(An) efficient ICI self-cancellation method with frequency offset and phase noise in OFDM systems

Abstract

OFDM (Orthogonal Frequency Division Multiplexing) System is a promising transmission technique due to its spectral efficiency. But, a major disadvantage of the OFDM system is its sensitivity to frequency offset and phase noise that makes intercarrier interference (ICI), which degrades the system performance severely. The ICI self-cancellation method has a good performance with frequency offset or phase noise. But, in practical system, there are both frequency offset and phase noise. So conventional ICI self-cancellation have to be changed for frequency offset and phase noise cancellation. This thesis proposed the N/2 spacing data-conjugate method that works well in large frequency offset and phase noise (normalized frequency offset=0.2~0.4, phase noise standard deviation=about 10deg). Also, an efficiency ICI cancellation method using pilot was proposed. Condition rule checks whether the frequency offset and phase noise is large or not. This scheme works as the symmetric data-conjugate method in small errors, the N/2 spacing data-conjugate method in large errors. Simulation results confirm that performance of the proposed scheme considering the pilot is better than conventional schemes.