Table of Contents
Advertisement
I360 Mobile Phone Maintenance Manual
2.1 GSM System Description
2.1.1 General Introduction to Cellular Theory
A cellular system differs from other wireless telephone systems by dividing the service
area into many contiguous cells, which enables more powerful call processing and higher
system utilization. Each cell contains a base station which is capable of transmitting and
receiving signals, and is allocated with a set frequency pair (channel) for duplex
communications. Covering a relatively small area, each cell requires lower transmission
power than other wireless systems. So in a cellular system, the wireless transmission over a
specific channel involves the cell containing this channel and the immediate neighbor cells.
And since a cell corresponding to a specific channel covers a limited small area (compared
with the area covered by the whole system), the same channel can be reused by another cell
which is far away enough. This makes it possible for multiple subscribers to use the same
channel separately within the same geographical region.
2.1.2 GSM Description
The GSM system utilizes digital wireless communications technology, which makes it
different from previous cellular systems. Compared with older analog systems, the GSM
system enjoys many advantages which include the following:
A. International Roaming -- Since the universal GSM specifications are adopted
internationally, subscribers can dial or answer an international call in any country with
GSM support.
B. Digital wireless interface – A GSM phone provides a complete digital link between
a base station and a subscriber. In other words, a GSM phone provides a digital link
into the switching center and the traditional PSTN.
C. Compatible with ISDN – As the digital communications specification adopted in
many countries, ISDN can be used to transmit voice and data over copper links. A GSM
phone can offer features similar to those of a ISDN phone.
LENOVO
Lenovo Mobile Telecommunications Co., Ltd.（OPEN DOC）
v0.1
6
6
Page
of
Advertisement
Table of Contents
Troubleshooting
