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
-
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.