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1. General Description
1-1 Dualband System
1-1-1 Calls
Dual band handsets supports the E-GSM and DCS system, DCS is an acronym for Digital Cellular system, and
GSM
is an acronym for Global System for Mobile communications
¨
operation. The GSM and DCS system consists of the sub-systems shown;
The Mobile Station (MS) talks to the Base Station System (BSS) via an RF air interface. The Base Station System
(BSS) consists of Base Transceiver Station (BTS) and a Base Station Controller (BSC). The interface between BTS
and BSC is called an Abis interface. Generally one BSC controls 20 to 30 BTSs, and a Mobile Switching Center
(MSC) controlling the traffic among different cells would be reported back from a number of BSSs. A Visitor
Location Register (VLR) will be allocated to one MSC to find the mobiles out of their home cell by listing them
to VLR. The MSC would also be connected to the Home Location Register (HLR), the Authentication Center
(AC) and the Equipment Identity Register (EIR) So the system verify that the users and equipment are legal
subscriber.
1-1-2 Channels
Channels used in the E-GSM and DCS system can be divided into two classes - Logical and Physical channel.
Physical channels can be described in terms of their frequency and time domain characteristics. They are the
actual frequencies and timeslots the MS and BS transmits or receives on. The logical channels are mapped onto
these physical channels logically. Any particular and instant, physical channels may be control or traffic
channels, which determines the function of a physical channel at a particular point in time.
1-1-3 Airinterface of ARFCN (Absolute Radio Frequency Channel Number)
975
880.2 MHz
975
925.2 MHz
512
1710.2 MHz
512
1805.2 MHz
Samsung Electronics
1023
0
1
2
890.2 MHz
E-GSM: TX: Ful(n) = 890MHz + (0.2MHz) • n, 0≤n≤124 and
Ful(n) = 890MHz + (0.2MHz) • (n-1024), 975≤n≤1023
1023
0
1
2
935.2 MHz
E-GSM: RX: Fdl(n) = Ful(n) + 45MHz
DCS Tx: Ful(n) = 1710MHz + (0.2MHz) • (n-511)
n = ARFCN,
DCS Rx: Fdl(n) = Ful(n) + 95MHz
< Fig. 1 ARFCN Diagram >
, using TDMA for wide-area cellular
©
3
...
...
...
3
...
...
...
512≤n≤885
...
123
124
914.8 MHz
...
123
124
959.8 MHz
885
1784.8 MHz
885
1879.8 MHz
1-1
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