Data Communication and Networking Fundamentals

Posted on Mar 6, 2026 in Computer Engineering

Fundamentals of Data Communication

Data communication is the exchange of data between devices through a transmission medium.

5 Core Components

  • Sender
  • Message
  • Transmission medium
  • Receiver
  • Protocol

Effective Communication Requirements

  • Delivery: Correct destination
  • Accuracy: No errors
  • Timeliness: On time

Telecommunication is communication over long distances. Data communication refers specifically to digital data exchange.

Transmission Media

Guided (Wired)

  • Twisted pair: Cheap, short distance, more noise
  • Coaxial: Better shielding
  • Optical fiber: Very high bandwidth, low attenuation, long distance

Unguided (Wireless)

  • Radio waves
  • Microwaves
  • Infrared

Network Topologies

  • Bus: One backbone cable; cheap, but backbone failure stops the network.
  • Star: Central hub/switch; easy troubleshooting, but hub failure stops the network.
  • Ring: Circular connection; data travels in a loop.
  • Mesh: Every node connected to every other node.

Mesh links formula: n(n − 1) / 2

Protocols and Standards

A protocol is a set of rules that allows devices to communicate. Standards are officially approved protocols (IEEE, ISO, IETF).

  • Syntax: Format (Physical layer)
  • Semantics: Meaning (Physical layer)
  • Timing: When/how fast (Session layer)

Layered Architecture (TCP/IP)

Layered architecture reduces complexity and improves design. However, it can be complex and unreliable.

OSI Layers and Functions

  • Application: User services
  • Presentation: Encryption, compression, format conversion
  • Session: Session control, synchronization
  • Transport: End-to-end delivery, segmentation, flow & error control (TCP, UDP)
  • Network: Logical addressing (IP), routing
  • Data Link: Framing, MAC, flow control, error control, physical addressing
  • Physical: Transmission of bits, voltage, signal

Data Units

  • Application: Data
  • Transport: Segment
  • Network: Packet
  • Data Link: Frame
  • Physical: Bits

TCP/IP Model (4 Layers)

  • Application
  • Transport
  • Internet
  • Network Access

Mapping OSI to TCP/IP

  • OSI (Application + Presentation + Session) → TCP/IP Application
  • Transport → Transport
  • Network → Internet
  • Data Link + Physical → Network Access

Encapsulation and Switching

During transmission, headers are added (encapsulation) and removed at the receiver (decapsulation). Circuit-switched networks use a dedicated path with reserved resources.

Network Criteria

Effective and efficient networks require performance, reliability, and security.

Physical and Network Layer Tasks

  • Physical layer: Physical characteristics, bit representation, data rate, synchronization, topology, transmission mode.
  • Network layer: Logical addressing, routing.

Noise Types

  • Thermal noise: Due to thermal agitation of electrons.
  • Inter-modulation noise: Signals at frequencies that are the sum or difference of original frequencies.
  • Crosstalk noise: Unwanted coupling between signal paths.
  • Impulse noise: Non-continuous, irregular pulses or spikes.

Modulation

Modulation shifts a low-frequency message signal to a high-frequency carrier for transmission.

Advantages

  • Enables long-distance transmission
  • Smaller antenna size
  • Allows multiplexing (FDM)
  • Better noise performance
  • Higher data rate possible

Disadvantages

  • System complexity
  • Higher cost
  • Power inefficient
  • Increases bandwidth
  • Overmodulation causes distortion