Network-Assisted Sidelink Beam Failure Recovery in DRX Mode

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Solution Overview

Problem

In wireless communication systems, particularly in NR and LTE, sidelink beam failures during discontinuous reception (DRX) mode lead to resource conflicts and difficulties in reestablishing communication links, resulting in wasted time, frequency, and power resources due to conflicting sleep states of UEs.

Innovation Solution

A base station assists in sidelink beam failure recovery by determining and transmitting resource sets to UEs, ensuring they can reestablish communication links efficiently, even during DRX mode, by coordinating resource allocation and wake-up signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If UEs operate in DRX mode to conserve power, then power consumption is reduced, but beam failure detection and recovery is delayed or missed

Engineering Contradiction:

Improvepower consumptionVSAvoidbeam failure detection reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The base station pre-configures UEs with multiple candidate beam pairs and recovery resources before beam failure occurs. During DRX sleep periods, UEs can still detect beam failures using pre-configured reference signals, and the base station has recovery resources ready to immediately reestablish links when UEs wake up, eliminating the need to stay awake for continuous monitoring.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The base station acts as an intermediary that coordinates between UEs in DRX mode and the sidelink communication. It monitors for beam failures using uplink reference signals from UEs, determines appropriate recovery beam pairs, and allocates recovery resources, thereby enabling reliable beam failure detection and recovery without requiring UEs to remain awake.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If UEs continuously monitor for beam failures, then detection reliability is improved, but power consumption increases

Engineering Contradiction:

Improvebeam failure detection reliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Instead of continuous monitoring, the system uses periodic monitoring aligned with DRX wake-up periods. UEs perform beam failure detection at scheduled intervals when awake, and the base station uses periodic uplink reference signals to monitor UE status. This periodic approach maintains detection capability while allowing UEs to sleep between periods, significantly reducing power consumption.

Inventive Principle:

Principle #19Periodic action

3Speed

If beam failure recovery resources are allocated without coordination, then recovery speed is improved, but resource conflicts occur between UEs in different DRX states

Engineering Contradiction:

Improverecovery speedVSAvoidresource coordination complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The base station serves as a central coordinator that allocates recovery resources to multiple UEs. It receives beam failure indications from UEs, determines appropriate recovery beam pairs, and assigns recovery resources in a coordinated manner. This centralized coordination eliminates resource conflicts between UEs in different DRX states while maintaining fast recovery through pre-configured resource pools.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The base station implements a universal resource allocation mechanism that handles beam failure recovery for multiple UEs simultaneously. It maintains pools of recovery resources that can be dynamically assigned to any UE experiencing beam failure, regardless of DRX state or timing. This multi-functional resource management system resolves conflicts while enabling parallel recovery operations for multiple UEs.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Speed

If UEs transmit beam failure recovery signals during DRX sleep periods, then recovery initiation is faster, but transmissions are wasted when UEs are not listening

Engineering Contradiction:

Improverecovery initiation speedVSAvoidwasted transmission energy

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The base station pre-configures UEs with recovery beam pairs and resource allocations before beam failure occurs. When UEs detect beam failures during DRX sleep periods, they can immediately initiate recovery using pre-configured resources without waiting for wake-up. The base station has already prepared the recovery framework, so UEs only need to execute pre-planned actions, achieving fast recovery without wasted transmissions.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11832329B2Sidelink DRX and network-assisted sidelink beam failure detection and recovery

Publication Date: 2023.11.28 QUALCOMM INC

AI summary

Certain aspects of the present disclosure provide techniques for network-assisted sidelink beam failure recovery. In certain aspects, a method performed by a base station may generally include receiving from a first UE a sidelink beam failure recovery (BFR) signal, indicating that a first communication link between the first UE and a second UE has failed; determining, based on the sidelink BFR signal, a set of resources for performing a sidelink beam failure recovery procedure to reestablish the first communication link between the first UE and the second UE; and transmitting information to the first UE and the second UE indicating the set of resources for performing the sidelink beam failure recovery procedure.