Multi-carrier modulation signal bit allocation method, device and system

Embodiments of the invention provide a multi-carrier modulation signal bit allocation method, a device and a system. The method comprises the steps of determining the signal-to-noise ratio (SNR) margin according to a preset probability of the maximum clipping noise which can be tolerated by a system, and allocating the bit number and power of modulation on each sub carrier for a multi-carrier modulation signal according to the SNR margin. By presetting a SNR margin for clipping noise, the tolerance of signals to clipping noise is improved, and the bit error rate is reduced effectively.