BCCH

A broadcast control channel (BCCH) is a point to multipoint, unidirectional (downlink) channel used in the Um interface of the GSM cellular standard. The BCCH carries a repeating pattern of system information messages that describe the identity, configuration and available features of the base transceiver station (BTS). These messages also provide a list of absolute radio-frequency channel numbers (ARFCNs) used by neighboring BTSs. This message pattern is synchronized to the BTS frame clock.[1] The minimum BCCH message set is system information messages 2–4, although other messages are normally present. The messages themselves are described in 3GPP Technical Specification 44.018.[2]

Any GSM ARFCN that includes a BCCH is designated as a beacon channel and is required to transmit continuously at full power



BCCH
BCCHNO Absolute RF channel number for BCCH. Absolute RF channel number already defined for a dedicated channel can not be used.
The frequency carrying the BCCH (Broadcast Control Channel) in a cell, is defined by the Absolute Radio Frequency Channel Number, ARFCN, with the parameter BCCHNO. The defined ARFCN must be unique within the cell..

Range: 128 to 251 (GSM 800).
1 to 124 (GSM 900, P-band).
512 to 885 (GSM 1800).
512 to 810 (GSM 1900)

BCCHTYPE: COMB, COMBC, NCOMB

COMB indicates that the cell has a combined BCCH and SDCCH/4 .

COMBC indicates that the cell has a combined BCCH and SDCCH/4 with a
CBCH subchannel.

NCOMB indicates that the cell does not have 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.
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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.