May 06 2014

Tech Tips: Deploying 802.11ac APs

The 802.11ac standard already is proving its worth with new features, throughput, range and capacity.

While most colleges and universities are busy deploying and optimizing 802.11n implementations, yet another wireless-LAN standard — IEEE 802.11ac — is hitting the market in the form of a vast array of new products. The 802.11ac standard already is proving its worth with new features, throughput, range and capacity.

The 802.11ac standard operates only in the 5-gigahertz band. While ­occasionally 5GHz is home to 802.11n deployments, most of these have historically been at 2.4GHz due to (unnecessary) concerns about range. The good news is that 5GHz offers plenty of spectrum to begin 802.11ac deployments now — something that every institution should consider. We expect that the majority of mobile ­devices sold will be 802.11ac-compatible by the end of 2014.

Make the most of 802.11ac when deploying wireless access points:

1. Perform a wired network audit.

Today's 802.11ac products ­support up to 1.3 gigabits per second, per radio channel, but their effective instantaneous demand should be only 200 to 500 megabits per second. This means that while Gigabit Ethernet switches will easily handle the load, it's time to ensure that sufficient ­capacity exists across the network when it comes to backhaul and ­interconnectivity. Also check that Power over Ethernet capacity is sufficient.

2. Implement a nondisruptive deployment.

While rip-and-replace can be justified in some cases — greenfield deployments should definitely go with 802.11ac — most institutions should pursue an overlay strategy, which leaves current 802.11n APs in place. On most campuses, it should be easy to operate one or two 80-megahertz 802.11ac channels. Some APs support dual 802.11ac radios, making a nondisruptive deployment of significant 802.11ac capacity relatively easy.

3. More throughput doesn't mean more range.

Some network managers ­mistakenly ­assume that higher raw throughput implies the need for fewer APs. But the higher speeds made possible by 802.11ac are the result of more aggressive modulation, which will normally yield benefits only when an AP's range is fairly limited. A strategy of dense AP deployments, then, is the optimal approach. Range limitations inherent to the 5GHz band mean this greater AP density will usually be required. Of course, that can be accomplished over time; there is no need to attempt an optimal deployment from the very first day. It's also a good idea to review current application demands, and extrapolate from there to estimate future capacity demand, which is going to grow regardless.

4. Do it now.

There's a good deal of buzz around the so-called Wave 2 of 802.11ac, which will include even greater throughput (to about 1.8Gbps, and perhaps even more over time) and the multi-user, multiple-input/multiple-output ­(MU-MIMO) technology, which allows multiple stations to receive distinct ­transmissions from an AP simultaneously. Many higher ed users will be tempted to wait, but given ­ever-growing network demands, waiting may mean the choice between doing nothing and suffering ­irritating capacity shortfalls, or buying more 802.11n ­infrastructure, which isn't the most cost-effective strategy for the long term. Given that 802.11ac APs cost only slightly more than their 802.11n counterparts, now really is the time to move forward.

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