1st International Conference on 5G for Ubiquitous Connectivity

Research Article

I/Q Imbalance Calibration for Higher Self-Interference Cancellation Levels in Full-Duplex Wireless Transceivers

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  • @INPROCEEDINGS{10.4108/icst.5gu.2014.258148,
        author={Ramez Askar and Nidal Zarifeh and Benjamin Schubert and Wilhelm Keusgen and Thomas Kaiser},
        title={I/Q Imbalance Calibration for Higher Self-Interference Cancellation Levels in Full-Duplex Wireless Transceivers},
        proceedings={1st International Conference on 5G for Ubiquitous Connectivity},
        publisher={IEEE},
        proceedings_a={5GU},
        year={2014},
        month={12},
        keywords={full-duplex pre-equalization self-interference cancellation i/q imbalance},
        doi={10.4108/icst.5gu.2014.258148}
    }
    
  • Ramez Askar
    Nidal Zarifeh
    Benjamin Schubert
    Wilhelm Keusgen
    Thomas Kaiser
    Year: 2014
    I/Q Imbalance Calibration for Higher Self-Interference Cancellation Levels in Full-Duplex Wireless Transceivers
    5GU
    IEEE
    DOI: 10.4108/icst.5gu.2014.258148
Ramez Askar1, Nidal Zarifeh1, Benjamin Schubert2, Wilhelm Keusgen2,*, Thomas Kaiser1
  • 1: Institute of Digital Signal Processing, Faculty of Engineering, University of Duisburg-Essen
  • 2: Fraunhofer Heinrich Hertz Institute
*Contact email: wilhelm.keusgen@hhi.fraunhofer.de

Abstract

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.