WiFi AC: How many STREAMS? HOW FAST should it be?

Discussion in 'MacBook Pro' started by CavemanMike, Jan 16, 2014.

  1. CavemanMike macrumors regular

    Nov 8, 2013
    How can you tell if (or how many) wifi streams my late 2013 macbook pro retina supports?

    I'm getting only 45 MB/sec (360 mb/sec) through my new airport extreme router.

    I think the MCS parameter in OPT wifi icon might be relevant (not sure).

  2. mneblett macrumors 6502

    Jun 7, 2008
  3. CavemanMike thread starter macrumors regular

    Nov 8, 2013
    How can you tell if it's using 3 streems?

    It seems sooo slow: at 360mb/sec (feels like it's only using 1 stream's worth)


  4. cbautis2 macrumors 6502a

    Aug 17, 2013
  5. CavemanMike thread starter macrumors regular

    Nov 8, 2013
    So 33% of 1300 is good?

    Thanks for the link.

    I guess I just expected wifi ac to be an alternative to a gigbit cable :-(
  6. priitv8 macrumors 68040

    Jan 13, 2011
    The MCS index has 1:1 relation to data rate. However, there are other variables involved (like number of concurrent streams and channel width).
    You can see details here: http://en.wikipedia.org/wiki/IEEE_802.11ac#Data_rates
    PS Looking at the chipsets at the end of the page, one can see that there is currently just one chip available with 4 streams.
    802.11ac spec allows for up to 8 parallel streams.
  7. CavemanMike thread starter macrumors regular

    Nov 8, 2013
    Here's my wifi parameters: (screen shot) = 3 streams

    PHY Mode: 802.11ac
    Channel: 149 (5 ghz)
    Security: WPA2 Personal
    RSSI: -44
    Transmit Rate 878 (though most of the time it's 1056

    I now see from my wifi scanner app that there are indeed 3 streams, so each stream is about 15 MB/sec - not that fast :-(

    Attached Files:

  8. tubbymac macrumors 65816


    Nov 6, 2008
    That's about the same as I'm getting. Max I've seen is in the 40 MB/sec range from Haswell rMBP to Time Capsule Wifi AC.
  9. CavemanMike thread starter macrumors regular

    Nov 8, 2013
    What you connecting to?

    Thanks for saying you are getting about the same throughput.

    Are you connecting to NAS by chance? If not, is this mac to mac xfer via wifi AC?

    Could whatever you are connecting to be the bottleneck?

    Just curious,
  10. mneblett macrumors 6502

    Jun 7, 2008
    I believe it is -- GigE to my Time Capsule during Time Machine backups is not that much faster than backing up to TM over wifi ac. Not enough to give me much incentive to go to the trouble of plugging in a CAT6 cable, rather than staying where I'm planted and letting TM do its thing over the air. (Note: I'm usually at a location where I'm getting enough signal to support ~1000-1300 Gb/s ac).

    If I'm moving a couple hundred GB's of files and I want to do so as quickly as possible, I'll go wired -- but for most other "stuff" as a practical matter ac's just as usable as GigE.
  11. tubbymac macrumors 65816


    Nov 6, 2008
    Haswell rMBP to hard drive built into Time Capsule gets just over 40 MB/s

    Same wireless speed if I'm going through time capsule to a ubuntu based NAS running an AFP share.

    Now here's where it gets weird. Wired gigabit Ethernet speed over Windows 7 via Parallels or Bootcamp gives 100 MB/s which is expected... But wired transfer to same SAMBA share via OS X Mountain Line was limited to 45 MB/s for some reason I could not figure out.

    Interesting that it matches your 45 MB/s over wireless.
  12. Freyqq macrumors 601

    Dec 13, 2004
    you have to factor in distance and overhead. Getting 1/3 of advertised speeds is actually pretty decent.
  13. CavemanMike thread starter macrumors regular

    Nov 8, 2013
    I'm 4' from the router, so that 1/3rd must all be overhead.

    I'd love to know if my DS214 synology NAS goes faster than the 45 MB/sec (it does, according to the benchmarks).

    Since my rMBP 2013 has a small 256 gig SSD drive, I'm not going to bother buying a USB to gigabit cable to transfer huge amounts of data, because huge amounts of data won't fit on my macbook anyway!

  14. whitedragon101 macrumors 65816

    Sep 11, 2008
    Yep those numbers seem right. I do network testing for PC Magazines and all the manufacturers lie. I don't think its even their fault any more. Long ago someone started using theoretical maximums as the speed specification and it has stuck. Make no mistake these theoretical maximums are unacheievable even with the most optimal conditions. Same is true for power line. Those guys really have their pants on fire. I connected two 500Mbps spec power line adapters to the same plug socket and it got 110Mbps, some don't even get that far.

    I just did testing of a whole bunch of 802.11ac adapters and their results were so low sometimes that I plugged in an ethernet cable to check my server was generating throughput fast enough. Yep it was zipping along at 980Mbps.

    802.11ac is still really good we just need the industry to decide on a new real world standard test for specs.

    Incidentally 802.11ac is very good at range. I just tested some 802.11ac USB adapters (so not as good as the 3x3MIMO in a rMBP) that hit 142Mbps at 82meters.

    In the real world 360Mbps is a very good speed for 802.11ac
  15. CavemanMike thread starter macrumors regular

    Nov 8, 2013
    Thanks for the Real World AC reality Check!

    Your reply was more helpful than the 3 hour support call with Apple! The 2nd tier apple tech didn't know what real-world expectations should be for wifi ac.

    If 360 mb/sec is ok, I'll stop obsessing.

    I remain confused by the other thread benchmarks which showed apple airport extreme only 1/3rd as fast as the fastest routers.

    Nonetheless, I'm delighted to have gotten a reply from someone who has done real word comparison between gigabit and wifi ac.

    Thanks a giga-bunch!


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