GSM Frequency Correction Channel (FCCH)

This page describes the GSM Frequency Correction Channel (FCCH). The FCCH is primarily used in the GSM frame for synchronization between the Base Transceiver Station (BTS) and the GSM Mobile Station (MS).

It’s a downlink channel that carries a continuous wave signal, helping the mobile station determine the frequency offset between the BTS and itself. The burst transmitted on this channel consists of all zeros, which generates a continuous sine wave approximately 67.7 KHz above the RF carrier center frequency. The FCCH channel utilizes the Frequency Burst (FB) for transmission.

The GSM FCCH operates within a 51-frame multiframe structure, transmitted on the broadcast GSM frequency. Within this 51-frame multiframe, it occupies the first time slot (TS0) and repeats its transmission once every 10 TDMA frames.

Figure depicts FCCH channel information through the physical layer modules.