Frequency offset cancellation in OFDM systems using special (1 - D - D2) correlative codes

This paper concentrates on the correlative coding used to cancel the frequency offset in orthogonal frequency division multiplexing (OFDM) systems in mobile radio applications, such as 802.11 (WLAN), 802.16 (WiMAX), and digital video broadcasting (DVB) systems, e.g., DVB-CS2. This frequency offset may result due to the time variations of the channel during one OFDM symbol interval, or the transmitter and receiver are not phase locked, which in turn destroys orthogonality between different subcarriers, leading to power leakage among the subcarriers, known as Inter-Carrier Interference (ICI). A carrier - to - interference ratio (CIR) will be derived for the (1-D-D2) correlative codes and the modified scheme, and hence an expression for the bit error probability for the modified scheme will be given. A comparison between the different correlative coding orders will be held considering the CIR and bit error probability for each scheme at different normalized frequency offset values, and then for different bit energy to noise ratios.