Postgrad Notes / PGD Computer Science / First Semester / CMS 703 Data Communication & Networks / Knowledge Map

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Knowledge Map: CMS 703: Data Communication and Networks

Generated: 2026-03-30 | Topics: 24 | Concepts: 54 | Relationships: 67

Course Overview

This course covers the foundational principles of data communication and computer networking, from the five basic components of a communication system, through signal representation and Fourier analysis, to physical and wireless transmission media, network types and topologies, switching and routing techniques, and the OSI reference model. It also covers how data is encoded as bit patterns, how serial and parallel transmission work in practice, and how Fourier mathematics powers real-world technologies like OFDM in 5G and LTE.

Concept Hierarchy

CMS 703: Data Communication and Networks
│
├── 1. Introduction to Data Communication                    [8 concepts]
│   ├── Definition & Core Components
│   │   ├── Key Concepts: Message, Sender, Receiver, Transmission Medium, Protocol
│   │   └── Central: Protocol (required for all communication to function)
│   ├── Data Representation Forms
│   │   ├── Text: bit patterns, Unicode (32-bit), ASCII (127 chars = Basic Latin)
│   │   ├── Images: pixel matrix, RGB and YCM colour models
│   │   ├── Audio: continuous signal → sampling → quantization → encoding
│   │   └── Video: analog or digital, encoding process
│   └── Fundamental Principles
│       └── Key Concepts: Delivery, Accuracy, Timeliness
│
├── 2. Fourier Analysis                                      [12 concepts]
│   ├── Fourier Series (Periodic Signals)
│   │   ├── Key Concepts: Periodic Signal, Fundamental Frequency (Ω), Harmonics
│   │   ├── Key Concepts: Dirichlet Conditions, Orthogonality, Period, Amplitude
│   │   ├── Formula: f(x) = a₀/2 + Σ[aₙcos(nπx/L) + bₙsin(nπx/L)]
│   │   ├── Worked: Square wave → only odd harmonics survive (even cancel out)
│   │   └── Central: bridges time domain ↔ frequency domain for periodic signals
│   ├── Fourier Transform (Non-periodic Signals)
│   │   ├── Forward: F(ω) = ∫f(t)e^{-iωt}dt
│   │   ├── Inverse: f(t) = (1/2π)∫F(ω)e^{iωt}dω
│   │   ├── Square Pulse: F(ω) = T·sinc(ωT/2), wider pulse = narrower freq spread
│   │   ├── Worked: f(t)=e^{-at}u(t) → F(ω) = 1/(a+iω), a>0
│   │   └── Real-world: OFDM in 5G/LTE uses Fourier Transform for spectrum allocation
│   └── Related Transforms
│       ├── Laplace Transform, design tool for continuous-time systems
│       └── Z Transform, discrete-time equivalent of Laplace
│
├── 3. Data Transmission Modes                               [3 concepts]
│   ├── Simplex, unidirectional only (keyboard→PC, TV broadcast)
│   ├── Half-Duplex, bidirectional, one direction at a time (walkie-talkie, WiFi)
│   └── Full-Duplex, simultaneous bidirectional (telephone, live chat)
│
├── 4. Data Transmission Forms                               [2 concepts]
│   ├── Analog, continuous waveform
│   └── Digital, discrete 0/1 states
│
├── 5. Data Transmission Speed                               [2 concepts]
│   ├── Bandwidth, data transfer capacity per unit time
│   └── BPS (Bits Per Second), rate of bit transmission
│
├── 6. Transmission Media                                    [9 concepts]
│   ├── Guided Media (physical path)
│   │   ├── Twisted Pair Wire, copper conductors twisted; STP and UTP types
│   │   │   └── Used in: telephone, 10Base-T and 100Base-T LANs
│   │   ├── Coaxial Cable, central copper core + insulated sheath + outer shield
│   │   │   └── Used in: cable TV, satellite, CCTV, analog/digital telephony
│   │   └── Fibre-Optic Cable, transmits light through glass/plastic core + cladding
│   │       ├── Advantages: high bandwidth, low attenuation (50km vs 5km repeaters),
│   │       │   immune to EM interference, corrosion-resistant, lightweight, hard to tap
│   │       ├── Disadvantages: expensive, fragile, requires expert installation
│   │       └── Used in: backbone networks, 100Base-FX, 1000Base-X, hybrid cable TV
│   └── Unguided Media (wireless)
│       ├── Radio Waves, 3 KHz to 1 GHz; omnidirectional; AM/FM radio, TV, paging
│       ├── Microwaves, 1 to 300 GHz; unidirectional (parabolic dish/horn antenna)
│       │   └── Line-of-sight; towers needed; restricted bands require regulatory approval
│       └── Infrared, 300 GHz to 400 THz; short-distance; cannot penetrate walls
│           └── Used in: remote controls, night vision, missile guidance, gas detectors
│
├── 7. Computer Networks                                     [7 concepts]
│   ├── Network Types (by scope)
│   │   ├── LAN, Local Area Network (office, home)
│   │   ├── MAN, Metropolitan Area Network (city, large campus)
│   │   └── WAN, Wide Area Network (global, e.g. Internet)
│   └── Network Topologies
│       ├── Bus, all nodes share single backbone cable
│       ├── Star, all nodes connect to central hub/switch; most common
│       ├── Ring, closed loop; sequential transmission
│       └── Mesh, every node interconnected; most redundant
│
├── 8. Switching Techniques                                  [2 concepts]
│   ├── Circuit Switching, dedicated physical path for full connection duration
│   │   └── Example: PTCL telephone network; reliable but wastes idle bandwidth
│   └── Packet Switching, data split into independently routed packets
│       └── Example: Internet; efficient; Central concept for modern networking
│
├── 9. Routing Techniques                                    [2 concepts]
│   ├── Source Routing, full path specified by source node
│   └── Hop-by-Hop Routing, each node forwards to the next
│
├── 10. Communication Protocols & OSI Model                  [10 concepts]
│    ├── Protocol Functions
│    │   └── Packet size, numbering, error control, security, routing
│    ├── Standards Organisations (ISO, IEEE, etc.)
│    └── OSI Model, 7 layers (ISO, 1984)           ← CENTRAL
│        ├── Layer 1: Physical, bit stream, hardware, NIC
│        ├── Layer 2: Data Link, frames, physical addressing
│        ├── Layer 3: Network, routing, logical addressing
│        ├── Layer 4: Transport, end-to-end delivery, flow control  ← Central
│        ├── Layer 5: Session, dialogue/session management
│        ├── Layer 6: Presentation, encryption, compression, syntax
│        └── Layer 7: Application, user interface and network services
│
├── 11. Modulation, Multiplexing & Channel Topics            [5 concepts]
│    ├── Modulation / Demodulation, encoding info onto a carrier signal
│    ├── TDM, Time Division Multiplexing
│    ├── FDM, Frequency Division Multiplexing
│    ├── FCM, Frequency Code Multiplexing
│    └── Noise, Distortion, Channel Characteristics
│
├── 12. Serial vs Parallel Data Transmission                 [6 concepts]
│    ├── Serial Transmission
│    │   ├── One bit at a time, single channel; reliable over long distances
│    │   ├── Less signal distortion; widely used in USB, Ethernet, RS-232
│    │   └── Embedded/SCADA: RS-232, RS-485, SPI, DNP3
│    └── Parallel Transmission
│        ├── Multiple bits simultaneously, multiple channels; fast but short-distance
│        └── Used in: CPU data bus, internal memory transfer, printer connections
│
├── 13. Asynchronous vs Synchronous Transmission             [6 concepts]
│    ├── Asynchronous
│    │   ├── Character-framed with Start + Stop bits; optional Parity bit
│    │   ├── No shared clock; synchronization per character
│    │   ├── Frame: [Start | D0 D1 D2 D3 D4 D5 D6 D7 | Parity | Stop]
│    │   └── Apps: RS-232, keyboard/mouse, dial-up modems
│    └── Synchronous
│        ├── Block/frame-based; clock-synchronized; no Start/Stop overhead
│        ├── Error detection: CRC or checksum
│        ├── Frame: [Sync | Sync | Data Data Data Data Data Data]
│        └── Apps: Ethernet, broadband, digital telephony, satellite
│
└── 14. Bandwidth Allocation & Real-World Applications       [3 concepts]
     ├── Signal Modelling, represent digital data as square pulses
     ├── Fourier Transform of Square Pulse → Sinc spectrum
     │   └── Identifies dominant frequencies, bandwidth needed, interference zones
     └── OFDM (Orthogonal Frequency Division Multiplexing)
         └── Core technology in 5G and LTE, allocates frequency bands per FT principles

