There are two types of BCH structure supported in the N7602B Signal Studio software. One is FCCH+SCH+BCCH+CCCH and the other is FCCH+SCH+BCCH+CCCH+SDCCH/4(0…3)+SACCH/4(0…3). Refer to 3GPP standard 3GPP TS 45.002 V7.6.0 (2007-11).
In the second structure of BCH, a multiframe should be 102 frames. But, it can be divided into two 51 frames structures which have little difference with each other. The only difference is the SACCH part. SACCH(0) and SACCH(1) are in the first 51 frames. SACCH(2) and SACCH(3) are the second 51 frames. As different SACCH contents for multi-users is not supported, only 51 frames is to be used in the structure.
Figure: Example of TDMA Frame mapping for control channels
TDMA Frame Structure (Advanced Downlink)