1. Basic Concepts of Wireless
Communication System
Prepared by: Mr. Gilbert De Castro
2. Computer Networking
Data Communication
Transmission Media
Distributed System
Objectives
3. Basic Principle of Networks
Computer network
Collection of computers
and devices connected
via communications
devices and
transmission
media
Bunch of computers
hook together in some
way
Each particular message
is usually routed to a
particular computer
4. Basic Principle of Networks
Networking
Is the problem of
delivering a message
from a source to a
destination
The problem of giving
meaning to these
messages received is
called communication
5. Use of Computer Networks
Networks for Companies
Resource sharing – Saves time and money.
Dynamic rerouting – Having alternative source of supply
data
Basic Principle of Networks
6. Networks for people
Access to remote information – Great source of
information
Person-to-person communication
Interaction between a person and a database
Person-to-person interaction
Interactive entertainment
Network gaming
Video-on-demand
Basic Principle of Networks
7. Advantages of networking
Connectivity and communication
Data sharing
Hardware sharing
Internet access
Internet access sharing
Data security and management
Performance enhancement and balancing
Entertainment
Basic Principle of Networks
8. Basic Principle of Networks
Communication channel
Is a pathway over which
information can be
transferred
Information sent over a
channel has source (often
called the transmitter), from
which the information
originates
And destination (often called
the receiver), to which the
information is delivered
Channel
9. Communication channels
Any communication has a direction associated with it
Simplex channel – is a channel whose direction of
transmission is unchanging
Half-duplex channel – is a channel in which the
direction may be reversed, but the transmission does
not occur at the same time
Full-duplex channel – is a channel that allows
simultaneous exchange in both directions
Basic Principle of Networks
10. Types of Transmission Technologies
Point-to-point network – consist of many connections
to individual pairs of machines
Broadcast networks – all the machines on the
network share a single channel
Basic Principle of Networks
11. Network Topologies
Computer networks come in different shapes and
sizes
The network’s topology can be thought of as its
“shape”, the way the computers on the network are
connected
Network topologies are categorized into the five
basic types
Basic Principle of Networks
13. Components of data communication
Message
Sender
Receiver
Medium
Protocols
Basic Principle of Networks
14. Protocol
Formal description of set of rule sand conventions
that govern how devices on a network communicate
Control aspects of data communication, which
include the following:
How the physical data is built
How computers connect to the network
How the data is formatted for transmission
How the data is sent
How to deal with errors
15. Basic Principle of Networks
Network Topologies
Bus network
A common channel
connect all devices
All computers and
devices connect to
central cable, or bus
16. Basic Principle of Networks
Ring network
All messages travel in a ring,
either in clockwise or
counterclockwise direction
Cable forms closed ring, or
loop, with all computers and
devices arranged along ring
Data travels from device to
device around entire ring, in
one direction
17. Basic Principle of Networks
Star network
All devices connect to a
central device, called hub
All data transferred from
one computer to another
passes through hub
18. Basic Principle of Networks
Tree network -
Integrates multiple star
topologies together into
a bus
19. Basic Principle of Networks
Mesh network – involves
the concept of routes,
where a message is sent
on the network can take
any of several possible
paths from source to
destination
Popular topologies are
bus, ring, and star
20. Communications device
Hardware component that enables a computer to
send and receive data, instructions and information
Occurs over cables, telephone lines, cellular radio
networks, satellites, and other transmission media
22. Modem
• Converts digital signals to analog signals and vice versa
Dial up modem
ISDN and DSL modems
Wireless modem
23. Network Card
Adapter card, PC Card, or flash card that enables
computer or device to access network
Sometimes called network interface card (NIC)
24. Gateway
Links network using different protocols
Contain devices such as protocol translators
28. Communication Channel
Transmission media on which data travels in
communications system
Transmission media - are materials capable of carrying
one or more signals
Bandwidth - amount of data that can travel over a
communications channel
Physical Transmission Media
Wireless Transmission Media
29. Physical Transmission Media
Wire, cable, and other tangible materials used
to send communications signals
Twisted-pair cable
Coaxial Cable
Fiber-optic cable
32. Fiber-optic cable
Capable of carrying
significantly more
data at faster speeds than
wire cables
Less susceptible to
interference (noise) and,
therefore, more secure,
Smaller size (thinner and
lighter)
34. Radio Signal
Broadcast radio distributes
radio signals over long and
short distances
Cellular radio is form of
broadcast radio used for
mobile communications
36. Satellites
Space station
that receives microwave
signals from earth-based
station, amplifies signals,
and broadcasts signals back
to any number of earth-
based stations
37. IrDA ( Infrared Data Association)
Physical specifications communications protocol
standards for the short-range exchange of data over
infrared light waves
38. Bluetooth
Short-range radio waves transmit data between
Bluetooth devices
Short distance transmission of about 30 feet
40. Basic Principle of Networks
Distributed Systems
There is considerable confusion between a computer
network and a distributed system
The key distinction is that in a distributed system, the
existence of multiple autonomous computers is
transparent to the user
The user can type a command to run a program, and it
runs
It is up to the operating system to choose the best
processor for the application, send the necessary data
and place the result to the proper location
41. Basic Principle of Networks
Client/Server
Extension of distributed data
processing wherein it provides
the best of both centralized and
distributed data processing
Client – issues a request to a
server to ask for work to be
done
Server – usually a host machine
that provides database,
printing, storage and
communications
42. Basic Principle of Networks
Types of network design
The networking industry refers to nearly every type of
network as an “area network”.
Local Area Network (LAN)
Wide Area Networks (WAN)
43. Basic Principle of Networks
Local Area Network (LANs)
Connect network devices
over relatively short
distances
Usually owned by an
individual or corporation
Network in limited
geographical area such as
home or office building
44. Basic Principle of Networks
Wide Area Networks (WANs)
Span a large physical distance
(geographically-dispersed
collection of LANs) and
mostly owned by any one
organization but rather exist
under collective or distributed
ownership and management
Network that covers large
geographic area using many
types of media
Internet is world’s largest
WAN
