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Digital Post-Cancellation of Nonlinear Interference for Millimeter Wave and Terahertz Systems
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  • Xiaojing Huang ,
  • Hao Zhang ,
  • Anh Tuyen Le ,
  • Andrew Zhang ,
  • Jay Guo
Xiaojing Huang
University of Technology Sydney

Corresponding Author:[email protected]

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Hao Zhang
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Anh Tuyen Le
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Andrew Zhang
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Abstract

Wideband millimeter wave and terahertz systems face severe nonlinearity and other practical impairments such as transmitter and receiver I/Q imbalances (IQIs), carrier frequency offset, and phase noise. Based on a simplified yet effective received signal model, this paper proposes a low-complexity digital post-cancellation (DPC) framework for transmitter IQI and overall system nonlinearity mitigation. The nonlinearity parameters with reduced nonlinearity order are firstly estimated with low-complexity using a novel transmission protocol incorporating both frame rotation and preamble power scaling. Through widely linear system equalization and interference cancellation, the signal distortion caused by frequency-dependent IQI and nonlinearity are then mitigated with significant performance improvement. The mean-squared-error measurement of the EMP-modelled signals also provides a practical means for the nonlinear system identification and characterization. Both simulation and experiment results obtained from a millimeter wave system with 2.5 GHz bandwidth and 73.5 GHz carrier frequency are presented to verify the theoretical analyses and demonstrate the effectiveness of the DPC technology.