In an orthogonal frequency division multiplex communication system, for example a HIPERLAN/2 system, power amplifiers (224) of mobile terminals (4, 6) are switched off when not in use, and then switched on again when a signal transmission is to be made. This conserves power, but introduces a power amplifier transient (315). An access point (2), i.e. a type of base station, compensates for these power amplifier transients (315) using a simple scalar constant gain transient correction, over a full OFDM symbol (or a plurality of OFDM symbols). The correction is updated on an OFDM symbol by symbol basis (or plurality of symbols by plurality of symbols basis).