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  • Hi. I just want to make sure I understand the concepts of radio chains properly as I start to delve deeper MIMO and SM.

    I found a definition of a radio chain in the 802.11n standard and the text of the latest CWNA-106 study guide both say that a radio chain is a single radio and all of its supporting architecture, including mixers, amplifiers, and analog/digital converters.

    What I am trying to understand is if in MIMO there is a 1:1 mapping of antennas onto each radio chain.

    According to CWNA-106, a MIMO system consists of multiple radio chains, with each radio chain having its own antenna.

    But in the associated diagram, Figure 18.2, all the radios appear to share all of the antennas. Therefore, is the diagram wrong, or in practise does a single radio chain use multiple antennas, simultaneously?

    Thanks

    Mark

  • I am not an RF hardware engineer, nor do I have a copy of CWNA-106, but I would assume that the 1:1 radio-to-antenna is still the case.

    I could imagine some kind of "configuration" parameter to control which antennas might be used overall, but the CPU overhead required to keep all of the MIMO channel parameters straight would be horrendous if the connections were dynamic.

    More important things need attending to.

  • Thanks Howard, because that was what was confusing me. I guess the diagram in the study guide is a little misleading. It could be corrected for the 107 study guide.

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