Massive MIMO Beamforming via Baseband and RF Segmentation
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Solution Overview
Problem
In sub-6 GHz frequency bands, massive MIMO systems face challenges with large-scale antennas and inter-user interference, where existing RF beamforming methods are inadequate due to high channel angles and limited Fronthaul capacity, especially in 5G systems with increased bandwidth requirements.
Innovation Solution
A beamforming method and apparatus for a massive MIMO system using a M-row N-column antenna array with cross-polarized elements, combining horizontal direction baseband beamforming, vertical direction digital beamforming, and analog beamforming to efficiently map data streams onto channels, employing uplink sounding reference signals to reduce complexity and estimate interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If RF beamforming is used in sub-6 GHz frequency band, then beamforming capability is provided, but the number of antennas required increases significantly due to large channel angles
Solution Approach 1:
The patent segments the beamforming process into two distinct stages: baseband beamforming that processes data streams before RF conversion, and RF beamforming that processes signals after conversion. This segmentation allows the system to achieve complete beamforming capability with fewer antennas by distributing functionality across both stages, rather than requiring all beamforming operations to be performed in the RF domain.
2Measurement precision
If more antennas are deployed in sub-6 GHz to distinguish users, then user separation capability improves, but inter-user interference inhibition deteriorates
Solution Approach 1:
The patent introduces baseband beamforming as an intermediary processing stage between data generation and RF transmission. This intermediary performs preliminary spatial processing and user separation in the baseband domain, which reduces the burden on RF beamforming and improves the system's ability to inhibit inter-user interference while maintaining user separation capability.
3Quantity of substance
If L1-layer processing is shifted to RF to avoid FH transmission, then FH capacity requirements are reduced, but RF module complexity increases
Solution Approach 1:
The patent segments the processing architecture to keep L1-layer processing in the baseband domain rather than shifting it to RF. Baseband beamforming handles data stream processing while RF beamforming handles signal transmission, allowing FH to carry only processed beamformed data. This segmentation reduces FH capacity requirements without increasing RF module complexity.
Data Source
AI summary
An object of the present disclosure is to provide a beamforming method for a massive MIMO system. Specifically, S routes of data streams to be transmitted via the antenna array are subjected to horizontal direction baseband beamforming processing, to obtain T routes of data streams; the T-routes of data streams are subjected to vertical direction digital beamforming processing to map the T routes of data streams onto a corresponding channel according to a predetermined rule; a data stream on each channel is subjected to analog beamforming processing to map the data stream on each channel onto a corresponding array element of the antenna array for transmission. Compared with the prior art, the present disclosure implements the following advantages: by combining the advantages of RF beamforming with the BB beamforming with limited antennas at the FH, a good flexibility regarding BB algorithm selection and RF beam design is provided, which balances the complexity and performance between BB and RF and implements a massive MIMO in sub-6 GHz.