Wireless Networks

1. Basics of Wireless Networks

  • Definition: Wireless networks use radio waves to transmit data without physical cables.
  • Types:
    • WPAN (Wireless Personal Area Network): Bluetooth (IEEE 802.15), ZigBee.
    • WLAN (Wireless Local Area Network): Wi-Fi (IEEE 802.11).
    • WMAN (Wireless Metropolitan Area Network): WiMAX (IEEE 802.16).
    • WWAN (Wireless Wide Area Network): Cellular networks (4G, 5G).

2. Wireless Standards

  • IEEE 802.11 (Wi-Fi):
    • 802.11a: 5 GHz, 54 Mbps.
    • 802.11b: 2.4 GHz, 11 Mbps.
    • 802.11g: 2.4 GHz, 54 Mbps.
    • 802.11n: Dual-band, 600 Mbps.
    • 802.11ac: 5 GHz, 1 Gbps+.
    • 802.11ax (Wi-Fi 6): Up to 9.6 Gbps.
  • Bluetooth: Short-range communication for devices.
  • ZigBee: Low-power IoT applications.
  • WiMAX (802.16): Broadband over long distances.

3. Frequency Bands

  • 2.4 GHz: Longer range, slower speed, more interference.
  • 5 GHz: Shorter range, faster speed, less interference.
  • 6 GHz: Emerging with Wi-Fi 6E.

4. Wireless Network Components

  • Access Point (AP): Connects wireless devices to a wired network.
  • Router: Manages traffic between networks.
  • Switch: Connects multiple devices in a network.
  • NIC (Network Interface Card): Enables devices to connect to the network.

5. Security in Wireless Networks

  • Common Threats:
    • Eavesdropping: Intercepting data.
    • Rogue Access Points: Unauthorized APs.
    • Denial of Service (DoS): Flooding network to disrupt service.
  • Protocols:
    • WEP (Wired Equivalent Privacy): Weak, outdated.
    • WPA (Wi-Fi Protected Access): Better than WEP.
    • WPA2: Strong encryption (AES).
    • WPA3: Latest, robust security.

6. Wireless Technologies

  • MIMO (Multiple Input Multiple Output): Uses multiple antennas to improve performance.
  • Beamforming: Directs signals to specific devices for better connectivity.
  • OFDM (Orthogonal Frequency Division Multiplexing): Efficient use of bandwidth.
  • CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance): Manages device communication in Wi-Fi.

7. Cellular Networks

  • Generations:
    • 1G: Analog voice.
    • 2G: Digital voice, SMS.
    • 3G: Mobile broadband.
    • 4G: High-speed internet, VoLTE.
    • 5G: Ultra-high speed, IoT support.
  • Key Terms:
    • LTE (Long Term Evolution): Standard for 4G.
    • NR (New Radio): Standard for 5G.

8. Ad Hoc and Mesh Networks

  • Ad Hoc: Devices connect directly without central control.
  • Mesh: Each device acts as a node, extending network coverage.

9. Applications of Wireless Networks

  • IoT (Internet of Things): Smart devices.
  • Healthcare: Remote monitoring.
  • Education: E-learning platforms.
  • Industrial: Automation.

10. Tips for Last-Minute Revision

  • Focus on key terms like MIMO, Beamforming, WPA3.
  • Remember frequency bands and their characteristics.
  • Revise the evolution of cellular networks (1G to 5G).
  • Understand basic security protocols (WEP, WPA, WPA2, WPA3).

Quick Memory Tip: Use mnemonics like “Wi-Fi Standards Go ANABC” for a/b/g/n/ac/ax.