802.11ac: 533Mbps Over WiFi

Haswell isn’t all that’s new with the 2013 MacBook Air, Apple also integrated support for 802.11ac. I wrote a primer on 802.11ac last year, but I’ll provide a quick recap here. 802.11ac is a 5GHz-only WiFi standard, with support for wider channels (80/160MHz vs. 40MHz in 802.11n) and better spatial efficiency within those channels (256QAM vs. 64QAM in 802.11n). Today, that means a doubling of channel bandwidth and a 4x increase in data encoded on a carrier, which are responsible for the significant increase in bandwidth. Usable bandwidth should also see improvements on 802.11ac as high-end access points are all expected to ship with beam forming enabled.

The first 802.11ac implementations we saw were on the smartphone side with HTC’s One and Samsung’s Galaxy S 4. Both of these devices were single antenna/single spatial stream implementations with 80MHz channels and 256QAM, resulting in a max PHY rate of 433Mbps. In his review of the HTC One, Brian documented peak performance using iPerf and a TCP transfer. In a smartphone, such high bandwidth from WiFi is really useful for improving battery life (race to sleep). In a notebook, you get the same potential improvement in battery life but there’s one more: a wireless alternative to Gigabit Ethernet.

In a 3-stream configuration given what’s available today, we’re talking about a 1.33Gbps PHY rate. Assuming better link efficiency on a notebook compared to what we’ve seen in smartphones thus far, we could be talking about a real alternative to Gigabit Ethernet - at least close to an AP. While wired GbE is always going to give you a more consistent experience, the vast majority of homes aren’t pre-wired with Gigabit Ethernet. In living situations where you can’t just run a bunch of Cat6 everywhere, but still want high speed networking, 802.11ac could be a real alternative.

The 2013 MacBook Air adds support for 802.11ac via Broadcom’s BCM4360. The controller is capable of supporting up to 3 spatial streams, but in its implementation in the MacBook Air we see a maximum of 2 used. I fully expect the 2013 rMBPs to use a third antenna to leverage all 3 streams. BCM4360 supports 80MHz channels, 256QAM and short guard intervals. The result is a max PHY rate of 867Mbps.

ASUS sent me its RT-AC66U based on the same BCM4360 silicon (coincidentally the same controller that’s in the new Airport Extreme), which I promptly used for testing the new MacBook Air. The ASUS router and MacBook Air combination worked perfectly. In the same room as the AP, I had no issues seeing the maximum 867Mbps PHY rate (above).

Within about 5 - 8 feet of the AP, I saw an average of 533Mbps using iPerf. That’s real data sent over TCP:

WiFi Performance

A 3-stream solution could definitely rival wired GbE, at least for short distances.

I then went about characterizing 802.11ac performance vs. distance to get an idea for how performance fell off as I moved away from the AP. My desk and test area is in the corner of my office, which is where I put the ASUS 802.11ac router. Performance around my desk was always up around 533Mbps.

Move around 18 feet away but remain in the same room and measured performance dropped to 450Mbps. One set of walls and another 10 - 15 feet dropped performance to between 250Mbps - 340Mbps. Another set of walls without moving much further and I was looking at 200Mbps. When I went one more set of rooms away, or dropped down to a lower level, I saw pretty consistent falloff in performance - dropping down to 145Mbps. Note that my setup is pretty much the worst case scenario for longer distances. The AP isn’t centrally located at all. If I were setting up an 802.11ac network for max coverage, I’d probably see 300 - 400Mbps in most immediately adjacent rooms.

So 802.11ac on the new MacBook Air is pretty awesome, there's just one issue...

PCIe SSD Performance Real World 802.11ac Performance Under OS X
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  • darwinosx - Monday, June 24, 2013 - link

    They are not biased and you don't understand the meaning of the word. Reply
  • MonkeyPaw - Monday, June 24, 2013 - link

    Just a thought, but how about stating your concerns via constructive criticism or in the form of a question. Crying bias while continuing to visit (and therefore, support) any website just doesn't make much sense since you will be dismissed as a troll by the very people you are hoping to influence. Reply
  • CalaverasGrande - Monday, June 24, 2013 - link

    Frankly I think users that expect to play heavy 3D games on a MacBook Air with chipset video bought the wrong computer. They should have spent a few hundred more for a 15" MBP with discrete graphics. Or if they really care about games they should hop the fence and go get an Asus or some other Windows gaming notebook.
    Intel's HD4000 graphics are better than previous Intel video attempts, but still pretty weak compared to other vid chips. It's also using system ram, not dedicated ram.
    As stated, this is the mobility platform, not the performance platform.
    Reply
  • CalaverasGrande - Monday, June 24, 2013 - link

    oops, HD5000. Reply
  • darwinosx - Monday, June 24, 2013 - link

    Nobody does. But the HD 5000 is quite capable for some games. Reply
  • hyrule4927 - Monday, June 24, 2013 - link

    The lack of thermal data in these Mac reviews is rather frustrating. If this data is included in all other PC reviews in Anandtech, why is it completely ignored when reviewing Apple products? They certainly aren't immune to heat/throttling problems. Reply
  • darwinosx - Monday, June 24, 2013 - link

    You didn't read the article you are commenting on. Reply
  • hyrule4927 - Monday, June 24, 2013 - link

    If you would like to tell me where specific CPU temperature data is given, be my guest. All I see is an anecdote about fan noise and speculation about throttling in several tests. Reply
  • darwinosx - Monday, June 24, 2013 - link

    Prove that Samsung makes a better screen than LG. I bet you can't tell the difference. Reply
  • spronkey - Monday, June 24, 2013 - link

    Samsung LCDs might have slightly better early quality control. LG Display have been a bit notorious for early run issues with their panels lately. But I agree - taking these away, LG has more cred as a panel maker than Samsung does. Reply

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