Massive MIMO Transceiver RF Chain Selection and Preprocessing
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Solution Overview
Problem
Massive MIMO systems face increased hardware complexity and energy consumption due to the large number of antennas and RF chains, which reduces performance, especially in channels with small angular spread, and existing methods for reducing complexity, such as antenna selection, do not provide optimal beamforming gain or are difficult to adapt to instantaneous channel state information.
Innovation Solution
A method that jointly determines the positions of switches and the elements of an RF preprocessing matrix based on instantaneous and average channel state information to optimize performance, using a computational numerical optimization procedure that reduces hardware complexity and energy consumption by selecting a subset of RF chains for preprocessing, thereby maintaining close-to-optimum performance with fewer RF chains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of antennas and RF chains is increased to achieve massive MIMO performance, then beamforming gain and signal-to-noise ratio are improved, but hardware complexity and energy consumption increase
Solution Approach 1:
The patent extracts only the necessary subset of RF chains (L out of N) required to achieve optimal performance, rather than using all available RF chains. This is accomplished through joint optimization of the preprocessing matrix and switch positions, identifying the minimal set of RF chains needed to maintain high signal-to-noise ratio while reducing hardware complexity and energy consumption.
Solution Approach 2:
The patent segments the full set of N RF chains into L active RF chains and N-L inactive RF chains. By dividing the system into active and inactive segments, the patent reduces the operational hardware complexity while maintaining performance through optimized signal processing in the active subset.
2Device complexity
If antenna selection is used to reduce complexity, then hardware requirements are reduced, but beamforming gain is not optimized
Solution Approach 1:
The patent makes the system dynamic by adapting the preprocessing matrix and switch positions based on instantaneous channel state information. This dynamic adaptation allows the system to optimize beamforming gain for current channel conditions while maintaining reduced hardware complexity, unlike static antenna selection methods.
Solution Approach 2:
The patent changes the parameters of the preprocessing matrix and switch positions based on channel state information to optimize beamforming gain. By adjusting these parameters dynamically, the system achieves optimal performance with a reduced number of RF chains, resolving the contradiction between hardware complexity and beamforming gain.
3Reliability
If preprocessing is adapted based on instantaneous channel state information, then close-to-optimum performance is maintained, but hardware reconfiguration speed and feedback overhead increase
Solution Approach 1:
The patent performs preliminary joint optimization of the preprocessing matrix and switch positions based on channel state information. By pre-computing the optimal configuration before transmission, the system maintains close-to-optimum performance without requiring high-speed reconfiguration during operation, thus resolving the speed-performance trade-off.
Data Source
AI summary
A method and apparatus is disclosed herein for transmitting information in massive MIMO system. In one embodiment, the apparatus comprises a plurality of antenna elements; a baseband processor; a plurality of radio-frequency (RF) chains coupled to the baseband processor; a plurality of switches coupled to the plurality of RF chains, wherein positions of switches in the plurality of switches being determined by instantaneous channel state information; a radio-frequency (RF) preprocessor coupled between the plurality of switches and the plurality of antenna elements, the RF preprocessor to apply a preprocessing matrix to signals, elements of the preprocessing matrix being adjusted as a function of average channel state information, and wherein the positions of the switches and elements of the preprocessing matrix are jointly chosen, and wherein the preprocessing matrix is chosen based on a metric related to expected performance obtained from at least one channel realization.