Gigabit Wi-Fi: 802.11ac is here: Five things you need to know

Gigabit Wi-Fi: 802.11ac is here: Five things you need to know

Summary: Gigabit Wi-Fi, 802.11ac is not really going to give you gigabit speeds - and there are other factors you need to consider before adding it to your wireless network.


Gigabit Wi-Fi, 802.11ac, is officially here, but what does that really mean? Here's my list of the five things you need to know before you invest in this new wireless technology.

1) 802.11ac is not going to give you a Gigabit of throughput

True, 802.11ac access points working with 802.11ac devices will give you faster data transmission feeds than 802.11n. The Wi-Fi Alliance claims that Wi-Fi Certified 802.11ac can deliver data rates up to more than double those of a typical 802.11n network. Practically speaking the Alliance claims that "this means a network can support simultaneously streaming multiple HD-quality videos to multiple devices."


Fair enough, but in practice you're not likely to see an 802.11ac reach its theoretical maximum of 1.3 Gigabit per second (Gbps). That's because the conditions you need to reach that speed requires a laboratory not your office.

To reach the highest speeds you need three data-streams, each of which can run up to 433 Megabits per second (Mbps). A typical 802.11ac access point can support up to eight data streams. Client devices must only support one.

For example, the Samsung Galaxy S4 supports 802.11ac with the Broadcom BCM4335 Wi-Fi chipset. This chipset only supports a single stream so, even in the best of all possible worlds, you'll only see 433Mbps.

The "unofficial" 802.11ac devices that have been shipping for the last few months, and the first generation of the standard 802.11ac devices aren't likely to hit these speeds even on a testbed. The fastest speeds here in CNeET/ZDNet land we've seen to date came from the NetGear R6300 WiFi Router, which hit a high of 331Mbps.

That's great, but it's not gigabit great. It is, however, a lot faster than you'll see then with any combination of 802.11n gear. 

2) Working out the range

802.11ac only supports the 5GHz frequency. The good news about that is that there's far more room in that frequency spread than there is in the over-used 2.4GHz . The bad news is that a 5GHz signal has less range.

At the same time, 802.11ac has another feature, beam-forming, that gets around the general 5Ghz range problem. For the Wi-Fi access point in your office today, the signal is omni-directional—it forms a communications sphere around the device. With 802.11ac the signal is broadcast directly from the access point (AP) to a specific device and back again.

While no one seems to have published much on what this means, I expect it means that if you're in an environment with few 802.11ac devices, say eight, you'll actually see excellent range. But, if you're in at a convention center with hundreds of 802.11ac devices I suspect you'll need to be much closer to an AP to get a signal. That said, life is always miserable for Wi-Fi users in hotels and large meetings rooms.

3) Backwards Compatibility

All 802.11ac devices will support older Wi-Fi technologies such as your 802.11n-equipped laptop or even your old 802.11g network bridge. 802.11ac can't do magic though. For example, if you buy an 802.11ac AP you'll still be limited to your older devices' maximum speeds.

Soon, there will be a lot of new gear that supports 802.11ac as clients. If you buy an 802.11ac AP now you're really buying for future use. It's not going to do you much good today.

As always you should remember that any network is only as fast as its slowest link. For instance, if you're buying 802.11ac to improve your Netflix viewing experience and your Internet connect is 10Mbps, it won't do you a darn bit of good. 802.11n, or even 802.11g, is all you'll need. 

4) AP Channel Conflict Ahoy

Anyone who does any Wi-Fi network management knows that the 2.4GHz range is as crowded as a Best Buy store on Black Friday morning. In theory, you can use up to 14 channels. In practice, to avoid interference, you can only use three or four channels. If you have conflicting channels, you'll see your network performance go down the toilet. The advantage of 802.11a and 802.11n's 5Ghz range is that was so much room that you didn't need to worry about interference. Get worried again.

One of the big ways that 802.11ac gains its speed is by using 80MHz wide channels. In 802.11ac wave two devices--the next generation of 802.11ac, which will start showing up in 2014--the channels will take up 160MHz of frequency. What that means exactly depends on your country, since there are a wide variety of rules on how the 5GHz range can be used. But, in the United States that means 802.11ac will have at most five available channel selections. When 802.11ac second-wave appears it will go down to one or two.

The 5GHz frequency range is messy, and using it is only going to get a lot messier as 802.11ac continues to evolve. (Credit: Cisco)

In other words, network administrators should start working out now where they'll be placing 802.11ac APs, because once more you'll need to be wary of fouling up performance because of AP interference. And, let's not talk about that business on the floor below you that's always munging up your network.

