Computer Networks Transmission Media

Telecommunications and Computer Networks

Agenda

• Purpose of Computer Networking

• Transmission Media

Communications

Communications

The analog signal(audible)

is sent throughtelephone lines.

MODEM MODEM 011010001011010001

Digital signal Digital signal

This modem convertsdigital to analog.

This modem convertsanalog to digital.

Computer Networking

• Interconnected collection of computers that share data, memory and other valuable resources.

• A computer network consists of communication media, devices and software needed to connect two or more computer systems and/or devices.

• Networks can be used to share hardware, programs and databases across the organization.

Purpose of networking

• Data communication

• Simultaneous Access

• Resource sharing

• Reliability

• Scalability

• Save money

The Uses of a Network - Simultaneous Access

• In organizations, many people may need to use the same data or programs

• Shared data and programs can be stored on a central network server

• Managers may assign access rights to users.

Read/writeRead/writeRead/writeRead/writeRead/writeRead only

• It is cost-effective to connect a device to a network so users can share it.

• Users can send multiple documents (called print jobs) to a networked printer at the same time.

• E-Mail• Teleconferencing• Video Conferencing

The Uses of a Network -Shared Peripheral Devices

The Uses of a Network - Personal Communication

1 2 3 4

Email service – process flow

Transmission Media

Types of Media

• Twisted-Pair

• Coaxial Cable

• Fiber-Optic Cable

• Microwave Transmission

• Satellite Transmission

Twisted-Pair

Twisted-Pair Wire Cable

Advantages

-least expensive

-widely available

-moderate capacity

-easy to install

-transfer 10-100Mbps

Disadvantages

-Slow(low bandwidth), Easily tapped

Coaxial Cable

Coaxial Cable

• -moderately expensive• -higher capacity• -bulky• --transfers 1-2 Gbps• -usually used to carry TV signals

Fiber Optic Cable

Fiber Optic Cable…

• -very expensive• -high capacity• -uses light• -travels long distance

without attenuation (several Gbps for about 100-200 Km)

Microwave Transmission

• -Expensive• -Requires no cabling• -best for high volume and long distance• -limited to line of sight• -waves travel in a straight line and

narrowly focused in a parabolic antennae• -can’t penetrate solid objects

Microwave Transmission

Satellite Transmission

Technological Updatesin Information Systems

Emerging Technologies

• WiFi

• WiMax

• VOIP

• GPS

• RFID

WiFi

• Wireless Fidelity = wireless LAN

• Wireless Connection to access a Network

• Wireless LAN

• Standard for transmitting information in the form of radio waves over distances up to about 100 - 300 feet

WiMax

• Worldwide Interoperability Microwave Access = Metro based broadband wireless access

• Longer distance coverage (~50 km)

• Connecting geographically remote areas

VOIP

• Voice Over Internet Protocol

• VOIP Phones are connected to the internet using n/w cables or WiFi

• Preferred over normal cabled telephone

• Interactive user interface

• Easy connectivity

VOIP

• Cost Reduction

• Quality

• Parallel calls using same connection

• No limitation on location

GPS

• Global Positioning System

• Satellite based tracking

• Used for navigation

• Applications:– Fleet Management– Logistics– Asset tracking

RFID

• Radio Frequency Identification• Transmitting signal over Radio Wave from an

object connected to RFID device to the reader

• Objective is to keep track• Applications :

– Inventory Management– Retail Store– Logistics

RFID Applications