Embodiments of the present invention disclose an RRU, which performs IDFT on a PUSCH signal that is obtained after resource block demapping, where due to a characteristic of an extremely low peak to average power ratio of SC-FDMA modulation, a signal after IDFT has an extremely low peak to average power ratio at this time, and an amplitude range of the signal changes slightly; amplitude/phase conversion is performed on the signal after the IDFT, where the signal after the IDFT is represented by using amplitude and phase, and then amplitude quantization and phase quantization are performed respectively to obtain a quantized amplitude signal and a quantized phase signal respectively.