Network and Telecommunication

1. Introduction to ICT

Information and Communication Technology (ICT) refers to technologies used for communication, data sharing, information processing, and economic development.

ICT helps in:

Fast communication

Information sharing

Education, business, banking, health

E-governance and development

Telecommunication

Transmission of data or information from one place to another using electronic means.

Examples:

Mobile phone

Internet phone

Television

Radio

Landline telephone

History of ICT

World

1950–1980: Electronic Data Processing (EDP) used in developed countries

Used mainly for calculations and record keeping

Nepal

1974: National Computer Center (NCC) established

1995 onward: Computers used in:

Banking

Hotel booking

Air ticketing

Email and Internet services

2. Communication

Communication is the process of sending and receiving data or information between two or more people or devices.

Elements of Communication

Sender

Message (Data)

Medium

Receiver

Feedback

2.1 Data Communication Modes

ModeDescriptionExampleSimplexOne-way communicationTV, RadioHalf DuplexTwo-way, one direction at a timeWalkie-talkieFull DuplexTwo-way simultaneouslyMobile phone

3. Components of Data Communication

Data (Message) – Information to send.

Sender – Device sending data.

Medium – Channel connecting devices.

Receiver – Device receiving data.

Protocol – Rules followed during communication.

4. Communication Media

Communication media is the path through which data is transmitted.

4.1 Guided (Wired) Media

a) Twisted Pair Cable

Two copper wires twisted together

Types:

UTP: Cheap, up to 100m, low bandwidth

STP: Shielded, high bandwidth

Connector: RJ-45

b) Coaxial Cable

Inner conductor + outer shield

Better bandwidth than twisted pair

Connectors: BNC, T-connector

c) Fiber Optic Cable

Uses light signals

Very high speed

Immune to electromagnetic interference

Connectors: ST, SC, SMA

4.2 Unguided (Wireless) Media

a) Radio Waves

Used in radio, TV, mobile communication

Types: AM, FM, PM

b) Microwave

Line-of-sight transmission

Requires towers and repeaters

c) Satellite Communication

Uses artificial satellites

Global coverage

5. Computer Network

A computer network is the interconnection of two or more computers to share data, hardware, software, and resources.

5.1 Advantages

Resource sharing

Fast communication

Centralized backup

Internet access

5.2 Disadvantages

Virus and malware risk

Cybercrime

High setup cost

Needs skilled administrator

5.3 Network Devices

DeviceFunctionNICConnects computer to networkHubBroadcasts data to all devicesSwitchSends data to selected deviceBridgeConnects similar networksRouterConnects different networksGatewayConnects different protocolsRepeaterBoosts weak signalsModemConverts digital ↔ analogFirewallProtects from unauthorized accessAccess PointProvides wireless connection

5.4 Bandwidth

Bandwidth is the amount of data transmitted per second.
Measured in bps (bits per second).

Higher bandwidth = faster data transfer.

6. Network Software

Network Operating System (NOS)

Software used to manage network resources.

Examples:

Windows NT

Linux

Novell NetWare

Functions:

User management

File and printer sharing

Security control

Protocol

A protocol is a set of rules for data communication.

Examples:

TCP/IP

HTTP

FTP

SMTP

POP

7. Types of Networks

TypeCoverageExampleLANSmall areaSchool labMANCityCable TVWANWorldwideInternet

 

8. Network Architecture

Peer-to-Peer (P2P)

Equal nodes, decentralized, no server.

Advantage: Easy sharing, no admin needed.

Disadvantage: Low security, difficult backup.

Client-Server

Central server provides resources.

Advantage: Centralized backup, better security.

Disadvantage: High cost, needs admin.

Centralized Network

Host computer does processing; workstations only for I/O.

Advantage: Cost-effective, secure data.

Disadvantage: Host failure affects all.

 

9. Network Topologies

TopologyAdvantageDisadvantageBusCheapCable failure stops networkRingHandles trafficFailure affects allStarFast, easy troubleshootingHub failure stops network

 failure stops network

10. Internet & Its Services

Definition: Global network of networks using TCP/IP.

History: ARPANET 1969 → Worldwide 1992 → Nepal 1994.

Services

WWW (World Wide Web) – Hyperlinked multimedia documents.

Email – Fast global communication with attachments.

Telnet – Remote computer access.

FTP – File transfer between computers.

Search Engine – Finds information using keywords (Google, Yahoo).

IRC/Chat/Video Conference – Real-time communication.

Online Banking – Conduct financial transactions online.

E-commerce – Buying/selling goods/services online (B2B, B2C, C2C, C2B).

11. Important Terms

Duplex Mode – Two-way data transmission.

Protocol – Rules for network communication.

Fiber Optic Cable – Light-based data transmission.

Radio Wave – Electromagnetic wave for wireless communication.

Repeater – Boosts signals for long-distance transfer.

Computer Network – Interconnection of multiple computers.

Hub – Connects multiple devices; broadcasts data.

Router – Connects multiple networks.

Network Software – Manages network.

Internet – Network of networks.

Email – Sending/receiving electronic messages.