Key Relationships

Hierarchical (Is-a / Part-of)

Causal (Causes / Enables)

Dependency (Requires)

Prerequisite Chains:

  1. Data Communication Basics → Transmission Modes → Transmission Media → Network Types
  2. Data Representation → Periodic Signals → Fourier Series → Fourier Transform → Bandwidth Allocation → OFDM/5G
  3. Network Types → Topologies → Switching → Routing → Protocols → OSI Model
  4. Serial vs Parallel Transmission → Asynchronous vs Synchronous Transmission
  5. OSI Layer 1 (Physical) → Layer 2 → Layer 3 → ... → Layer 7 (Application)

Contrast (Contrasts-with)

Central Concepts

These are the most connected concepts, master these first:

Concept Connections Why Central
Protocol 7 Governs ALL communication; required by every network layer and device
OSI Model 9 Organises entire network architecture into 7 functional layers
Transmission Media 7 Parent of all physical and wireless communication channels
Fourier Transform 6 Bridges signal analysis (periodic + non-periodic) to real-world applications (OFDM)
Packet Switching 5 Foundation of the Internet and all modern data networks
Serial Transmission 5 Underpins long-distance comms, SCADA systems, USB, Ethernet, 4G/5G
Transport Layer (L4) 4 Bridges the network and application worlds; handles end-to-end delivery

