Hybrid Beamforming Precoder Boresight Alignment
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Solution Overview
Problem
Current wireless communication systems face challenges in determining a precoder for hybrid beamforming, which is essential for optimizing beamforming in massive MIMO environments, where analog and digital beamforming techniques have limitations in hardware complexity and flexibility, especially in broadband transmissions.
Innovation Solution
A method and apparatus for determining a precoder in a wireless communication system that involves acquiring information about a first precoder for hybrid beamforming, generating a pre-compensation precoder, and reporting it to the base station, allowing for adjustment of the boresight of the signal to zero degrees and subsequent transmission with a second precoder to achieve optimal beamforming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If analog beamforming technique is used, then hardware complexity is reduced, but transmission rate and system capacity are limited due to inability to perform multi-stream transmission
Solution Approach 1:
The beamforming function is segmented into two independent parts: analog beamforming (first beamforming) that handles coarse directional control with reduced hardware complexity, and digital beamforming (second beamforming) that handles fine-grained multi-stream processing for high transmission rates. This segmentation allows each part to operate optimally within its capabilities.
Solution Approach 2:
The patent merges analog and digital beamforming techniques into a hybrid architecture where the analog beamformer provides initial signal conditioning and the digital beamformer performs sophisticated precoding. This combination achieves both low hardware complexity and high transmission rate by leveraging the strengths of each approach.
2Productivity
If digital beamforming technique is used, then transmission rate and system capacity are maximized, but hardware complexity increases due to requirement for multiple RF chains
Solution Approach 1:
The beamforming functionality is divided such that the analog beamformer handles the computationally intensive directional control, reducing the burden on digital signal processing hardware. The digital beamformer then focuses only on multi-stream precoding, requiring fewer RF chains and reducing overall hardware complexity.
Solution Approach 2:
The analog beamformer acts as an intermediary that pre-processes signals before they enter the digital beamforming stage. This intermediary processing reduces the dimensionality of the problem faced by the digital beamformer, thereby reducing the number of RF chains and hardware complexity required.
3Measurement precision
If analog beamforming is used, then beam control accuracy is sufficient for narrow band transmission, but adaptability to broadband environments is poor
Solution Approach 1:
The beamforming process is segmented across frequency domains: the analog beamformer provides frequency-independent coarse beam control that maintains accuracy across broadband, while the digital beamformer applies frequency-specific precoding matrices that adapt to broadband channel variations, achieving both accuracy and adaptability.
Solution Approach 2:
The system dynamically adapts to broadband conditions by selecting different precoding matrices from codebooks at different frequency subcarriers. The digital beamforming component can adjust its precoding strategy per subcarrier while the analog beamforming maintains a stable widebeam structure, providing both accuracy and broadband adaptability.
4Adaptability or versatility
If hybrid beamforming is implemented without pre-compensation, then system flexibility is maintained, but beamforming performance degrades due to misalignment of boresight
Solution Approach 1:
The pre-compensation precoder performs preliminary adjustment of the analog beamforming boresight to align with the desired transmission direction before the digital beamforming stage. This preliminary action ensures that subsequent digital precoding operates from an accurately aligned reference, maintaining both system flexibility and beamforming performance.
Solution Approach 2:
The system employs feedback mechanisms where the user equipment reports channel state information and preferred beam directions. Based on this feedback, the pre-compensation precoder adjusts the analog beamforming to achieve accurate boresight alignment, maintaining performance while preserving system flexibility through adaptive configuration.
Data Source
AI summary
Disclosed in the present application is a method by which a terminal receives a signal, to which hybrid beamforming is applied, from a base station in a wireless communication system. More specifically, the method comprises the steps of: acquiring information on a first precoder for first beamforming of the hybrid beamforming; generating information on a precompensation precoder for the first beamforming by using the information on the first precoder; reporting the information on the precompensation precoder to the base station; and receiving, from the base station, a signal to which the precompensation precoder, the first beamforming, and second beamforming are applied, wherein the precompensation precoder adjusts, to zero degrees, a boresight direction of a signal to which the first precoder for the first beamforming is applied, and a second precoder for the second beamforming is configured to enable the signal to be transmitted in a final boresight direction on the basis of a boresight direction of zero degrees.