5) 802.11ac requires additional infrastructure

I know, you thought 802.11ac would let you get rid of some of your Gigabit wiring. Nope. Not going to happen. First, as I already explained you're not really going to get Gigabit speeds out of 802.11ac.

Second, and what many people don't know, is that second-wave 802.11ac APs will require two, not one, Gigabit Ethernet ports. That just doubled your need for switch ports and cable runs. Oh boy!

Sure, you can get by with one port for now, but remember you're not really going to have that many 802.11ac clients in 2013. Next year is when they'll start showing up in large numbers and that's when the second wave 802.11ac APs will be appearing.

So, you can forget about doing a drop and replace for your existing 802.11g/n network APs. You won't be able to do it. Look on the bright side: Even with the next generation of 802.11ac you probably won't need to back them up with 10Gbps up-links.

What all this means is that Gigabit Wi-Fi isn't really here. Faster Wi-Fi is but it's not really going to take off until 2014 and when it does come deploying it is going to be expensive. I foresee all of us using 802.11n Wi-Fi for years still to come. 802.11ac is not going to roll out quickly.

Related Stories:

Topics: Wi-Fi, Broadband, Networking

Kick off your day with ZDNet's daily email newsletter. It's the freshest tech news and opinion, served hot. Get it.


Log in or register to join the discussion
  • My understanding wasn't that you'd get gigabit speed for one device

    but that 802.11ac is beneficial if you have several devices that need high speed capabilities. I think in full houses/offices or even in just a geek's apartment with a lot of high speed devices, you'll see 802.11ac adoption and they will reap benefits.
    Michael Kelly
    • Steven,

      You forget that access points with more antennas can increase speed of clients with more antennas, each antenna = 1 stream (433Mbps at 80MHz channel bandwidth, or 867 at 160MHz).

  • even in the best of all possible worlds, you'll only see 433Mbps

    Ok, so you only see 433 mbps. Yippee. My internet connection is capped about 20 mbps and does just fine on everything including movie files. Unless I'm transferring huge movie files, the 433 mbps is so far ahead of needs today, well, you'll think transfers are about instant.

    As devices are designed and marketed to take advantage of wireless gigabit transfer rates, this will obviously change, but for now, it's a phenomenal data rate.

    So, why is the tone of the article so negative? Why, in an otherwise good article, does Steven dwell on the negative? It's such a small negative, the article proceeds into the ridiculous to tell everyone that they won't get 100% throughput on their single device.

    Funny, my 300mbps N router doesn't give me 100% throughput on any single device either. So why expect that from Gigibit?

    Just Steven being Steven I guess.
    • SVJN is being informative, not negative.

      Many other people (and especially businesses) have network bandwidth needs that go beyond their 20mbps internet uplink. If your only bandwidth concern is that your network bandwidth doesn't bottleneck your internet connection then just use 802.11g and disregard this article.
      • Actually showing his limited understanding

        A gigabit router will never allow a single device to have a full gigabit of bandwidth. Gigabit is total possible bandwidth that must be shared by all devices, so nothing can have the entire band all at once. It's designed that way.

        He's just using the design as a click bait to whine about not getting full gigabit via wireless.

        Just following his normal, less than competent, writing style that is designed to get responses instead of being informative.

        If he'd been informative, he'd have concentrated on how to make it as efficient as possible instead of listing purposely implemented design limitations as negatives.
        • incorrect

          Incorrect. I have a usb 3.0 dongle on my laptop that does AC @ 80Mhz. I get the full AC, and when 160Mhz comes out.. the same company will make 160Mhz dongles.
          David Dutton
        • I think you may be correct in the wireless world

          but wired networks are not that way. Each gigabit port on a wired switch is supposed to give 1Gb up and down. The backplane determines the limits on the total bandwidth for the device. In practice I've never seen any equipment reach it's speed potential outside of a very controlled lab environment.
    • fair enough

      But some of us do have gigabit connections at home. Not that we fill it day and night, but it is there. It will take sometime, before that will be possible to utilize wireless.

      What Steven seems to try to printout is that with the next wave of 802.11ac we will have exactly the same problem we had with 2.4 GHz - you are more or less limited to one channel if you want the faster speeds... More sophisticated encoding does help, until you have much older and unfriendly equipment nearby.

