Early 802.11ac speeds are not quite 'gigabit Wi-Fi'

Just how fast are the real-world gigabit Wi-Fi speeds offered by 802.11ac technology? Well, that depends.

Actual data rates being achieved are variable, depending upon a number of factors related to the equipment used and how it is deployed, according to Network World. Impacting performance are channel size employed (80 MHz vs. 40 MHz), modulation (256 QAM vs. 64 QAM) and the number of spatial streams supported by both access points and clients.

The 802.11ac standard, an upgrade from 802.11n, runs on the 5 GHz band and incorporates beam-forming, wide bands and multiple antennas to deliver theoretical data speeds up to 1.3 Gbps, more than double peak rates of 600 Mbps with 802.11n. Of course, 802.11ac's maximum rate is only achievable when using a three-stream radio in perfect conditions close to an access point, and even then the protocol overhead will keep end-users from actually achieving 1.3 Gbps.

Nonetheless, vendor and user tests of 802.11ac equipment in lab conditions as well as in actual or simulated production networks are revealing consistent throughputs of 400 Mbps to 800 Mbps for 802.11ac clients in best-case scenarios. Among other things, testing has also shown that 802.11ac is capable of higher throughput as range increases compared to older 802.11n technology.

Testing by chipmaker Broadcom has shown single-stream 802.11ac over an 80 MHz channel delivers starting speeds of 250 Mbps and maxes out at about 433Mbps.

The University of Delaware installed 3,700 of Aruba's 802.11ac access points on campus last summer. "We are seeing over 800 Mbps on the new Apple 11ac-equipped Macbook Air laptops, and 400 Mbps on the 11ac phones, such as the new Samsung Galaxy S4, that [currently] make up the bulk of 11ac devices on campus," said Mike Davis, systems programmer, University of Delaware, who was quoted by Network World.

Wave 2 features--planned for inclusion in 802.11ac equipment starting in late 2014 and into 2015--include wider deployment of transmit beamforming coupled with multiuser MIMO as well as the capability to make use of 160 MHz of channel width by combining 80 MHz + 80 MHz channels.

For more:
- see this Network World article

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