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I/Q imbalance calibration for higher self-interference cancellation levels in Full-Duplex wireless transceivers

: Askar, R.; Zarifeh, N.; Schubert, B.; Keusgen, W.; Kaiser, T.


Latva-aho, M. ; Institute of Electrical and Electronics Engineers -IEEE-; IEEE Computer Society:
1st International Conference on 5G for Ubiquitous Connectivity, 5GU 2014 : Akaslompolo, Finland, 26 - 28 November 2014
Piscataway, NJ: IEEE, 2014
ISBN: 978-1-63190-055-6
ISBN: 978-1-4799-6029-3
International Conference on 5G for Ubiquitous Connectivity (5GU) <1, 2014, Akaslompolo>
Fraunhofer HHI ()

This paper investigates a Full-Duplex transceiver using an active cancellation technique where an additional transmit chain is employed to create the self-interference cancellation signal. Both transmitters and also the receiver are impaired by frequency-dependent I/Q imbalance with different parameters. It is shown how an I/Q parameter deviation in these chains deteriorates the achievable self-interference suppression level. Three different types of pre-equalization units, with variable complexity degree and different implementation approach, are then introduced and investigated. These units correct the I/Q imbalance and retain the self-interference level to its value as in a perfectly I/Q matched full-duplex transceiver. They can even be used to fully calibrate the I/Q imbalance. Simulative results show that self-interference suppression levels of more than 71 dB can be achieved.