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PostPosted: Mon Apr 26, 2010 12:58 pm 
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Do you have the option for CTS protection? What authenticaiton method and cipher method are you using? What throughput did you see with you g router? What channel did your g router use? Can you provide more info about your trenda usb card? These problems could be from the usb card. May not have good drivers or a good chip set. Do you know what your SNR (Signal to Noise Ratio) is?

Did you try turning the transmit power down? With your laptop a foot away a low power will still work great and may help to see if the problem goes away. Try it at it's lowest power and slow go up until you have a problem again. Who knows you might have all the coverage you need on a lower setting. Usually most site surveys start off with using a max power of 30mW so give that a try.

Just to let you know a g router only has 48 data subcarriers. A n router using 20 MHZ channels in 2.4Ghz only has 52 data subcarriers. So it's only a little faster. If you go to 40 MHz channels in 5 Ghz then you get 108 data subcarriers. So a 2.4Ghz n router is only going to be a little faster than a g (unless you use some of the other feature a n router has like MIMO or dual stream and your usb card would need to support it also).

As for the channels I'm trying to tell you the industry standard is to only use channels 1,6,11. Any other channel will mess things up for you and your neighbors. If you have clean airspace with no one else using wifi then yes use whatever channel you like. If channel 8 is working for you then great it's not like the FCC is coming to get you. Just know that some people may do things to knock you off air for using the wrong channel so their channel works good.


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PostPosted: Tue Apr 27, 2010 5:16 am 
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Ok so I got the CRC errors down to around 5% by changing the 300mbs mode bandwith to 20mhz vs 40mhz. The only problem is now the laptop only connects at 65Mbps :( Is this standard for a 150Mbps nic to only connect at 65Mbps in 20mhz bandwidth?


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PostPosted: Tue Apr 27, 2010 5:36 am 
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Yes your going to loose bandwidth going from 40mhz to 20mhz. Or you went from 108 data subcarriers to 52 data subcarriers (a g router would be using 48 data subcarriers). But you are probably getting much better throughput because there is to much interference in the 2.4Ghz band to use 40mhz channels. 40mhz is bonding two channels together, and it takes up just about the entire band in 2.4GHz. So if it is connecting at 65Mbps you should have a throughput around 32Mbps. So better than what you would have on g. 40mhz channels kill in the 5Ghz range, not much interference going on up there (until everyone moves up there anyway).

Another thing to try is 802.11 frame fragmentation is used to increase throughput by decreasing frame retransmissions. Large frames have a high probability of corruption when there is RF interference in the immediate area around the transmitter and/or receiver. By making the frames smaller, each frame has a greater chance of being completely received and acknowledged. But I don't think this will help you, but you can try it (it can also lower you speeds too). Larger frame sizes result in greater throughput in a low RF interference environment.


Last edited by jlh304 on Tue Apr 27, 2010 6:02 am, edited 1 time in total.

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PostPosted: Tue Apr 27, 2010 5:39 am 
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Thanks. Actually my throughput dropped but the crc errors dropped too. This is starting to suck.

Final question. Even at 15Mbps I should still be able to stream a DVD to my xbox right?


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PostPosted: Tue Apr 27, 2010 6:03 am 
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Yes I think you should be able to stream a dvd (not bluray).


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