NR V2X UE Power Management via Mandatory Slot Alignment
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Solution Overview
Problem
In New Radio (NR) vehicle-to-everything (V2X) communications, pedestrian UEs (PUEs) face challenges with high power consumption during resource selection procedures, as they need to continuously monitor all subchannels to avoid collisions, which is not feasible due to limited power resources, and existing power-saving techniques like partial sensing and random resource selection do not guarantee Tx and Rx alignment, leading to potential communication failures.
Innovation Solution
The introduction of mandatory slots for Tx and Rx alignment, where UEs must monitor specific slots to receive alignment information, and dynamic resource reselection procedures to allow PUEs to conserve power while ensuring communication reliability, including pre-emption mechanisms and wake-up/sleep signaling to optimize power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PUEs continuously monitor all subchannels to avoid collisions, then collision avoidance is improved, but power consumption increases
Solution Approach 1:
The patent applies partial sensing instead of continuous full monitoring. PUEs monitor only a subset of subchannels during specific sensing occasions rather than all subchannels continuously, reducing power consumption while maintaining adequate collision avoidance capability through selective monitoring of critical resources
Solution Approach 2:
The patent implements periodic sensing and monitoring at specific intervals and occasions rather than continuous monitoring. PUEs wake up at predetermined sensing occasions to monitor subchannels and return to sleep mode, creating a periodic action pattern that reduces power consumption while maintaining communication reliability
2Use of energy by moving object
If PUEs use partial sensing and random resource selection to save power, then power consumption is reduced, but collision protection decreases
Solution Approach 1:
The patent incorporates feedback mechanisms where PUEs exchange sensing results and resource selection information with neighboring UEs through SCI messages. This feedback allows UEs to adjust their resource selection based on observed channel conditions and neighboring transmissions, improving collision protection despite using partial sensing
Solution Approach 2:
The patent implements preliminary resource reservation and sensing before actual transmissions. PUEs perform sensing and select resources in advance during wake-up periods, reserve these resources through SCI signaling, and then can sleep until the next sensing occasion, ensuring collision protection is established before power-saving mode activates
3Use of energy by moving object
If LTE partial sensing and random selection are used in NR V2X, then power saving is achieved, but Tx and Rx alignment is not guaranteed
Solution Approach 1:
The patent merges Tx and Rx operations into aligned time windows. PUEs coordinate their transmission and reception activities to occur during the same wake-up periods, ensuring that when one UE is transmitting, the receiving UE is also awake and monitoring, thus guaranteeing Tx and Rx alignment while maintaining power-saving benefits
Solution Approach 2:
The patent makes the wake-up window serve multiple functions simultaneously: it is used for both sensing/monitoring incoming transmissions and for actual data transmission. This multi-functionality ensures that PUEs are guaranteed to be listening when neighbors transmit (Rx function) while also enabling them to transmit their own data (Tx function) during the same period, achieving both alignment and power saving
Data Source
AI summary
A method and apparatus are provided for pre-emption, congestion control, and transmission (Tx)/reception (Rx) alignment for use by user equipments (UEs) with limited power. The method includes identifying a set of mandatory slots per at least one resource pool or bandwidth part (BWP); monitoring the set of mandatory slots; and receiving transmission (Tx) and reception (Rx) alignment information during at least one of the monitored mandatory slots.