PUSCH Default Beam Selection in Multi-TRP NR Systems
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Solution Overview
Problem
In a multi-transmission reception point (TRP) multi-antenna panel environment, the existing scheme for default spatial relation of physical uplink shared channel (PUSCH) scheduled by downlink control information (DCI) format 0_0 is inadequate, leading to incorrect spatial relation usage, particularly when multiple TRPs are involved.
Innovation Solution
The proposed solution involves determining the default spatial relation for PUSCH by aligning it with a specific PUCCH resource from the same UE panel or TRP, ensuring that the PUSCH transmission follows the spatial relation of a PUCCH resource with the lowest ID within the same antenna port group.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing scheme for default spatial relation of PUSCH is used, then the system maintains simplicity in spatial relation configuration, but the spatial relation alignment with intended TRP becomes incorrect in multi-TRP environments
Solution Approach 1:
The patent applies local quality by associating different spatial relations with different TRPs through antenna port groups. Each antenna port group is directionally aligned with a specific TRP, and the default spatial relation is selected based on the local TRP context rather than using a uniform approach across all TRPs. This ensures that the PUSCH transmission uses the correct spatial relation for the intended target TRP.
Solution Approach 2:
The patent implements preliminary action by pre-establishing antenna port groups that are directionally aligned with specific TRPs before PUSCH transmission. The UE determines the appropriate antenna port group and its associated default spatial relation in advance, based on directional alignment criteria, so that when PUSCH transmission is needed, the correct spatial relation is already identified without requiring complex real-time determination.
2Reliability
If multiple antenna port groups are maintained for different TRPs, then accurate spatial relation selection is enabled, but the device complexity and resource overhead increase
Solution Approach 1:
The patent applies universality by designing antenna port groups that serve multiple functions: they are used for both PUCCH transmissions and PUSCH transmissions. The same antenna port group can be associated with different TRPs at different times, and the default spatial relation stored in the antenna port group can be reused for both uplink control and data channels, reducing the total number of spatial relations needed.
Solution Approach 2:
The patent merges the spatial relation configuration for PUCCH and PUSCH by using the same antenna port group for both. Instead of maintaining separate spatial relation sets for control and data channels, the invention combines them into a unified antenna port group structure where the default spatial relation serves both purposes, thereby reducing overall system complexity.
3Ease of operation
If the default spatial relation is selected from all PUCCH resources, then the selection process is simplified, but the alignment with the specific TRP and antenna panel is lost
Solution Approach 1:
The patent applies local quality by restricting the default spatial relation selection to only those PUCCH resources within the same antenna port group that is directionally aligned with the target TRP. This local selection criterion ensures both ease of operation (by limiting the search space) and directional alignment precision (by ensuring the selected spatial relation corresponds to the correct TRP direction).
Solution Approach 2:
The patent segments the set of all PUCCH resources into multiple antenna port groups, where each group is directionally aligned with a specific TRP. This segmentation allows the UE to easily select the default spatial relation by first identifying the appropriate antenna port group based on directional alignment, then selecting from the segmented subset of PUCCH resources within that group, maintaining both simplicity and precision.
Data Source
AI summary
Techniques are provided for selecting a spatial relation for a physical uplink shared channel (PUSCH) transmission by a user equipment (UE) operating in a multi-transmission reception point (TRP) multi-antenna panel environment. For example, the UE prepares a PUSCH transmission intended for a first TRP of a plurality of TRPs available to the UE in the wireless network, and determines a first antenna port group of a plurality of antenna port groups of the UE that is more directionally aligned with the first TRP than other antenna port groups of the plurality of antenna port groups. The UE further transmits the PUSCH transmission to the first TRP via the first antenna port group using a default spatial relation used for a physical uplink control channel (PUCCH) communication with the first TRP via the first antenna port group.