MAC CE for Beam Failure Recovery in Multi-Cell 5G

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Solution Overview

Problem

Current beam failure recovery (BFR) mechanisms in next-generation wireless communication systems, such as 5G NR, are inadequate for User Equipment (UE) operating with multiple serving cells, as they fail to efficiently handle beam failures across multiple cells.

Innovation Solution

A User Equipment (UE) is provided with a method to perform a beam failure recovery (BFR) procedure by transmitting a MAC Control Element (CE) to a base station, which includes a cell information field indicating the serving cell and a presence indicator field for a preferred Reference Signal (RS), enabling efficient beam recovery across multiple serving cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the current BFR mechanism is used in 5G NR systems with multiple serving cells, then the existing BFR procedure can be maintained, but it fails to efficiently handle beam failures across multiple cells

Engineering Contradiction:

Improvebeam failure recovery efficiencyVSAvoidmulti-cell beam failure handling capability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The BFR mechanism is segmented to handle each serving cell independently. The MAC entity maintains separate BFI counters for each serving cell and can trigger BFR procedures specifically for individual cells that experience beam failure, allowing targeted recovery without affecting other cells.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extends the BFR mechanism from single-cell to multi-cell dimension by introducing cell-specific BFI counters and recovery procedures. This dimensional expansion allows the system to track and recover beam failures across multiple serving cells simultaneously, transforming the BFR capability from scalar to vector-based handling.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If a preamble-based BFR solution is used on SCell, then beam failure can be reported, but the procedure can be interrupted by the expiry of the SCell deactivation timer

Engineering Contradiction:

Improvebeam failure reporting capabilityVSAvoidSCell deactivation timer duration

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The MAC entity performs preliminary actions by maintaining separate BFI counters for each serving cell and monitoring beam failure conditions independently before the SCell deactivation timer expires. This allows the BFR procedure to be initiated proactively based on beam quality degradation, preventing interruption by timer expiry.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms where the MAC entity continuously monitors beam failure indications for each serving cell and triggers BFR procedures based on counter thresholds. This feedback loop ensures timely detection and recovery before the SCell deactivation timer causes interruption.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP3925405B1Methods and apparatuses for beam failure recovery

Publication Date: 2023.06.21 FG INNOVATION CO LTD

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AI summary

A method performed by a User Equipment (UE) is provided. The method includes performing at least one Beam Failure Recovery (BFR) procedure. The at least one BFR procedure includes transmitting a Medium Access Control (MAC) Control Element (CE) for BFR to a base station, where the MAC CE for BFR includes a cell information field indicating information of a serving cell in which the BFR procedure is triggered, and a presence indicator field indicating whether an identity of a preferred Reference Signal (RS) for BFR is included in the MAC CE for BFR. The preferred RS is associated with the serving cell.