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