One thing about the modulation schemes. A great way to see the QAM and QPSK modulation schemes is to look at the "constellation" of the signal. This is a sort of rectangular plot that shows all the possible symbol values.
Question: Do you know of any/can you recommend some sort of simulat[or][ion] (non-HW; just for illustration) that might help develop an intuitive sense of how these various modulation schemes (/beam manipulation/etc) work? I know there are modeling packages that can probably be used for that, but, let's say I don't need that functionality (at the moment, anyway).
regarding different antenna types, there is a lot of creative work happening, particularly to enable lower correlation in small handsets and any technique is considered. polarization is one way to enable 2 streams in a small space - you need low XPR (cross polarization ratio)
Another question, is it viable to use say one antenna type, like PIFA, or printed dipole, etc, in multiple positions in a MIMO system? And must we use different polarizations in the array? Can we use only one polarization type and be successful?
Thank you -- though I, clearly, have much to go over and dig deeper into before I can be close to "owning" this material, I did appreciate the technical level of this presentation in particular. (I understand that giving us the entire context of radio comm was necessary; and likewise, I appreciate that you didn't leave anything out there, even if it was a now-waning spec.)
regarding antenna separation, that's correct - they are typically separated by a multiple of wavelengths; higher frequencies require less separation for the same correlation and that works in favor of higher MIMO capacity.
Question: it seems that 802.11 and LTE standards are settled with OFDM modulation. In your opinion, would there be a need for a new modulation scheme for even higher throughput requirements and what that modulation scheme would likely be?
Alaskaman also had a good question, that I'll add to: How do we select a separation of transmit antennae, or receive antennae, in MIMO systems? Spacing is related to wavelengths? How do we consider wavelength when the BWs are becoming wider?
re slide 19 comment - yes - high power is allowed but path loss is very high in the 60 GHz band so you need all the power you can get. For all practical purposes CMOS power amps cannot get that much power out today.
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