of rings is necessary to reach the Shannon capacity. This originates from the fact that, at high SNR, the capacity is better
maximized by filling the complex plane than adding symbols on a single or a few rings. Figure 3a can be used to determine
the gain in capacity possible by moving from a single ring, i.e. pure PSK, to multiple rings, i.e. N-ASK/PSK (N integer), at
powers below the nonlinearity threshold.