Sidelink DRX Source Ranking for Synchronized UE Sleep Cycles

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Solution Overview

Problem

Existing wireless communication systems face challenges in implementing discontinuous reception (DRX) on sidelinks due to the lack of a central point for synchronizing DRX cycles among user devices, leading to increased power consumption in devices with limited power supplies.

Innovation Solution

A hierarchical DRX configuration source selection mechanism is introduced, where user devices prioritize DRX configurations from ranked sources, including base stations and other user devices, to synchronize DRX cycles and align ON durations, reducing power consumption by ensuring synchronized sleep and wake cycles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If DRX cycles are implemented on sidelinks without a central synchronization point, then devices can operate independently, but power consumption increases due to misaligned sleep and wake cycles

Engineering Contradiction:
Improvepower consumptionVSAvoidsynchronization mechanism complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent introduces a base station as a central intermediary to synchronize DRX cycles among multiple user devices. The base station configures and coordinates the DRX parameters (cycle length, ON duration, offset) for all devices in the cell, ensuring their sleep and wake cycles are aligned. This mediator approach resolves the contradiction by providing centralized control that reduces power consumption through synchronized DRX operation, while the complexity is managed by the network infrastructure rather than individual devices.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If DRX ON duration is extended to capture retransmissions, then reliability improves, but power consumption increases

Engineering Contradiction:
Improvetransmission reliabilityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic DRX configuration where the base station can adjust DRX parameters (cycle length, ON duration, offset) based on traffic conditions and device behavior. The system transitions between different DRX states (short cycle, long cycle, on-demand) to balance reliability and power consumption. This dynamic adaptation allows the system to extend ON duration only when necessary for retransmissions while returning to shorter cycles for normal operation, resolving the contradiction between reliability and power usage.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent employs feedback mechanisms where devices report their DRX status and traffic patterns to the base station, which then optimizes DRX configuration. The base station monitors transmission success rates and adjusts DRX parameters accordingly, extending ON duration only when retransmissions are likely while maintaining power efficiency during stable transmission conditions. This feedback-driven approach balances reliability requirements with power consumption constraints.

Inventive Principle:
Principle #23Feedback

3Reliability

If devices use shorter DRX cycles to miss fewer transmissions, then reliability improves, but power savings decrease

Engineering Contradiction:
Improvetransmission detection reliabilityVSAvoidpower savings
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic DRX cycle length adjustment, allowing devices to switch between short and long DRX cycles based on traffic conditions. During active transmission periods, shorter cycles are used to ensure reliable detection of transmissions and retransmissions. During idle periods, the system transitions to longer DRX cycles to maximize power savings. This dynamic adaptation resolves the contradiction by using short cycles only when necessary for reliability while leveraging long cycles for power efficiency during stable conditions.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4104629B1Apparatus and method for sidelink discontinuous reception
Publication Date: 2026.03.25 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP4104629B1 patent drawingFigure 1(a)~1(b)
  • EP4104629B1 patent drawingFigure 2~3
  • EP4104629B1 patent drawingFigure 4(a)

AI summary

A user device, UE, for a wireless communication system is described. The wireless communication system includes a plurality of user devices, UEs. The UE communicates with one or more further UEs using a sidelink, SL. To operate in a Discontinuous Reception, DRX, mode, the UE receives a DRX configuration from one of a plurality of DRX configuration sources. The plurality of DRX configuration sources are ranked such that each of the DRX configuration sources has a rank different from the remaining DRX configuration sources, and the UE is to select the DRX configuration from the DRX configuration source having the highest rank among the available DRX configuration sources.