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Thread: what should I realistically expect from 802.11n?

  1. #1

    what should I realistically expect from 802.11n?

    I upgraded all my wifi equipment to wifi N but don't see anything near the 300Mb I was promised. I'm swamped by all the different settings they have as well as the draft nature of N. That said, I am getting shoddy coverage as compared to my old 9dbi antenna for 802.11g but I am able to stream my mp3's with no problem. My Wireless Zero Config normally tells me I have 130 to 144Mb bandwidth while my transfer speed next to the router goes no more than 7Mb/sec. Away from the router on the other side of the room, I get no more than 3MB/sec. When WZC shows 2 bars of signal, I get about 1-2MB/sec.

    That said, what should I do to really utilize that 300Mb bandwidth - how do I make sense of all those crazy settings such as bursting, WMM, fat channel, HD mode, etc?

    I am currently using 3 wifi N devices including a Netgear 802.11n with gigabit switch, a centrino pro laptop, and a dell wireless draft-n laptop. Many thanks in advance!

  2. #2
    Elite Member TonyT's Avatar
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    Every switch/hub/router that wifi passes through reduces throughput by approx 50%. I'd suggest reading up on your AP settings so as to config for best performance.
    No one has any right to force data on you
    and command you to believe it or else.
    If it is not true for you, it isn't true.

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  3. #3
    50%?! WOW..... that's unbelievable. Well, the Netgear router I'm using does't have much to configure for wifi. It has a channel selector, wifi mode (abgn), and that's about all. I selected 802.11n full mode with the channel to auto select. Setting it to autoselect helped me instantly but I'm still not able to do much else past that.

    So if I were to do an ad-hoc network I would see my network connection read as a 300Mb line?

  4. #4
    Elite Member TonyT's Avatar
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    No one has any right to force data on you
    and command you to believe it or else.
    If it is not true for you, it isn't true.

    LRH

  5. #5
    Interesting read ... can't wait till N is finalized. But on another note, do you know how much throughput degrades when using WPA2-PSK with a 63 character key? Could that have a sizable impact on network performance?

  6. #6
    Elite Member TonyT's Avatar
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    In any 80211x do not expect more than 50% of the max throughput. Using encryption reduces throughput approx 15-20% depending on what type is used. This is because the key and other data gets added to the header of each paclet that is transmitted-received which increases the overall size of the data being transmitted. Also, it takes more cpu cycles to encrypt-decrypt the keys in each packet. The chipset in the wifi adapter is also a factor in that some chipsets offload certain things to the comp cpu while other chipsets handle everything on their own. For example, some chipsets use a driver as well as "virtual firmware", some chipsets just use a driver w/ the firmware burned into the adapter chipset.
    No one has any right to force data on you
    and command you to believe it or else.
    If it is not true for you, it isn't true.

    LRH

  7. #7
    ah, i see, thanks for the nfo. I guess that helps bring my expectations roughly in line with 802.11n.

    On a slightly unrelated note, how should I interpret the Windows network status icon that shows that speed of the connection? I have three laptops in the home, each with different 802.11n chipsets. All of them, when sitting within 10 feet of the 802.11n router get about 5MB/sec stable wifi transfer. However, in the network status window, one will read a connection of 144Mb, another fluxuates between 108 and 230, and another will fluctuate between 130 and 210. What should I make of those numbers?

  8. #8
    Elite Member TonyT's Avatar
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    The numbers are fairly accurate, they display the connection between the adapter and the AP at that point in time. Wifi fluctuates constantly.
    No one has any right to force data on you
    and command you to believe it or else.
    If it is not true for you, it isn't true.

    LRH

  9. #9
    ah, that kinda is good or bad. I was hoping it was really inaccurate because while in my room, it drops to 1Mb never gets better than 12Mb!

    so far, wifi N has been really good unless I'm far away from the access point (I'm getting 7 to 8MB/sec from my NAS - sweet!). The issue is primarily signal propagation, which seems to drop off much faster with this particular access point (drops off like off a stupid cliff). The lack of external antennas, my door, walls, really did a number compared with my original 802.11g with a 9dbi antenna. I used to get 24Mb+ easily....

    I'm really going to have to get a new router when draft n gets finalized - something with a really strong antenna.... or for the time being, setup a repeater of some kind.

  10. #10
    Elite Member TonyT's Avatar
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    There's probab a few AP setting that can be adjusted to better performance. But...the greater the distance, the lesser the throughput.

    Also, if all clients use n adapters then the wlan will perform best, but as soon as a a-b-g client connnects the AP will auto kill n and switch to the other protocol.
    No one has any right to force data on you
    and command you to believe it or else.
    If it is not true for you, it isn't true.

    LRH

  11. #11
    Thanks so much for all your input. I hope you don't mind me bouncing a few more questions here ...

    So after using setting some settings including frame aggregation and bursting, I'm getting some really good throughput with the network status monitor showing me 220 to 300Mb. However, when I set one computer to transfer 6GB of data to my NAS, and then turned on another 802.11n system, my whole wireless network crashed when that second system tried to authenticate with the router. This is while the system was transferring about 6GB of data to the NAS and was achieving a 7MB/sec rate in filezilla.

    I'm guessing the router went crazy when the 802.11n bandwidth sucked dry and something tried to authenticate. Is this supposed to happen or could it be something else causing this?

    And to add, it was only the wireless component of the router that died. My gigabit ethernet still kept working without a hitch. After looking through some of the settings, I also noticed that on one system, it had something called a surge stream driver while the other did not - does that have anything to do with it? Both 802.11n systems use the same Buffalo N-Finiti MIMO USB adapters - one connected through a USB hub, the other directly to the PC (the stream surge driver seems to be present only on the system with the adapter plugged directly in).

    Many thanks again for all your input!

  12. #12
    just an update ...

    I set my one laptop to transfer that massive multi GB file again but this time, i started up a second laptop that does not use the buffalo adapter but rather the intel centrino pro adapter. My wireless network has not crashed!

    I'm beginning to think this is a driver issue with the other PC that caused it to crash the network while one system was transferring large data over the network.

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