Consider the $16-$ary modulation scheme as shown $($horizontal and vertical distances of the points are the same$).$ Define the optimum decision regions and determine the general formula to evaluate the bit error rate of the system with respect to received bit energy $`$Eb$`$ and noise spectral density $\text{'}$No$\text{'}.$ Compare the above modulation scheme with regular $16$QAM scheme from bit$-$error$-$rate, bandwidth, and complexity points of view.