Precoding Weight Hopping for MIMO Reception Quality in LOS
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Solution Overview
Problem
In multi-antenna communication systems, particularly in spatial multiplexing MIMO systems, reception quality deteriorates in Line of Sight (LOS) environments due to increased Rician factors, posing challenges for broadcast or multicast communication where high electric field strength is insufficient for reliable service.
Innovation Solution
A precoding method that generates precoded signals by selecting and regularly hopping between a plurality of predetermined precoding weight matrices, expressed using positive real numbers, to improve 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 with high Rician factors
Solution Approach 1:
The patent applies dynamics by making the precoding matrix variable over time through regular hopping between multiple predetermined precoding matrices. This time-varying precoding approach adapts to the propagation environment changes in LOS conditions, preventing the system from being locked into a suboptimal fixed precoding configuration that degrades performance at high Rician factors.
Solution Approach 2:
The patent changes the parameter of precoding matrix selection by regularly hopping between multiple predetermined precoding matrices with different properties. This parameter variation allows the system to explore different signal spatial distributions, ensuring that at least some matrices provide robust performance across varying LOS propagation conditions and Rician factor levels.
2Reliability
If maximal ratio combining is used to achieve excellent reception quality in LOS environments, then reliability is improved, but it is incompatible with spatial multiplexing MIMO systems
Solution Approach 1:
The patent segments the precoding process into multiple predetermined matrices, each optimized for different propagation conditions. This segmentation allows the system to select or hop between matrices that provide maximal ratio combining-like performance while maintaining spatial multiplexing capability, thus achieving both reliability and adaptability.
Solution Approach 2:
The patent creates a universal precoding framework that can operate effectively in both NLOS and LOS environments by designing a set of predetermined precoding matrices that cover various propagation conditions. This multi-functional approach allows the same system to achieve excellent reception quality across different environment types without requiring separate processing paths.
3Device complexity
If a fixed precoding matrix is used to simplify the system, then device complexity is reduced, but reception quality deteriorates in stable propagation environments
Solution Approach 1:
The patent applies preliminary action by pre-designing and storing multiple predetermined precoding matrices before transmission. This preparation ensures that when transmission occurs, the system can quickly switch between pre-optimized matrices without complex real-time calculations, maintaining low device complexity while improving reception quality through selective matrix usage.
Solution Approach 2:
The patent implements periodic action by regularly hopping between predetermined precoding matrices in a systematic sequence. This periodic switching provides diversity gain and prevents performance degradation in stable propagation environments without requiring complex adaptive algorithms, thus maintaining simplicity while enhancing reliability.
Data Source
AI summary
A transmission scheme for transmitting a first modulated signal and a second modulated signal in the same frequency at the same time. According to the transmission scheme, a precoding weight multiplying unit multiplies a precoding weight by a baseband signal after a first mapping and a baseband signal after a second mapping and outputs the first modulated signal and the second modulated signal. In the precoding weight multiplying unit, precoding weights are regularly hopped.