Cellular network evolved gradually .Generations of computer network like 1st generation (1g) ,second generation (2g) evolved .Then came 3g ,4g, each time with increased speed and security

1. Cellular Networks –First Generation-
Second Generation
Harish Kumar Upadhyay
IT-A , Roll-31 ,s8

2. Cellular Networks
 Cellular networks are wireless WAN that
establish a connection between mobile users.
 The network is comprised of many cells that
typically cover 2 to 20 miles in area.
 The communications are wireless within the cell
only.
 Many initial cellular network were
predominantly analog because they were
primarily targeted for voice users.
 The use of cellular networks to support digital
applications is increasing rapidly.

3. Cellular Concept
 Another advantage of several small cells instead of a single transmitter=> frequency reuse:
better efficiency
 R cell radius and
 D distance at which a frequency can be reused with acceptable interference

4. Cellular Network Organization
 Areas divided into cells
o Each served by its own antenna
o Served by base station consisting of
transmitter, receiver, and control unit
o Band of frequencies allocated
o Cells set up such that antennas of all neighbors
are equidistant (hexagonal pattern)

5. Cellular Network Organization
 Areas divided into cells
o Each served by its own antenna
o Served by base station consisting of
transmitter, receiver, and control unit
o Band of frequencies allocated
o Cells set up such that antennas of all neighbors
are equidistant (hexagonal pattern)

6. Frequency Reuse
 Adjacent cells assigned different
frequencies to avoid interference or
crosstalk
 Objective is to reuse frequency in nearby
cells
o 10 to 50 frequencies assigned to each cell
o Transmission power controlled to limit power at
that frequency escaping to adjacent cells
o The issue is to determine how many cells must
intervene between two cells using the same
frequency

7. Cellular System Overview

8. Cellular Systems Terms
 Base Transceiver Station (BTS) also known as
Base Station (BS)– includes an antenna, a
controller, and a number of receivers
 Mobile telecommunications switching center
(MTSC) also known as Mobile Switching
Center(MSC)– connects calls between mobile
units
 Two types of channels available between mobile
unit and BS
o Control channels – used to exchange information having
to do with setting up and maintaining calls
o Traffic channels – carry voice or data connection
between users

9. First Generation
First-generation cellular networks were introduced
in the 1980s are primarily intended for voice .
These networks are very slow less than 1 kilobits
per sec(kbps).
The key idea of 1G cellular networks is that the
geographical area is divided into cells ,each served
by a base station.Cells are so small that frequency
reuse is possible in the near by cells.
They are primarily based on analog
communications.
Each phone has 32 bit serial number and 10 digit
phone number in its PROM.

10. Security issues with 1G
Analog cellular phones are insecure.
Anyone with an all-band radio receiver can listen
in to the conversation.There are also theft of
airtime.
A thief uses an all-band radio receiver that is
connected to a comuter.This computer can record
the 32-bit serial numbers and phone numbers of
subscribers when calling
The thieves can collect a large database by
driving around and then can go into business bu
reprogramming stolen phones and reselling them .

11. Second Generation
Second generation cellular network introduced in
1980s ,are based on digital transmission.
Primarily intended for voice they also support fax
and email services at low bit-rate(8 to 9 kbps).
The higher 2G systems use GSM(Global System
For Mobile Communication) and low-tier system is
intended for low-cost,low-power,low-mobility.
Digital transmission offer several benefits overe
analog :
 Voice,data such as email and fax can be
integrated into a single system.
Better compression can lead to a better channel
utilization.
Error correction code can be used for better
quality.
Sophisticated encryption can be used.

12. Differences Between First and
Second Generation Systems
 Digital traffic channels – first-generation systems
are almost purely analog; second-generation
systems are digital
 Encryption – all second generation systems
provide encryption to prevent eavesdropping
 Error detection and correction – second-
generation digital traffic allows for detection and
correction, giving clear voice reception
 Channel access – second-generation systems
allow channels to be dynamically shared by a
number of users

13. REFERENCES :
 www.wikipedia.org
 McGrawHill :Mobile computing

14. Thank You 
Open to questions ..