Channel-State Information Determination in Massive MIMO
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Solution Overview
Problem
In massive MIMO systems, determining channel-state information (CSI) such as rank information and precoding matrix index is complex due to the large number of transmit antennas, leading to increased UE complexity, power consumption, and memory usage, especially in FDD-based systems where ideal linear precoding is not practical.
Innovation Solution
An iterative search method is employed to reduce the complexity of finding CSI by utilizing the prior rank information from past reports, assuming it changes minimally during normal communications, thereby avoiding exhaustive searches and reducing computational load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If exhaustive search over all precoding codebook elements is performed to determine CSI, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the exhaustive search process into two stages: first performing a limited search over a subset of codebook elements to obtain initial CSI, then using this initial result to guide a second stage of search. This segmentation reduces the computational burden at each stage while maintaining overall accuracy, directly resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent performs preliminary action by conducting an initial limited search to obtain preliminary CSI results before performing the final CSI determination. This preliminary search narrows down the search space and provides initial estimates that guide subsequent more precise measurements, reducing overall complexity while maintaining accuracy.
2Measurement precision
If exhaustive search over all precoding codebook elements is performed to determine CSI, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The patent segments the exhaustive search into multiple stages, performing a limited initial search followed by a refined search based on preliminary results. This segmentation reduces the total number of computations required, directly lowering power consumption while maintaining CSI determination accuracy.
Solution Approach 2:
The patent applies partial action by performing a limited initial search over a subset of codebook elements rather than exhaustively searching all elements immediately. This partial search consumes less energy initially, and the results guide subsequent more targeted searches, reducing overall energy consumption.
3Measurement precision
If exhaustive search over all precoding codebook elements is performed to determine CSI, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent segments the CSI determination process into multiple stages with decreasing search granularity. The initial stage performs a quick limited search, and subsequent stages refine results with more targeted searches. This segmentation significantly reduces total computation time while maintaining final measurement precision.
Solution Approach 2:
The patent performs preliminary action by conducting an initial limited search to obtain preliminary CSI estimates before performing final precise measurements. This preliminary action reduces the search space for subsequent operations, decreasing overall computation time while preserving measurement accuracy.
4Adaptability or versatility
If codebook size increases to support more transmit antennas, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent segments the large codebook search into staged processes, where initial searches cover subsets of codebook elements and subsequent searches refine results. This segmentation enables support for large codebooks in massive MIMO systems without proportionally increasing UE complexity, as each stage operates on a manageable subset.
Solution Approach 2:
The patent applies partial action by performing limited initial searches over subsets of the large codebook rather than exhaustive searches over all elements. This approach enables the system to handle large codebooks required for massive MIMO adaptability while keeping per-operation complexity manageable through iterative refinement.
Data Source
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AI summary
A method for channel-state information determination in a wireless network comprises determining an initial channel-state information for a wireless channel based on a search of a plurality of sets of precoding codebook elements stored in a multiple input multiple output user equipment (UE) and determining a subsequent channel-state information based on the initial channel-state information.