On the Estimation of the ICI in OFDM in Conditions of Multipath Doppler Spreading and Carrier Frequencies Offset

In this paper, we consider the negative simultaneous effect of fast Relay fading in the channel and mutual "frequency shifts of subcarrier" subchannels between the transmitting and receiving sides of the channel, causing a violation of orthogonality between the signals of individual subchannels of the OFDM system. Violation of orthogonality is manifested by the appearance of a mutual interference signal on the receiving side of the channel in each OFDM subchannel. The paper evaluates the joint effect of fast fading and frequency shifts on the magnitude of transient interference between subchannels (ICI).