Precoding Matrix Switching for MIMO Reception Quality
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Solution Overview
Problem
In multi-antenna communication systems, particularly in spatial multiplexing MIMO systems, reception quality degrades in Line of Sight (LOS) environments due to increased Rician factors, leading to poor service delivery in broadcast or multicast communications, where feedback information from communication partners is unavailable.
Innovation Solution
A transmission method that generates precoded signals by switching between multiple precoding matrices, ensuring that each data symbol and adjacent symbols in either the frequency or time domain use different precoding matrices, thereby improving reception quality in LOS environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spatial multiplexing MIMO system is used to increase transmission speed, then productivity is improved, but reception quality deteriorates in LOS environments due to increased Rician factors
Solution Approach 1:
The patent applies dynamics by making the precoding matrix variable over time. Specifically, the precoding matrix changes in the time domain according to a predetermined pattern, allowing the system to adapt to LOS conditions where direct waves dominate. This time-varying precoding prevents degradation of reception quality while maintaining spatial multiplexing benefits.
Solution Approach 2:
The patent changes the parameter of precoding matrix selection based on transmission conditions. By switching between different precoding matrices (e.g., different interleave patterns) and adjusting precoding weights, the system optimizes performance for LOS environments while maintaining high transmission speed through spatial multiplexing.
2Reliability
If maximal ratio combining is used in LOS environment with large Rician factor, then reception quality is improved for single modulated signal, but reception quality deteriorates in spatial multiplexing MIMO system
Solution Approach 1:
The patent segments the precoding process by applying different precoding matrices to different transmit antennas and different time slots. This segmentation allows the system to handle LOS conditions effectively while maintaining spatial multiplexing capability, resolving the conflict between reception quality and system compatibility.
Solution Approach 2:
The patent applies local quality by using different precoding matrices for different antennas and different time slots. Each antenna and time slot can be optimized locally for LOS conditions while the overall system maintains spatial multiplexing functionality, achieving both high reception quality and system versatility.
3Reliability
If different interleave patterns are used for each transmit antenna, then reception quality is improved through iterative phase detection, but device complexity increases
Solution Approach 1:
The patent uses periodic action by employing predetermined periodic patterns for precoding matrix changes and interleave operations. This periodic structure simplifies the processing complexity compared to adaptive methods, while still achieving improved reception quality through systematic variation of precoding matrices in LOS environments.
Data Source
AI summary
All data symbols used in data transmission of a modulated signal are precoded by switching between precoding matrices so that the precoding matrix used to precode each data symbol and the precoding matrices used to precode data symbols that are adjacent to the data symbol along the frequency axis and the time axis all differ. A modulated signal with such data symbols arranged therein is transmitted.