Self-Interference Cancellation in Full-Duplex Transceivers
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Solution Overview
Problem
In wireless communication systems, especially in-band full-duplex mode, self-interference signals pose a challenge due to the difficulty in separating transmit and receive antennas, which degrades reception performance and is not feasible in radar systems, leading to increased operational costs and space requirements.
Innovation Solution
A transceiver apparatus that includes a self-interference signal canceling unit with a circulator, load generator, signal shifter, phase shifter, and transmission line to physically copy and adjust the self-interference signal, generating an estimation signal to cancel it from the receive signal, thereby compensating for magnitude and phase differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transmit and receive antennas are separated by sufficient interval to reduce self-interference, then reception performance is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent creates a physical copy of the transmit signal path using a second circulator and load generator to generate an estimation signal that replicates the self-interference characteristics. This copy is then used to cancel the actual self-interference in the received signal, eliminating the need for large antenna spacing while maintaining reception performance.
Solution Approach 2:
The patent introduces a self-interference signal canceling unit as an intermediary component between the transmit and receive paths. This unit processes the transmit signal to create an estimation of the self-interference and subtracts it from the received signal, acting as a mediator that eliminates harmful interference without requiring physical antenna separation.
2Productivity
If in-band full duplex mode is implemented without separate antenna spacing, then link capacity is doubled, but self-interference signal degrades reception
Solution Approach 1:
The patent applies preliminary anti-action by generating an estimation signal that predicts the self-interference before it corrupts the received signal. This estimation is created by physically copying the transmit signal through a second circulator and load generator, then adjusting magnitude and phase to match the actual self-interference characteristics. The cancellation occurs in advance of the reception process.
Solution Approach 2:
The patent implements feedback by using the transmit signal itself to generate the self-interference estimation. The second circulator and load generator create a closed-loop representation of the transmit path, allowing the system to continuously generate an accurate estimation signal that tracks the actual self-interference and enables real-time cancellation.
3Measurement precision
If radar system uses in-band full duplex mode with same frequency for transmit and receive, then target detection capability is improved, but system installation space and operational costs increase
Solution Approach 1:
The patent merges the transmit and receive antenna functions into a single antenna system. By using the self-interference cancellation technique, the system combines what would traditionally require separate spaced antennas into one integrated antenna, reducing installation space while maintaining the ability to perform both transmit and receive operations on the same frequency for improved target detection.
Data Source
AI summary
An apparatus for canceling a self-interference signal and a transceiver including the same are disclosed. The transceiver may include an antenna; a circulator transmitting a portion of a transmit signal to the antenna and transmitting a receive signal received through the antenna to a receiver; and a self-interference signal canceling unit receiving a first signal, which is a portion of the transmit signal, and physically copying a self-interference signal generated by the antenna and the circulator to generate an estimation signal of the self-interference signal.