SDCCH

Common Control Channel. Common Control Channels support common procedures required to establish a dedicated link with the network . Typical channels include the RACH (Random Access Channel), PCH (Paging Channel) and AGCH (Access Grant Channel) within GSM.

Dedicated control channel (DCCH): A point-to-point bidirectional channel that transmits dedicated control information between a UE and the network . It is used by UEs that have RRC connection. The traffic channels are exclusively used for the transfer of user-plane information.

The traffic channels are the resources available to the user for either speech or data . A logical traffic channel in GSM is abbreviated by TCH. It can be used for either data or speech. The radio interface must support bi-directional transmission in order to support speech and data communication.

Broadcast control channels are transmitted in downlink direction only i.e. only transmitted by BTS . . The broadcast channels are used to broadcast synchronization and general network information to all the MSs within a cell. .

GSM uses a variety of ‘channels’ in which the data is carried. In GSM, these channels are separated into physical channels and logical channels . The Physical channels are determined by the timeslot, whereas the logical channels are determined by the information carried within the physical channel.