Terminal Spatial Reception Parameter Determination for Beam Failure Recovery
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Solution Overview
Problem
In a radio communication system, when a terminal performs Beam Failure Recovery (BFR) using a Contention-Based Random Access procedure (CBRA), the base station device cannot distinguish whether the CBRA is for BFR or another purpose, leading to inefficiencies in configuring Quasi-co-location (QCL) parameters.
Innovation Solution
A terminal is equipped with a control unit that determines spatial reception parameters for a control channel based on QCL information from synchronization signals or reference signals. During BFR performed via CBRA, the control unit assumes a QCL parameter associated with a Synchronization Signal Block (SSB) detected in the CBRA procedure to select a random access preamble, acting as a QCL parameter for monitoring the downlink control channel in a search space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal performs BFR using CBRA, then beam recovery can be achieved, but the base station cannot distinguish whether the CBRA is for BFR or another purpose, leading to inefficiencies in configuring QCL parameters
Solution Approach 1:
The patent introduces a specific SSB selection rule as an intermediary mechanism to indicate BFR purpose. When a terminal performs CBRA for BFR, it selects an SSB based on specific rules that differ from other CBRA purposes. This SSB selection pattern acts as a mediator that allows the base station to distinguish BFR-related CBRA from other CBRA without adding explicit signaling overhead, thereby resolving the contradiction between maintaining reliable beam recovery and improving configuration efficiency.
Solution Approach 2:
The patent changes the SSB selection parameter based on the purpose of CBRA. For BFR purposes, the terminal applies specific SSB selection rules that differ from other CBRA scenarios. This parameter change in SSB selection enables the base station to identify BFR intent through the chosen SSB, improving QCL parameter configuration efficiency while maintaining beam recovery reliability.
2Productivity
If the terminal uses Contention-Free Random Access procedure for BFR, then beam recovery efficiency is improved, but when the beamFailureRecoveryTimer expires, the terminal must fallback to CBRA, losing the distinction capability
Solution Approach 1:
The patent applies preliminary action by establishing SSB selection rules before the terminal needs to perform CBRA. The terminal is pre-configured with specific SSB selection criteria for BFR purposes. When the beamFailureRecoveryTimer expires and the terminal must fallback to CBRA, it can still apply these pre-established SSB selection rules, thereby preserving the ability to indicate BFR purpose even after timer expiration, and preventing loss of identification information.
3Loss of information
If the base station monitors all CBRA procedures without distinction, then no information is lost about terminal intent, but the system complexity and processing overhead increase
Solution Approach 1:
The patent extracts the purpose identification information from the CBRA procedure itself through SSB selection. Instead of requiring the base station to monitor and analyze multiple parameters to determine terminal intent, the relevant information (BFR purpose) is extracted and embedded in the SSB selection choice. This reduces base station processing complexity while preserving terminal intent information, as the base station only needs to observe which SSB the terminal selects to understand the CBRA purpose.
Data Source
AI summary
A terminal includes a control unit that determines a spatial reception parameter of a control channel based on Quasi-co-location (QCL) information on a synchronization signal or a reference signal; and a receiving unit that receives the control channel based on the determined spatial reception parameter, wherein, when Beam Failure Recovery (BFR) is performed by applying a contention-based random access procedure, the control unit assumes a QCL parameter associated with a Synchronization Signal Block (SSB) detected in the contention-based random access procedure to select a random access preamble, as a QCL parameter for monitoring a downlink control channel in a search space.