Sub-band SRS Resource Indicator for Uplink Precoding
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Solution Overview
Problem
Current NCB-based frequency-selective uplink precoding techniques do not provide control over sub-band specific precoders, leading to significant inter-UE interference due to the use of identical SRS resources across all frequency sub-bands.
Innovation Solution
A method where a user equipment determines whether the bandwidth of a sounding reference signal (SRS) resource is smaller or greater than or equal to the bandwidth of a physical uplink shared channel (PUSCH) resource, and accordingly uses either a wideband precoder or a sub-band specific precoder for PUSCH communication, with the option to receive a sub-band specific SRS resource indicator for precise precoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If identical SRS resources are used across all frequency sub-bands, then device complexity is reduced, but inter-UE interference increases significantly
Solution Approach 1:
The patent segments the frequency band into multiple sub-bands and introduces sub-band specific SRI fields in DCI format 0_1 to enable independent precoder selection for each sub-band. This segmentation allows the system to move from a unified wideband precoding approach to sub-band specific precoding, thereby reducing inter-UE interference while maintaining manageable complexity through standardized signaling mechanisms.
Solution Approach 2:
The patent applies local quality by enabling different precoding parameters to be assigned to different frequency sub-bands based on local channel conditions. The base station can configure UE-specific SRS resources with sub-band specific SRI, allowing each UE to use optimized precoders tailored to its specific frequency-selective channel characteristics, thus reducing interference to other UEs in the same time-frequency resources.
2Object-generated harmful factors
If sub-band specific precoders are implemented, then inter-UE interference is reduced, but signaling overhead increases
Solution Approach 1:
The patent implements dynamic sub-band specific SRI indication through DCI format 0_1, where the SRI field can be dynamically configured to point to different SRS resources for different sub-bands. This dynamic approach allows the system to adapt precoding parameters in real-time based on current channel conditions while using compact signaling fields to minimize overhead. The base station can activate sub-band specific precoding only when channel conditions warrant it, rather than always using the most granular precoding approach.
Solution Approach 2:
The patent changes the precision and granularity of SRI parameters based on configuration. The base station can configure the SRI field to indicate either wideband SRS resources or sub-band specific SRS resources, allowing flexible adjustment of signaling overhead versus interference reduction performance. This parameter change capability enables the system to optimize the trade-off between signaling overhead and precoding accuracy according to specific deployment scenarios and channel conditions.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment may receive a sub-band specific sounding reference signal (SRS) resource indicator identifying subsets of SRS resources, of a set of SRS resources, associated with precoding a physical uplink shared channel (PUSCH) communication that is to be transmitted in a PUSCH resource. The user equipment may precode the PUSCH communication based at least in part on the sub-band specific SRS resource indicator. The user equipment may transmit the PUSCH communication after precoding the PUSCH communication based at least in part on the sub-band specific SRS resource indicator. Numerous other aspects are provided.