Global System for Mobile Communications (GSM) utilizes common channels for various essential functions, including call setup, registration, and handovers. These channels are crucial for the efficient operation of the GSM network. Here are the common channels in GSM:
1. Random Access Channel (RACH):
The Random Access Channel is used by mobile devices to initiate communication with the network. When a mobile device is powered on or moves into a new location area, it sends a request on the RACH to establish a connection with the network.
2. Broadcast Control Channel (BCCH):
The Broadcast Control Channel is a downlink channel used for broadcasting system information. It provides essential details about the network, including cell identity, frequency, and neighboring cell information.
3. Frequency Correction Channel (FCCH):
The Frequency Correction Channel is a downlink channel that helps mobile devices synchronize their frequencies with the base station. It assists in maintaining accurate frequency synchronization for effective communication.
4. Synchronization Channel (SCH):
The Synchronization Channel is another downlink channel that provides synchronization information to mobile devices. It helps the mobile device align its timing with the network.
5. Common Control Channel (CCCH):
CCCH includes several channels used for common control purposes:
a. Paging Channel (PCH):
The Paging Channel is used by the network to alert a mobile device about an incoming call or a message.
b. Access Grant Channel (AGCH):
The Access Grant Channel is used to assign a dedicated channel to a mobile device after successful access on the Random Access Channel.
c. Access Reject Channel (AGCH):
The Access Reject Channel is used to indicate that the network cannot grant access to a mobile device.
6. Dedicated Control Channel (DCCH):
Dedicated Control Channels are used for specific connections and carry signaling information related to dedicated channels established for voice or data communication.
7. Standalone Dedicated Control Channel (SDCCH):
The SDCCH is a dedicated control channel used for signaling during call setup, location updating, and short message service.
In summary, these common channels play a crucial role in facilitating communication, synchronization, and control functions within the GSM network, ensuring seamless operation and efficient utilization of resources.