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Getting ready for gigabit Wi-Fi

Pre-standard products are already emerging, so now is the time to start planning

By , Network World
August 21, 2013 07:11 AM ET

Network World - Even though the IEEE 802.11ac standard for gigabit Wi-Fi has yet to be finalized, that fact doesn't seem to be holding back key players across the wireless LAN equipment value chain. Everyone from chip suppliers to vendors of access points for both residential and enterprise-class applications are ramping up.

So while only a few 802.11ac-based infrastructure products, and very few client devices, are available today, enthusiasm is building. And as is typical with still-emerging advances in WLANs, serious questions are being posed around upgrade plans -- one of which is whether an upgrade to .11ac should even been in the cards at all.

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The controversy here resides in the basic underlying technologies of .11ac and what value they might ultimately offer organizations that have spent handsomely on 802.11n over the past few years and are hoping to continue to gain return on those investments. But an excellent case can be made, as we'll explore here, for the eventual replacement of 802.11n by .11ac, provided the vendors can deliver demonstrable benefits in 802.11ac-based products, and that IT organizations take a few simple steps to prepare their networks for the enhanced data volumes that will most certainly be realized over the next few years no matter what 802.11 technology is in place.

The enticement for 802.11ac? Well, for starters, throughput numbers like 1.3Gbps, and the standard will, in fact, specify performance all the way to 6.93Gbps. But, as has been the case since the early days of 802.11n, raw throughput should not be the key motivator for the adoption of higher-performance WLANs. Rather, it's important to think instead in terms of capacity -- making the most efficient use of radio spectrum in the service of a large, diverse and growing base of users and applications, rather than provisioning gigabit-plus speed for any single user alone. And .11ac makes significant strides here.

With BYOD driving the new normal of multiple simultaneous devices per user, and WLANs now supporting essentially every IT application, including many that require time-bounded services, enterprises everywhere are well-served to contemplate upgrades in terms of how best to handle that ever-growing traffic load.

And for many, and eventually most organizations, that vehicle will ultimately be 802.11ac. And the decision here will be easy -- not only will capacity be improved, but we expect that the price of .11ac-based products will be essentially the same as that for .11n, meaning price/performance will be substantially improved as well.

Key technology advances in 802.11ac

802.11ac is really more evolutionary than revolutionary, building upon technologies proved in 802.11n. Nonetheless, five key technical enhancements at the core of the standard stand out:

* 256-QAM: This term is an abbreviation for quadrature amplitude modulation with 256 points in the phase/amplitude constellation. Without delving too deeply here, what this means is that 8 bits of encoded channel information (which is not the same as user data bits) can be sent during each clock period of transmission. 802.11n was much less efficient, with only up to 64-QAM specified.

There is, however, controversy here: It is unclear just how often 256-QAM will be effective in any given environment. The more complex a radio signal is, the more likely it is to be damaged during transmission and thus require a retransmission, hardly the key to efficiency. Nonetheless, 256-QAM is a proven technology and we do expect to see its benefits in .11ac in many cases.

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