Speeding Up Wi-Fi

The new 802.11ac Wi-Fi standard delivers up to Gigabit speeds, making wireless networks as fast as their wired counterparts.

WiFi-web

A wireless network was once a “nice-to-have” technology that companies set up in the conference room for executives with laptops. No longer. Organizations of all sizes have come to rely upon their wireless LANs (WLANs) for day-to-day operations. More than a mere convenience, WLANs enable greater efficiency, productivity and customer service, all of which contribute to a bigger bottom line.

WLANs give employees anytime, anywhere access to the business applications and data they need from their favorite mobile devices. No longer tied to their desks to do their jobs, they become more accessible, available and collaborative.

But simply having a WLAN is not enough. Much of the value derived from the WLAN comes from access to bandwidth-intensive applications and collaboration tools such as videoconferencing. Many organizations are finding that their existing wireless networks lack the speed, coverage, capacity and reliability to meet today’s business demands. To help satisfy the hunger for ever-faster WLANs, the Institute of Electrical and Electronics Engineers (IEEE) has ratified a new Wi-Fi standard — 802.11ac — that promises to deliver Gigabit speeds.

“802.11ac has the potential to provide data speeds of around 1Gbps — comparable to many wired networks,” said Michael Stenger, IT Director, Atlantic-IT.net. “Actual performance is dependent upon a number of technological and environmental variables. But organizations are going to see dramatic performance improvements with 802.11ac compared to older Wi-Fi protocols.”

The Nth Degree

In order to understand the technology behind 802.11ac, you have to look at its predecessor, 802.11n. It gave a real boost to WLAN performance, delivering speeds in excess of 100Mbps and theoretical raw data rates of 500Mbps or more.

“While older 802.11g technology provides real WLAN throughput in the 20Mbps to 25Mbps range, 802.11n delivers at least 100Mbps by improving the efficiency of data communication,” Stenger said. “It also uses more of the wireless spectrum, when available, to enhance performance. While 802.11g uses 22MHz-wide channels, 802.11n supports up to 40MHz-wide channels. In addition, it is designed to resist interference from neighboring Wi-Fi systems and 2.4GHz devices.”

But the heart of 802.11n is a technology called MIMO — short for multiple input, multiple output — that employs multiple antennas and radios to transmit and receive data. This not only increases bandwidth but provides greater coverage, enabling very high-speed connections over distances of 150 feet or more. As a result, a state-of-the-art 802.11n WLAN can achieve speeds of 300Mbps using two spatial streams, and speeds of up to 600Mbps using three or four spatial streams.

The 802.11ac standard features these proven technologies along with an increase in the radio channel. Just as 802.11n increased throughput by doubling channel width from 22MHz to 40MHz, 802.11ac provides even greater speeds thanks to wide 80MHz channels. In addition, 802.11ac uses the 5GHz band, easing congestion in the crowded 2.4GHz band used by most wireless devices.

Catching the Wave

802.11ac products are being introduced in two “waves.” Wave 1 products, which are available now, use the less-crowded 5GHz band and 20MHz, 40MHz and 80MHz channels. Although Wave 1 access points (APs) generally support three spatial streams, many tablets and smartphones are single-stream devices, resulting in a wide variety of data rates.

Wave 2 products support a new technology called multi-user MIMO (MU-MIMO) that increases throughput by maximizing the number of megabits transmitted per megahertz of spectrum. MU-MIMO improves upon the capabilities of 802.11n technology by supporting up to four simultaneous user transmissions on each spatial stream. 802.11ac also doubles the number of spatial streams from four to eight. This allows for much higher user density.

With any WLAN technology, the real throughput is generally a fraction of the theoretical throughput. Thus, the Gigabit data rates of 802.11ac will likely exist only in ideal conditions. However, early adopters have seen consistent throughput in the 400Mbps to 800Mbps range for 802.11ac devices, better performance for 802.11n devices, and increased range and density.

“The adoption strategy for 802.11ac depends upon your technology roadmap. If you’ve recently deployed 802.11n and haven’t noticed any bottlenecks, you might want to wait for Wave 2 equipment,” Stenger said. “But if you need better performance, have adopted 802.11ac devices or are still using older Wi-Fi protocols, Wave 1 equipment may make good sense.  Either way, we see 802.11ac as a must-have technology for any organization that depends upon its WLAN.”