Wireless Communication Apparatus Interference Subtraction
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Solution Overview
Problem
MIMO multiplexing in wireless communication systems faces challenges with high computational complexity and increased channel information feedback, particularly with methods like MLD, which becomes impractical for higher degrees of multiplexing and modulation, and results in deteriorated reception characteristics.
Innovation Solution
A wireless communication apparatus and system that acquires and processes channel information to subtract interference signals at the transmitting side, reducing the amount of calculations and feedback information needed, by using a channel information acquiring unit, interference signal calculating unit, and interference signal subtracting unit to separate and transmit signals from different antennas, and further employs modulo units to suppress signal power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MLD (maximum likelihood detection) is used for MIMO signal separation at the receiving side, then reception characteristics are improved, but computational complexity increases exponentially
Solution Approach 1:
The patent applies preliminary action by performing interference signal subtraction at the transmitting side before signal transmission. The transmitting apparatus calculates and subtracts interference signals from the transmitted signal group, so that the receiving apparatus only needs to perform simple detection without complex MLD calculations. This shifts the heavy computational workload from the receiving side to the transmitting side, resolving the contradiction between reception characteristics and computational complexity.
Solution Approach 2:
The patent introduces an intermediary approach by using a dedicated interference signal calculating unit that computes interference components separately. This intermediary calculation allows the system to pre-determine interference characteristics, enabling the receiving apparatus to simplify its detection process while maintaining good reception performance through the pre-processed signal structure.
2Device complexity
If transmitting equalization techniques (ZF, THP) are used to suppress interference at the transmitting side, then receiving processing is simplified, but reception characteristics deteriorate
Solution Approach 1:
The patent employs feedback by having the receiving apparatus send back channel information about the actual received signals. The transmitting apparatus uses this feedback to accurately calculate and subtract interference signals. This feedback mechanism allows the system to adapt to actual channel conditions, maintaining good reception characteristics while simplifying receiving processing through pre-subtracted interference.
Solution Approach 2:
The patent applies preliminary action by performing interference signal calculation and subtraction at the transmitting side before transmission. Instead of waiting for the receiving apparatus to perform complex equalization, the transmitting apparatus proactively calculates interference components and removes them in advance, achieving both simplified receiving processing and maintained reception characteristics.
3Productivity
If MIMO multiplexing degree is increased to achieve higher transfer rates, then spatial multiplexing capacity is improved, but channel information feedback amount increases
Solution Approach 1:
The patent applies the extraction principle by separating and calculating only the necessary interference signal components needed for subtraction, rather than transmitting all channel information. The interference signal calculating unit extracts and processes only the interference-related channel characteristics, reducing the amount of channel information that needs to be fed back while still enabling effective interference removal for high-order MIMO multiplexing.
Data Source
AI summary
A wireless communication apparatus includes: a channel information acquiring unit that, acquires a transmitted signal channel matrix that is channel information as a transmitted signal of a pre-interference-removal transmitted signal group and an interference signal channel matrix that is channel information as an interference signal of the non-interference-removed transmitted signal group; an interference signal calculating unit that generates an interference signal group at the time of reception by the non-interference-removed transmitted signal group with respect to the pre-interference-removal transmitted signal group, based on the pre-interference-removal transmitted signal group, the non-interference-removed transmitted signal group, the transmitted signal channel matrix, and the interference signal channel matrix; a subtracting unit that subtracts the interference signal group from the pre-interference-removal transmitted signal group to generate a post-interference-removal transmitted signal group; and a transmission antenna group that transmits the post-interference-removal transmitted signal group and the non-interference-removed transmitted signal group from mutually different transmission antennas.