Wireless Networks
IEEE 802.11 Wi-Fi Standards
The IEEE 802.11 family of standards defines wireless LAN (Wi-Fi) protocols. Each generation improves speed, range, and efficiency:
| Standard | Wi-Fi Name | Frequency | Max Speed | Year |
|---|
| 802.11b | Wi-Fi 1 | 2.4 GHz | 11 Mbps | 1999 |
| 802.11a | Wi-Fi 2 | 5 GHz | 54 Mbps | 1999 |
| 802.11g | Wi-Fi 3 | 2.4 GHz | 54 Mbps | 2003 |
| 802.11n | Wi-Fi 4 | 2.4 / 5 GHz | 600 Mbps | 2009 |
| 802.11ac | Wi-Fi 5 | 5 GHz | 3.5 Gbps | 2013 |
| 802.11ax | Wi-Fi 6 | 2.4 / 5 / 6 GHz | 9.6 Gbps | 2019 |
| 802.11be | Wi-Fi 7 | 2.4 / 5 / 6 GHz | 46 Gbps | 2024 |
2.4 GHz vs 5 GHz
| Feature | 2.4 GHz | 5 GHz |
|---|
| Range | Longer (better wall penetration) | Shorter |
| Speed | Lower | Higher |
| Congestion | More crowded (shared with Bluetooth, microwaves) | Less crowded |
| Channels | 3 non-overlapping (1, 6, 11) | 23+ non-overlapping |
| Best for | Large areas, IoT devices, long range | High-speed streaming, gaming, dense environments |
Wi-Fi Security: WPA2 and WPA3
| Protocol | Encryption | Key Exchange | Vulnerability |
|---|
| WEP (1997) | RC4 (40-bit) | Shared key | Easily cracked — deprecated |
| WPA (2003) | TKIP | PSK or 802.1X | TKIP vulnerabilities — deprecated |
| WPA2 (2004) | AES-CCMP (128-bit) | PSK or 802.1X | KRACK attack, dictionary attacks on PSK |
| WPA3 (2018) | AES-GCMP (192-bit) | SAE (Dragonfly) | More resistant to offline dictionary attacks |
WPA3 improvements over WPA2:
- SAE (Simultaneous Authentication of Equals): Replaces PSK handshake; resistant to offline dictionary attacks
- Forward Secrecy: Past sessions cannot be decrypted even if the password is later compromised
- Enhanced Open: Encrypts open (public) Wi-Fi connections without a password
- 192-bit security suite for enterprise networks
Bluetooth
Bluetooth is a short-range wireless technology for personal area networks (PAN). It operates in the 2.4 GHz ISM band using frequency hopping spread spectrum (FHSS).
| Version | Max Speed | Range | Key Feature |
|---|
| Bluetooth 4.0 (BLE) | 1 Mbps | 50 m | Low Energy — IoT, wearables |
| Bluetooth 5.0 | 2 Mbps | 240 m | 4x range, 2x speed vs 4.0 |
| Bluetooth 5.3 | 2 Mbps | 240 m | Improved coexistence, energy efficiency |
Other Wireless Technologies
| Technology | Frequency | Range | Speed | Use Case |
|---|
| Zigbee | 2.4 GHz | 10–100 m | 250 Kbps | Smart home, IoT sensors, low power |
| Z-Wave | 908 MHz | 30 m | 100 Kbps | Smart home automation |
| NFC | 13.56 MHz | < 20 cm | 424 Kbps | Contactless payments, access cards |
| RFID | Various | cm to meters | Low | Asset tracking, inventory, access control |
| 4G LTE | 700 MHz–2.6 GHz | Cellular | ~150 Mbps | Mobile broadband |
| 5G | Sub-6 GHz / mmWave | Cellular | ~10 Gbps | Ultra-fast mobile, IoT, autonomous vehicles |
4G vs 5G
- Speed: 5G offers up to 10 Gbps vs 4G's ~150 Mbps peak
- Latency: 5G achieves ~1 ms vs 4G's ~30–50 ms — critical for real-time applications
- Capacity: 5G supports up to 1 million devices per km² vs 4G's 100,000
- Frequency bands: 5G uses mmWave (high speed, short range) and sub-6 GHz (balance of speed and range)
- Use cases: 5G enables autonomous vehicles, remote surgery, smart cities, massive IoT