Wireless Communication Standards — IEEE 802.11 Types Explained
The IEEE wireless communication standards explained — what the 802.11 family covers, how the standards differ in speed…
802.11ac (also called WiFi 5) is a wireless networking standard that operates exclusively on the 5 GHz band and supports theoretical speeds up to 3.5 Gbps. It introduced MU-MIMO (Multi-User Multiple Input Multiple Output), beamforming, and 80/160 MHz channel widths to significantly improve over 802.11n.
Key takeaways
- 802.11ac = WiFi 5 — released in 2013, ratified by IEEE in 2014 (Wave 1) and 2016 (Wave 2)
- 802.11ac operates ONLY on 5 GHz band (not 2.4 GHz like 802.11n/b/g)
- Maximum theoretical speed: 3.5 Gbps (Wave 2, 4-stream) — real-world speeds typically 300–900 Mbps
- Key features: MU-MIMO (Wave 2), beamforming, 80 MHz channels (mandatory), 160 MHz (optional)
- 802.11ac Wave 2 added MU-MIMO allowing simultaneous transmission to multiple clients
- Succeeded by 802.11ax (WiFi 6) which added OFDMA, better performance in dense environments
- Most home routers sold 2016–2022 use 802.11ac — still fully capable for most home use cases
802.11ac, retroactively branded WiFi 5, was ratified in 2013 and became the dominant wireless standard for roughly seven years. It operates only on 5 GHz — a dual band 802.11ac router falls back to 802.11n on the 2.4 GHz band.
It remains extremely common. Most devices bought between 2014 and 2020 are WiFi 5, and for a household internet connection under a few hundred megabits it is still entirely adequate.
What It Changed
| Feature | 802.11n (WiFi 4) | 802.11ac (WiFi 5) |
|---|---|---|
| Bands | 2.4 and 5 GHz | 5 GHz only |
| Channel width | 20 / 40 MHz | 20 / 40 / 80 / 160 MHz |
| Modulation | 64-QAM | 256-QAM — 33% more bits per symbol |
| Spatial streams | Up to 4 | Up to 8 |
| MU-MIMO | No | Yes (downlink only, Wave 2) |
| Beamforming | Optional, non-standard | Standardised |
| Max theoretical rate | 600 Mbps | 6.9 Gbps (8 streams, 160 MHz) |
Three of these carry most of the improvement: wider channels (80 MHz is four times 20 MHz), denser modulation (256-QAM), and more spatial streams. Multiply them together and the headline figures follow.
Wave 1 vs Wave 2
802.11ac shipped in two phases, and the distinction still matters when buying used or budget hardware:
| Wave 1 (2013) | Wave 2 (2016) | |
|---|---|---|
| Max channel width | 80 MHz | 160 MHz |
| Spatial streams | 3 | 4 |
| MU-MIMO | No | Yes |
| Max theoretical rate | 1.3 Gbps | 3.5 Gbps |
MU-MIMO is the meaningful difference. Without it, an access point serves one client at a time — everyone else waits. With it, the AP transmits to several clients simultaneously using spatial separation. In a busy household that produces a real improvement in consistency, not just peak speed.
The caveat, and it is a significant one: 802.11ac MU-MIMO is downlink only. Uploads from clients to the AP still queue one at a time. WiFi 6 added uplink MU-MIMO.
Realistic Speeds
Advertised link rates and actual throughput are far apart, for reasons that are structural rather than a fault:
| Streams × width | Link rate | Realistic throughput |
|---|---|---|
| 1 × 80 MHz | 433 Mbps | ~200 Mbps |
| 2 × 80 MHz | 867 Mbps | ~400 Mbps |
| 3 × 80 MHz | 1,300 Mbps | ~600 Mbps |
| 4 × 160 MHz | 3,470 Mbps | ~1,500 Mbps in ideal conditions |
Roughly half the link rate is normal. WiFi is half duplex on a shared medium, with acknowledgements, contention windows, beacons and management frames all consuming airtime. Most phones and laptops are 2×2 anyway, so 867 Mbps negotiated and ~400 Mbps achieved is the common real-world case.
