How to find the reqd SNR increase to maintain BER constant in an increased constellation size?

This is usually done in some sort of simulator like Matlab, ADS, etc. You generate the signal constellation, add system imperfections like noise, phase error, amplitude imbalance, filter characteristics, and such that your system generates. Then you demodulate the signal and compare it bit-by-bit to the signal that was sent. You do this as you vary the system imperfections parametrically. This generates a series of BER and SNR points that you then plot. This can take a considerable amount of time if you need good resolution.

mini countryman

sailboats for sale