Specific emitter identification (SEI) is a powerful technique that identifies different emitters utilizing the features generated from hardware imperfections. The features, also known as radio frequency fingerprints (RFFs), can be extracted via model-based methods or data-based methods. In this paper, we analyze the identification accuracy of SEI system and provide criteria for evaluating different SEI schemes. We use in-phase/quadrature (I/Q) imbalance as an example to examine the identification performance by analyzing the Euclidean distance between radio frequency (RF) signals of different emitters. This derivation can also be generalized to different modulation schemes and distortion models.
