Time-Varying Carrier Offsets in Mobile OFDM

A carrier offset in OFDM system simulation is generally considered to be slowly time-varying, so that, over short simulation periods, it may be considered to be a constant quantity. However, depending on system mobility, carrier frequency, and communication duration, time-varying carrier offsets caused by Doppler effects can be significant in a real physical environment. Few researchers have addressed this in their works. Of those who have addressed this, many present simplified, vague, or inaccurate time-varying carrier offset models. In this paper, we present a more realistic time-varying carrier offset model and present expressions for carrier offset correction that maximize the signal-to-interference ratio (SIR). We also provide guidelines for when the application of the time-varying carrier offset model is crucial for correct OFDM system evaluation.