MIMO Channel State Information Estimation Using Iterative Ranking

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Solution Overview

Problem

Existing MIMO-based wireless communication systems face inefficiencies in estimating channel state information (CSI) due to suboptimal use of physical specifics and high computational complexity, particularly in multiple input and multiple output (MIMO) setups.

Innovation Solution

The method involves estimating MIMO CSI from sparse data using iterative ranking and simple least square estimation, grouping channels with collocated antennas to share tap delay positions, and employing ranking functions to direct the algorithm toward sparse solutions, thereby reducing computational complexity and improving estimation accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If convex optimization is used to estimate the time domain tap delay model, then estimation accuracy is improved, but computational complexity increases significantly

Engineering Contradiction:
ImproveCSI estimation accuracyVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transforms the convex optimization problem in the time domain into a non-convex but computationally simpler problem in the frequency domain by applying discrete Fourier transform. This parameter transformation allows achieving similar estimation accuracy with significantly reduced computational complexity, especially for MIMO systems with multiple antenna pairs.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the computationally intensive convex optimization mechanism with a simpler frequency-domain processing approach using discrete Fourier transform and spectral analysis. This substitution maintains estimation accuracy while dramatically reducing the computational burden for MIMO channel estimation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If independent estimation is applied to each transmit-receive antenna pair in MIMO systems, then estimation can be performed using standard techniques, but the amount of computational resources required increases

Engineering Contradiction:
Improveestimation process simplicityVSAvoidcomputational resources
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent merges the estimation processes of multiple antenna pairs by exploiting the shared time domain tap delay structure across all antenna pairs. By performing joint estimation in the frequency domain and then transforming to time domain, the system processes all antenna pairs simultaneously rather than independently, reducing overall computational resources while maintaining simplicity through standardized transformation operations.

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If more reference symbols are transmitted to improve CSI estimation accuracy, then estimation quality increases, but overhead on resource utilization increases

Engineering Contradiction:
ImproveCSI estimation qualityVSAvoidresource utilization efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent changes the processing domain from time to frequency, enabling accurate CSI estimation with fewer reference symbols. The frequency-domain approach exploits spectral correlations and structure more effectively, achieving high estimation quality with reduced overhead by transforming the estimation problem rather than increasing sample density.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS9148803B2MIMO channel state information estimation with coupled iterative two-stage ranking
Publication Date: 2015.09.29 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • US9148803B2 patent drawing
  • US9148803B2 patent drawing
  • US9148803B2 patent drawing

AI summary

A plurality of wireless channels link a transmitter and a receiver, each channel corresponding to a different transmit-receive antenna pair. Channel state information is estimated for the plurality of wireless channels by grouping the plurality of channels into one or more groups, each group including the channels associated with two or more collocated transmit and/or receive antennas. A set of delay tap values is iteratively estimated in the time domain for each group of channels so that the channels included in the same group are associated with the same delay tap values. A frequency domain channel response of each of the channels included in the same group of channels is estimated based on the set of delay tap values estimated for the group.