Connectivity & Networks | Data Transmission & Protocols
Connectivity & Networks
Wired Connections
USB (Universal Serial Bus)
Versions:
USB 2.0: 480 Mbps
USB 3.0: 5 Gbps
USB 3.1: 10 Gbps
USB-C: Newer standard
Uses:
Data transfer
Power supply
Peripherals (printers, drives)
Advantages:
Fast data transfer
Supplies power
Reliable connection
Disadvantages:
Limited range (up to 5m)
Requires physical cable
Cable clutter
Ethernet (Network Cable)
Standards:
Cat5e: 1 Gbps
Cat6: 10 Gbps
Cat7: 100 Gbps
Cat8: Future standard
Uses:
Local network (LAN)
Internet connection
Stable connections
Advantages:
Very high speed
Stable connection
Secure (harder to intercept)
Disadvantages:
Not portable
Installation cost
Fixed locations
Wired vs Wireless Comparison
Feature
Wired
Wireless
Speed
Very fast (1-10 Gbps)
Good (50-600 Mbps)
Reliability
Stable, no interference
Can have interference
Mobility
Limited by cable
Very mobile
Cost
Installation costs
Low cost once set up
Best for
Fixed servers, high data
Laptops, mobile devices
Scenario: A school office needs desktop computers wired with Ethernet for maximum speed and stability. But in classrooms, teachers use laptops and need Wi-Fi to move around. The school uses both technologies for different purposes.
Wireless Connections
Bluetooth
Specifications:
Frequency: 2.4 GHz
Range: 10–100 meters
Speed: 1–3 Mbps (older)
Bluetooth 5.0: Much faster
Uses:
Headphones/speakers
Wireless mice/keyboards
Personal devices
PAN (Personal Area Network)
Advantages:
Wireless convenience
Easy pairing
Low power use
Common standard
Disadvantages:
Short range only
Interference from other devices
Lower bandwidth
Not suitable for streaming
Wi-Fi (802.11)
Standards:
802.11b: 11 Mbps
802.11g: 54 Mbps
802.11n: 300 Mbps
802.11ac: 1300 Mbps
802.11ax: 10 Gbps (Wi-Fi 6)
Uses:
Internet access
Home/office networks
Mobile device connectivity
Hotspots
Advantages:
Wireless freedom
Flexible positioning
Multiple devices supported
Reasonable speed
Disadvantages:
Security risks (encryption needed)
Interference from other networks
Slower than Ethernet
Range limitations
Network Topologies
Star Topology
Structure: All devices connect to central switch/hub
Most common: Used in offices and schools
Advantage: Easy to add/remove devices
Advantage: One device failure doesn't affect others
Disadvantage: Central point failure affects all
Disadvantage: More cabling needed
Ring Topology
Structure: Devices form a ring/circle
Data flow: Travels around the ring
Advantage: No central point
Advantage: Fair bandwidth sharing
Disadvantage: Break anywhere affects all
Disadvantage: More complex to install
Bus Topology
Structure: All devices share single cable
Oldest design: Simple and cheap
Advantage: Low cost
Advantage: Simple installation
Disadvantage: Collision issues
Disadvantage: Cable break affects all
Mesh Topology
Structure: Multiple connections between nodes
Redundant: Multiple paths for data
Advantage: Very reliable
Advantage: One failure doesn't disrupt network
Disadvantage: Very expensive
Disadvantage: Complex to manage
Network Topology Comparison
Topology
Structure
Reliability
Cost
Star
Devices → Central hub
Good (hub failure=down)
Moderate
Ring
Devices in circle
Fair (break affects all)
Moderate
Bus
Linear chain
Poor (cable break=down)
Low
Mesh
Multiple connections
Excellent (multiple paths)
High
Scenario: A hospital needs reliable patient data networks. Using star topology is standard and cost-effective. But critical ICU units use mesh topology so if one connection fails, vital signs still transmit through alternative paths.
Network Types — Scope & Scale
PAN (Personal Area Network): Device to device connection (phone to laptop via Bluetooth); very short range (up to 10m); example: phone connected to wireless headphones
LAN (Local Area Network): Same building or small area; fast speeds (Ethernet); secure connection; example: office network, school network
WAN (Wide Area Network): Large geographic area (cities, countries); connected via Internet; slower than LAN; example: company with multiple offices
VPN (Virtual Private Network): Secure encrypted connection over public network; appears as private connection; used for remote working; protects data while using public Wi-Fi
Data Transmission & Protocols
Key Protocols — How Internet Works
Email Protocols
SMTP (Simple Mail Transfer Protocol): Sends emails FROM client to server
POP (Post Office Protocol): Downloads emails to client; deletes from server
IMAP (Internet Message Access Protocol): Accesses emails on server; syncs across devices
When to use IMAP: Multiple devices, cloud access needed
When to use POP: Single device, offline access preferred
Web Protocols
HTTP (HyperText Transfer Protocol): Unencrypted web traffic
HTTPS: Encrypted version (secure); 'S' = SSL/TLS encryption
When to use HTTPS: Always for sensitive data (banking, shopping)
SSL Certificate: Proves website is legitimate
Port 80: HTTP default
Port 443: HTTPS default
Other Protocols
FTP (File Transfer Protocol): Transfers files between computers
SFTP: Secure version with encryption
VoIP: Voice over IP; internet phone calls
DNS: Converts domain names to IP addresses (google.com → 142.251.32.46)
TCP/IP: Foundation of internet communication
Protocol Selection
Email sending: SMTP required
Email retrieval: POP or IMAP
Web browsing: HTTP or HTTPS
Sensitive data: Always use encrypted versions
Video calls: Often VoIP-based
Bandwidth & Latency
Bandwidth
Amount of data transferred per second
Measured in Mbps or Gbps
Higher is faster
Affects download/upload speed
Latency
Delay in data transmission
Measured in milliseconds
Lower is better
Affects responsiveness
Data Compression — Reducing File Size
Lossy Compression
How it works:
Removes some data permanently
Data cannot be recovered
Unnoticeable to human senses
Examples:
JPG (images)
MP3 (audio)
MP4 (video)
When to use:
Photos/videos
When file size matters
Streaming media
Lossless Compression
How it works:
No data is lost
Decompresses to original
Uses clever encoding
Examples:
PNG (images)
ZIP (archives)
FLAC (audio)
When to use:
Documents/text
When accuracy matters
Archival storage
File Types for Transmission
Image Files
PNG: Lossless, transparent background, best quality
JPG: Lossy, smaller files, best for photos
GIF: Lossless, animations, limited colors
WebP: Modern, smallest files, browsers may not support
BMP: Uncompressed, very large, rarely used online
Audio Files
MP3: Lossy, small files, most compatible
WAV: Uncompressed, large files, professional quality
FLAC: Lossless, medium file size, high quality
AAC: Lossy, better quality than MP3 at same size
Bitrate: 128kbps (streaming) to 320kbps (high quality)
Video Files
MP4: Most common, good quality, small files
MKV: Container format, multiple tracks/subtitles
AVI: Older format, larger files
WebM: Optimized for web, open source
Resolution: 480p, 720p, 1080p, 4K
Codecs (Coder-Decoder)
What is it: Software that compresses/decompresses media