Prerequisite Learning Path

Recommended study order based on dependencies:

  1. Introduction to Data Communication: 5 components, data representation (text/image/audio/video), principles
  2. Data Transmission Modes: simplex, half-duplex, full-duplex
  3. Data Transmission Forms: analog vs digital
  4. Transmission Media: guided (twisted pair, coaxial, fibre-optic) and unguided (radio, microwave, infrared)
  5. Serial vs Parallel Transmission: how bits actually travel; advantages and trade-offs
  6. Asynchronous vs Synchronous Transmission: timing and framing at character/block level
  7. Fourier Analysis: signal representation; Fourier Series for periodic signals, Fourier Transform for non-periodic
  8. Bandwidth & Data Transmission Speed: capacity, BPS, signal spectrum
  9. Bandwidth Allocation & OFDM: real-world application of Fourier in 5G/LTE
  10. Computer Networks: LAN/MAN/WAN, topologies (bus/star/ring/mesh)
  11. Switching Techniques: circuit switching vs packet switching
  12. Routing Techniques: source routing, hop-by-hop routing
  13. Communication Protocols & OSI Model: 7 layers, functions per layer
  14. Modulation & Multiplexing: encoding and combining signals (TDM, FDM)

Definitions Quick Reference

Term Definition
Data Communication Sharing information locally or remotely via a system of 5 components
Message The information to be transmitted (text, image, audio, video, numbers)
Sender The originating device that sends the data
Receiver The destination device that receives the message
Transmission Medium The physical path a message travels from sender to receiver
Protocol A set of rules governing data communication; enables synchronization
Simplex Unidirectional data flow only
Half-Duplex Bidirectional but not simultaneous (walkie-talkie)
Full-Duplex Simultaneous bidirectional communication (telephone)
Analog Continuous waveform signal representation
Digital Discrete 0/1 electrical state representation
Unicode 32-bit global character encoding system; ASCII (127 chars) is a subset
Pixel Smallest unit of a digital image; assigned a bit pattern
RGB / YCM Methods for representing colour images as bit patterns
Quantization Approximating sampled analog values with finite set → encoding as bit patterns
Twisted Pair Copper conductors twisted together; STP (shielded) and UTP (unshielded)
Coaxial Cable Central copper core + insulation + outer shielding; used in cable TV, CCTV
Fibre-Optic Glass/plastic fibre transmitting data as light; high bandwidth, low attenuation
Radio Waves 3 KHz–1 GHz; omnidirectional; AM/FM, TV, maritime radio
Microwaves 1–300 GHz; unidirectional; line-of-sight; terrestrial and satellite links
Infrared 300 GHz–400 THz; short-distance; cannot penetrate walls; remote controls
Bandwidth Measure of data transfer capacity over a network per unit time
LAN Local Area Network, limited geographic area (office, home)
MAN Metropolitan Area Network, city or large campus
WAN Wide Area Network, global interconnection
Star Topology All nodes connect to a central hub/switch
Ring Topology Nodes connected in a closed loop
Bus Topology All nodes share a single backbone cable
Mesh Topology Every node interconnected with every other
Circuit Switching Dedicated physical path held for full connection duration
Packet Switching Data split into independently routed packets; basis of Internet
Source Routing Full path from source to destination specified by source node
Hop-by-Hop Routing Each node passes data to the next along the path
OSI Model 7-layer network reference model released by ISO in 1984
Physical Layer Layer 1, hardware, bit stream transmission, NIC
Data Link Layer Layer 2, frames, physical addressing
Network Layer Layer 3, routing, logical addressing
Transport Layer Layer 4, end-to-end delivery, error control, flow control
Session Layer Layer 5, session and dialogue management
Presentation Layer Layer 6, encryption, compression, syntax translation
Application Layer Layer 7, user-facing network services
NIC Network Interface Card, hardware connecting a device to a network
Serial Transmission Data sent one bit at a time over a single channel; reliable long-distance
Parallel Transmission Multiple bits sent simultaneously over multiple channels; fast, short-distance
Asynchronous Transmission Character-framed with Start/Stop bits; no shared clock
Synchronous Transmission Block/frame-based; clock-synchronized; CRC/checksum error detection
Fourier Series Represents periodic signals as a sum of sinusoidal harmonics
Fourier Transform Decomposes non-periodic signals from time domain to frequency domain
Harmonic Frequency component at an integral multiple of the fundamental frequency
Dirichlet Conditions Three conditions a periodic signal must meet for Fourier Series to exist
Orthogonality Property of harmonics, each is independent of the others
OFDM Orthogonal Frequency Division Multiplexing, core 5G/LTE technology using Fourier Transform
Modulation Encoding information onto a carrier signal
Multiplexing Combining multiple signals over a shared medium (TDM, FDM, FCM)

Tutor Reference Notes