Samsung SGH-600BL User Manual download pdf (Page 4)

1-2 Samsung Electronics

General Description

1-1-5 Logical Channel

TCH (Traffic CH) is used mainly for transferring the speech information, and the BCH (Broadcast CH) is

related to control information.The major function of BCH is transferring information on the downlink for MS

synchronization, identification, paging, and controll. BCH is always radiated from every cells and the MS tries

to find the BCH which has highest level soon after turned on. The organization of BCH is shown belows;

FCCH (Frequency Correction Channel), SCH (Synchronization Channel), and BCCH (Broadcast Control

Channel). CCCH (Common Control Channel) will play a role like a message board, and is divided into two

control channels - PCH (Paging Channel) and AGCH (Access Grant Channel). SACCH (Slow Associated

Control Channel) exists every 12 frames, controlling and controls the TX power level and timing advance of

MS, transferring cell information to MS on downlink, transferring the information about RX level, Quality, and

RX level of adjacent cell on uplink. FACCH (Fast Associated Control Channel) steals and changes the TCH

when needing a Handover. SDCCH (Stand-alone Dedicated Control Channel) and RACH (Random Access

Channel) operate during the call setup procedure.

1-1-4 GSM TDMA Timeslots, Frames, and Multiframes

0 1 2 3 4 ... ... ... ... ... ... 24 25

TCH

Multiframe

0 1 2 3 4 ... ... ... ... ... ... 49 50

01234567

BCH

Multiframe

TDMA

Frame

T Information F Midamble F Information T Guard

Timeslot

< Fig. 2 Concept of Frames and Timeslots >

1 2 3 4 5 6 7 8 9 ... 73 74

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Samsung SGH-600BL User Manual Page 4