Lattice Enumeration-Aided MIMO Detection Reducing Complexity

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Solution Overview

Problem

Existing MIMO detection algorithms face complexity issues that increase exponentially with the number of transmit antennas, leading to impractical solutions with significant performance sacrifices.

Innovation Solution

The implementation of a lattice enumeration-aided detector (LEAD) that approximates a hyperellipsoid detection search space using eigenvectors and eigenvalues of the effective channel, allowing for improved detection in a regular alphabet independent of the channel, and employing QR decomposition and successive interference cancellation to simplify the detection process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the number of transmit and receive antennas is increased to increase data throughput and diversity, then system capacity increases linearly and fading probability decreases exponentially, but detection complexity increases significantly

Engineering Contradiction:
Improvedata throughputVSAvoiddetection complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the detection process into two phases: first identifying a reduced subset of candidate symbols from the complete signal constellation, then performing final detection only on this reduced set. This segmentation reduces the exponential search space into manageable segments, lowering detector complexity while maintaining performance in MIMO systems with multiple antennas.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If the optimal brute force detector is used to achieve best performance, then detection accuracy is maximized, but complexity increases exponentially with the number of channel inputs

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

Solution Approach 1:

The patent applies partial action by performing exhaustive search only on a reduced subset of candidate symbols rather than the complete constellation. The detector identifies and evaluates only the most promising candidates based on initial metrics, performing partial exhaustive search that achieves near-optimal performance with significantly reduced computational complexity compared to complete brute force detection.

Inventive Principle:
Principle #16Partial or excessive action

3Loss of information

If list-sphere detection is used to compute log-likelihood ratio information, then reliability information for each bit is provided, but processing resources are significantly consumed

Engineering Contradiction:
Improvereliability informationVSAvoidprocessing resources
Core Design Contradiction:
Loss of informationVSUse of energy by moving object

Solution Approach 1:

The patent segments the LLR computation process by first identifying a reduced candidate subset and then computing reliability information only for these candidates. This segmentation allows the system to provide bit-level reliability information through LLR computation while consuming significantly fewer processing resources compared to computing LLRs for the complete signal constellation.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS7945008B2Systems and methods for lattice enumeration-aided detection
Publication Date: 2011.05.17 TEXAS INSTRUMENTS INC
  • US7945008B2 patent drawing
  • US7945008B2 patent drawing
  • US7945008B2 patent drawing

AI summary

Embodiments provide systems and methods for improved multiple-input, multiple-output (MIMO) detection comprising generating at least one list of candidate vectors by employing lattice enumeration which approximates hyperellipsoid detection search space and calculating a reliability of the candidate vectors. At least one advantage to embodiments is that improved detection occurs because detection can be performed in a search space defined by the eigenvectors (which define the general shape of an ellipsoid/hyperellipsoid, depending upon number of dimensions) and eigenvalues (which provide the appropriate scaling in each direction of the eigenvectors) of the effective channel.