Sidelink Relay UE RRC Triggering for Low-Latency V2X Links

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Solution Overview

Problem

Existing wireless communication systems face challenges in efficiently managing RRC connection requests from relay UEs in sidelink communication, particularly in scenarios requiring high reliability and low latency, such as vehicle-to-everything (V2X) applications, which are not adequately addressed by current radio access technologies.

Innovation Solution

The proposed solution involves optimizing the RRC connection process for relay UEs in sidelink communication by implementing enhanced resource allocation mechanisms, including both network-scheduled and autonomously selected resource allocation modes, to improve communication efficiency and reliability in V2X scenarios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If relay UE uses conventional RRC connection establishment procedures, then connection can be established, but connection establishment time and latency are excessive for V2X applications

Engineering Contradiction:
ImproveRRC connection establishment timeVSAvoidconnection reliability
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The relay UE performs RRC connection establishment in advance before actual data transmission is needed. The UE establishes the RRC connection proactively when entering the network or when predicting potential communication needs, so that when V2X data transmission is required, the connection is already in place, eliminating establishment delay and ensuring immediate reliable communication.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces dynamic state transitions for the relay UE, allowing it to switch between RRC_IDLE and RRC_CONNECTED states based on predicted communication needs. The UE can transition to connected state proactively when certain conditions are met (e.g., entering service area, detecting potential traffic), enabling adaptive connection management that reduces latency while maintaining reliability only when needed.

Inventive Principle:
Principle #15Dynamics

2Loss of time

If relay UE establishes RRC connection proactively, then latency is reduced, but network resource consumption increases

Engineering Contradiction:
Improveconnection establishment latencyVSAvoidnetwork resource consumption
Core Design Contradiction:
Loss of timeVSUse of energy by moving object

Solution Approach 1:

The relay UE applies different connection strategies to different communication scenarios. For high-priority V2X services requiring low latency, the UE maintains proactive connected state. For lower-priority or less time-sensitive communications, the UE remains in idle state and establishes connection only when needed. This localized application of connection establishment based on service requirements optimizes the balance between latency and resource consumption.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the parameter of connection state timing based on service requirements and network conditions. Instead of always maintaining connected state or always using conventional establishment, the UE dynamically adjusts when to establish or maintain connection based on QoS parameters, traffic patterns, and network status, thereby optimizing resource usage while meeting latency requirements for critical services.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If relay UE uses conventional resource allocation, then resource management is simplified, but communication efficiency and reliability are insufficient for V2X

Engineering Contradiction:
Improvecommunication efficiencyVSAvoidresource allocation complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The resource allocation is segmented into different pools: dedicated resources for high-priority V2X communications, shared resources for lower-priority traffic, and dynamic resources for adaptive allocation. The relay UE can select from multiple resource pools based on service requirements, allowing efficient resource utilization for time-critical V2X applications while maintaining manageable complexity through structured resource categorization.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The relay UE is designed to support multiple resource allocation modes (dedicated, shared, dynamic) within a single device, enabling it to adapt to different V2X service requirements using the same hardware and protocol stack. This multi-functionality allows the UE to efficiently handle both low-latency critical communications and best-effort traffic without requiring separate specialized systems.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4333544B1Operation method of relay UE in sidelink in wireless communication system
Publication Date: 2025.11.19 LG ELECTRONICS INC
  • EP4333544B1 patent drawingFigure 1
  • EP4333544B1 patent drawingFigure 2
  • EP4333544B1 patent drawingFigure 3(a)~3(b)

AI summary

A sidelink relay related operating method of a relay user equipment (UE) in a wireless communication system includes receiving a first message including a first cause value from a remote UE by the relay UE, configuring a second cause value based on the first cause value by the relay UE, and attempting RRC connection to a base station (BS) by transmitting a second message including the second cause value by the relay UE, and in this case, the first message is related to trigger of attempting RRC connection, and whether configuration of the second cause value of the relay UE is dependent upon the first cause value is determined based on a type of the first cause value.