📘 06-01: Wireless Fundamentals & 802.11 Standards¶
📌 IEEE 802.11¶
The 802.11 family defines Wi-Fi WLAN standards. Wireless uses radio frequencies and the CSMA/CA access method (Collision Avoidance, since collisions can't be reliably detected on air).
📌 The 802.11 Standards¶
| Standard | Wi-Fi name | Band(s) | Max rate (approx) |
|---|---|---|---|
| 802.11a | — | 5 GHz | 54 Mbps |
| 802.11b | — | 2.4 GHz | 11 Mbps |
| 802.11g | — | 2.4 GHz | 54 Mbps |
| 802.11n | Wi-Fi 4 | 2.4 & 5 GHz | 600 Mbps (MIMO) |
| 802.11ac | Wi-Fi 5 | 5 GHz | ~1.3+ Gbps (MU-MIMO) |
| 802.11ax | Wi-Fi 6/6E | 2.4, 5, (6) GHz | Multi-Gbps (OFDMA) |
📌 Key Technologies¶
| Feature | Introduced | Benefit |
|---|---|---|
| MIMO | 802.11n | Multiple antennas/spatial streams → more throughput |
| MU-MIMO | 802.11ac | Serve multiple clients simultaneously |
| OFDMA | 802.11ax | Subdivide a channel to serve many clients efficiently |
| Band steering | — | Push capable clients to 5 GHz |
📌 Modes of Operation¶
- Infrastructure mode — clients connect through an access point (the norm).
- Ad hoc mode — devices connect directly, no AP.
- Wireless bridge — link two wired segments over RF (point-to-point).
Tip
Key idea — Wi-Fi = 802.11, using CSMA/CA. Know the generations: n = Wi-Fi 4, ac = Wi-Fi 5, ax = Wi-Fi 6. MIMO/OFDMA boost capacity in dense environments.
See also: Frequencies, Channels & Antennas, Wireless Security
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