approach the Shannon limit very closely. For rate 1/2, the best code found has a threshold
within 0.0045 dB of the Shannon limit of the binary-input additive white Gaussian noise
channel. Simulation results with a somewhat simpler code show that we can achieve within
0.04 dB of the Shannon limit at a bit error rate of 10/sup-6/using a block length of 10/sup 7/.