SRS Beam Determination Using DL RS Indicators for STxMP Uplink
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Solution Overview
Problem
Existing beam management methods in wireless communication systems face issues of signaling overhead and latency due to the need for beam change/indication procedures, particularly in supporting simultaneous transmission across multiple panels (STxMP), and the difficulty in measuring UL interference for optimal beam combinations, which can result in bad beam combinations with high UL interference.
Innovation Solution
A method where a user equipment (UE) reports channel state information (CSI) and transmits a sounding reference signal (SRS) based on DL RS resource indicators, determining UL Tx spatial filters without additional signaling, allowing for efficient beam determination and reducing latency and overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If beam change/indication procedure is performed to support STxMP PUSCH transmission, then beam management capability is improved, but signaling overhead and latency increase
Solution Approach 1:
The UE autonomously determines the UL Tx spatial filter for SRS transmission by applying the spatial filter used for receiving the DL RS, without requiring explicit beam indication from the base station. This self-service approach eliminates the need for additional beam change/indication signaling while maintaining appropriate beam alignment for uplink transmission.
Solution Approach 2:
The DL RS spatial filter configuration serves dual purposes: it is used for downlink reception and simultaneously serves as the basis for determining the uplink transmit spatial filter for SRS. This multi-functionality allows the same configuration to support both DL and UL beam management, reducing the need for separate beam indication procedures.
2Device complexity
If SRS beam follows unified TCI for all UL channels/signals, then beam configuration simplicity is improved, but UL interference measurement capability deteriorates
Solution Approach 1:
The patent applies different spatial filter determination approaches for different uplink channels and signals. Specifically, SRS transmission uses the DL RS spatial filter (without unified TCI), while other UL channels can use appropriate beam configurations. This segmentation allows the base station to receive SRS on specific beam combinations for interference measurement without forcing all UL channels to use the same beam configuration.
3Measurement precision
If additional signaling is used for SRS beam change/indication, then beam accuracy is improved, but signaling overhead increases
Solution Approach 1:
The UE self-determines the appropriate UL Tx spatial filter by reusing the DL RS spatial filter configuration, eliminating the need for additional beam indication signaling from the base station. This maintains beam accuracy while avoiding the signaling overhead that would result from explicit beam change commands.
Solution Approach 2:
The patent changes the parameter determination approach from explicit signaling to implicit derivation. Instead of the base station signaling the beam parameter for SRS, the UE derives it from the DL RS spatial filter parameters already configured for downlink reception, thereby reducing signaling overhead while maintaining beam accuracy.
Data Source
AI summary
A method according to an embodiment of the present disclosure includes reporting channel state information (CSI) and transmitting a sounding reference signal (SRS). The CSI includes at least one DL RS resource indicator. The SRS is transmitted based on at least one SRS resource. An uplink transmit (UL Tx) spatial filter related to the at least one SRS resource is determined based on the at least one DL RS resource indicator.