Control Channel

A control channel ( CCH ) is a control channel in a cellular network that is used to exchange signaling and control information between various network elements and terminals. SMS text messages are also sent via control channels.

GSM control channels

The control channels of the GSM mobile radio system can be divided into 4 groups according to their use:

Broadcast Control Channels , channels for the non-directional transmission of control information

FCCH - Frequency Correction Channel

SCH - Synchronization Channel

BCCH - Broadcast Control Channel

PBCCH - Packet Broadcast Control Channel

Common Control Channel , CCCH , a shared channel in which control information is transmitted. It transports the following control channels:

PCH - paging channel

RACH - Random access channel

AGCH - Access grant channel

NCH - Notification channel

or Packet Common Control Channel , PCCCH , like CCCH, but for GPRS

PRACH - Packet Random Access Channel

PPCH - Packet Paging Channel

PAGCH - Packet Access Grant Channel

Dedicated control channels , channels in which control information is exchanged with a specific terminal device

SACCH / TF - Slow TCH / F / E-TCH / F associated control channel

FACCH / F - Fast TCH / F associated control channel

SACCH / TH - Slow TCH / H / O-TCH / H associated control channel

FACCH / H - Fast TCH / H associated control channel

SDCCH / 8 - Stand alone dedicated control channel

SACCH / C8 - Slow SDCCH / 8 associated control channel

SDCCH / 4 - Stand alone dedicated control channel combined with CCCH

SACCH / C4 - Slow SDCCH / 4 associated control channel

SACCH / M - Slow TCH / F / O-TCH / F / E-TCH / F associated control channel for multislot configurations

SACCH / CTS - Slow TCH / F associated control channel for CTS

E-FACCH / F - Fast E-TCH / F associated control channel

E-IACCH / F - Inband E-TCH / F associated control channel

SACCH / TPF - Slow TCH / F / O-TCH / F associated control channel for enhanced power control

SACCH / MP - Slow TCH / F / O-TCH / F associated control channel for enhanced power control in multislot configurations

SACCH / TPH - Slow TCH / H / O-TCH / H associated control channel for enhanced power control

EPCCH / F - Enhanced power control, TCH / F / O-TCH / F associated channel

EPCCH / M - Enhanced power control, TCH / F / O-TCH / F associated channel in multislot configuration

EPCCH / H - Enhanced power control, TCH / H / O-TCH / H associated channel

O-FACCH / F - Fast O-TCH / F associated control channel

O-FACCH / H - Fast O-TCH / H associated control channel

PACCH - Packet Associated Dedicated Control Channel

PTCCH / U - Packet Timing advance Control Channel Uplink

PTCCH / D - Packet Timing advance Control Channel Downlink

CTS Control Channels , control channels for GSM- CTS

BCH - CTS beacon channel

CTSPCH - CTS paging channel

CTSARCH - CTS access request channel

CTSAGCH - CTS access grant channel

Single descriptions

FCCH

The Frequency Correction Channel is a downlink channel in GSM that helps the end device to find the frequency channels in which a BCCH is transmitted. The FCCH is always transmitted in timeslot 0 of the frequency channel in which a BCCH is located. The timeslot numbering can therefore be found out by receiving the FCCH, followed by the SCH and thus the BCCH. In the FCCH only frequency correction bursts are sent.

SCH

The synchronization channel is a downlink channel in GSM that helps the end device to recognize the channel structure and to find the BCCH. The SCH is always transmitted exactly in the eighth timeslot after the FCCH. By receiving the SCH, the frame structure can be recognized and the BCCH can be found. In the SCH, only the current frame number and the BSIC are transmitted.

BCCH and PBCCH

The broadcast control channel is a downlink channel in GSM that provides the terminal with information about the transmitting cell. These are e.g. B. the PLMN identifier of the network, cell ID, location area , channel structure, access restrictions, availability of data services and frequencies of neighboring cells.

RACH and PRACH

The Random Access Channel is an uplink channel in GSM in which the end device can request a connection to be established from the network.

PCH and PPCH

The paging channel is a downlink channel in GSM, which is used to deliver a connection request from the network to individual terminals, for example because of an incoming call or a short message. A terminal called in this way will, when it receives this connection request, attempt to request a dedicated channel for further communication via the RACH or PRACH. The base station then allocates a channel to the terminal via the Access Grant Channel (AGCH). A terminal is called based on its TMSI , in exceptional cases based on its IMSI .

NCH

The notification channel is a downlink channel in GSM, which is used to inform end devices about calls from the VGCS and the VBS . For this purpose, the IDs of the corresponding participant groups are transmitted in this channel.

Individual evidence

↑ 3GPP TS 45.002: Multiplexing and multiple access on the radio path ( English , ZIP / DOC; 569 kB) October 1, 2009. Accessed December 8, 2009.

[1] 3GPP TS 45.002: Multiplexing and multiple access on the radio path ( English , ZIP / DOC; 569 kB) October 1, 2009. Accessed December 8, 2009.