We can measure this in real links in the next months, but I would appreciate very much references or hints about theoretical fundamentals. MIMO systems use spatial diversity to obtain important channel gain, but it is not clear to me whether this option is always better than channel bonding on two parallel channels when there is Line Of Sight. Imagine that dual parabolic antennas are being used that can transmit/receive signal both with horizontal and vertical polarization simultaneously. Should we use two radios at each end and channel bonding, or a 2x2 MIMO system. What is the accurate comparison between those two options?
Hi Javier,
may be this might help: www.dtic.upf.edu/~alozano/papers/Diversity.pdf
If the two links are orthogonal to each other, because of polarisation, of just because each receiver only "sees" the corresponding transmitter, the situation is easy and the two links are independent. In case they are interfering, MIMO spatial diversity can decompose the interference paths into different orthogonal paths. From the outside, this is identical to the first scenarion. As far as I know, MIMO cannot do better. So if you can isolate the links that is your best choise.
Apart from that, if you decide to use MIMO, there should be sufficient scattering/multipath to differentiate between the two transmitters. In case two parabolic transmitters next to each other have a line of sight to two receivers next to each other -I understand this is your situation- it is very difficult to do the previously described decomposition of the interference, because the channels between each of the antennas and each of the receivers will be very similar. In other words, the antenna outputs at the receiver will be almost identical, making it clear that they don't offer much advantage over only one receiving antenna.
(Hope this helps, sorry if it was too obvious :-) )
@ G. Cuypers
Thanks Gert, it helps, it was not so obvious before and it is now, so thank you very much!
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