MIMO Array Precoding for Defective Transmit Chain Mitigation
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Solution Overview
Problem
Manufacturing antenna arrays for Massive Input Massive Output (MIMO) faces a tradeoff between maximum power transmission and element reliability, with defected Tx chains leading to significant performance degradation.
Innovation Solution
A method for defected transmit chain mitigation in MIMO systems involves determining the number of defected Tx chains and computing a precoding matrix that accounts for these defects, enabling improved signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If higher power transmission is enabled from each antenna element, then the transmitted power is improved, but the malfunction rate of the element increases
Solution Approach 1:
The patent changes the power allocation parameters dynamically by detecting defected transmit chains and adjusting the precoding matrix to redistribute power among healthy elements, thereby maintaining high transmitted power while avoiding overloading vulnerable elements
Solution Approach 2:
The system implements feedback mechanisms to detect defected transmit chains and uses this information to adaptively adjust the precoding matrix and power distribution, ensuring reliable operation while maximizing transmitted power
2Ease of manufacture
If defected Tx chains are present in the antenna array, then the manufacturing cost is reduced, but the throughput performance degrades significantly
Solution Approach 1:
The patent changes the precoding matrix parameters based on detected defected chains, adapting the signal transmission parameters to compensate for the reduced number of functional elements and maintain throughput performance
Solution Approach 2:
The system dynamically adjusts the precoding matrix and power distribution based on real-time detection of defected transmit chains, enabling the system to adapt to manufacturing variations and maintain high throughput performance
3Device complexity
If a precoding matrix is computed without considering defected Tx chains, then the computational complexity is reduced, but the spatial null steering performance deteriorates
Solution Approach 1:
The patent performs preliminary detection of defected transmit chains and incorporates this information into the precoding matrix computation in advance, ensuring accurate spatial null steering without requiring complex real-time adjustments
Data Source
AI summary
In the case that several transmitting elements (e.g., a Tx chain) are simultaneously impaired, at least two different layouts are possible: the defected Tx chains are randomly scattered around the array; or, the defected Tx chains are aligned vertically on a random column (for 12 and 24 defected Tx chains—1 and 2 such columns are randomly chosen, respectively). It can be seen that the throughput is worse when the defected Tx chains are aligned in a column rather than randomly scattered, unless the defective Tx chains are known, in which case it is the opposite. This is because disabling an entire column has the most significant effect on the spatial null steering. When defected Tx chains are known the performance of all layouts are almost the same, though column yields slightly better results due to the antenna subarrays (2 vertical antennas have the same feed, therefore we lose less degrees of freedom).