3 ms·
What you are describing is antenna polarization, not phase. It seems another reply covered phase pretty well, but yes you are correct that you can also put more
by gorkish 3y ago
What you are describing is antenna polarization, not phase. It seems another reply covered phase pretty well, but yes you are correct that you can also put more than one signal into the same bandwidth - so long as you are able to disambiguate them from one another. This can be done generally by 1) sending signals at different times but on the same frequency 2) sending signals at different frequencies at the same time (multiple carriers within the same bandwidth) or 3) sending separate signals between separate antennas at the same time and frequency. Using antennas with different polarity is a crude and simple form of spatial multi access, but as it turns out, it’s not the only way. This is the trickery behind how sm-ofdm / mimo and other spatial modulations multiply their spectral efficiency, with current state of the art being around 20 bits per second per hz in 8x8 configurations.
- pclmulqdq 3y agoThere are a few attempts today to combine polarization with QAM to effectively double data rates again without impacting SNR. You can have two polarizations of radio waves at any time (horizontal + vertical or left-handed + right-handed), and each of these polarizations can carry separate QAM-modulated data. Supposedly this all also works with MIMO as long as you have the appropriate antennas.
- gorkish 3y agoSpatial division works regardless of whether the antennas self interfere; it works better when they don't. Overlapping two polarity-isolated qam signals is a good way to explain rudimentary spatial multiplexing but the current state of the art is way way beyond that, I'm pleased to say.