User Terminal BWP Switching for Reliable SSB Availability
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Solution Overview
Problem
In future radio communication systems, the use of synchronization signal blocks (SSBs) is not guaranteed within each bandwidth part (BWP), leading to potential communication quality deterioration due to improper activation/deactivation of BWPs, which affects operations like radio link monitoring and beam management.
Innovation Solution
The system controls the activation/deactivation of BWPs by reporting the correspondence between SSB frequency positions and BWPs, allowing the user terminal to switch seamlessly between BWPs with and without SSBs, using SSBs for specific operations when present and alternative signals like CSI-RS when not.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple BWPs are configured and activated/deactivated by switching, then communication flexibility and resource efficiency are improved, but the availability of SSB for operations like radio link monitoring and beam management cannot be guaranteed, leading to communication quality deterioration
Solution Approach 1:
The base station performs preliminary configuration by indicating to the UE which BWP contains the SSB through higher-layer signaling (e.g., bwp-SSB-DL-Link parameter). This advance information allows the UE to proactively switch to the correct BWP when SSB is needed for operations like radio link monitoring or beam management, ensuring SSB availability is maintained while allowing flexible BWP switching for resource efficiency.
Solution Approach 2:
Higher-layer signaling (RRC configuration, MAC CE, or DCI) acts as an intermediary between the base station and UE to convey the mapping relationship between BWP and SSB. This intermediary mechanism enables the UE to understand which BWP contains SSB without directly monitoring all BWPs, thus maintaining communication quality while enabling flexible BWP management.
2Reliability
If the UE monitors all configured BWPs for SSB, then SSB availability is ensured, but power consumption increases significantly
Solution Approach 1:
The UE extracts and focuses monitoring efforts only on the specific BWP indicated by the base station as containing the SSB. By taking out the SSB monitoring function from all BWPs and concentrating it on a single indicated BWP, the UE ensures SSB availability while dramatically reducing power consumption compared to monitoring all configured BWPs.
Solution Approach 2:
Instead of uniformly monitoring all BWPs with the same intensity, the UE applies local quality by concentrating monitoring resources only on the BWP where SSB is located (as indicated by higher-layer signaling). This localized approach ensures reliable SSB detection while minimizing overall power consumption across the multi-BWP configuration.
3Ease of operation
If SSB is included in every BWP, then operations like radio link monitoring and beam management are always possible, but system complexity and overhead increase
Solution Approach 1:
The indicated BWP containing SSB serves multiple functions: it provides synchronization signals for radio link monitoring, beam management reference signals, and system information. By making this single BWP multi-functional, the system ensures operation availability without the need to include SSB in every BWP, thus reducing system complexity and overhead.
Solution Approach 2:
The base station performs preliminary configuration by indicating which BWP contains the SSB through higher-layer signaling. This advance configuration allows the UE to know in advance which BWP to use for various operations, eliminating the need for complex real-time searches across multiple BWPs and reducing overall system complexity while maintaining operation availability.
Data Source
Figure 1A~1C
Figure 2
Figure 3A~3B
AI summary
To appropriately control communication using at least one of a synchronization signal block and a reference signal even when communication is performed using a BWP, according to one aspect of the present disclosure, there is provided a user terminal including: a receiving section that receives at least one of a synchronization signal block and a given reference signal in a given bandwidth part (BWP); and a control section that decides whether to apply a synchronization signal block to a specific operation based on at least one of information regarding a frequency position of a synchronization signal block commonly reported by a serving cell and information regarding a frequency position of a synchronization signal block in the BWP.