Fundamentals of Communication Networks

Fundamentals of Communication Networks

• Text is Part 1/5, presented by Professor Ana Belén Pérez.

Characteristics of Computer Networks

• A computer network is defined as two or more devices connected to share network components and stored information.
• Andrew S. Tanenbaum defines a computer network as a set of interconnected computer equipment that sends and receives electrical impulses or electromagnetic waves to share information and resources.
• Essential to understand communication systems, architecture, protocols, connection methods, and components when working with computer networks.
• Key characteristics include connectivity, scalability, security, and cost optimization.
• Connectivity allows for resource sharing.
• Scalability enables easy expansion and connection with other networks for increased performance.
• Security measures enhance protection against data loss through duplication or reducing data availability.
• Cost optimization is achieved by sharing resources, increasing productivity, streamlining tasks, and maximizing investment return

Communication System

• A communication system consists of elements following specific rules to transmit signals, enabling information exchange between a sender and a receiver.
• Key components include:
  • Sender: the element sending the information.
  • Receiver: the element receiving the information.
  • Channel: The medium used to transmit information through coded signals.
• Protocols set the rules of communication for senders and receivers, which allows the devices to better understand.
• Physical medium is defined as the channel through which information is transported, coded, and standardized via established protocols.

Communication System Classification

• Based on transmission medium:
  • Wired Systems: Systems that rely on cables and physical lines
  • Wireless Systems
• Based on directionality of transmission, systems can be classified as:
  • Simplex: Communication only in one direction.
  • Half-Duplex: Communication in both directions, but not simultaneously.
  • Full-Duplex: Simultaneous communication in both directions.

Communication System Classification

• Simplex communication occurs in one direction only, such as radio broadcasting where the listener only receives.
• Half-duplex communication occurs in both directions, but not simultaneously. An example is with walkie-talkies, where one person speaks and then the other responds.
• Full-duplex communication occurs simultaneously in both directions. Computer networks and telephone systems are examples.
• Sychronizing signals:
  • Synchronous Communication: timing coordinated between emitter and receiver. Email is an example
  • Asynchronous Communication: no timing co-ordination required. Like telephone calls or chat
• Signal Nature
  • Analog Transmissions: naturally occurring signals.
  • Digital Transmission: human created signals. Digital signals are used in computers.
• Related concepts in communications include:
  • Data Terminal Equipment (DTE): all equipment that either sends or receives information.
  • Data Communication Equipment (DCE): Any device that participates in communication but is neither the original sender or receiver.

Computer Networks

• Computer networks enable capabilities such as:
  • Resource Sharing: Sharing a single internet connection is more cost effective than having individual connections for each computer and having shared peripherals such as printers
  • Sharing Software: Shared software is useful and often required in business environments
  • Information Sharing: Enables shared databases and documents that can be read and created by multiple users
• Networks can be categorized by:
  • Range or extension
  • Function of components
  • How components connect
  • Type of connection
  • Level of diffusion

Computer Network Classification by Range or Extension

• Personal Area Network (PAN): a short range network designed for personal use
• Local Area Network (LAN): a network limited to a small area (room, single floor, building)
• Metropolitan Area Network (MAN): a high-speed network covering an extensive geographic area, requiring more resources than a LAN.
• Wide Area Network (WAN): an information network that spreads across a large geographical area. Internet is a communications networks permitting this use.

Classification by Component Function

• Peer-to-Peer Networks: Where no single computer is in charge, such as networks where each computer controls it's own information and can act as either client or server
• Client-Server Networks: Where one or more servers provide service to various client computers.

Classification by Connection Method

• Topology defines how the computers connect in a physical network like star, ring, or mesh topologies.

Classification by Connection Type

• Wired Networks: utilize different cable types to connect computers.
• Wireless Networks: communicate without cables, using various wireless technologies.