GSM Broadcast Control Channel(BCCH)
This page describes GSM Broadcast Control Channel(BCCH).
This is the very critical of all control channels and transmitted/broadcasted to all the Mobiles in the cell. It is the downlink only signalling channel carrying following information to mobiles segregated to different SI messages called as System Information messages.
It is transmitted in 51 frame multi frame structure in frame next to SCH on TS0. It requires at least 4 consecutive TDMA frame to carry complete BCCH information. If needed next four frames are also used for the purpose.
Base Station continuously broadcasts critical system information (SI) messages. When frond-end synchronization is completed mobile reads these informations which helps mobile determine whether it can camp on to this GSM cell or not and also helps access the GSM network. Some of the SI messages are mandatory and some are optional to be transmitted. There are also some SI messages which are transmitted using SACCH channel. To know more on SI-1,SI-2,SI-2bis,SI-2ter, SI-3,SI-4,SI-7,SI-9,SI-13,SI-16 and SI-17 message content follow link mentioned below.
Figure describes BCCH channel information processing through the physical layer.