– 15 –
SECTION 4
900 MHz SYSTEM OPERATION
4-1. ACCESS METHOD
1. Transfer format & rate
The transfer format & rate of our system is as follows;
Table 4-1. Transfer method
Access method
FDMA-TDD
Channel number
20 channel
Channel spacing
1.2 MHz
Modulation method
DBPSK
Baseband transfer rate
960 Kbps
Spread method
Direct Sequence Spread Spectrum
Chip rate
12 chips/bit
Data transfer rate
80 Kbps
2. Channel Number & Frequencies
RF channels occupy the frequency band 902 – 928 MHz are num-
bered 1 to 20.
RF channel numbers & center frequencies are specified as fol-
lows.
Table 4-2. Channel number & Channel frequency
Channel
Channel Center
Channel
Channel Center
Number
Frequency (MHz)
Number
Frequency (MHz)
1
903.6
11
915.6
2
904.8
12
916.8
3
906.0
13
918.0
4
907.2
14
919.2
5
908.4
15
920.4
6
909.6
16
921.6
7
910.8
17
922.8
8
912.0
18
824.0
9
913.2
19
925.2
10
914.4
20
926.4
4-2. PROTOCOL
1. General
This system realizes the TX/RX superframe by TDD system. The
relation of master/slave dose not decide identification regarding
the protocol between BS and HS, but the initiated side is the mas-
ter and the requested side is the slave when the RF link has been
established.
2. Initial acquisition
In order to establish the RF link between BS and HS, both of BS
and HS need to have the same system ID. When “power” is ap-
plied to this system, the system have to do Initial Acquisition in
order to have the same system ID. It is to exchange a parameter
when the HS is parked on the BS, as soon as the system do System
Parameters Re-initialization.
3. System parameter re-initialization
This System Parameters Re-initialization can realize that the HS
is parked on the BS. So after the BS recognized to be parked the
HS, the BS calculates a system parameter, and then it outputs this
data from the ARTO port, and then the system establishes the RF
link. In order to establish this link, the HS send the A-Frame to the
BS after the HS received the system parameter, and then the BS
send the A-Frame to the HS. The process of System Parameters
Re-initialization is as follows.
Fig. 4-1. System Parameters Re-initialization
Base Station
Handset
System ID
confirmed
System ID
confirmed
(Park Detect)
(Park Detect)
(PARK)
System Parameters
A-Frame
A-Frame
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