Inband Full Duplex Self-Interference Cancellation via Analog-Digital Processing

The patent replaces the mechanical/physical separation approach with signal processing methods. Specifically, it uses analog signal processing circuits including variable gain amplifiers and finite impulse response filters to cancel self-interference signals, and digital signal processing units that perform self-interference cancellation through computational algorithms. This substitution eliminates the need for complex physical antenna separation while achieving effective self-interference reduction.

The patent introduces intermediary signal processing components between the transmission and reception signal paths. These include analog circuits with variable gain amplifiers and FIR filters, and digital processing units that act as intermediaries to cancel self-interference. The intermediary processing stages enable self-interference cancellation without requiring physical isolation, thereby simplifying the overall device structure.

The patent segments the self-interference cancellation process into multiple stages: analog signal processing and digital signal processing. The analog stage uses variable gain amplifiers and FIR filters to handle strong self-interference signals, while the digital stage performs additional cancellation and quantization error reduction. This segmentation allows the system to manage the complexity of self-interference cancellation in inband full duplex operation by dividing the task across different processing domains.

The patent employs dynamic signal processing techniques including variable gain amplification where the gain is adaptively adjusted based on signal conditions, and digital signal processing that dynamically cancels self-interference. The system dynamically adapts its processing characteristics to handle the strong self-interference inherent in inband full duplex operation, enabling capacity doubling while managing the interference through adaptive rather than static processing.

The patent performs preliminary self-interference cancellation in the analog domain before digital quantization. By using analog circuits with variable gain amplifiers and FIR filters to reduce the strength of self-interference signals beforehand, the subsequent digital quantization process encounters weaker interference components, thereby reducing quantization error. This preliminary analog processing action protects against quantization error by reducing the dynamic range requirements for subsequent digital processing.

The patent segments the signal processing into analog and digital stages, with the analog stage performing initial self-interference cancellation and gain control, and the digital stage performing additional cancellation and quantization. This segmentation allows the system to handle strong self-interference signals in the analog domain where they can be processed with higher precision before conversion to digital, thereby reducing the impact of quantization error on the final cancellation precision.