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802.11ac Bandwidth Planning

Ever since the much anticipated 802.11ac standard was ratified and supported by Enterprise class access points (AP), I’ve asked myself the question that perhaps other network and Radio-Frequency (RF) engineers have:  how much of the theoretical 1.3Gbps 802.11ac data-rate can I really deliver to my users and what is the overall throughput experience when I deploy at scale or in high-density (HD) scenario? On the surface, it may seem intuitive that I should allocate 80MHz to my 802.11ac radios to achieve the best throughput BUT as it turns out, this approach has limited scale and may lead to less total throughput than a smaller 40Mhz channel -- so in this case; less may be more!

This is due to the fact that while in a single-cell (AP) scenario (say 5000 sq. ft) it is realistic to expect most capable devices can reach 1.3Gbps (1Mbps of throughput) with 3 spatial stream (SS) & 80MHz  (e.g. MacBook Pro) and 433Mbps (300Mb/s of throughput) with 1 SS & 80MHz (e.g. iPhone 6)  BUT this throughput degrades quickly in a multi-cell environment where co-channel-interference (CCI) from neighboring APs can dominate. So we need to look at the primary CCI contributors, which are:  Read More »

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Winning Back the Weather Radio Channels Adds Capacity to 5GHz Wi-Fi Spectrum

In my last blog on 5 GHz spectrum, I discussed the recent FCC ruling that permitted outdoor access points to use the U-NII 1 band (5150-5250 MHz).

But the story doesn’t  stop there. As mentioned last time, there are significant technical challenges to using the 5 GHz band. It is not cleared spectrum. It contains incumbent uses that are important for national security and public safety. Therefore, it is imperative that Wi-Fi not create harmful interference to these incumbent systems. Cisco will not settle for less.

On the topic of interference, a particularly interesting component of the same  FCC ruling that opened the U-NII1 band for outdoor AP’s is that it also re-opened the Terminal Doppler Weather Radar (TDWR) band (channels 120, 124, 128) with new test requirements for DFS protection. Hold on, let’s backtrack a bit before diving into what this means:

What is TDWR?

In brief, Terminal Doppler Weather Radar (TDWR) “is a Doppler weather radar system used primarily for the detection of hazardous wind shear conditions, precipitation, and winds aloft on and near major airports situated in climates with great exposure to thunderstorms in the United States.” TDWR uses the frequency band from 5600-5650 MHz which is why wireless network equipment needs to be proven to “do no harm” to TDWR. If you’re curious for more information on TDWR, then please click here and/or here.

A Brief History

Many of you reading this will recall that the FCC closed the use of the TDWR band several years ago as the result of numerous reports of wireless equipment creating interference with TDWR. Read More »

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802.11ac: That’s the Answer. What’s the question?

Everybody’s talking about 802.11ac, but we’ve sensed some confusion for next steps as far as how CIO’s and IT organizations should be approaching the new standard.

3700internal2Should I move to 802.11ac?

You’re probably thinking: Chris, you’re a leader at Cisco, of course you want me to migrate to 802.11ac. That, my friends, is where you are wrong. There is no simple answer to the question of whether you should move your network to 802.11ac. Here’s my simple rule of thumb:

There is no premium for 802.11ac from Cisco. If you are deploying new Access Points’s today, you should be buying 802.11ac. If you’re not buying, you are probably satisfied with your network and how it will handle the growth of more and more clients associating with your network and the bandwidth demands that come with that client demand. If you feel you have a plan to handle this demand, then you are one of the few that can pass on 802.11ac.

That said, there is a strong ramp up for Cisco 802.11ac products in the market, the AP3700 is the fastest ramping access point in our history and we have yet to see if the AP2700 will claim that crown in the coming months. ABI Research estimates that currently 50% of new device introductions are 802.11ac enabled, a statistic expected to increase to 75% by the end of 2015.  This is enough proof of the overwhelming interest in adding the benefits of 11ac to networks. Let’s take a step back and consider the basics of why people are moving to the new standard.

Why .11ac?

Today, everything is about getting what we want, when we want it. Instant gratification. It’s not just the millennials—we’ve all been conditioned to expect things within seconds. Could you imagine the days pre-Internet if you had the capability for on-demand movies? Read More »

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What, Why, Where, When, How: The New FCC Ruling Around 5 GHz

You don’t need me to tell you to know that we are in the midst of a technology revolution.  It’s mobilizing the internet.  And it’s transforming the way billions of people around the globe collaborate, communicate, and connect to the internet.

•           The education customers I work with are incorporating video and mobile applications into their curriculum with up to a 100 students in an auditorium accessing the Wi-Fi network simultaneously.

•           Healthcare customers are relying on Wi-Fi to connect patients, devices and provide nurses instant access to medical records.

•           Manufacturing customers are increasingly using Wi-Fi to enable workers on the factory floor to have real-time video conversations with experts anywhere in the globe.

What do these things have in common?  They all depend on Wi-Fi for connectivity.  In these areas, and so many more, Wi-Fi has become a central way that people access the Internet.

The FCC released a historic decision on April 1, 2014 (adopted March 31)with regards to the use of 5 GHz spectrum. Although there were many technical aspects included within this decision, one of the most interesting was making the 5150-5250 MHz U-NII 1 band available for outdoor WLAN use. Read More »

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Wi-Fi & Taxes: Digging into the 802.11b Penalty

It’s that time of year again in the US – Tax Time!  That time of year where we review the previous year’s bounty, calculate what’s due, and re-evaluate our strategies to see if we can keep more of what we worked for.  Things change; rules, the economy, time to retirement, and before you know it you find yourself working through alternatives and making some new decisions.

Anyway, as I was working through the schedules and rule sheets, my mind wandered and I started to think about Wi-Fi and the taxes associated with it.  In my day job, I often play the role of forensic accountant.  Like a tax accountant, I’m always looking for a way to get more or understand why there isn’t more already.  So along those lines, lets talk about a little known tax that you may well be paying needlessly.  I’m talking of course about the dreaded 802.11b Penalty.

Wi-Fi protocols like 802.11b are referenced by standards committees for the workgroup that develops them.  In the 2.4 GHz spectrum, there is 802.11b, 802.11g, and 802.11n.  Back in 1997, 802.11b  was the first modern Wi-Fi protocol ratified by the IEEE and it allowed transmissions of 11 Mbps, a major jump forward from the previous 2 Mbps  that was possible with the original 802.11 standard.


After 802.11b came 802.11a, and then 802.11g.  Both of these protocols where a radical departure from the simplistic 802.11b structure and employed Orthogonal frequency-division multiplexing (OFDM) modulation (now standard in every 802.11 protocol created since then).  OFDM allowed for Read More »

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