MIMO Receiver Phase Alignment via Wideband Pilot Signals
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Solution Overview
Problem
MIMO radio systems face challenges in precise phase alignment and time synchronization between channels, which are costly and complex, especially when transmitters are remotely located, requiring improvements in calibration processes.
Innovation Solution
A method using a wideband pilot signal to measure time delays at sub-sample precision, allowing for precise alignment of receivers and generators through programmable delays, reducing misalignment to picosecond levels without requiring high digital sampling rates or additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional phase alignment and time synchronization methods are used in MIMO systems, then channel alignment can be achieved, but computational complexity and cost increase significantly
Solution Approach 1:
The patent replaces complex computational phase alignment algorithms with a hardware-based solution using a phase alignment device that directly measures and corrects phase differences between antenna elements. This substitution of computational methods with a dedicated measurement device reduces computational complexity while maintaining alignment precision.
Solution Approach 2:
The patent introduces a phase alignment device as an intermediary component between the antenna elements and the signal processing system. This device serves as a mediator that performs real-time phase measurement and correction, simplifying the overall system complexity by handling phase alignment in a dedicated hardware module rather than through complex software algorithms.
2Measurement precision
If high digital sampling rates are used to achieve sub-sample precision, then time delay measurement accuracy improves, but hardware costs and spectral bandwidth requirements increase
Solution Approach 1:
The patent changes the measurement parameter from time-domain sampling to frequency-domain phase analysis. Instead of increasing sampling rate to achieve sub-sample precision, the system measures phase differences across frequency components and derives time delay information from these phase measurements, thereby achieving high precision without requiring high sampling rates or additional hardware resources.
3Adaptability or versatility
If remote transmitters are used in MIMO systems, then system flexibility improves, but calibration complexity and difficulty increase
Solution Approach 1:
The patent introduces a phase alignment device as an intermediary that simplifies calibration of remote transmitters. This device provides a standardized interface for measuring and correcting phase differences, making the calibration process less complex and more automated, thereby enabling greater system flexibility with remote transmitters without proportionally increasing calibration complexity.
Data Source
AI summary
Systems and methods are described for using a single wideband pilot signal to reduce a timing misalignment between receivers in a multiple-input multiple-output (MIMO) radio system. The multiple generators of the MIMO radio system may be aligned using a second wideband pilot signal subsequent to performing the receiver alignment. The calibration kit of the MIMO radio system may be aligned using a third wideband pilot signal prior to performing the receiver alignment. Alignment may be achieved to subsample precision by determining time delays from the rate of change of the phase shift of the wideband pilot signals.