SDCCH : Required number of SDCCH/8.
SDCCH are used for
Call set up
location updating
SMS are using the SDCCH channel.
The system supports four types of combination for SDCCH
channels
SDCCH/4: The SDCCH is combined with the BCCH
in time slot 0 on the BCCH carrier. This SDCCH configuration provides 4
subchannels for signalling. Only one SDCCH/4 can be defined for each cell. (BCCHTYPE
= COMB).
SDCCH/4 including CBCH: One subchannel is replaced by a CBCH.
This SDCCH/4 configuration provides 3 subchannels for signalling and one for
transmission of 47SMSCB messages. (BCCHTYPE = COMBC).
SDCCH/8: This SDCCH configuration provides 8 subchannels
for signalling (BCCHTYPE = NCOMB, CBCH = NO).
SDCCH/8 including CBCH: One subchannel is replaced by a
CBCH. This SDCCH/8 configuration provides 7 subchannels for signalling and one
for transmission of SMSCB messages (BCCHTYPE = NCOMB, CBCH =
YES).
Up to 32 SDCCH/8 can be specified per cell. This number
is reduced by one if an SDCCH/4 is defined for the cell.
ave any type of combined BCCH and SDCCH/4.
The BCCH is always allocated
to time slot number 0 (TN0) in the defined ARFCN.
The CBCH is used for
transmission of the messages when the function Short Messages Service Cell
Broadcast (SMSCB) is activated in the cell. SMSCB enables the operator to
submit short messages for broadcasting to a specific area within the PLMN.