Sounding Reference Signal Resource Association for Downlink CSI
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Solution Overview
Problem
Current wireless communication systems do not effectively support indicating to user equipment (UE) how a sounding reference signal (SRS) is used for deriving downlink channel state information (CSI) on associated bandwidths, leading to suboptimal SRS transmission adjustments.
Innovation Solution
The system implements methods and apparatuses that allow a base station to indicate to a UE how an SRS is used, specifically for deriving CSI on associated bandwidths, enabling the UE to adjust SRS transmission parameters such as uplink precoding, path-loss adjustments, or spatial transmit beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the base station does not indicate SRS usage association to the UE, then the system complexity is reduced, but the downlink CSI acquisition accuracy deteriorates
Solution Approach 1:
The patent segments the SRS resource configuration into multiple independent parameters including frequency domain position, bandwidth, cyclic shift, and usage type. Each parameter can be independently configured and indicated to the UE, allowing precise control over SRS transmission characteristics without overwhelming system complexity. This segmentation enables the base station to selectively indicate only the necessary association parameters for downlink CSI acquisition.
Solution Approach 2:
The base station performs preliminary configuration of SRS resources and pre-establishes the association between SRS resources and downlink bandwidth parts. By pre-configuring the usage types and associations before actual downlink CSI acquisition, the system avoids real-time complex calculations and reduces operational complexity while maintaining high measurement precision.
2Loss of information
If the UE transmits SRS on all carriers and bandwidths, then the channel state information coverage is improved, but the uplink transmission overhead increases
Solution Approach 1:
The patent enables a single SRS resource to serve multiple downlink bandwidth parts and component carriers simultaneously through the usage type indication mechanism. The UE transmits one SRS that can be reused for downlink CSI acquisition across multiple frequency resources, eliminating the need for separate SRS transmissions on each carrier and bandwidth, thus reducing uplink overhead while maintaining comprehensive channel state information coverage.
Solution Approach 2:
The base station creates virtual copies of the SRS channel measurements for use across multiple downlink bandwidth parts and component carriers. Instead of requiring actual separate SRS transmissions on each frequency resource, the system copies and reuses the channel state information derived from a single SRS transmission, significantly reducing uplink transmission overhead while maintaining complete channel state information coverage.
3Measurement precision
If the UE adjusts SRS transmission parameters based on associated bandwidth conditions, then the channel estimation accuracy is improved, but the UE processing complexity increases
Solution Approach 1:
The base station pre-configures the SRS transmission parameters including frequency domain position, bandwidth, cyclic shift, and usage type associations before the UE needs to transmit. By providing all necessary configuration information in advance, the UE simply needs to follow the pre-established rules without performing complex real-time calculations, thereby improving channel estimation accuracy while keeping UE processing complexity manageable.
Solution Approach 2:
The UE autonomously determines the appropriate SRS transmission parameters by self-evaluating the configured associations between SRS resources and downlink bandwidth parts. The UE uses the pre-configured usage type indications to automatically select the correct transmission parameters without requiring complex base station instructions or extensive processing, achieving accurate channel estimation with minimal processing complexity.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive a configuration identifying a first set of frequency resources for transmitting a sounding reference signal, where the sounding reference signal may be used at least for downlink channel state information acquisition. The UE may receive an indication of an association between the configuration for the sounding reference signal and a second set of frequency resources and determine, based on the association, values for one or more sounding reference signal transmission parameters for the first set of frequency resources. The UE may transmit the sounding reference signal on the first set of frequency resources based on the determined one or more values.