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WLAN White Papers & Other In Depth Wi-Fi Documentation Needed

Hello:

        I want to apologize in advance for length of the following  request but these issues have been driving me crazy for some time now  and I finally decided to seek help. :-)   I like to fully understand  technical challenges and by that I mean in great depth.   I am looking  for help in the four areas listed below.   Most of these are covered  superficially in Datasheets and User Manuals but never in depth.  I am  looking for technical app notes, white papers or other engineering  documents, such as in depth WLAN design, architecture, deployment  techniques, advanced guidelines and trouble shooting. Documents that  address these issues in great detail and with practical examples and  illustrations.  I am hoping that someone on this Forum can help me find  his information.  I have been searching the "Net" for answers but most  of what I find is superficial or at best wanting for real detail and  practical explanations.

  • Wi-Fi Routers / APs / Extenders / Repeaters
    • The effects of "wireless networking transmission methods such as  "a", "b", "g", "n" & "ac" on network throughput?  My understanding  is that the speed (throughput / upload /download) of a Wi-Fi AP is  determined by the slowest user connection to that AP.  That being said  then a 802.11b user will pull down the throughput of a 802.11g/n/ or /ac  AP to 10 Mbps or less and it remain that way until that user breaks his  connection to that AP (assuming that he is the only "b" user on that  AP). I would like to find a "technical document" that explains in detail why this happens and why it is necessary, this where I need your help.  This phenomenon does not happen with Ethernet Routers and hardwired LANs, why is it necessary with Wi-Fi?

  • On an AP with dual radios, using one for "Receive" and one for  "Transmit" actual speed up Wi-Fi throughput, and if so by how much? 

  • On APs that have the ability to support two (or more) antennas  can one be an Omnidirectional and the other be Directional, or do they  both have to be the same and if so why?

  • Wi-Fi Cards or Adapters
    • Understanding  OS Wi-Fi Adapter Advanced Settings;  "/Configure/Advanced". My notebook wireless card is an Intel 802.11n  card. Under the advanced settings it clearly shows that 802.11n mode is  enabled and then at the bottom of the list of are three options; /b, /g,  /bg,  but no "/n" option, this is a bit confusing.  The assumption here  is that the card selects the highest speed available from the AP but is that necessarily true?  I have seen some adapter though rated a "n" capable the connect to the network a "g" and sometimes at "b" speeds even though the signal strength to the AP is "Five Bars", what would cause this besides a poorly designed adapter?

  • Antennas
    • Polarization:  I am looking for 3D diagrams of antenna patterns  (lobes) that clearly show what Vertical and Horizontal Polarization look  like and their effects and effectiveness, and ones that show what  happen when an AP polarizes the antenna(s) with both vertical and  horizontal on the same antenna. Additionally, how are the lobes/patterns  changed by placing two or more antenna in close proximity on a multiple  antenna AP or a an AP with multiple radio and multiple antennas?

  • Signal Stability:  I have noticed on several 2.4xx Hz WLANs that  signal strength on most if not all the APs can vary greatly from moment  to moment sometimes as great as -20dBm to -30dBM (ie... the signal  varies from -50dBm to -80dBM), for no apparent reason.  i have not been  able to run a spectrum analyzer on the APs as yet but I have seen this  in open areas which are close to other APs, or obvious sources of  2.4xxGHz interference, nor multipath, nor trees or other structures in  the area.  This obviously reeks havoc with Wi-Fi connectivity and  throughput.   Has anyone else seen this and what did you find as the  root cause?

  • Using two antennas, one for "Receive" and one for "Transmit":
    • Does this configuration have any true useful benefit, such as faster throughput, etc...?

Thank you in advance for your time and consideration, your help is truly appreciated!

Doug

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