In wireless communication system, there is a large frequency bias between carrier frequency and local oscillating frequency. AFC is contributed to eliminate it. A traditional AFC adopts analog loop filter that must work consecutively. However, in W CDMA system, the pilot parts are discontinuous. A novel digital approach of AFC is presented. In this algorithm, we first estimate the fading channel to get the phases and amplitudes of the pilot part symbols, and then combine estimations of multiple paths in one slot length, i.e., obtain one decision variable in each slot. Finally, these judged variables adjust the local oscillating frequency to track the carrier frequency by NCO. The simulation results show that the new AFC algorithm is effective and credible.
