• Would disabling higher data rates (and associated modulation and encoding) be effective in reducing corrupted frames being transmitted at higher rates in the 2.4 Ghz band assuming you do not require the additional throughput? And if so, would you recommend it? This would be in addition to using right type of antenna, reduced output power, sufficient cell overlap, channel seperation, etc.

    Thanks in advance

  • Your STAs should be adjusting to the correct Data Rate, so if a certain number of failures are seen the STA should rate adapt and not shift back up again until a certain number of frames are received with no errors.

    Are you seeing a large number of corrupted frames? do you have any more information you can give us on the problem?

  • If you're getting a high amount of CRCs there's something else going wrong. Are you looking at the analyzer or the radio's settings and saying you're receiving too many? Be wary of interpreting too much info from a large amount of CRCs from frames that are received at very low signal levels. That can skew your results. Also, some client utilities are horrible in what they report. Look at the data that's actually being sent from and from your test clients and monitor it with an analyzer with a filter, so you're only looking at that data. Then tell me if you're seeing that out of whack.

    Don't disable the higher datarates. If you do have a spectrum/interference problem frames with higher data rates will actually provide more resiliency to getting corrupted because they get on and off the medium faster. Make sense?

  • Don't pay too much attention to CRC errors in a situation like this. The main figure to look at is Retry Percentage. Retry Percentage is like the blood pressure of a wireless network. If it's high, you have a problem. Further tests have to be run to isolate the cause.

    As long as your STA's and AP's are auto rate shifting properly, don't disable the higher data rates. Packet capture is the only way to answer the problem you are having.


  • I completely forgot that I posted this question. I wasn't actually experiencing the problem, it was just in theory. My thought was that the more complex the modulation, the higher the chances that a retry would occur thus decreasing the throughput. Thanks for all speedy responses and I apologize for the extended delay.

    On a completely separate note, I passed my CWNA on the very last day (31rst of December) with 76%. Not extremely proud of the mark but I am very pleased with the acquired knowledge. I am relatively new to networking in general (less than 2 years) but have really enjoyed learning 802.11 and RF from these posts, study guide (4th Edition), white papers, and hands on experience. Pretty sure I read Devin's RSN Fast BSS paper 4 times before I grasped all the concepts. Yeah, a lot of free time- Thanks again-

    I did have a follow up question that I have dealing with site surveys.

    AirMagnet Survey includes a feature that displays uplink and downlink performance using IPERF. I haven't really used it too extensively and was wondering if anyone had experience as to how accurate the uplink stats were. I believe uplink stats are very important to proper cell size (open for comments,) and I was wondering how/if everyone else measures the uplink stats?

  • IPERF works well and there is also JPERF which will allow you to do the same testing in a GUI interface rather than in a CLI.

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