MIMO Precoding Matrix Switching for LOS Broadcast Reception
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Solution Overview
Problem
Existing MIMO systems experience degradation in reception quality in line-of-sight (LOS) environments, particularly in broadcast or multicast communication, where high received electric field strength does not guarantee service reception due to the deterioration of reception quality.
Innovation Solution
A precoding method that involves switching between multiple precoding matrices to generate precoded signals, ensuring that different precoding matrices are used for adjacent data symbols in the frequency or time domain, thereby improving reception quality in LOS environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spatial multiplexing MIMO is used to increase transmission speed, then data transmission efficiency is improved, but reception quality deteriorates in LOS environments with high Rician factor
Solution Approach 1:
The patent applies dynamic precoding by switching between multiple precoding matrices in the time domain. The transmission device changes the precoding matrix for each data symbol or group of symbols, making the precoding configuration time-variant. This dynamic adjustment prevents the system from being vulnerable to fixed LOS channel characteristics, thereby maintaining reception quality while preserving spatial multiplexing benefits.
Solution Approach 2:
The patent changes the precoding parameters by selecting from multiple different precoding matrices. Each precoding matrix has different weight coefficients that are applied to the transmission signals. By varying these parameters (precoding matrix selection) over time, the system adapts to changing channel conditions and maintains optimal performance in both NLOS and LOS environments.
2Device complexity
If a fixed precoding matrix is used for all data symbols, then device complexity is reduced, but reception quality deteriorates in LOS environments
Solution Approach 1:
The system transitions from static to dynamic precoding by switching between multiple precoding matrices. This is achieved through a precoding switching mechanism that selects different matrices based on time or frequency domain criteria. While this increases operational complexity, it significantly improves reception quality in LOS environments where fixed precoding fails.
Solution Approach 2:
The patent implements periodic precoding switching where the precoding matrix changes in a periodic manner across different data symbols. This periodic action creates time-variability in the precoding configuration, which is particularly effective in combating the stability of LOS channels. The periodic switching pattern ensures that no single precoding matrix is used continuously, thereby maintaining system performance.
3Ease of manufacture
If the same precoding matrix is used for adjacent data symbols in frequency or time domain, then manufacturing and implementation are simplified, but reception quality deteriorates due to interference in LOS environments
Solution Approach 1:
The patent introduces dynamic precoding variation where the precoding matrix changes for adjacent data symbols in the time or frequency domain. This dynamic approach creates sufficient separation between the precoded signals to avoid interference, particularly important in LOS environments where channel stability causes signal degradation. The variation in precoding matrices ensures that signals remain distinguishable at the receiver.
Solution Approach 2:
The patent employs asymmetric precoding matrix selection where different precoding matrices are assigned to different data symbols in an asymmetric pattern. Rather than using a symmetric or uniform precoding configuration, the system varies the precoding matrices in a deliberate asymmetric manner to optimize signal separation and prevent interference in LOS conditions.
Data Source
AI summary
Provided is a precoding method for generating, from a plurality of baseband signals, a plurality of precoded signals to be transmitted over the same frequency bandwidth at the same time, including the steps of selecting a matrix F[i] from among N matrices, which define precoding performed on the plurality of baseband signals, while switching between the N matrices, i being an integer from 0 to N−1, and N being an integer at least two, generating a first precoded signal z1 and a second precoded signal z2, generating a first encoded block and a second encoded block using a predetermined error correction block encoding method, generating a baseband signal with M symbols from the first encoded block and a baseband signal with M symbols the second encoded block, and precoding a combination of the generated baseband signals to generate a precoded signal having M slots.