A New Method for I/Q Impairment Detection and Evaluation in OFDM Transmitters

Detection and evaluation of impairments in the baseband section (I/Q impairments) of orthogonal frequency-division multiplexing digital transmitters are dealt with. A new measurement method is, in particular, proposed with the aim of overcoming key limitations exhibited by already-available approaches, which are generally designed for traditional digital transmitters and based on I/Q diagram analysis. The method is nonintrusive, exploits an analytical model that properly accounts for the way I/Q impairments affect the radio frequency output signal, with special regard to mirror subcarrier interference, and implements an original procedure to estimate impairment amounts. Aside from describing the analytical model along with the fundamental stages of the measurement procedure, this paper gives details of the extended experimental activity carried out on laboratory signals characterized by known I/Q impairments in order to assess the performance of the method