Full Duplex Radio Self-Interference Cancellation via Adaptive Power Reduction
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Solution Overview
Problem
In-band single-antenna full duplex radios face significant self-interference issues due to signal leakage from the transmit chain to the receive chain, limiting their performance and energy efficiency, especially when transmit power exceeds the threshold for effective self-interference cancellation.
Innovation Solution
The implementation of a power reduction unit with an energy harvesting unit and a DC/DC converter, coupled with an adaptive baseband module that splits the received signal to optimize the signal-to-interference-plus-noise ratio, allowing for effective self-interference cancellation and energy reuse, even at high transmit powers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transmit power is increased to improve system throughput, then transmission rate is improved, but self-interference power increases making cancellation ineffective
Solution Approach 1:
The patent applies preliminary action by performing self-interference cancellation before the harmful effect of high transmit power degrades the received signal. The system pre-calculates and subtracts the self-interference component from the received signal, enabling effective cancellation even when transmit power is high. This preliminary processing allows the system to operate at high power levels without suffering from self-interference degradation.
2Device complexity
If in-band single antenna full duplex is used to reduce device cost, then device complexity is reduced, but self-interference leakage increases
Solution Approach 1:
The patent applies the extraction principle by isolating and removing the self-interference component from the received signal. The system extracts the self-interference portion that leaks from the transmit chain to the receive chain and subtracts it from the composite signal. This allows the simple in-band single antenna architecture to effectively eliminate the harmful leakage, maintaining both low device complexity and low self-interference levels.
3Power
If high transmit power is used to overcome propagation attenuation, then received signal power is improved, but self-interference dominates the received signal
Solution Approach 1:
The patent converts the harmful self-interference into a beneficial element by using it as a reference signal for cancellation. The system exploits the known structure and characteristics of the self-interference component to accurately estimate and subtract it from the received signal. This transforms the previously harmful high-power leakage into a useful reference that enables effective cancellation, allowing the system to operate at high transmit powers without self-interference dominance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances both spectral and energy efficiency of the full duplex radio, enabling effective self-interference cancellation and reducing energy wastage, with the flexibility to operate across various power levels and scenarios without additional power consumption.
Implementation Method 1
The power reduction unit comprises an energy harvesting unit, coupled between the circulator and the reception unit, and adapted to provide an energy saving
Data Source
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AI summary
A full duplex radio unit (2) comprising a transmission unit (3), an antenna (6), a reception unit (4), a circulator (5) and a power reduction unit (14) is provided. The transmission unit (3) is adapted to generate a first signal (20). The circulator (5) is adapted to provide the first signal (20) from the transmission unit (3) to the antenna (6). The antenna (6) is adapted to transmit the first signal (20) and simultaneously receive a second signal (21) using an identical frequency or frequency band. The circulator (5) is adapted to provide a third signal (22) to the power reduction unit (14), wherein the third signal (22) comprises the second signal (21) and interference generated from the first signal (20) by the antenna (6) and the circulator (5). The power reduction unit (14) is adapted to reduce the power of the third signal (22) by multiplying the third signal (22) by factor of p, wherein p is between zero and one, thereby generating a fourth signal (23). The reception unit (4) is adapted to receive the fourth signal (23).