Nonlinear Digital Cancellation in Full-Duplex Devices Using Spline-Based Hammerstein Model

In this paper, a novel digital self-interference canceller based on a Hammerstein adaptive filter is proposed and examined. The proposed system consists of a spline-interpolated lookup table to model the nonlinear power amplifier, followed by a linear filter accounting for the impulse response of th...

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Bibliographic Details
Published in2018 IEEE Globecom Workshops (GC Wkshps) pp. 1 - 7
Main Authors Campo, Pablo Pascual, Korpi, Dani, Anttila, Lauri, Valkama, Mikko
Format Conference Proceeding
LanguageEnglish
Published IEEE 01.12.2018
Subjects
Adaptation models
adaptive tracking
Computational complexity
decoupled model
digital cancellation
inband full-duplex
Interference cancellation
Nonlinear distortion
Performance evaluation
self interference
Spline interpolation
Splines (mathematics)
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Summary:In this paper, a novel digital self-interference canceller based on a Hammerstein adaptive filter is proposed and examined. The proposed system consists of a spline-interpolated lookup table to model the nonlinear power amplifier, followed by a linear filter accounting for the impulse response of the linear self-interference channel. The gradient descent based parameter learning algorithms are derived, which estimate the spline control points and the filter coefficients in a decoupled manner. The proposed digital canceller leads to a complexity reduction of 77% when compared to the existing state-of-the-art solutions. Performance evaluations using measured data from a complete inband full-duplex prototype system operating at 2.4 GHz ISM band show the effectiveness of the proposed technique, demonstrating that it obtains similar cancellation performance as the existing state-of-the-art canceller, regardless of its lower complexity. The measured digital self-interference cancellation values are 45 dB, 43 dB and 38 dB with 20 MHz, 40 MHz and 80 MHz channel bandwidths, respectively. These results indicate that the complexity-accuracy trade-off of the proposed decoupled spline-based cancellation approach is very favorable. Owing to the resulting decrease in the computational complexity, the proposed digital cancellation technique brings inband full-duplex transceivers one step closer to commercial deployments.
DOI:10.1109/GLOCOMW.2018.8644362