      For example, being in Europe I can use 13 channels in 2.4 GHz, but some idiot nearby apparently brought an wifi device from the US and that broadcasts its setting, sometimes confusing my 802.11d devices and not letting them connect to mine at channel 13. With more standards, things will just get worse.
    • Unnecessary

      I really don't understand why a residential person would want 802.11ac. What person needs that much speed? Some people will argue for internally transferring large files, but remember that most hard drives cannot even write data that fast! If a person is buying it to download files from the Internet faster that is silly too. Majority of the companies would not even be able to upload that much data to satisfy those speeds. Like Steven said the biggest benefit is going to be in areas where people are doing video streaming from multiple devices, but 802.11n is already sufficient. I mean, a person would have to be trying to feed service off one 802.11ac router to a hotel for it to be reasonable. And last time I checked most hotels provide extremely slow speeds anyways. Basically, 802.11ac just doesn't seem necessary right now.
      Nicholas McDonald
  • Equipment Quality

    Recently, I thought about getting an 802.11ac router, but I became discouraged after reading one consumer review after another that state how shoddy the currently available equipment is. Furthermore, it seems like most of the manufacturers are aware of the problems with their current offerings and don't seem to care about fixing them. So I for one will just sit this out for a year or so and wait for the hardware to become more mature and hopefully more reliable. My main bottleneck is not my 802.11n equipment anyway. It's my crappy Internet broadband service. When will the US finally get an decent Internet infrastructure? Sigh.
    • First gen equipment

      Wait for second or third gen hardware and let someone else work out the bugs. It's so new, even the vendors don't quite understand it.

      Give it a year, then jump in. It'll be much more mature and maybe be reliable.
      • Not even first generation

        802.11ac is not even a ratified spec yet.
        • Clarification

          The equipment you can buy is now all pre-spec.
  • Gigabit, or not?

    First, just because you have a router, and a device that are capable of 802.11ac, doesn't mean you will get the higher speeds. The data has to come from somewhere, and with most devices only capable of Ethernet speeds, the source just isn't up to the job. Connecting a gigabit card, to a gigabit router, driven by a cable modem delivering 100mbps just isn't going to do anything for you.
    • I agree, but

      in my situation I might be full throttle on my internet connection, plus have three simultaneous media streams to three different devices from my media center, plus perhaps a large multi-gigabyte file transfer between the media center and the computer I use to edit videos all going on at the same time. Obviously the media center needs (and has) multiple connections to handle the load, but the router is also the switch that handles the load, and the more it can handle the better my network is going to be.

      Like most people I will hold off until some real world reviews come in, but things look promising from what I can see.
      Michael Kelly
  • It isn't about getting gigabit speed

    Every time you raise the ceiling on network throughput you get a bit better access to what your internet connection is intended to provide.

    In powerline networking, the upgrades have been very worthwhile. The problems aren't the same as for WiFi but some aspects are. With the 85 Mbps bridges, the users downstairs could connect but only at speeds best measured in Kilobytes. With 200 Mbps bridges, the downstairs users could get 3-4 megabit downloads. A big improvement, although only a fraction of the 30 Megabit service evident to those upstairs. Recently, the latest 500 Mbps bridge got the downstairs access up to the 10-15 Mbps range.

    The only thing that changed in that house was changing out the powerline bridges as better grades hit the market. With each upgrade new services became viable for the downstairs users and updates became less drearily slow. It would have been far better to just run a proper Cat5 line between the floors but it wasn't an option. Improvements to the networking standards have made a big difference.
  • so many bits

    Psh... Just 1.3 GIGABIT? That's only like... five hundred times faster than what I have now!

    Of course that's definitely my Internet and not my router, but hopefully that should change when Google gets their ass out here ;3
  • I get 200 mbps wth 802.11ac on Galaxy S4

    I have :
    Samsung Galaxy S4
    ac router Linksys EA6500
    200 mbps download link with my ISP (Vidéotron in Québec city in Canada :

    On 802.11n, I get 100 mbps with application Speedtest.
    On 802.11ac, I get 200 mbps with application Speedtest.
    • but, in real life, does it make a difference

      Working with a Galaxy S4, in a real life test, like loading a movie optimized for the small screen, can you really see a difference? How long does it take for N and how long does it take for ac? The difference in a real world test would be interesting.
  • I still want to know ...

    ... why would anyone go wireless if wired is an option? I've heard of companies tearing out the wiring and going wireless ... why???

    Wireless should be deligated to the "but there was no other option" category ... like when a building designated as a Heritige buiding requires networking, but running cables is prohibited.

    IMHO, wireless networking should never be used in business, ever. While Security issues have decressed with each new version, until radio interference can be eliminated, wireless is a no-go technology.