ) feedback can lead to excessive overhead and latency issues due to frequent retransmissions when one UE in a group fails to receive data, especially in large groups or congested scenarios.
Innovation Solution
A method is proposed to define a critical communication area for receive UEs, using sidelink communications to determine the locality of transmit UEs, and enable/disable HARQ feedback based on whether the transmit UE locality coincides with this critical area, utilizing network and UE conditions to set constraints on this area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ feedback is enabled for all groupcast transmissions, then reliability of data reception is improved, but control overhead increases significantly
Solution Approach 1:
The patent applies local quality by enabling HARQ feedback selectively based on the spatial relationship between transmit and receive UEs. Specifically, HARQ feedback is enabled only when the transmit UE is located within a critical communication area of the receive UE, while disabled outside this area. This localized approach ensures high reliability for critical local communications while reducing overall control overhead across the entire groupcast system.
Solution Approach 2:
The patent implements dynamics by making the HARQ feedback configuration adaptive rather than static. The gNB dynamically configures HARQ feedback enablement based on real-time location information of UEs. The critical communication area is determined using network conditions and UE conditions, allowing the system to adapt HARQ feedback behavior to changing spatial and channel conditions, thereby optimizing the trade-off between reliability and overhead.
2Reliability
If HARQ feedback is enabled for large groups, then reception reliability is improved, but latency increases due to frequent retransmissions
Solution Approach 1:
The patent reduces latency in large groups by applying local quality - enabling HARQ feedback only for UEs within the critical communication area where reliable reception is critical. For UEs outside this area, particularly in large dispersed groups, HARQ feedback is disabled, avoiding the latency penalty of retransmissions for non-critical receivers while maintaining reliability for those who need it.
Solution Approach 2:
The patent applies partial action by enabling HARQ feedback for only a subset of receive UEs (those within the critical communication area) rather than for all group members. This selective approach provides sufficient reliability for critical local communications while avoiding the excessive retransmissions that would occur if feedback were enabled for all UEs in large groups, thereby reducing overall latency.
3Reliability
If HARQ feedback is enabled in congested scenarios, then data reception reliability is improved, but network throughput decreases
Solution Approach 1:
The patent addresses the throughput-reliability trade-off in congested scenarios by dynamically configuring HARQ feedback based on UE location and network conditions. The gNB determines the critical communication area considering current network load and channel conditions, enabling HARQ feedback only where necessary for reliability while allowing data to flow more freely in congested areas outside the critical zone, thereby maintaining higher overall network throughput.
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AI summary
Methods for performing location functions in a wireless communications using user equipment devices which communicate using a sidelink communication link. Information may be transmitted from a transmit user equipment to a receive user equipment, and the information may be utilised to establish a locality of the transmit user equipment. If it is determined that the transmit user locality coincides with a communication area of the receive user equipment HARQ feedback may be enabled.