RACH Triggering for Low-Latency D2D Collision Avoidance

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Solution Overview

Problem

Existing methods for providing warnings to vulnerable road users about the presence of moving vehicles are inefficient in terms of battery consumption and latency, and do not adequately address the need for timely collision avoidance.

Innovation Solution

A mobile wireless communication device initiates a Random-Access Channel (RACH) procedure upon entering a potential safety scenario, triggered by a signal from a base station, which includes transmitting or sensing device-to-device (D2D) safety messages to avoid collisions, utilizing D2D resources and reducing power consumption by selective monitoring and localized broadcasting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If a mobile wireless communication device continuously monitors for safety messages to enable timely collision avoidance, then the latency for warning vulnerable road users is reduced, but battery consumption increases

Engineering Contradiction:

ImprovelatencyVSAvoidbattery consumption

Core Design Contradiction:

Loss of timeVSUse of energy by moving object

Solution Approach 1:

The base station performs preliminary actions by pre-configuring D2D resources and transmitting indication messages to mobile devices before collision scenarios occur. When a mobile device enters a monitored area, the base station proactively triggers the RACH procedure and provides D2D resource allocations in advance, eliminating the need for continuous monitoring while enabling rapid response when needed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of continuous monitoring, the system uses periodic triggered actions. The base station periodically monitors device locations and triggers safety procedures only when devices enter predefined zones or potential collision scenarios are detected, converting continuous energy-consuming monitoring into intermittent, event-driven communication.

Inventive Principle:

Principle #19Periodic action

2Device complexity

If existing methods provide warnings to vulnerable road users without network coordination, then device complexity is reduced, but the efficiency and timeliness of collision avoidance deteriorates

Engineering Contradiction:

Improvedevice complexityVSAvoidefficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The base station serves as an intermediary that coordinates safety messaging without requiring complex peer-to-peer negotiation between mobile devices. The network infrastructure manages resource allocation, triggers RACH procedures, and facilitates D2D communication, simplifying device complexity while improving overall system efficiency through centralized coordination.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12520372B2Local broadcast to trigger RACH procedure as part of initiation of collision-avoidance procedure

Publication Date: 2026.01.06 KYOCERA CORP

AI summary

The methods, devices, and systems discussed herein involve a mobile wireless communication device (WCD) receiving a signal containing an indicator upon entering a first area that is near a potential safety scenario, such as an intersection. In response to receiving the signal, the WCD initiates a Random-Access Channel (RACH) procedure, which triggers initiation of a collision-avoidance procedure. In some examples, the collision-avoidance procedure includes abase station transmitting a safety message that indicates the presence of the mobile WCD. In other examples, the collision-avoidance procedure includes the mobile WCD transmitting a device-to-device (D2D) safety message using D2D resources. In further examples, the collision-avoidance procedure includes the mobile WCD sensing D2D resources in order to detect D2D transmissions from a D2D-capable device.