MIMO Spatial Layer Decorrelation for PAPR Reduction

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Solution Overview

Problem

In wireless communication systems employing MIMO techniques, the peak-to-average power ratio (PAPR) of transmission signals is increased due to correlated signals across multiple spatial layers, leading to inefficient power amplification and potential distortion.

Innovation Solution

The system performs a decorrelation operation across spatial layers by applying unique phase rotation configurations to each spatial layer, ensuring orthogonality and reducing correlation between signals, thereby minimizing PAPR and enhancing power amplifier efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If spatial multiplexing MIMO is used to increase data throughput, then productivity is improved, but the peak-to-average power ratio increases causing harmful effects

Engineering Contradiction:
Improvedata throughputVSAvoidpeak-to-average power ratio
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent applies phase rotation transformations to the precoding matrix parameters, specifically rotating the phase of complex-valued precoding coefficients by an angle φ. This parameter transformation changes the signal characteristics across spatial layers, reducing the peak-to-average power ratio while preserving the data throughput benefits of spatial multiplexing MIMO.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If correlated signals are transmitted across spatial layers to simplify transmission, then device complexity is reduced, but power amplifier efficiency deteriorates due to increased PAPR

Engineering Contradiction:
Improvetransmission processing complexityVSAvoidpower amplifier efficiency
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The patent modifies the phase parameters of the precoding matrix by applying a rotation angle φ to the complex-valued coefficients. This parameter change decorrelates the signals across spatial layers, reducing constructive superposition and thereby lowering the peak-to-average power ratio, which improves power amplifier efficiency without significantly increasing device complexity.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3455968B1Signal processing in spatial multiplexing MIMO communications
Publication Date: 2023.09.20 NOKIA SOLUTIONS & NETWORKS OY
  • EP3455968B1 patent drawingFigure 1~2
  • EP3455968B1 patent drawingFigure 3~4
  • EP3455968B1 patent drawingFigure 5~6

AI summary

This document discloses s solution for improving transmission characteristics of a communication signal transmitted from a transmitter. According to an aspect, a method comprises: arranging, in a transmitter, information to be transmitted to a receiver, to a plurality of spatial layers where each spatial layer is associated with a unique precod-ing configuration amongst the plurality of spatial layers, wherein the information comprises at least one signal that is identical in a plurality of the plurality of spatial layers; per-forming, in the transmitter, a decorrelation operation across the plurality of spatial layers such that the at least one signal in one of the plurality of spatial layers becomes decorrelated with the at least one signal in another one of the plurality of spatial layers; and causing, in the transmitter, transmission of a transmission signal comprising the information in the plurality of spatial layers to the receiver.