The 802.11ac spec can be found on wikipedia.
Today, I am going to give you my short review of the Edimax AC1200. They claim it is the world's first USB 3.0 Wifi Dongle that supports 802.11AC. I don't know if that is true or not but they also noted they had OSX drivers so I decided to take it for a spin. It goes for $40 street price.
So if you are a USB 3.0 mac user who hasn't bought a new summer 2013 Haswell Macbook Air, this is the dongle for you.
I also recently upgraded to a TP-Link AC1750 (Archer C7) dual-band AC Wi-Fi Gigabit Router that supports the new 802.11AC standard. This would be a good test to see how the TP-Link router fares in "AC" mode.
First of all the build quality of the Edimax dongle is very cheap. I has a very flimsy build. Next, they did not supply a cap. This is something I don't want to throw in my backpack as I head out the door in the morning. Lastly, it is a rather bulky device. On either side of my Macbook Retina, it blocks either the HDMI or a Thunderbolt port. I figure this was designed more for stationary use than for mobile road warriors. The antenna flips our for reception but I didn't notice any gains with it open or closed.
Like many 3rd party Wi-Fi dongle for OSX, there is a separate application to control the Wi-Fi connection. It is not built into the OS and the OS merely sees it as another NIC. This basically means, you can't switch networks in the top menubar. Furthermore, in the past, most 3rd party Wi-Fi apps I've dealt with were buggy and problematic. The jury is still out on how the Edimax's implementation differs from others in the past. Time will tell if the drivers and apps will be continued to be fully supported.
As you can see below, I am running at 5GHZ channel and the Link speed is 867 Mbps (which is 802.11AC's spec)
The system profiler reports it as a USB 3.0 device that uses up the 5 Gb/sec bandwidth so everything looks good.
Now for the testing.
Connected to a standard Apple Airport (I believe it is a 2.4 GHZ 802.11g), I didn't see any real gains compared to the built in Wi-Fi on my 15 inch Macbook Pro Retina. I am running iperf to my Thinkpad which normally reports 112 MB/sec when connected to a gigabit switch.
I then took it home and tested it on my new TP-Link AC Wi-Fi router. I ran a few tests.
The first is in my basement of my 3 story house. This is where I would need the speed the most as it is farthest from Wi-Fi router. I ran two sets.
From the screenshot below, I ran the following: Edimax 802.11AC, the built in Macbook 802.11n Wifi, and the last is the Thunderbolt to Gigabit adapter.
The Edimax did so-so at 6.5 MB/sec. This was an improvement over internal which ran at 4.5 MB/second. Connected to a machine that is directly wired via CAT6 gigabit in the same basement room, the Thunderbolt gigabit dongle easily hits gigabit's theoretical ceiling at 112MB/sec.
It appears that 802.11AC suffers the same fate as 5GHZ 802.11n. Performance degrades when you are not in line-of-sight. I think I might be better off just getting a 802.11n 5GHZ repeater in the basement so all my portable devices benefit.
So,before returning this dongle, I took my Macbook Pro to the main floor where the router is and re-ran the test several times. I was able to hit over 50 MB/sec. Not quite "gigabit" speeds but clearly a strong showing. All devices will have some overhead and hitting 50 MB/sec is pretty impressive. The last 25 MB/sec reading was a test as I was on the stairs; walking down another floor. Impressive indeed.
Your results will definitely vary depending on many circumstances. You definitely need to re-invest in new routers that support 5GHZ 802.11AC. Using an old G/N router won't yield you any gains. Furthermore, 5GHZ vs 2.4GHZ has its pro and cons. 2.4GHZ is more heavily trafficked and congested but it does have better range. For example, on my third floor, it doesn't matter if I am running 2.4GHZ or 5GHZ. I don't know if I can recommend this product yet.
The jury is still out on reliability and long-term usage. Customer reviews have been mixed. I'm personally used to wired Gigabit and where I need the speed the most (my basement), the dongle doesn't give me any significant gains for my uses. I'm impatient and when I need to copy large files over the network, I simply plug in wherever I have a wired port.
Links: Edimax Product page, Amazon Product page