Introduction to ICT

Introduction to ICT

• ICT encompasses data communication, data transmission modes, forms and types of data transmission, computer networks, types of computer networks, network architecture, and wireless networks.

Data Communication

• Data communication is the electronic transfer of data from one location to another.
• Key elements include the sending device, receiving device, communication device, and transmission medium.
• Sending devices (sources) include computers, fax machines, and mobile phones.
• Receiving devices (sinks) also include computers, fax machines, and mobile phones.
• Communication devices, such as modems and network cards, facilitate message transmission between sending and receiving devices.
• Transmission media can be physical cables or wireless connections.

Data Transmission Modes

• Data transmission mode defines how data is transmitted between points.
• Three modes exist: simplex, half-duplex, and full-duplex.
• Simplex: Data flows in one direction only, like a one-way street (e.g., traditional television broadcast).
• Half-duplex: Data flows in both directions, but only one way at a time (e.g., internet surfing).
• Full-duplex: Data flows in both directions simultaneously, like a two-way street (e.g., telephone).

Forms of Data Transmission

• A signal is an electromagnetic or light wave used to transmit data.
• Propagation of signals across a medium is known as signaling.
• The process of transmitting data using signals is called transmission.
• Two main forms of data transmission exist: digital and analog.
• Digital Transmission: Data is represented as discrete binary values (0s and 1s) via electrical pulses. This method is faster, more efficient, and has lower error rates.
• Analog Transmission: Data is represented by continuous electrical signals. Common media include telephone lines.

Types of Data Transmission

• Transmission can be either asynchronous or synchronous.
• Asynchronous Transmission: Data is transmitted character by character, with gaps between characters. This is comparatively cheaper to implement.
• Synchronous Transmission: Data is transmitted in blocks. This is significantly faster and more efficient due to the elimination of inter-character gaps.

Synchronous vs Asynchronous Transmission

• Synchronous Transmission uses a shared clock between sender and receiver, enabling simultaneous data transmission (fast transmission). It is costlier and complex to implement.
• Asynchronous Transmission sends each character with its start and stop bits, creating gaps between characters (slower transmission). It is less expensive and comparatively easier to implement.

Computer Networks

• A computer network links two or more computers to share information and resources.
• Networks can be local (LAN), wide-area (WAN), or personal-area (PAN).
• Communication media include cables and wireless connections.
• Computers in a network can be in the same room, building, or different locations.

Computer Network Examples

• An office's network facilitates information sharing, file exchange, and printing among people.
• The internet is a large network uniting millions of computers through phone lines to share data, files, and communication.

Computer Network: Network Criteria

• Crucial network characteristics include performance, reliability, and security.
• Performance: Measured by transit time (time to travel) and response time (time taken for a response).
• Reliability: Evaluated through data accuracy, frequency of failure, and recovery time after failure.
• Security: Refers to data protection from unauthorized access and damage and subsequent recovery procedures.

Computer Network: Advantages

• Shared information and resources
• Cost savings
• Easy communication
• Shared internet access
• Enhanced data security and management
• Entertainment possibilities

Computer Network: Disadvantages

• High initial hardware/software costs
• Continuous hardware/software management costs
• Potential for undesirable sharing
• Risks of illegal or undesirable behavior
• Concerns about data security

Types of Computer Networks

• LAN (Local Area Network): Connects computers within a small area like an office or building for resource sharing.
• WAN (Wide Area Network): Spans larger geographic areas (e.g., countries) using phone lines or satellites, connecting multiple LANs and encompassing a large number of users.
• PAN (Personal Area Network): Connects personal devices within a limited area (approximately 30 feet). Wireless PANs are more common and use technologies like Bluetooth or Wi-Fi. Data transfer is within close proximity for personal devices.

LAN vs. WAN

Network Architecture

• Network architecture defines how computers communicate and are arranged within the network.
• There are multiple possible architectures, but two common types are peer-to-peer (P2P) and client-server.
• Peer-to-Peer (P2P): Simple, inexpensive networks connecting fewer than ten computers. Each computer stores files and shares information with other computers in the network. Data transfers among all connected devices, and each is a 'peer' with equal access.
• Client-Server: Networks where one or more computers act as servers, offering services to other client computers in the network. Servers have greater computational power and storage capacity than client computers.

Wireless Networks

• Wireless networks can be classified as fixed or mobile.
• Fixed Wireless Systems: The computing equipment has limited mobility.
• Mobile Wireless Systems: The equipment (such as smartphones) and users have considerable freedom to move within the network. The equipment readily transfers resources and information. Typically, these operate over wireless technologies like Bluetooth or Wi-fi.