Physical Combination of Logical Channel in GSM
As shown above, CCCH=PCH+RACH+AGCH; downlink CCCH=PCH+AGCH; and uplink CCCH=RACH. In the above combinations, combination 3 and 4 must be allocated to slot 0 of the BCCH carrier configured for the cell; while combination 5 must be allocated to timeslots 2, 4 and 6 of the BCCH carrier. The FACCH works in the frame stealing mode, for which no fixed time sequence will be allocated. In addition, the cyclic multiframe period of SACCH/C4 and SACCH/C8 is 102 frames.