How does spatial multiplexing help MIMO increase throughput?

Question

WiFi

spatial multiplexing/spatial coding/spatial separation

First, the wording itself is confusing. The signals between the receiver and the transmitter exist in the same space for everyone, and not in parallel worlds. How are differences made on transmission and how can they be distinguished at reception?

Yes, if the antennas are separated by some distance from each other, the signal(s) arriving at the receiver antennas will most likely (or maybe not?) be out of phase with each other or with different amplitudes, especially if they are reflected from something . But he (s) are created at one frequency, in one phase and with a given amplitude. This will help to receive the signal as it was intended for transmission, but I cannot see the multiplexing here.

Answer 1

Everything is quite simple - we transmit different signals over MIMO. Therefore, we do not have one channel - but several. Therefore, the speed is several times greater.

Answer 2

Have you read the article ?
In particular, it says the following:

Mathematically, the signal at the receiver after passing through the radio channel is the sum of the product of the original signal and some complex transfer function (CTF) and noise. The notorious fading that occurs in the radio channel is precisely the CTF. The KPF distribution law, as a random variable, determines the presence of a line of sight between the transmitter and the receiver and factors affecting the multipath signal propagation (walls in an apartment, houses in a city, etc.) In our case, the most universal case will be the lack of line of sight - Rayleigh fading .
Since there are several antennas in the system, the paths traversed by signals from different antennas are also different, therefore their CPF will be different for each transmitter-receiver pair. This is a fundamentally important point. Based on the structure of the FPC system, all its subchannels can be reduced to a matrix.
And now the most interesting. It turns out that each channel has its own characteristics that differ from the neighboring ones, therefore, the signal transmitted through it can be unambiguously separated from the signals transmitted through other channels transmitted in the same frequency band.