Patent ID: 7978777

Claim:
A digital communication system, comprising: a transmitter configured to transmit signals to a receiver via a communication channel; wherein the transmitter, comprises: a coder configured to receive user bits and output encoded bits at an expanded output encoded bit rate; a mapper configured to map encoded bits to symbols in a symbol constellation; a modulator configured to generate a signal for transmission via the communication channel using symbols generated by the mapper; wherein the receiver, comprises: a demodulator configured to demodulate the received signal via the communication channel; a demapper configured to estimate likelihoods from the demodulated signal; a decoder that is configured to estimate decoded bits from the likelihoods generated by the demapper; and wherein the symbol constellation is a capacity optimized geometrically spaced symbol constellation that provides a given capacity at a reduced signal-to-noise ratio compared to a signal constellation that maximizes d min .