You can find the reference code in NS-3 or Omnet++ Simulator.

NS-3: https://www.nsnam.org/ (MIMO Model: https://www.nsnam.org/docs/release/3.27/models/singlehtml/index.html )

INET (framework for Omnet++): https://inet.omnetpp.org/Protocols.html (LTE: MIMO Model)

Best regards

Thank you Oleksandr for these resources. Do you have such code in MATLAB?

Matlab also includes a very detailed physical model; check it here -

https://www.mathworks.com/products/lte-system.html

https://de.mathworks.com/help/phased/examples/improve-snr-and-capacity-of-wireless-communication-using-antenna-arrays.html .

The problem is that it is not open-source project; this means that you will not be able to see the "reference code". I believe that you need to be more specific about your question/task: for example, it is very simple to simulate a SINR calculation, but it may be much more difficult to simulate a multi-cell MIMO behaviour, especially if you take physical effects or protocol details into account.

Best regards.

To be specific, I want to simulate the massive MIMO to check the SINR and data rates of user 'k' in cell 'l'.

To do that, I want to design a Rayleigh and Shadow fading channel and check the SINR and data rates of that user 'k' in a multi-cell environment.

I guess the problem is very simple bu t in my head I have messed it up.