Secondary Cell Beam Failure Recovery via HARQ New Data Indicator
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Solution Overview
Problem
In 3GPP NR systems, beam failure recovery for Secondary Cells (SCells) is challenging because the User Equipment (UE) cannot confirm if the beam failure recovery information message has been received by the network, as there is no explicit acknowledgement for uplink Hybrid Automatic Repeat Request (HARQ) transmissions, leading to uncertainty in the completion of the beam failure recovery procedure.
Innovation Solution
The UE considers the beam failure recovery procedure complete when it receives a new Uplink (UL) grant for the HARQ process used for transmitting the beam failure recovery information message, with the grant indicating 'new data', which serves as an implicit acknowledgement from the base station, allowing the UE to perform necessary actions for successful recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE transmits beam failure recovery information message using uplink HARQ, then the beam failure recovery information can be sent to the network, but the UE cannot confirm if the message was received due to lack of explicit acknowledgement
Solution Approach 1:
The patent introduces a feedback mechanism where the network sends an implicit acknowledgement to the UE by transmitting a new UL grant for the HARQ process used for beam failure recovery. The UE monitors for this new grant as confirmation that its beam failure recovery information message was successfully received and processed by the network
Solution Approach 2:
The UL grant acts as an intermediary signal between the network and UE. Instead of sending a direct explicit acknowledgement, the network uses the UL grant transmission as a mediator to convey the acknowledgement information indirectly to the UE through the HARQ process state
2Measurement precision
If the UE continuously monitors for beam failure recovery completion, then it can detect when recovery is complete, but this increases power consumption and processing overhead
Solution Approach 1:
The UE leverages its existing HARQ monitoring functionality to simultaneously detect beam failure recovery completion. Instead of implementing a separate continuous monitoring mechanism, the UE uses the HARQ process it already needs to monitor for other purposes, making the existing system serve multiple functions including beam failure recovery status detection
Data Source
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AI summary
Systems and methods for beam failure recovery are disclosed. In particular, embodiments of a method performed by a wireless device for beam failure recovery and corresponding embodiments of a wireless device are disclosed. In one embodiment, a method performed by a wireless device for beam failure recovery comprises transmitting, to a base station, an uplink transmission comprising beam failure recovery information, where the uplink transmission is associated with a particular Hybrid Automatic Repeat Request (HARQ) process. The method further comprises receiving, from the base station, an uplink grant for the particular HARQ process, where the uplink grant comprises a new data indicator. The method further comprises determining, based on the new data indicator comprised in the uplink grant, that a beam failure recovery procedure related to the beam failure recovery information is complete.