Sidelink HARQ Timer Management for PUCCH Transmission Reliability
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Solution Overview
Problem
In wireless communication systems, particularly in 5G networks, devices face challenges with discontinuous reception (DRX) during sidelink communication, leading to issues with measurement gaps and Listen-Before-Talk (LBT) failures, which result in failed HARQ feedback transmissions and subsequent retransmission delays due to unstarted timers.
Innovation Solution
A method where a first device in a wireless communication system receives a sidelink grant and starts or restarts a timer for the HARQ process after the end of a Physical Uplink Control Channel (PUCCH) resource, even if no sidelink HARQ feedback is transmitted due to measurement gaps or LBT failures, ensuring timely retransmissions by monitoring the Physical Downlink Control Channel (PDCCH) when specific timers expire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the device waits for PUCCH transmission to complete before starting the HARQ timer, then the timer starts at the correct time, but retransmission is delayed when measurement gaps or LBT failures occur
Solution Approach 1:
The patent applies preliminary action by starting the HARQ timer at the expected PUCCH transmission time rather than waiting for actual transmission completion. This proactive approach ensures the timer is already running when measurement gaps or LBT failures occur, enabling timely retransmission without unnecessary delays.
2Reliability
If the device continuously monitors PDCCH, then retransmission can be detected quickly, but energy consumption increases
Solution Approach 1:
The patent implements periodic action through DRX (Discontinuous Reception) mechanisms where the device monitors PDCCH periodically based on timer status rather than continuously. When the HARQ timer is running, the device activates PDCCH monitoring; when stopped, it enters low-power mode, achieving energy-efficient periodic monitoring that balances reliability and power consumption.
Data Source
AI summary
Methods, systems, and apparatuses can comprise receiving a Sidelink (SL) grant, wherein the SL grant indicates a SL transmission, starting or restarting a first timer for a SL Hybrid Automatic Repeat Request (HARQ) process in a first symbol after the end of a Physical Uplink Control Channel (PUCCH) resource associated with the SL grant, or the SL transmission, when the first device does not transmit a SL HARQ feedback for the SL HARQ process on the PUCCH resource due to measurement gap or Listen-Before-Talk (LBT) failure, starting or restarting a second timer for the SL HARQ process in a first symbol, after the first timer expires, when the first device does not transmit the SL HARQ feedback for the SL HARQ process on the PUCCH resource due to measurement gap, or LBT failure, and the SL HARQ feedback is a negative acknowledgement, and monitoring a Physical Downlink Control Channel (PDCCH) when the second timer is running.