It is used in the configuration of cells of low traffic density and small capacity. The Combined BCCH is only configured at timeslot 0.
Channel combination: FCCH＋SCH＋BCCH＋CCCH+SDCCH/4+SACCH/4
SDCCH/4: Stand-alone dedicated control channel. Each TDMA multiframe with 51 frames has 4 SDCCH;
SACCH/4: Slow SDCCH/4 associated control channel;
Compared with the main BCCH channel, 4 signaling channels are added to the 51 frames. The functions of these 4 signaling channels are the same as those of the SDCCH8 channel. Therefore, this channel combination can be taken as a combination of the functions of the above two channels. This combination take effect on two aspects: first, this reduced the quantity of AGCH+PCH on CCCH and only a small-capacity system is provided; second, this combination provides a certain quantity of signaling channels in timeslot 0. Thus, it is unnecessary to assign SDCCH8 channels in a small-capacity system. This channel suitable for small-capacity systems. And it is also an example of the flexible GSM network configuration.