Frequency Offset Tracking for OFDM Systems via Scattered Pilots and Virtual Carriers

In this paper, we propose a new carrier frequency offset (CFO) tracking algorithm for orthogonal frequency division multiplexing (OFDM) systems. Assuming that the channel remains constant during two consecutive OFDM blocks, a CFO estimation algorithm is proposed based on the limited number of pilots in each OFDM block. Identiflability of this pilot based algorithm is fully discussed under the noise free environment. A weighted algorithm is then developed by considering both pilot carriers and virtual carriers. The asymptotic mean square error (MSE) of the proposed algorithm is provided, and simulation results clearly show the performance improvement of the proposed algorithm over the existing methods.