OFDM Hybrid Beamforming for Extremely Large Array Interference Control
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Solution Overview
Problem
In ultra-high frequency channels, the use of extremely large array antenna systems with hundreds or thousands of antennas leads to spatial sparsity, making it difficult to form independent beams for each user or stream, and resulting in hybrid-field interference that affects data rate and frequency resource efficiency.
Innovation Solution
A two-step OFDM-based hybrid beamforming method is proposed, where a common analog beamforming matrix is designed to maximize beam gain and mitigate hybrid-field interference, followed by a baseband beamforming matrix design for each subcarrier to optimize data rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a large number of antennas are used to overcome high pathloss and form narrow beams, then beamforming gain is improved, but hardware complexity and power consumption greatly increase
Solution Approach 1:
The patent divides the beamforming function into two independent parts: analog beamforming (RF domain) and digital beamforming (baseband domain). The analog beamforming uses a limited number of RF chains to form broad beams, while the digital beamforming processes signals for multiple users and streams. This segmentation allows the system to achieve high beamforming gain with fewer RF chains, thereby reducing hardware complexity and power consumption while maintaining effective signal concentration.
Solution Approach 2:
The patent transitions from a single-domain beamforming approach to a two-domain hybrid approach by adding the digital baseband dimension to the existing analog RF dimension. This dimensional expansion allows independent optimization of RF resources for beam formation and baseband resources for user multiplexing, enabling the system to achieve high gain with reduced RF hardware complexity.
2Power
If spatial sparsity occurs in ultra-high frequency channels with hundreds or thousands of antennas, then beamforming gain between transceivers can be acquired, but it becomes difficult to form independent beams for each user or stream
Solution Approach 1:
The patent separates beamforming operations into analog and digital domains with distinct functions. Analog beamforming creates broad spatial beams using RF phase shifters, while digital beamforming in the baseband independently processes signals for multiple users and streams. This segmentation resolves the conflict by allowing broad beam formation for gain while maintaining independent user beam capability through digital signal processing.
Solution Approach 2:
The analog beamforming block serves as a universal resource that provides spatial filtering and gain for all users simultaneously through broad beams. The digital beamforming then customizes these broad beams for individual users and streams. This multi-functionality approach allows the system to achieve both overall beamforming gain and user-specific beam independence.
3Productivity
If baseband digital beamforming is designed for all subcarrier channels to optimize frequency resource efficiency, then data rate can be improved, but hardware structural limitations make it difficult to optimize frequency resource efficiency
Solution Approach 1:
The patent divides the beamforming processing into RF domain (analog) and baseband domain (digital). The analog beamforming handles frequency-independent spatial processing with simple phase shifters, while the digital beamforming performs frequency-specific optimization for each subcarrier. This segmentation enables frequency resource optimization in the digital domain without requiring complex hardware changes in the RF domain.
Solution Approach 2:
The patent replaces complex RF hardware structures with simpler analog phase shifters, and moves the complex frequency-specific processing to the digital baseband domain. This substitution allows sophisticated frequency resource optimization through software/algorithms rather than through complex hardware modifications, overcoming hardware structural limitations.
4Area of stationary object
If Rayleigh distance increases according to large antenna aperture in a wideband extremely large array antenna system, then near-field and far-field simultaneously exist, but hybrid-field interference affects data rate and frequency resource efficiency
Solution Approach 1:
The patent segments the beamforming process into analog and digital domains to handle different field regions. The analog beamforming creates broad spatial coverage suitable for both near-field and far-field users, while the digital beamforming performs user-specific processing that can account for hybrid-field characteristics. This segmentation allows the system to manage hybrid-field interference while maintaining the benefits of large antenna aperture.
Solution Approach 2:
The patent applies different processing characteristics to different spatial regions and users through digital beamforming. By processing each user's signal independently in the digital domain, the system can optimize beamforming parameters for specific near-field or far-field users while suppressing interference from other field regions, thereby managing hybrid-field interference effectively.
Data Source
AI summary
This disclosure relates to a wideband extremely large array antenna system and an OFDM-based hybrid beamforming for hybrid-field interference control of the same. The wideband extremely large array antenna system for OFDM-based hybrid beamforming of this disclosure may include a transmitter having a plurality of transmit antennas, and a receiver capable of communication with the transmitter and having a plurality of receiving antennas, and the system may be configured to perform a first step for designing a common analog beamforming matrix for all subcarriers between the transmitter and the receiver, and a second step for designing a baseband beamforming matrix for each of the subcarriers.