ERICSSON EF738 SystIntro
System Introduction
Ericsson Mobile Phone EF738
System Introduction
2
System Introduction
Contents
The Mobile Telephone Network _______________________ 5
Base Station and Cell ______________________________________ 6
Radio Channels ___________________________________________ 6
Radio Coverage ___________________________________________ 7
Transmission Control and Communication ____________________ 8
Quality Control ___________________________________________ 9
Data Transmission________________________________________ 10
Frequency Tables ___________________________________11
Table 1: Channels 1329 - 2047 ______________________________ 12
Channels 1329 - 1478___________________________________ 12
Channels 1479 - 1628___________________________________ 13
Channels 1629 - 1778___________________________________ 14
Channels 1779 - 1928___________________________________ 15
Channels 1929 - 2047___________________________________ 16
Table 2: Channels 0 - 600 __________________________________ 17
Channels 0 - 149_______________________________________ 17
Channels 150 - 299_____________________________________ 18
Channels 300 - 449_____________________________________ 19
Channels 450 - 600_____________________________________ 20
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System Introduction
4
The Mobile Telephone Network
cellular mobile telephone system
A
illustrated in
•
mobile services switching centre (MSC)
the
•
base stations
the
•
mobile telephones
the
fig. 1
. The basic units of such a system are:
(BS)
(MT)
(CMS) controlled by one single exchange is
System Introduction
The MSC is the interface between the radio system and the
phone network
MSC, which also provides all signalling functions needed to establish the calls.
In order to obtain radio coverage of a given geographical area, a certain number of
base stations is required. The number of base stations may range from one up to a
hundred or more. Such a geographical area is called an
The number of MSCs varies from one country to another, depending on traffic density, the number of base stations, and so on. Each MSC handles calls from one
ice area
number of
(PSTN). Calls to and fr om the mobi le su bscri ber ar e swit ched by the
which, in turn, is divided into radio z ones. A service area consists of a
radio zones
(or
cells
), each of which is serviced by a base station.
public switching tele-
MSC service area
.
serv-
Figure 1: Basic Units in the Mobile Telephone System
5
System Introduction
Base Station and Cell
A base station is able to communicate with any mobile telephone within a certain
area close to it. This area is called a cell.
The base station contains channel units. Each channel unit is equipped with a
transmitter
communication with the MS C and for data sign alling wit h the mobile tel ephones on
the radio path. A channel uses two separate radio frequencies, one for transmission
by the mobile telephone and one for transmission by the base station. Such a channel is called a
duplex distance, is always the same and is 45 MHz.
All base stations wit hin a se rvi ce area are connected to the MSC via dedicate d l ine s
in the public telephone network.
radio receiver
, a
duplex channel
, and a
control unit
. The distance between these two frequenci es, the
Figure 2: Channel Unit
. The control unit is used for data
radio
Radio Channels
Two different types of radio channels exist in a base station:
• voice channels
• control channels
The majority of channel units are voice channel units. Such a voice channel unit is
engaged in carrying one telephone call at a time. Depending on how many simultaneous calls a base station is required to handle, the number of
voice-channel units i n some base stations may be only a f ew, while in other s up to a
hundred or more.
There is normally only one control channel in each cell. A mobile telephone being
within a cell, and not in the conversation state, is always tuned to the control channel of this cell. The telephone supervises the continuous data stream.
The total number of channels available in a mobile telephone system is limited. As
the radio waves only reach so far from the base station, however, identical channel
frequencies can be used by several base stations, provided the distance between
them is suffic ie nt t o pre vent interference. This method is use d to i ncrease the capacity of the system.
(VC)
(CC)
6
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