Relay Communication Management for Cellular Radio Link Failure

Solution Overview

Problem

Conventional wireless communication systems face challenges in managing relay connections when a radio link failure occurs, particularly in distinguishing between Uu link and PC5 link failures, leading to inefficiencies in relay reselection processes and potential loss of connectivity for out-of-coverage UE devices.

Innovation Solution

The system introduces mechanisms for UE devices to manage relay reselection by refraining from sending signals through the initial relay upon receiving a Uu radio link failure notification, maintaining a candidate relay list, and performing relay reselection based on RRC connection status and SD-RSRP levels, allowing for efficient reconnection to the base station through alternative relay devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the remote UE device continues to send signals through the initial relay UE device after Uu link failure, then the device complexity is reduced, but the reliability of communication is worsened due to potential connectivity loss

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidrelay management complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The remote UE device performs relay reselection in advance upon receiving RLF notification, before the Uu link is fully lost. The device identifies and selects alternative relay UE devices while maintaining the current connection, so that when the link fails, the switch to alternative relay is immediate, ensuring continuous communication without interruption

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary mechanism where the remote UE device monitors RLF notifications and manages multiple relay UE devices. This intermediary layer handles the complexity of relay management, allowing the device to seamlessly switch between relays and maintain reliable communication without requiring complex end-to-end protocols

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of time

If the remote UE device performs relay reselection immediately upon receiving RLF notification, then the latency is reduced, but the device complexity increases due to additional relay selection procedures

Engineering Contradiction:

Improvereconnection latencyVSAvoidrelay reselection complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The remote UE device performs relay reselection in advance upon receiving RLF notification, before the Uu link is fully lost. The device identifies and selects alternative relay UE devices while maintaining the current connection, so that when the link fails, the switch to alternative relay is immediate, ensuring continuous communication without interruption

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements partial relay reselection where the remote UE device maintains connections to multiple relay UE devices simultaneously. When RLF occurs, the device can immediately switch to an alternative relay without completing full reselection procedures, reducing latency while minimizing the complexity overhead by performing only necessary actions

Inventive Principle:

Principle #16Partial or excessive action

3Productivity

If the remote UE device maintains connection through the initial relay UE device without reselection, then the device complexity is minimized, but the productivity is worsened due to communication interruptions

Engineering Contradiction:

Improvecommunication continuityVSAvoidrelay management complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The remote UE device performs relay reselection in advance upon receiving RLF notification, before the Uu link is fully lost. The device identifies and selects alternative relay UE devices while maintaining the current connection, so that when the link fails, the switch to alternative relay is immediate, ensuring continuous communication without interruption

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where the remote UE device monitors the status of the Uu link through RLF notifications from the relay UE device. Based on this feedback, the device automatically triggers relay reselection procedures, enabling adaptive communication continuity without requiring complex manual intervention or pre-configuration

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20240214900A1Relay communication management in response to cellular connection radio link failure (RLF)

Publication Date: 2024.06.27 KYOCERA CORP

AI summary

An initial relay user equipment (UE) device transmits a llu radio link failure (RLE) notification to a remote UE device when the Uu communication link from the initial relay UE device to the serving base station fails. The remote UE device refrains from sending signals to the serving base station through the initial relay UE device at least until receiving a Uu link reestablished notification indicating that the Uu communication link has been reestablished. In some situations, the remote UE device identifies a preferred candidate relay UE device after receiving the Uu RLF notification and selects the preferred candidate relay UE device for relay communication in response to receiving a Uu link reestablished notification indicating the Uu communication link could not be reestablished.