MIMO Signal Detection via QR Decomposition and Zero-Forcing

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Solution Overview

Problem

Current MIMO-OFDM systems face high computational complexity in detecting data due to the need for exhaustive searches in high-order constellations, leading to prohibitive processing times and hardware requirements.

Innovation Solution

The implementation of a QR decomposition-based zero-forcing, maximum-likelihood (ZF-ML) algorithm that transforms the channel matrix and rotated signal vector to set complex elements to zero, reducing computational complexity and enabling efficient log likelihood ratio (LLR) calculations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If exhaustive search methods are used for data detection in MIMO-OFDM systems, then detection accuracy is improved, but computational complexity and processing time increase prohibitively

Engineering Contradiction:
Improvedetection accuracyVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the detection process into two distinct stages: (1) QR decomposition stage that processes the channel matrix to obtain triangularized forms, and (2) detection stage that performs simplified calculations using the preprocessed matrices. This segmentation allows the computationally intensive matrix decomposition to be performed once, followed by efficient detection calculations, thereby reducing overall complexity while maintaining accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary action by performing QR decomposition of the channel matrix before the actual detection process. The channel matrix is preprocessed into triangular forms (R1 and R2) and the received signal is pre-multiplied by QH to obtain transformed signals. This preliminary processing simplifies subsequent detection calculations, avoiding the need for exhaustive searches during the actual detection phase.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If high-order constellations are used to increase data throughput, then data rate is improved, but processing time and hardware requirements increase

Engineering Contradiction:
Improvedata throughputVSAvoidprocessing time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The detection algorithm is segmented into preprocessing (QR decomposition) and detection phases. For high-order constellations, the QR decomposition is performed once regardless of constellation size, and the simplified detection phase efficiently handles the increased number of constellation points without proportionally increasing processing time, thus enabling high throughput with manageable processing delays.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the parameter representation by transforming the detection problem into a simplified form using QR decomposition. The original complex detection problem with multiple intertwined signals is transformed into a triangularized form where detection can proceed sequentially with reduced computational burden, allowing high-order constellations to be processed efficiently.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If complex matrix operations are performed without transformation, then detection accuracy is maintained, but hardware resources and power consumption increase

Engineering Contradiction:
Improvedetection accuracyVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent performs preliminary QR decomposition to transform the channel matrix into triangular forms before detection. This preliminary action simplifies the detection calculations, reducing the number of complex matrix operations required during actual detection. The simplified detection process using transformed signals and triangular matrices reduces computational load, thereby lowering power consumption while maintaining detection accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent extracts the computationally intensive matrix decomposition operations and performs them separately as a preprocessing step. The main detection process then uses only simplified calculations based on the extracted triangular forms, reducing the computational burden and power consumption during the critical detection phase while preserving accuracy.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentUS9929884B2Systems and methods for detecting data in a received multiple-input-multiple-output (MIMO) signal
Publication Date: 2018.03.27 MARVELL ASIA PTE LTD
  • US9929884B2 patent drawing
  • US9929884B2 patent drawing
  • US9929884B2 patent drawing

AI summary

Systems and methods for detecting data in a received multiple-input-multiple-output signal are provided. N signals are received from N antennas, with M being greater than or equal to three. The N signals form a vector y and are associated with M sets of data values, where the M sets of data values form a vector x. A channel matrix (H) is estimated, and a QR decomposition of the channel matrix is performed, such that H=QR. The vector y is transformed into a vector z according to z=QHy. The R matrix and the rotated signal vector z are transformed such that one or more elements of the R matrix having complex number values are set equal to zero. Distance values are calculated using the transformed vector z and the vector x. Log likelihood ratio (LLR) values are calculated based on the distance values.