Distributed Beamforming Phase Coherence Correction
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Solution Overview
Problem
Distributed beamforming systems face challenges in maintaining phase coherence between transmitters and receivers due to independent timing, phase, frequency offset, and geometric position variations, leading to suboptimal signal-to-noise ratio performance, especially in open-loop systems and mobile channels.
Innovation Solution
A method and apparatus for providing error correction in distributed beamforming systems by generating correction weights at receivers and transmitting them back to transmitters, which includes determining phase, timing, magnitude, and frequency offsets using synchronization sequences, and averaging these weights to adjust transmitted signals, enabling coherent summation and improved signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If distributed beamforming is implemented with multiple transmitters and receivers, then signal-to-noise ratio performance is improved, but phase coherence between transmitters and receivers deteriorates due to independent timing, phase, frequency offset and geometric position variations
Solution Approach 1:
The patent implements closed-loop feedback mechanisms where receivers measure phase offsets and feed back correction information to transmitters. This allows the system to maintain phase coherence despite independent variations in timing, frequency, and position. The feedback loop continuously adjusts transmitter phases based on receiver measurements, resolving the contradiction between using multiple nodes for improved SNR and maintaining phase coherence.
Solution Approach 2:
The patent dynamically adjusts phase, timing, frequency, and magnitude parameters of transmitted signals based on measured offsets. By changing these parameters in real-time according to actual channel conditions and node variations, the system maintains phase coherence while utilizing multiple transmitters and receivers for improved signal-to-noise ratio performance.
2Measurement precision
If closed-loop feedback methods are used to maintain phase coherence, then phase coherence is improved, but convergence time increases requiring hundreds of time slots
Solution Approach 1:
The patent performs preliminary phase offset measurements and corrections using synchronization sequences before actual data transmission begins. By pre-establishing phase coherence through preliminary actions, the system reduces the number of feedback iterations needed during operation, thereby decreasing convergence time while maintaining phase coherence.
Solution Approach 2:
The patent accelerates the feedback convergence process by optimizing the feedback loop to quickly estimate and correct phase offsets. The system uses efficient algorithms that can rapidly converge to the optimal phase alignment, skipping unnecessary intermediate steps and reducing the number of time slots required for convergence from hundreds to a minimal number.
3Device complexity
If one-bit feedback methods are used in mobile channels, then device complexity is reduced, but performance deteriorates due to deterministic signal perturbations requiring hundreds of time slots to converge
Solution Approach 1:
The patent implements adaptive feedback mechanisms that dynamically adjust the feedback resolution and update rate based on channel conditions. In mobile channels with high Doppler shifts, the system uses more frequent updates and optimized feedback schemes that account for deterministic signal perturbations. This dynamic adaptation maintains performance in mobile environments while keeping device complexity manageable through selective use of feedback precision.
Data Source
AI summary
Transmitting a data signal employing a digital beamforming technique including determining a first phase offset in response to a first transmitted signal received at a first antenna and a second phase offset in response to a second transmitted signal received at the first antenna, determining a third phase offset in response to the first transmitted signal received at a second antenna and a fourth phase offset in response to the second transmitted signal received at the second antenna, generating a first correction weight in response to an average of the first phase offset and the third phase offset, generating a second correction weight in response to an average of the second phase offset and the fourth phase offset, and transmitting the first correction weight to the first transmitter and the second correction weight to the second transmitter.