NR V2X UE Sleep Mode via HARQ ACK and SCI
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Solution Overview
Problem
In NR V2X communication, user equipment (UE) must maintain an active state for a predetermined time to receive and transmit messages, leading to increased power consumption and reduced battery life.
Innovation Solution
A method where a UE receives a physical sidelink control channel (PSCCH) and a physical sidelink shared channel (PSSCH) from another device, determines a PSFCH resource, transmits SL HARQ ACK information, and enters a sleep state if the PSSCH is the last transmission, as indicated by the sidelink control information (SCI).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE maintains active state for predetermined time to receive and transmit messages, then communication reliability is improved, but power consumption increases
Solution Approach 1:
The patent applies dynamics by making the UE's operational state flexible rather than fixed. The UE dynamically transitions between active and sleep states based on real-time communication needs and HARQ feedback, allowing the system to adapt the active state duration to actual requirements rather than maintaining a predetermined active state regardless of communication completion.
Solution Approach 2:
The patent utilizes feedback mechanisms where the UE receives HARQ feedback information from the network and adjusts its state accordingly. The feedback from HARQ ACK/NACK decisions enables the UE to determine when communication is complete and can safely transition to sleep state, thereby optimizing the balance between reliability and power consumption based on actual communication outcomes.
2Use of energy by moving object
If UE enters sleep state immediately after transmission, then power consumption is reduced, but communication reliability may deteriorate
Solution Approach 1:
The patent applies preliminary action by having the UE prepare and transmit HARQ feedback information before finalizing the sleep state transition. The UE determines the PSFCH resource and transmits HARQ ACK/NACK feedback in advance, ensuring that the network is notified of the transmission status before the UE enters sleep state, thus maintaining reliability while enabling early power savings.
3Reliability
If UE transmits HARQ feedback for every transmission, then communication reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by differentiating the treatment of different transmissions based on their characteristics. The UE determines whether to transmit HARQ feedback for each specific transmission based on local conditions such as transmission success, data type, and network configuration, rather than uniformly applying feedback transmission to all cases. This selective approach reduces device complexity while maintaining necessary reliability.
Data Source
AI summary
Proposed is a method for performing wireless communication by a first device. The method may comprise the steps of: receiving a physical sidelink control channel (PSCCH) from a second device; receiving a physical sidelink shared channel (PSSCH) related to the PSCCH from the second device, wherein sidelink control information (SCI) is received via the PSCCH or the PSSCH related to the PSCCH, and the SCI includes information indicating whether the PSSCH corresponds to last PSSCH transmission: determining a PSFCH resource on the basis of a slot index and a sub-channel index which are related to the PSSCH: transmitting SL HARQ ACK information to the second device via the PSFCH resource; and entering a sleep state on the basis that the SCI includes information indicating that the PSSCH corresponds to the last PSSCH transmission, and the first device transmits the SL HARQ ACK information via the PSFCH resource.