Digital Phased Array Self-Interference Cancellation
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Solution Overview
Problem
Existing methods for simultaneous transmit and receive (STAR) operations in phased array antennas are limited by the dynamic range of individual transmit and receive channels, particularly in high-power array antennas that require extremely high isolation to mitigate self-interference and distortion.
Innovation Solution
The implementation of a digital phased array system that uses auxiliary receive channels, digital beamformers, and an adaptive digital canceler to combine signals from both transmit and receive paths, enabling adjacent sub-arrays to operate simultaneously in the same frequency band by generating an isolated signal through digital beamforming and cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-power transmit channels are used to increase transmitted power, then transmitted signal strength is improved, but self-interference and distortion increase causing receiver saturation
Solution Approach 1:
The phased array is divided into separate transmit subarrays and receive subarrays, physically segmenting the antenna elements to spatially isolate transmit and receive functions. This segmentation allows high-power transmission from dedicated transmit elements while receive elements are positioned to minimize exposure to self-interference, resolving the contradiction between transmitted power and self-interference.
Solution Approach 2:
An auxiliary receive channel is introduced as an intermediary to capture a copy of the transmitted signal before it radiates. This intermediary channel provides a reference signal that can be processed through digital beamforming and cancellation to generate a cancellation signal, which when combined with the main receive signal, eliminates self-interference and prevents receiver saturation.
2Adaptability or versatility
If multiple transmit and receive channel pairs are used to enable STAR operations, then simultaneous transmit and receive capability is improved, but system complexity and isolation requirements increase
Solution Approach 1:
The patent replaces complex physical isolation mechanisms (analog domain techniques requiring precise mechanical positioning and high-isolation apertures) with digital signal processing. Digital beamforming and adaptive cancellation algorithms perform the isolation function in the digital domain, dramatically reducing the complexity of physical channel isolation while enabling STAR operations across multiple channel pairs.
3Reliability
If digital beamforming and cancellation are used to reduce self-interference, then isolation performance is improved, but computational complexity increases
Solution Approach 1:
The auxiliary receive channel captures and processes the transmitted signal in advance, performing digital beamforming and generating the cancellation signal before it is needed. This preliminary action allows the cancellation signal to be pre-computed and stored, reducing real-time computational complexity during actual STAR operations while maintaining high isolation performance.
Data Source
AI summary
A method and apparatus for achieving simultaneous transmit and receive operation with a digital phased array is described. Digital beamforming and cancellation enables adjacent transmitting and receiving sub-arrays to operate simultaneously in the same frequency band.