1. The document discusses 1G and 2G mobile communication technologies. 1G used analog FDMA technology for voice calls only, while 2G introduced digital TDMA and CDMA to support voice, data, and multimedia on mobile networks. 2. 1G speeds ranged from 28-56kbps while 2G networks supported speeds up to 115kbps. Digital encoding in 2G also made networks more spectrum efficient and enabled features like SMS and internet access. 3. The document provides details on GSM, CDMA, and GPRS as the main 2G standards and discusses frequency reuse techniques like cell sectoring to reduce interference in mobile networks.

1. PRESENTED BY:-
SOURABH KANT

2.  ANALOG
communication
 1G Frequency
Division
Multiple Access
(FDMA)
 DIGITAL
communication
 2G, 3g, 4g… Time
Division Multiple
Access (TDMA) &
Code Division
Multiple Access
(CDMA)

3.  Communication is done wirelessly by using FDMA technique
between Base Stations(BS) & Mobile Stations(MS).
 It only supports voice communication.
 Although 1G & 2G systems uses digital signaling to connect the
radio towers (Base Stations) to the rest of the telephone system, the
voice during a call is encoded to digital signals (TDM & CDM) in
2G, whereas voice in 1G is only modulated to higher frequency (i.e.
FM), typically at 150 MHz and up.
 1G speeds vary between 28k modem(28kbit/s) and 56k
modem(56kbit/s).
 Example : AMPS (Advanced Mobile Phone System) used in the
North America and Australia.

4.  uses separate frequencies, or "channels", for each conversation
(FDMA). It therefore required large bandwidth for a large number of
users.
 the Base station could flexibly assign channels to handsets based on
signal strength, allowing the same frequency to be re-used in various
locations without interference. This allows a larger number of phones to
be supported over a geographical area.
 Disadvantage (compared to Digital systems):
1. very sensitive to noise and static.
2. no protection against call theft.
3. Only supports voice communication

5.  Communication is done wirelessly by using TDMA or CDMA technique
between Base Stations(BS) & Mobile Stations(MS). Thus, digital systems
are significantly more efficient on the spectrum, allowing for far
greater mobile phone penetration levels.
 It supports voice, data, and multimedia communication. Thus, data
processing became possible and SMS, MMS, Internet Access, VoIP, Fax,
etc. existed.
 Digital voice data can be compressed and multiplexed much more
effectively than analog voice encodings. Thus, Less power used by BS
and MS, and small & cheap BS /MS equipments existed.
 After 2G, newer technologies 2.5G, 2.75G, 3G, 4G, etc. are now
launched which has increased the speed of data transfer from 56
kbit/s up to 115 kbit/s and more, as the need for speed is increasing
day by day.

6.  2G technologies can be divided into TDMA-based and CDMA-
based standards depending on the type of multiplexing used. The
main 2G standards are:
1. GSM (TDMA-based), originally from Europe but used in almost
all countries.
2. Over 60 GSM operators are also using CDMA2000 in the 450
MHz frequency band (CDMA450).
3. IS-95 or CDMA-One (CDMA-based, commonly referred as
simply CDMA in the US), used in the Americas and parts of Asia.
4. GPRS (General Packet Radio Service), used for WAP,
MMS, internet service. It is sometimes called 2.5G
5. EDGE (Enhanced GPRS) is also a GPRS with increased
speed. It is sometimes called 2.75G

9. Forward link is from
BS to MS
Downward link is from
MS to BS
 There are two types of
Logical channels: 1. control
channels, and 2. traffic
channels.
 Control channels are less
and are used for sending
beacon signals, page
signals, control information,
SMS and orders. MS users
share this channel.
 Traffic channels are used for
transmitting the voice signals
at the time of conversation,
and it is individually given to
each MS user by BS

10.  Same frequency band used in a
cell can be used by in another cell
at far distance D from the cell of
radius R.
 This increases the efficiency
available bandwidth.
 Reuse Distance D=R√3N (N= no.
of cells in a cluster)
 Common hex cell clusters are of
1, 3, 4, 7, 9, 12, 13, 16 cells.

11. Cell Sectoring by Directional
Antennas
The Base transceiver station, or
BTS, contains transceivers (the
equipment for transmitting and
receiving radio signals), antennas,
and a tower.
Directional BTS has more then one
antennas on its tower which covers
different sectors of cell areas. This
is cell sectoring.
This reduces the interference of
the same frequency signals coming
from adjacent BTS, in frequency
reuse pattern.