Phase Rotation for Interference Mitigation in Wireless Signal Transmission

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Solution Overview

Problem

In wireless communication systems, especially in multi-user environments, interference between different users' data layers leads to signal power imbalances, affecting signal restoration at the receiving end, necessitating effective interference cancellation methods.

Innovation Solution

A signal transmission method that selects a phase compensation value for user data layers to apply phase rotation and interference cancellation, ensuring the output reference and data signals maintain signal power within a pre-defined threshold, using phase rotation and modulo operations to control power and suppress interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If interference cancellation is applied to multi-layer user data in wireless communication systems, then interference between users is reduced, but signal power imbalances occur affecting signal restoration

Engineering Contradiction:
Improveinterference between usersVSAvoidsignal restoration
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies phase rotation to user data layers, changing the phase parameter of transmitted signals. By adjusting phase compensation values for different layers, the system maintains signal power within defined limits while enabling effective interference cancellation, thus resolving the contradiction between reducing interference and maintaining signal restoration reliability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary phase rotation and power control on user data layers before transmission. By pre-compensating phase and controlling signal power at the transmitter side, the system prepares signals to maintain power balance after interference cancellation at the receiver, preventing signal restoration issues before they occur

Inventive Principle:
Principle #10Preliminary action

2Reliability

If phase rotation is applied to control signal power within a pre-defined threshold, then signal power balance is maintained, but system complexity increases

Engineering Contradiction:
Improvesignal power balanceVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent controls signal power by changing phase parameters through phase rotation rather than directly adjusting amplitude or power. This approach maintains signal power balance while using simpler phase modulation operations, avoiding the complexity of real-time power control mechanisms

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3407507B1Signal transmission method of wireless communication system, base station and user equipment
Publication Date: 2020.11.04 NTT DOCOMO INC
  • EP3407507B1 patent drawingFigure 1~2
  • EP3407507B1 patent drawingFigure 3~4
  • EP3407507B1 patent drawingFigure 5~6

AI summary

Embodiments of the invention provide a signal transmission method of a wireless communication system, the method comprising: selecting a phase compensation value for a k-th layer of user data of the wireless communication system, performing, according to the phase compensation value, phase rotation on a reference signal in the k-th layer user data, so that a signal power of the reference signal, after performing interference mitigation thereon at a transmission end, does not exceed a predetermined power threshold, wherein, k is selected from 1 to M, and M is less than or equal to K, and K is the total number of layers of user data of the wireless communication system; and transmitting, through a wireless channel, the reference signal after the phase rotation.