Performance of amplitude limited multitone signals

The multitone data transmission format has been receiving increasing interest recently as a potentially viable technique for transmission over both fixed and mobile links. However a disadvantage of the modulation format is that each transmitted multitone symbol has a non-constant envelope, with large instantaneous power spikes possible. This can lead to non-linear effects in the modulator causing intermodulation distortion and spectral spreading. In this paper the use of a peak power limit (or clip level) is considered for each symbol which can help to maintain linearity. The impact of applying such a clip level is analysed in terms of the symbol error rate (SER) caused on each subchannel, both theoretically and through simulation. Also a simple strategy for reducing the SER on each subchannel under a given clip constraint is introduced.<>