Mobile telephone systems have evolved from early cordless phones with limited range to modern cellular networks. First generation analog cellular systems from the 1980s used technologies like AMPS and NMT. Second generation digital systems in the 1990s included GSM and CDMA, using TDMA and CDMA for access. Third generation systems developed in response to increasing data demand, including UMTS in Europe based on GSM and WCDMA, and CDMA2000 in the US based on IS-95 CDMA. These 3G technologies provide multimedia services up to 2Mbps for stationary users and 384kbps for mobile.

1. Mobile Telephone system

2. Content
• Cordless Telephones
• Analog Cellular Systems
• Digital Second Generation Cellular Systems
• Third Generation Cellular Systems

3. Cordless Telephones
• Cordless phones were originally developed for
the residential market and they were designed
to cover only one local area such as a house
and garden.
• They support only local mobility and should
not be considered competitors for cellular
mobile networks.

4. Applications of cordless
telephones

5. Analog Cellular Systems
• The first cellular technologies were analog and they became
available in the first half of the 1980s.
• These systems are often referred to as first generation cellular
systems
• The important analog cellular systems are:
– Advanced Mobile Phone System (AMPS) in the United States;
– Nordic Mobile Telephone (NMT) used in Nordic countries;
– Total Access Communications System (TACS) in the United Kingdom.
• They use a frequency band in the range of 800 to 900 MHz
(NMT uses 450 MHz as well)
• And they both uses FDMA

6. Digital Second
Generation Cellular Systems
• The important Digital Second Generation
Cellular Systems
– Global System for Mobile communications (GSM),
originally from Groupe Spécial Mobile)
– Code Division Multiple Access (CDMA)

7. GSM
• GSM operates at the 900-MHz frequency band
and it became the most widely used second
generation cellular technology.
• In GSM the subscription information is stored
on a smart card and a subscriber can change
his or her mobile telephone any time.
• When he or she inserts his or her card into the
new telephone, he or she has access to exactly
the same service as previously.
• The access method used in GSM is TDMA, in
which each frequency channel is divided into
time slots for multiple users.

8. CDMA
• CDMA was selected in the early 1990s to become the
main digital cellular standard in the United States.
• The main difference between CDMA and other
technologies discussed previously is that on the radio
path it does not use either FDMA or TDMA.
• Instead the mobiles use the wide frequency band all of
the time with the help of a unique code for each user.
• This unique code is used to spread the signal over a
wide frequency band and to detect the wanted signal
at the receiving end.
• This American system is also referred to as narrowband
CDMA (N-CDMA) or the Interim Standard-95 (IS-95)
system.

9. Third Generation
Cellular Systems
• The main forces behind development of the
third generation systems (3G) have been
driven by
– Low performance data services,
– Incompatible service in different parts of the
world, and
– lack of capacity of the 2G systems.

10. Universal Mobile
Telecommunications System (UMTS)
• UMTS is a European concept for integrated mobile
services and it is based on the GSM and GPRS.
• Its goal is to provide a wide range of mobile services
wherever the user is located.
• For UMTS cordless (TDD), cellular and satellite
interfaces are defined. It will provide multimedia
service with data rates up to 2 Mbps for steady MSs
and up to 384 Kbps for moving MSs.
• The cellular radio access method for UMTS approved
ETSI is wideband CDMA (WCDMA).
• The basic operating principle is the same as in CDMA,
which was introduced previously.

11. UMTS
• The new frequency band at the 2-GHz range is
allocated for UMTS. The channel bandwidth is
5 MHz, and each channel is used by all cells.
• The core network of UMTS is based on the
core network of GSM and GPRS.
• The UMTS BSs can be added to the GSM/GPRS
network to operate in parallel with GSM base
stations.
• Even handovers between UMTS and
GSM/GPRS are supported.

12. CDMA 2000
• The main 3G technology for the United States
is based on second generation IS-95 CDMA.
• CDMA2000 is specified to use a sophisticated
modulation scheme to increase the data rate
over an ordinary 1.25-MHz CDMA channel.
• The problem with 3G systems in the United
States is that a much smaller frequency band
is available for 3G service than in areas
following European frequency division.