Hybrid Beamforming Matrix Construction for MU-MIMO Complexity Reduction
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Solution Overview
Problem
Massive MIMO systems face challenges in practical implementation due to high baseband computation complexity and cost, power consumption, and the impracticality of full Channel State Information (CSI) availability for analog precoding matrix calculation, especially with limited RF chains.
Innovation Solution
The proposed method constructs subspaces for each user based on principal angle information from partial CSI, deriving a unified analog beamforming matrix for all users and employing baseband beamforming to overcome these limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full CSI is used for analog precoding matrix calculation, then beamforming performance is improved, but baseband computation complexity and cost increase significantly
Solution Approach 1:
The patent extracts only the essential phase information from the full CSI to construct the analog precoding matrix, rather than using all CSI components. This extraction principle reduces the data processing burden while maintaining the critical beamforming functionality, directly addressing the contradiction between performance and computational complexity.
Solution Approach 2:
The patent applies partial action by using only a subset of CSI (phase information) rather than the complete CSI for analog precoding. This partial information approach achieves sufficient beamforming performance while significantly reducing computation complexity, as full CSI processing would be excessive for the specific requirement of analog precoding matrix construction.
2Productivity
If each antenna element has a dedicated RF chain, then signal processing capability is improved, but implementation cost and power consumption increase substantially
Solution Approach 1:
The patent merges multiple antenna elements to share common RF chains through the hybrid beamforming architecture. By combining the functionality of multiple antennas with fewer RF chains via analog precoding, the system maintains signal processing capability while reducing the total number of RF chains required, thus lowering cost and power consumption.
Solution Approach 2:
The patent makes RF chains universal by enabling each RF chain to serve multiple antenna elements through the analog precoding network. This multi-functionality allows fewer RF chains to handle signals for more antenna elements, reducing hardware requirements while maintaining processing capability across the antenna array.
3Productivity
If digital baseband precoding is applied to all antennas, then spatial multiplexing gain is improved, but power consumption of mixed signal components becomes impractically high
Solution Approach 1:
The patent segments the beamforming function into two distinct parts: analog precoding for spatial direction control and digital baseband processing for data transmission. This segmentation allows the system to achieve spatial multiplexing gain through digital processing only for reduced-dimensional signals, while analog handling manages the physical antenna signals, thereby reducing overall power consumption.
Solution Approach 2:
The patent introduces an analog precoding layer as an intermediary between the digital baseband signals and the physical antenna elements. This intermediary converts full-dimension digital signals into reduced-dimension analog signals before transmission, reducing the power consumption of mixed signal components while preserving spatial multiplexing capabilities through the two-stage processing architecture.
Data Source
AI summary
This invention presents methods for MU-MIMO wireless communication systems comprising a BS with plural of antennas placed as a linear array or planar array, plural of UEs, for conducting two-level signal processing at the BS to reduce the system implementation complexity, i.e., the RF precoding/combination and the baseband precoding/detection, for the BS to obtain the second-order statistical information of the channel matrix of each UE to computing the RF precoding matrix through a much smaller number of pilots than that of the transceiving antennas at the BS, where the second-order statistical information of the channel matrix can be obtained through the uplink reference signals or downlink reference signals plus uplink feedback.