Specifications

1–3
DECT Time Slot and Frame Structure
•
1 DECT FRAME : 10mS
•
1 DECT SLOT : 417µS (480bit)
•
1 DECT Bit : 868nS
Basic Functions of the DECT System
DECT System
DECT System DECT System
DECT System
!
The DECT system uses a pico-cellular technology (the cell range is 15 m to 300 m depending
on the environment).
! The frequency ranges between 1,880 and 1,900MHz (UHF); i.e. 20MHz is shared out into 10
carriers.
! The pass-range of a channel is equal to 1.728MHz and two channels are separated by 2MHz
in order not to disturb the neighbouring channels.
DCS System
DCS SystemDCS System
DCS System
The DCS system:
!
controls and maintains the BSI;
! maintains and downloads DBS functions;
!
controls the data from the DECT handset, and sends display data to the DECT handset.
DBS
DBSDBS
DBS
! A DBS uses one of 10 channels (FDMA technology) and 24 time slots per frequency (TDMA
technology).
! GFSK (Gaussian Frequency Shift Keying) modulation technology is used.
BSI
BSIBSI
BSI
The BSI:
! maintains subscriber information and communicates with the DCS system;
!
handles fault information.
1 TDMA frame 24 timeslots (10mS)
Fix to Portable Portable to Fix
0 1 2 3 4 5 6 7 8 9 10 11 0 1 2 3 4 5 6 7 8 9 10 11
417µs
28µs 340µs 49µs
Guard-Space(56bits) D-Field(388bits)
Z
Sync,-Field(32bits)
56µs 278µs 3µs 3µs
Z-Field (4bits)
X-Field (4bits) B-Field (320bits)
A-Field (64bits)
SLOT
D-Field
I-Field (320bits) CRC (16bits) Tail (40bits) Header (8bits)
FRAME