The Shannon bit error limit for linear coded modulation
We find the Shannon limit to bit error rate (BER) as a function of E_b/N_0 for linear coded modulations. Error performance of TCM and other schemes can be compared to this curve. As the bandwidth of the signals in Hz-s/data bit drops, capacity becomes sensitive to the stopband spectrum, and the limit moves strongly away from the BER of practical systems when the stopband rolloff is not severe.