MAC Beam Failure Recovery With New Candidate Beam Switching

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Solution Overview

Problem

Existing beam failure recovery mechanisms in 5G mobile communication systems face challenges in efficiently switching to new candidate beams during link blockages, leading to potential failures in data transmission due to unclear handling of new candidate beams by the MAC layer.

Innovation Solution

The MAC layer processes the random access procedure in a preset manner when obtaining new candidate beams during beam failure recovery, ensuring efficient beam switching by orthogonal resource utilization and selecting optimal beams based on measurement criteria.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the terminal transmits beam failure recovery request using contention-free PRACH, then the beam failure recovery can be triggered, but the terminal cannot determine how to deal with new candidate beams indicated by the PHY layer during the RACH procedure, which may cause failure to beam failure recovery

Engineering Contradiction:

Improvebeam failure recovery reliabilityVSAvoidMAC layer operation clarity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent introduces feedback mechanisms where the MAC layer monitors and responds to new candidate beams indicated by the PHY layer during the RACH procedure. The terminal provides feedback about beam quality measurements and adjusts its behavior based on whether new candidate beams are detected, creating a closed-loop control system that resolves the operational ambiguity.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent makes the beam failure recovery procedure dynamic by allowing the MAC layer to adapt its behavior based on real-time beam conditions. When new candidate beams are indicated during the RACH procedure, the terminal can dynamically switch between continuing the current procedure or initiating recovery with the new beam, making the system flexible rather than rigid.

Inventive Principle:

Principle #15Dynamics

2Productivity

If the terminal continues the random access procedure with original candidate beam, then the procedure can be completed, but beam failure recovery may be delayed or fail when better candidate beams are available

Engineering Contradiction:

Improvedata transmission efficiencyVSAvoidbeam failure recovery success rate

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by having the PHY layer identify and indicate new candidate beams to the MAC layer before the random access procedure is fully completed. This allows the MAC layer to proactively switch to better beams if available, rather than waiting until the procedure fails and then attempting recovery.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The terminal performs self-service by autonomously evaluating beam quality measurements and determining whether to switch to new candidate beams or continue with the original procedure. The MAC layer independently makes decisions about procedure continuation or termination based on beam conditions without requiring external intervention.

Inventive Principle:

Principle #25Self-service

Data Source

PatentEP3742844B1Beam failure recovery method and terminal

Publication Date: 2025.12.24 VIVO MOBILE COMM CO LTD

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AI summary

A beam failure recovery method and a terminal are provided. The method is applied to a media access control (MAC) layer of the terminal, and includes: processing a random access procedure in accordance with a preset processing manner, when obtaining a new candidate beam during the random access procedure of transmitting a beam failure recovery request.