CSI Reporting for Multi-TRP FDD Reciprocity
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Solution Overview
Problem
In 5G wireless communication systems, the existing methods for channel state information (CSI) reporting from user equipment (UE) to the network are inefficient, especially for multi-transmit/receive points (TRP) and frequency division duplex (FDD) reciprocity, leading to excessive control signaling and high overhead in CSI feedback, particularly with the NR Type-II codebook which requires a large number of Precoding Matrix Indicator (PMI) bits.
Innovation Solution
The proposed solution involves new CSI reporting enhancements, including priority rules for CSI reports, new channel measurement resource (CMR) grouping for non-coherent joint transmission (NCJT), and codebook design for FDD reciprocity, which reduce the number of PMI feedback bits by using DFT-based compression and prioritizing CSI reports based on transmission hypotheses and resource availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If NR Type-II codebook is used for CSI reporting, then transmission accuracy is improved, but feedback overhead increases significantly due to large number of PMI bits required
Solution Approach 1:
The patent segments the CSI feedback into two parts: Part 1 contains essential CSI information (RI, CQI, and subset of PMI) that enables basic transmission optimization, while Part 2 contains additional PMI bits for enhanced codebook precision. This segmentation allows the system to achieve acceptable transmission accuracy with reduced feedback overhead by transmitting only the necessary precision level in Part 1, and optionally enhancing with Part 2 when channel conditions permit.
Solution Approach 2:
The patent applies partial action by transmitting only a subset of PMI bits in Part 1 of the CSI feedback rather than the complete codebook requirements. This partial feedback approach provides sufficient information for basic transmission optimization while significantly reducing the feedback overhead, and the system can optionally include additional PMI bits in Part 2 when transmission conditions allow for enhanced precision.
2Reliability
If multiple TRP transmissions are supported, then system reliability is improved, but control signaling overhead increases excessively
Solution Approach 1:
The patent merges multiple TRP CSI reporting into a unified feedback structure where the UE reports CSI for multiple TRPs simultaneously using a consolidated codebook approach. The gNB configures a unified codebook that encompasses multiple TRP transmission hypotheses, allowing the UE to report compressed CSI information for all TRPs in a single feedback message rather than separate reports for each TRP, thereby reducing control signaling overhead while maintaining support for multiple TRP transmissions.
Solution Approach 2:
The patent changes the codebook parameters to support multi-TRP scenarios by configuring a unified codebook with modified PMI bit structures that can represent multiple TRP transmission hypotheses. This parameter change allows the system to encode multiple TRP CSI reports in a more compact format, reducing the overall feedback overhead while maintaining the ability to support multiple TRP transmissions for enhanced reliability.
3Productivity
If complete CSI feedback is transmitted for all transmission hypotheses, then transmission optimization is improved, but feedback delay increases due to processing time
Solution Approach 1:
The patent segments the CSI feedback into priority-based parts where Part 1 contains high-priority essential CSI information needed for immediate transmission optimization, and Part 2 contains additional enhancement information. This segmentation allows the gNB to process and act on the most critical CSI information quickly for Part 1, reducing feedback delay for basic transmission optimization, while optionally processing Part 2 for enhanced optimization when time permits.
Solution Approach 2:
The patent applies partial action by transmitting essential CSI information in Part 1 that is sufficient for immediate transmission optimization without requiring complete feedback processing. This partial feedback approach enables the system to achieve acceptable transmission optimization quickly, reducing feedback delay, while the option to include additional enhancement information in Part 2 provides a trade-off between optimization completeness and feedback time when channel conditions and processing capacity permit.
Data Source
AI summary
Various aspects of the present disclosure relate to channel state information reporting for multiple transmit/receive points and frequency division duplex reciprocity. One apparatus includes at least one memory and at least one processor that is configured to a channel state information (“CSI”) reporting configuration, the CSI reporting configuration comprising an indicator of multi-point transmission, and a configuration comprising at least two groups of channel measurement resources (“CMRs”). The at least one processor determines at least one CSI report based on the at least two groups of CMRs, the at least one CSI report mapped to a transmission hypothesis corresponding to one of a single-point transmission and a multi-point transmission. The at least one processor transmits the at least one CSI report to the mobile wireless communication network, the at least one CSI report ordered according to a predefined priority.