Study of the estimation techniques for the Carrier Frequency Offset (CFO) in OFDM systems

摘要

Orthogonal frequency division multiplexing (OFDM) has been selected for broadband wireless communication system. OFDM can provide large data rates with sufficient robustness to radio channel impairments. One of the major drawbacks for OFDM system is Carrier frequency offset (CFO). Frequency offset has been recognized as a major disadvantage of OFDM. The OFDM systems are sensitive to the frequency synchronization errors in form of Carrier Frequency Offset (CFO), because it can cause the Inter Carrier Interference (ICI) which can lead to the frequency mismatched in transmitter and receiver oscillator. Lack of the synchronization of the local oscillator signal (L.OSC); for down conversion in the receiver with the carrier signal contained in the received signal can cause to degrade the performance of OFDM. On the other hand the orthogonality of the OFDM relies on the condition that transmitter and receiver operate with exactly the same frequency reference. To compensate the effect of CFO the researchers have proposed various CFO estimation and compensation techniques and algorithms by now. In this paper, the reason of creating CFO and the effects of the CFO on the performance of the OFDM system will study. The major CFO estimation algorithm and techniques will be reviewed and discussed in literature briefly and then our proposed algorithm and technique for estimating and compensation of the effect of CFO will be offered.