Hybrid MU-MIMO Precoding With Three-Way Switch Analog Beamforming
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Solution Overview
Problem
Existing massive MIMO systems face challenges in implementing a large number of antennas with a low number of RF chains due to high hardware complexity, power consumption, and manufacturing costs, particularly in hybrid precoding architectures that rely on expensive and inefficient analog components, leading to degraded performance.
Innovation Solution
A hybrid precoding method using a fully connected architecture with three-way switches and inverters, optimizing the setting of these switches to maximize system sum-rate, reducing the need for high-resolution phase shifters and incorporating a digital beamformer matrix for baseband signals and an analog beamformer matrix for passband signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large number of antennas are used in massive MIMO systems, then array gain and system performance are improved, but hardware complexity and cost increase due to requiring one RF chain per antenna
Solution Approach 1:
The patent combines digital and analog processing domains into a hybrid architecture. Digital beamforming is applied to a reduced set of antenna groups, while analog processing handles the remaining antenna elements. This merging allows the system to achieve massive MIMO performance with fewer RF chains, resolving the contradiction between system performance and hardware complexity.
Solution Approach 2:
The antenna array is segmented into multiple groups, with each group processed by a separate RF chain. This segmentation allows the system to handle a large total number of antennas using fewer RF chains, as each RF chain manages a subset of antennas through hybrid digital-analog processing. The segmentation directly addresses the hardware complexity issue while maintaining overall system performance.
2Device complexity
If hybrid precoding is used to reduce the number of RF chains, then hardware complexity is reduced, but system performance degrades due to constraints on freedom degrees in analog processing
Solution Approach 1:
The patent implements dynamic switching between different beamforming modes and configurations. The system can adaptively adjust the number of active RF chains, the segmentation of antenna groups, and the allocation between digital and analog processing based on channel conditions and traffic requirements. This dynamics allows the system to maintain high performance while reducing hardware complexity when conditions permit.
Solution Approach 2:
The hybrid precoding architecture is designed to be universal, supporting multiple operating modes and configurations. The same hardware structure can operate with different numbers of RF chains, different antenna groupings, and different splits between digital and analog processing. This multi-functionality allows the system to achieve good performance across various scenarios without requiring dedicated hardware for each configuration.
3Adaptability or versatility
If high-resolution analog phase shifters are used in hybrid precoding, then signal processing flexibility is improved, but power consumption and manufacturing cost increase
Solution Approach 1:
The patent applies different processing qualities to different parts of the signal chain. Digital beamforming, which requires high precision, is applied only to the reduced set of antenna groups processed by RF chains. Analog beamforming with phase shifters handles the remaining antenna elements where lower resolution is acceptable. This local differentiation of quality requirements reduces overall power consumption and cost while maintaining sufficient signal processing flexibility where it matters most.
Data Source
AI summary
A method for performing multiple user multiple input multiple output (MU-MIMO) communication, comprising: computing a digital beamformer matrix with a digital precoder for processing baseband signals; processing the baseband signals with a plurality of radiofrequency (RF) chains; computing an analog beamformer matrix with an analog precoder for processing analog or passband signals. The analog precoder comprises: a plurality of adders connectable to the plurality of antennas; a plurality of three-way switches connectable to the plurality of RF chains and the plurality of adders. One of the three terminals of the three-way switches is directly connected to a RF chain, the other terminal is connected to an inverter, and the last one turns off the signal. Computing an optimization function to obtain a maximization of the system sum-rate with basis on the digital and analog beamforming matrixes, the analog precoder sets a position of the three-way switches.