NR V2X Sidelink HARQ Feedback via Uplink During DRX Off-Time
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Solution Overview
Problem
In NR V2X sidelink communication, transmission resources allocated by the base station may be wasted due to the UE performing sidelink discontinuous reception (SL DRX) operations, particularly for transmitting UEs using resource allocation mode 1, as these resources fall outside the active time period.
Innovation Solution
A method for a transmitting UE to transmit Hybrid Automatic Repeat Request (HARQ) feedback to the base station using uplink resources, optimizing resource allocation and utilization within the SL DRX active time period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a transmitting UE is allocated transmission resources outside the SL DRX active time period to enable continuous sidelink communication, then communication continuity is improved, but resource waste occurs because the receiving UE cannot receive transmissions during its off-duration periods
Solution Approach 1:
The transmitting UE reports SL HARQ feedback information to the base station, enabling the network to understand the actual reception status. This feedback mechanism allows the base station to make informed resource allocation decisions that balance communication continuity with resource efficiency, preventing waste by aligning allocations with actual UE availability during SL DRX active periods.
Solution Approach 2:
The system dynamically adjusts resource allocation based on SL DRX configurations and HARQ feedback. The base station can modify transmission resource assignments in real-time according to the receiving UE's active time periods and actual reception outcomes, optimizing both communication continuity and resource utilization rather than using static allocation.
2Ease of operation
If the base station allocates transmission resources without considering SL DRX active time periods, then resource allocation simplicity is maintained, but resource utilization efficiency deteriorates due to allocations falling outside active periods
Solution Approach 1:
By implementing SL HARQ feedback reporting, the system gains visibility into actual reception success without significantly complicating the allocation process. The base station receives feedback information that guides future allocations, maintaining operational simplicity while dramatically improving resource utilization efficiency through informed decision-making.
Solution Approach 2:
The base station can pre-configure resource allocations based on known SL DRX patterns before transmissions occur. By anticipating which time periods will fall within active durations, the network can proactively allocate resources that are guaranteed to be usable, improving efficiency without requiring complex real-time adjustments.
3Duration of action of moving object
If transmission resources are allocated outside SL DRX active time periods, then the transmitting UE can maintain continuous transmission capability, but the receiving UE experiences increased power consumption as it must remain active to receive allocations
Solution Approach 1:
The SL HARQ feedback mechanism provides the base station with information about successful receptions, enabling it to optimize resource allocation timing. The network can schedule transmissions to coincide with active periods identified through feedback, ensuring the receiving UE only needs to be active when transmissions are actually scheduled, thereby reducing unnecessary power consumption while maintaining transmission capability.
Solution Approach 2:
The system leverages the periodic nature of SL DRX cycles to align transmissions with active periods. By scheduling resources periodically according to known DRX patterns and confirmed through HARQ feedback, the receiving UE can enter sleep modes during off-periods with confidence that no transmissions will occur, reducing power consumption while the transmitting UE maintains continuous operational capability.
Data Source
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AI summary
According to an embodiment of the present disclosure, provided is a method for performing wireless communication by a first apparatus. The method may comprise: obtaining sidelink (SL) discontinuous reception (DRX) configuration including information related to an active time of a second apparatus, receiving, from a base station, first information related to a first SL resource and second information related to an uplink (UL) resource, and transmitting, to the base station, SL hybrid automatic repeat request (HARQ) feedback information on the UL resource based on a time domain of the first SL resource not being included within the active time of the second apparatus. The SL HARQ feedback information may be SL HARQ acknowledge (ACK) information.