Wireless Receiver MMSE Feedback for Overloaded MIMO Interference

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Solution Overview

Problem

In overloaded MIMO systems, the number of transmission stations exceeds the number of reception antennas, leading to increased demodulation errors due to uncancelled interference signals, which existing methods like MLD and spatial filtering struggle to address effectively.

Innovation Solution

A wireless communication control method using MMSE weights to calculate and recalculate interference signal power, accounting for uncancelled interference signals, to suppress interference and reduce demodulation errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the number of transmission stations exceeds the number of reception antennas (overloaded MIMO), then the system capacity and number of simultaneous transmissions are improved, but demodulation errors increase due to uncancelled interference signals

Engineering Contradiction:
Improvesystem capacityVSAvoiddemodulation accuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies feedback by iteratively recalculating MMSE weights based on the calculated interference signal power. The process calculates interference power, updates MMSE weights, and recalculates interference power again to achieve convergence, allowing the system to adaptively suppress interference in overloaded MIMO conditions while maintaining high system capacity

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the MMSE weight parameters dynamically by incorporating interference signal power calculations into the weight determination process. This parameter adjustment allows the receiver to optimize signal separation performance in overloaded conditions where traditional fixed MMSE weights would fail to suppress interference effectively

Inventive Principle:
Principle #35Parameter changes

2Reliability

If MLD or spatial filtering is used to suppress interference in overloaded MIMO, then demodulation errors are reduced, but system complexity and processing overhead increase

Engineering Contradiction:
Improvedemodulation accuracyVSAvoidprocessing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses a computationally efficient MMSE weight calculation approach that can be quickly recalculated based on current interference conditions, replacing more complex but computationally intensive methods like MLD. This provides a practical balance between interference suppression performance and implementation complexity for real-time systems

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Reliability

If the number of reception antennas is increased to match the number of transmission stations, then interference cancellation capability is improved, but system cost and hardware complexity increase

Engineering Contradiction:
Improveinterference cancellation capabilityVSAvoidnumber of reception antennas
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent changes the signal processing parameters (MMSE weights) to compensate for the hardware limitation of having fewer reception antennas than transmission stations. By dynamically adjusting weights based on interference power calculations, the system achieves effective interference suppression without requiring additional antenna elements

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent moves the interference suppression capability from the spatial dimension (requiring more antennas) to the signal processing dimension (using iterative MMSE weight calculation). This allows the system to achieve the same interference cancellation effect through computational methods rather than hardware expansion

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP3985892B1Wireless communication control method, receiving station, and program
Publication Date: 2025.08.27 TOYOTA JIDOSHA KK
  • EP3985892B1 patent drawingFigure 1
  • EP3985892B1 patent drawingFigure 2
  • EP3985892B1 patent drawingFigure 3

AI summary

A wireless communication control method suppresses interference using an MMSE weight in an environment of wireless communication where the number of transmission stations transmitting a signal to a receiving station is larger than the number of reception antennas of the receiving station. The receiving station calculates power of an interference signal included in a signal received by the receiving station from the transmission stations the number of which is larger than the number of reception antennas, the interference signal corresponding to a part by which the number of transmission stations exceeds the number of reception antennas. The receiving station calculates the MMSE weight depending on the power of the interference signal, recalculates the power of the interference signal using the MMSE weight, and recalculates the MMSE weight depending on the recalculated power of the interference signal.