Communication systems capable of receiving and processing data using unequally spaced and uniform quadrature amplitude modulated 64 point symbol constellations

A communication system, comprising:

• a sink device capable of receiving data bits;
• a receiver that receives signals via a communication channel having a channel signal-to-noise ratio (SNR) and providing data bits to the sink device, wherein the receiver comprises:
• a demodulator that demodulates a received signal into a demodulated signal;
• a demapper that determines likelihoods using the demodulated signal and a symbol constellation selected from a set of symbol constellations comprising:
• an unequally spaced Quadrature Amplitude Modulated 64 point (QAM-64) symbol constellation;
• and
• a uniformly spaced QAM-64 signal constellation that maximizes the minimum distance, dmin, between the constellation points;
• and
• a decoder that uses the likelihoods determined by the demapper to provide a sequence of received bits based upon a low density parity check (LDPC) code selected from a set of LDPC codes having different code rates;
• wherein the demapper is interposed between the demodulator and the decoder, and the demapper receives information from the demodulator and provides information to the decoder;
• and
• wherein use of a specific LDPC code having a code rate that is greater than 1/2 from the set of LDPC codes in combination with the unequally spaced QAM-64 symbol constellation provides a larger SNR gain than the SNR gains achieved using the unequally spaced QAM-64 symbol constellation in combination with any of the other LDPC codes from the set of LDPC codes.

A communication system, comprising:

• a sink device capable of receiving data bits;
• a receiver that receives signals via a communication channel having a channel signal-to-noise ratio (SNR) and provides data bits to the sink device;
• wherein the receiver uses a symbol constellation selected from a set of symbol constellations and a low density parity check (LDPC) code selected from a set of LDPC codes having different code rates to transform the received signals into received bits;
• wherein the set of symbol constellations comprises:
• an unequally spaced Quadrature Amplitude Modulated 64 point (QAM-64) symbol constellation;
• and
• a uniformly spaced QAM-64 signal constellation that maximizes the minimum distance, dmin, between the constellation points;
• wherein use of a specific LDPC code having a code rate that is greater than 1/2 from the set of LDPC codes in combination with the unequally spaced QAM-64 symbol constellation provides a larger gain than the gains achieved using the unequally spaced QAM-64 symbol constellation in combination with any of the other LDPC codes from the set of LDPC codes.