Downlink Reference Signal Reporting for MPE-Aware Uplink Beam Selection
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Solution Overview
Problem
Wireless communication devices face challenges in determining optimal uplink beams due to Maximum Power Reduction (MPE) limitations, leading to potential UL coverage loss and inefficient beam management procedures, especially in high-frequency bands where narrow beams are used.
Innovation Solution
Implementing a method for determining a set of default uplink beams based on downlink reference signals, such as CORESETs or TCI states, to facilitate efficient uplink beam management with reduced latency and overhead, allowing for fast beam adaptation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If narrow beams of high beamforming gains are used for uplink transmissions, then beamforming gain is improved, but MPE limitation causes transmit power reduction leading to coverage loss
Solution Approach 1:
The patent changes the beam parameters by selecting alternative downlink reference signals (different CSI-RS resources or SSBs) that correspond to uplink beams with lower MPE impact. This allows dynamic adjustment of beam characteristics to balance beamforming gain with MPE constraints, maintaining coverage while optimizing signal quality.
Solution Approach 2:
The system dynamically adapts uplink beam selection based on real-time MPE conditions and downlink reference signal measurements. The UE can switch between different uplink beams corresponding to different downlink reference signals, enabling flexible adaptation to changing channel and MPE conditions to maintain reliable coverage.
2Ease of operation
If conventional uplink beam management procedures are used, then beam selection is performed, but high latency and signaling overhead occur
Solution Approach 1:
The patent performs preliminary measurements of downlink reference signals and pre-determines uplink beam candidates before actual uplink transmission is needed. By having measurement results and beam candidates prepared in advance, the system reduces the time required for beam selection during actual transmission, lowering latency while maintaining ease of operation.
Solution Approach 2:
The patent uses downlink reference signals (CSI-RS and SSB) that serve multiple functions: they are used for downlink channel estimation, quality measurement, and simultaneously for determining uplink beam directions. This multi-functionality eliminates the need for separate uplink beam training procedures, reducing signaling overhead and latency.
3Adaptability or versatility
If separate procedures for downlink and uplink beam management are used, then beam optimization is achieved, but signaling overhead increases
Solution Approach 1:
The patent merges downlink and uplink beam management procedures by establishing correspondence between downlink reference signals and uplink beams. The same downlink reference signal measurements used for downlink beam optimization are also used to determine uplink beam directions, combining two separate procedures into one unified process that reduces signaling overhead while maintaining beam optimization capabilities.
Data Source
AI summary
Configuration information of DL RS measurements and reporting can be received (310). The configuration information can configure the UE to report a DL RS for DL reception and a DL RS for UL transmission, respectively, and the configuration information can include information of a plurality of DL RSs. The plurality of DL RSs can be measured (320). A first DL RS can be selected (330) for DL receptions and a second DL RS can be selected for UL transmissions based on measurements of the plurality of DL RSs. An indication of the first and second DL RSs can be reported (340).