“AC1900” on a box means 600 Mbps of 2.4 GHz plus 1,300 Mbps of 5 GHz added together. No single device ever sees the combined figure.
Channel Width — the Setting That Matters Most
| Width | Speed | Interference tolerance | Non-overlapping channels |
|---|---|---|---|
| 20 MHz | Lowest | Best | ~24 |
| 40 MHz | 2× | Good | ~12 |
| 80 MHz | 4× | Reasonable — the sensible default | ~6 |
| 160 MHz | 8× | Poor | 2, both requiring DFS |
80 MHz is the right default. 160 MHz doubles theoretical throughput but requires DFS channels — which the AP must vacate for a minute whenever it detects radar, dropping every client. In a dense apartment building, 160 MHz also means you are occupying a large slice of spectrum your neighbours need, and the interference cuts both ways.
Beamforming and Its Limits
802.11ac standardised explicit beamforming: the AP and client exchange channel information, and the AP shapes its transmission to focus energy toward that client rather than radiating equally in all directions.
It genuinely improves signal quality at range — but only when both ends support it, and only where the AP has more antennas than the client. It is not a substitute for placing an access point closer to where coverage is needed.
WiFi 5 vs WiFi 6 — Should You Upgrade?
| WiFi 5 (802.11ac) | WiFi 6 (802.11ax) | |
|---|---|---|
| Bands | 5 GHz only | 2.4 and 5 GHz |
| Modulation | 256-QAM | 1024-QAM |
| OFDMA | No | Yes |
| MU-MIMO | Downlink only | Downlink and uplink |
| Target Wake Time | No | Yes — better battery life for IoT |
| BSS colouring | No | Yes — less interference between nearby APs |
| Max theoretical rate | 6.9 Gbps | 9.6 Gbps |
OFDMA is the reason to upgrade, not the speed figures. It lets one transmission carry data for several clients at once by dividing the channel into sub-carriers. On a network with thirty devices — phones, TVs, sensors, plugs — most sending small amounts of data, this removes an enormous amount of queuing overhead. The improvement shows up as lower latency and better consistency, not a higher speed test number.
Upgrade if
- You have 25 or more connected devices.
- Several people stream or video call simultaneously.
- Your internet connection exceeds ~500 Mbps and WiFi is the bottleneck.
- Many battery-powered IoT devices would benefit from Target Wake Time.
- You live somewhere dense enough that BSS colouring helps.
Do not bother if
- Your connection is under 200 Mbps — WiFi 5 already exceeds it.
- You have few devices and no complaints.
- All your client devices are WiFi 5 anyway. The router cannot use features the clients lack.
- Your actual problem is coverage. Buy an access point, not a faster router.
That last point is worth emphasising — a newer standard does not increase range. See 2.4 GHz vs 5 GHz for why, and dual band routers for how the bands divide the work.
Frequently Asked Questions
Is 802.11ac the same as WiFi 5?
Yes. The WiFi Alliance introduced simplified names in 2018 and applied them retroactively — 802.11ac became WiFi 5, 802.11n became WiFi 4.
Does 802.11ac work on 2.4 GHz?
No, it is 5 GHz only. A dual band 802.11ac router runs 802.11n on its 2.4 GHz radio.
Why is my 802.11ac WiFi slower than advertised?
Advertised figures add both bands together and assume ideal conditions with the maximum stream count. Realistic throughput is roughly half the negotiated link rate, and most client devices are 2×2 rather than 4×4.
Is 802.11ac still good enough?
For most homes, yes. A 2×2 client at 80 MHz delivers around 400 Mbps of real throughput, which exceeds the majority of internet connections. Upgrade for device density, not raw speed.
What is MU-MIMO and does it help?
It lets the access point transmit to several clients at once instead of serving them in turn. In 802.11ac it is downlink only, and it requires client support. It helps in busy households and does nothing with one active device.
Should I enable 160 MHz channels?
Only with a clean RF environment and a genuine need. 160 MHz requires DFS channels, which drop the network briefly when radar is detected, and it is far more sensitive to interference. 80 MHz is the better default.
