Multiple carriers in wireless communications - curse or blessing?

The use of multi-carrier techniques is a natural choice when regarding wireless systems with high bandwidths and for which the application environment exhibits severe multipath propagation. These techniques provide a way to cope with and benefit from the time-dispersive channel. This, however, comes at the cost of a higher sensitivity to imperfections in the analogue radio frequency front-end. This paper illustrates the sensitivity of the most frequently used multi-carrier technique, i.e. ortho gonal frequency division multiplexing (OFDM), to three of the main impairments: phase noise, IQ imbalance and nonlinearities. Furthermore, it is shown that the use of digital signal processing can largely compensate the effects of these non-idealities, overcoming the disadvantages of the use of multi-carrier techniques.