It’s not a new thing that users can’t distinguish 802.11ac and 802.11n when using a product datasheet. Today, I will show you the difference between these two.
IEEE 802.11 is a set of media access control (MAC) and physical layer (PHY) specifications for implementing wireless local area network (WLAN) computer communication in the 900 MHz and 2.4, 3.6, 5, and 60 GHz frequency bands.
Wireless networking using the 802.11 standard, also known by its trade name, Wi-Fi, has become common in the home and has a significant and growing role in corporate settings.
The develope timeline of 802.11
From this timeline, we can find that 802.11ac is an evolution of 802.11n.
These series is exactly an Iteration update process of Cisco Aironet Access Point.
The figure following shows the updating of Cisco Aironet Access Point.
802.11ac is a transformational wireless LAN technology that represents a significant performance increase over its highly successful predecessor, 802.11n. 802.11n provided the wireless connectivity speeds that businesses needed to embrace Wi-Fi in their day-to-day operations and let workers begin using wireless as their primary network medium of choice. The 802.11ac IEEE standard allows for theoretical speeds up to 6.9 Gbps in the 5-GHz band, or 11.5 times those of 802.11n. And now 802.11ac has two versions: wave 1 and wave 2.
802.11ac is about delivering an outstanding experience to each and every client served by an AP, even under demanding loads.
Wireless speed is the product of three factors: channel bandwidth, constellation density, and number of spatial streams. 802.11ac pushes hard on the boundaries on each of these, as shown in following figure.
For the mathematically inclined, the physical layer speed of 802.11ac is calculated according to following table following.
Calculating the Speed of 802.11n and 802.11ac
|PHY||Bandwidth (as Number of Data Subcarriers)||×||Number of Spatial Streams||×||Data Bits per Subcarrier||÷||Time per OFDM Symbol||=||PHY Data Rate (bps)|
|802.11n or 802.11ac||56 (20 MHz)||1 to 4||Up to 5/6 × log2(64) = 5||3.6 microseconds (short guard interval)|
|108 (40 MHz)||4 microseconds (long guard interval)|
|802.11ac only||234 (80 MHz)||5 to 8||Up to 5/6 × log2(256) ≈ 6.67|
|2 × 234 (160 MHz)|
The most important difference is the speed. WiFi is always promoted using ‘theoretical’ speeds and by this standard 802.11ac is capable of 1300 megabits per second (Mbps) which is the equivalent of 162.5 megabytes per second (MBps). This is 3x faster than the typical 450Mbps speed attributed to 802.11n.802.11ac vs 802.11n: What’s the difference?
802.11ac real world speeds recorded in testing are around 720Mbps (90MBps). By contrast 802.11n tops out at about 240Mbps (30MBps) so the 3x estimate is still true, just much lower.
There is one more crucial part to understand for your real world experience: antennas.
Long term 802.11ac has the headroom to support up to eight antennas each running at over 400Mbps each, but the fastest router to date only has four antennas. 802.11n only supports up to four antennas at roughly 100Mbps (12.5MBps) each.
802.11n does include many options with reduced value, and 802.11ac takes a very pragmatic approach to them. If a “useless” option is used and affects a third-party device, 802.11ac typically forbids an 802.11ac device (operating in 802.11ac mode) from using the option. If a “useless” option has not been used in 802.11n products or affects only the devices that activate the option, the feature is not updated for 802.11ac but is instead “left to die.”