Sidelink Mode-1 Grant Scheduling Around SL DRX Active Time
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Solution Overview
Problem
Sidelink mode-1 grants are dropped due to misalignment with the discontinuous reception active time of target devices, leading to poor reliability, increased latency, and excessive power consumption in sidelink communication.
Innovation Solution
A mechanism where the transmitting user equipment (TX UE) reports a message to the base station (gNB) indicating the cause of grant drop and proposes a resolution, allowing the gNB to align subsequent grants with the active states of the receiving user equipment (RX UE) to avoid future misalignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sidelink mode-1 grants are scheduled without alignment with RX UE active time, then scheduling simplicity is maintained, but grant reliability deteriorates due to drops
Solution Approach 1:
The transmitting UE sends a feedback message to the base station indicating that a grant was dropped due to misalignment with RX UE active time. The base station uses this feedback to adjust future grant scheduling, ensuring alignment with active times and preventing repeated drops.
Solution Approach 2:
The grant scheduling system transitions from a static, fixed scheduling approach to a dynamic approach where the base station adjusts grant timing based on real-time information about RX UE active states and feedback about dropped grants, enabling adaptive alignment.
2Use of energy by moving object
If grants are continuously sent without DRX alignment, then communication productivity is maintained, but power consumption increases due to unnecessary RX UE activation
Solution Approach 1:
The base station proactively adjusts grant scheduling based on predicted or known RX UE active times, ensuring grants are sent only when the RX UE is awake and ready to receive, preventing wasted energy from unnecessary reception attempts.
Solution Approach 2:
Feedback information about grant drops and RX UE active state patterns enables the base station to optimize scheduling, sending grants only during appropriate time windows when the RX UE is active, thereby reducing power consumption without sacrificing communication effectiveness.
3Loss of time
If misalignment between grants and active time is allowed, then scheduling flexibility is maintained, but latency increases due to retransmission requirements
Solution Approach 1:
The scheduling system dynamically adapts to changing active time patterns and feedback about dropped grants, adjusting grant timing in real-time to minimize latency while maintaining flexibility for various communication scenarios.
Solution Approach 2:
The base station uses feedback information to predict future misalignment issues and proactively adjusts scheduling to prevent latency-causing retransmissions before they occur, optimizing timing while preserving scheduling flexibility.
Data Source
AI summary
A UE may receive a first grant for sidelink transmission; determine that respective inactive states, of one or more target user equipments, at least partially overlap with the first grant for sidelink transmission; determine dropping of the first grant for sidelink transmission; transmit, to a base station, a message regarding dropping of the first grant for sidelink transmission, wherein the message comprises at least one of: an indication of a cause for the dropping of the first grant for sidelink transmission, or an indication of information configured to enable avoidance of dropping of a grant for sidelink transmission; and receive a second grant for sidelink transmission, wherein the second grant for sidelink transmission overlaps with at least one respective active state of the one or more target user equipment, wherein the second grant for sidelink transmission is at least partially different from the first grant for sidelink transmission.