Multi-TRP CSI Phase Feedback for Coherent Downlink Precoding
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently utilizing channel state information (CSI) for multi-antenna transmission, particularly in scenarios involving multiple transmission and reception points (TRPs), leading to reduced throughput and coverage due to interlayer interference.
Innovation Solution
A method for CSI reporting that includes measuring and reporting phase and amplitude differences among CSI-RSs from multiple TRPs, enabling coherent joint transmission (CJT) by compensating for timing and power differences, thereby improving throughput and coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple TRPs transmit CSI-RS for downlink multi-antenna transmission, then transmission capacity and coverage are improved, but interlayer interference increases and reduces throughput
Solution Approach 1:
The patent implements a feedback mechanism where the UE measures CSI-RS from multiple TRPs and reports phase and amplitude differences back to the network. This feedback enables the network to adjust precoding parameters to mitigate interlayer interference while maintaining the benefits of multi-TRP transmission for increased capacity and coverage.
Solution Approach 2:
The patent changes the parameters being reported by the UE from traditional CSI metrics to specifically include phase differences and amplitude differences among TRPs. This parameter transformation allows the network to optimize precoding weights and reduce interlayer interference, thereby resolving the contradiction between maintaining transmission capacity and reducing harmful interference.
2Productivity
If phase and amplitude differences among multiple TRPs are compensated, then coherent joint transmission is achieved and throughput is improved, but system complexity increases
Solution Approach 1:
The patent segments the complex task of multi-TRP coordination into distinct components: the UE measures and reports phase/amplitude differences, and the network separately processes this information to determine precoding parameters. This segmentation distributes complexity across different entities and simplifies the overall system architecture while achieving coherent joint transmission.
Solution Approach 2:
The patent introduces CSI reporting as an intermediary mechanism that bridges the UE and multiple TRPs. Instead of direct complex coordination between network entities, the UE acts as an intermediary by measuring and reporting channel characteristics, which then enables simplified precoding calculations at the network side to achieve coherent transmission.
3Ease of operation
If traditional CSI reporting is used without phase and amplitude difference information, then system operation is simple, but coherent joint transmission cannot be achieved and coverage is limited
Solution Approach 1:
The patent applies preliminary action by having the UE measure and report phase and amplitude differences before the network performs precoding optimization. This advance preparation of channel information enables the network to configure appropriate precoding parameters that achieve coherent joint transmission, thereby extending coverage while maintaining operational simplicity through standardized reporting procedures.
Data Source
AI summary
A method of channel state information (CSI) report can include receiving a CSI report configuration at a user equipment (UE) from a base station. The CSI report configuration indicates CSI reference signal (CSI-RS) resources configured for transmitting CSI-RSs from multiple transmission and reception points (TRPs). An CSI-RS measurement process can be performed at the UE based on the CSI-RSs transmitted from the multiple TRPs using the CSI-RS resources indicated by the CSI report configuration. A CSI report can be transmitted from the UE to the base station based on the CSI report configuration. The CSI report includes information of one or more phase differences or one or more amplitude differences among the CSI-RSs transmitted from the multiple TRPs.