Control Channel (CCH)

introduction

GSM system channel classification:

Cellular communication systems to transmission of different types of information, including business information and various control information, so you need to in physical channel arrangement of logical channel. These logical channel some used to call in stages, some are used for communication underway, also some for system operation of all time.

Logical channel is divided into business channel (TCH) and control channel (CCH) two kinds big.

Control channel (CCH) was used to transmit signaling information and short packet data channel.

classification

Control channel is divided into three categories:

Broadcast information

1) broadcast information (BCH) is a kind of "point-to-multipoint" single direction control channel, used for mobile station radio stations to all public information. Transmission is the content of the mobile station net and call set-up needed all kinds of information. Among them were divided into:

A, frequency correction channel (FCCH) : transmission for mobile station correction its working frequency information;

B, synchronous channels (SYCH) : transmission for mobile station synchronously and to base station identification of information;

C, radio control channel (BCCH) : transmission general information, used in mobile station to measure the signal strength and identify district mark etc.

Public control channel

2) public control channel (CCCH) is a kind of "point-to-multipoint" two-way control channel, its usage is the call succeeded stage, transmission link connection needed to control signaling and information. Among them were divided into:

A, paging channel (PACH) : transmission stations paging mobile platform of information;

B, random access channel (RACH) : mobile station application into the net, send request information to base station,

C, allow access channel (AGCH) : base station at the call succeeded begins, send to the mobile station distribution channel of special control signaling.

D, community radio channel (CBCH) : used for base station to village inside the mobile station broadcast news channels.

Special control channel

3) special control channel (DCCH) is a kind of "peer-to-peer" two-way control channel, its usage is the call in stages and in communication underway in the mobile station and base station transmitted between the necessary control information. Among them were divided into:

A, independent special control channel (SDCCH) : transmission mobile station and base station connection and channel allocation of signalling, Also carry call forwarding and short message information.

B, accompany channel (ACCH), can accompany SDCCH, also can accompany business channel (TCH), in other words, it is SDCCH coupled with a TCH or.

(1) slow accompany channel (SACCH) : in the mobile platform and base station transmission, cycle between certain information, such as power adjustment, frame adjustment and measurement data information; etc. SACCH is arranged in business channel and the relevant control channel to complex connecting mode transmit information. Arranged in business channel when, with SACCH/T says, arranged in control channel when, with SACCH/C, said SACCH often used in combination with SDCCH.

2 quickly with channel (FACCH) : for blitting executing user jian right and the handoff information. When used to halt the business information (4), FACCH insert the frame, but only in did not assign SDCCH will only use this control channels. This control channel transmission rate faster, occupy 4 each frame time, about 18.5 ms.

Community radio channel

(4) community radio channel (CBCH)

Community radio channel used to broadcast village short message bit/s it only downward direction, carrying village broadcast short message service (SMSCB) information, use the same SDCCH the same physical channel.