Wireless fundamentals and 802.11 standards
In one line
Wi-Fi is a half-duplex shared medium - so the real design currency is airtime, not headline data rates.
The physics that drive design
- Bands: 2.4 GHz (range, few non-overlapping channels - 1/6/11, congested), 5 GHz (more channels, the workhorse), 6 GHz (Wi-Fi 6E, lots of clean spectrum).
- Channel width (20/40/80/160/320 MHz): wider = faster but fewer non-overlapping channels and more co-channel interference - a capacity-vs-reuse tradeoff.
- Shared medium / CSMA-CA: only one device transmits at a time per channel; airtime is the scarce resource. OFDMA (Wi-Fi 6) and MU-MIMO let an AP serve multiple clients per transmit opportunity, improving efficiency and density.
Generations (headline)
| Gen | Standard | Headline | Bands |
|---|---|---|---|
| Wi-Fi 5 | 802.11ac | DL MU-MIMO, wider channels | 5 GHz |
| Wi-Fi 6 | 802.11ax | OFDMA, UL/DL MU-MIMO, efficiency/density | 2.4/5 GHz |
| Wi-Fi 6E | 802.11ax | + 6 GHz spectrum | +6 GHz |
| Wi-Fi 7 | 802.11be | 320 MHz, 4K-QAM, MLO (multi-link) | 2.4/5/6 GHz |
Why it matters for design
Newer generations mostly buy density and efficiency, not just speed - the right lens for high-density design (RF design - coverage, capacity, high density, voice, location). Outdoor/point-to-point bridging is a transport option too (WAN and last-mile transport selection).
IPv6 / dual-stack note
802.11 is L2 transport for both families; dual-stack clients ride identically (mind RA/ND on large wireless VLANs - Layer 2 security).
Related
- WLAN architectures
- RF design - coverage, capacity, high density, voice, location
- WAN and last-mile transport selection
Spaced repetition
Why is "airtime" the real design currency in Wi-Fi rather than data rate?
Wi-Fi is a half-duplex shared medium (CSMA-CA) - one transmitter per channel at a time, so contention/airtime, not peak rate, limits real capacity.
Wider channels (80/160/320 MHz) trade [...] against [...].
Wider channels (80/160/320 MHz) trade higher per-client speed against fewer non-overlapping channels / more co-channel interference (worse reuse).
What do Wi-Fi 6/6E/7 mainly add? 6 = [...]; 6E = [...]; 7 = [...].
What do Wi-Fi 6/6E/7 mainly add? 6 = OFDMA + efficiency/density; 6E = 6 GHz spectrum; 7 = 320 MHz, 4K-QAM, multi-link (MLO).
Sources
- IEEE 802.11; Cisco Press, CWNA-aligned wireless design references.