CSI Reporting with Frequency Compression and Rank-Based Coefficient Limits
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Solution Overview
Problem
Current wireless communication systems, particularly in 5G NR and LTE, face challenges in efficiently reporting channel state information (CSI) with frequency compression, leading to increased overhead and variability in payload size due to the need to report non-zero and zero coefficients across multiple beams, which complicates the quantization and reporting process.
Innovation Solution
The method involves configuring user equipment (UE) to report a total number of non-zero linear combination coefficients across all layers and zero beams, using a CSI report configuration that determines a second maximum number of coefficients for higher ranks based on a ratio of coefficients for lower ranks, allowing for consistent payload size and efficient compression by quantizing coefficients differently based on their strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If frequency compression is applied to CSI reporting, then spectral efficiency is improved, but payload size variability increases due to different numbers of non-zero coefficients
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the maximum number of linear combination coefficients to report based on the rank indicator. Different rank ranges are assigned different maximum coefficient values, which standardizes the payload size while maintaining the benefits of frequency compression. This resolves the contradiction by changing the reporting parameters adaptively.
Solution Approach 2:
The patent introduces dynamic adjustment of reporting parameters based on channel conditions and rank indicators. The maximum number of coefficients is not fixed but varies according to the rank range, allowing the system to adapt to different transmission scenarios while maintaining payload consistency. This dynamic approach resolves the contradiction between compression efficiency and payload variability.
2Measurement precision
If different quantization methods are used for different coefficients, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by using different quantization methods for different types of coefficients. Strong coefficients are quantized with higher precision while weaker coefficients use lower precision, optimizing the balance between accuracy and overhead. This local differentiation resolves the contradiction by applying appropriate precision only where needed.
Solution Approach 2:
The patent changes the quantization parameters based on coefficient strength and position. Different bits are allocated to different coefficient groups, with more significant coefficients receiving more bits. This parameter variation achieves high measurement precision for critical coefficients while keeping the overall system complexity manageable.
3Reliability
If maximum number of coefficients is increased for higher ranks, then reliability is improved, but overhead increases
Solution Approach 1:
The patent introduces dynamic adjustment of the maximum coefficient count based on rank ranges. Higher ranks are assigned larger maximum coefficient values to improve reliability, but this is done adaptively rather than uniformly. The system dynamically selects the appropriate maximum based on the reported rank, balancing reliability improvements with overhead control.
Solution Approach 2:
The patent applies partial action by not increasing the maximum coefficient count for all ranks uniformly, but only for specific rank ranges where it is most beneficial. This selective approach improves reliability where needed while avoiding excessive overhead increases, resolving the contradiction through targeted rather than universal application.
Data Source
AI summary
Certain aspects of the present disclosure provide techniques for channel state information (CSI) reporting with frequency compression. A method that can be performed by a user equipment (UE) includes receiving a CSI report configuration. The CSI report configuration configures the UE for reporting precoding matrix information including, for each layer, a plurality of selected beams L, a plurality of frequency domain compression bases F for the L beams, and a subset of linear combination coefficients associated with the frequency domain compression bases and beams. The UE can determine a number of coefficients to report for a higher rank based on a configured maximum number of coefficients to report for a lower rank.