ICI Cancellation Techniques Based on Data Repetition for OFDM Systems

Orthogonal frequency division multiplexing (OFDM), as a kind of multicarrier technique, has been deemed as the signal waveform for both uplink and downlink transmission for the fifth generation (5G) wireless network. OFDM enjoys free inter‐symbol interference (ISI) by converting the broadband channel into multiple orthogonal narrowband subchannels. However, the orthogonality can be easily destroyed by the carrier frequency offset (CFO) and/or Doppler. The breaking of subchannel orthogonality leads to intercarrier interference (ICI), which seriously deteriorates the system performance. This chapter first revisits the principle of OFDM and the impact of ICI on the carrier‐to‐interference power ratio (CIR) performance of the plain OFDM system, then introduces four effective ICI cancellation schemes without explicitly estimating ICI coefficients based on mirror‐mapping rules and their resulting CIR performance, and finally demonstrates the benefits of the four ICI cancellation schemes for OFDM underwater acoustic (UWA) communications that suffers from strong ICI by a sea experiment conducted in Taiwan.