Methodology and method and appartus for signaling with capacity optimized constellations
First Claim
1. 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 the encoded bits to symbols in an N-dimensional 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 an N-dimensional capacity optimized geometrically spaced symbol constellation that provides a given capacity at a reduced signal-to-noise ratio compared to an N-dimensional signal constellation that maximizes dmin.
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Abstract
Communication systems are described that use geometrically shaped constellations that have increased capacity compared to conventional constellations operating within a similar SNR band. In several embodiments, the geometrically shaped is optimized based upon a capacity measure such as parallel decoding capacity or joint capacity. In many embodiments, a capacity optimized geometrically shaped constellation can be used to replace a conventional constellation as part of a firmware upgrade to transmitters and receivers within a communication system. In a number of embodiments, the geometrically shaped constellation is optimized for an Additive White Gaussian Noise channel or a fading channel.
47 Citations
31 Claims
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1. 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 the encoded bits to symbols in an N-dimensional 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 an N-dimensional capacity optimized geometrically spaced symbol constellation that provides a given capacity at a reduced signal-to-noise ratio compared to an N-dimensional signal constellation that maximizes dmin. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of transmitting bits of user information between a transmitter and a receiver over a communication channel, comprising:
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using a coder within the transmitter to encode the bits of user information in accordance with a coding scheme; using a mapper within the transmitter to map the encoded bits of user information to an N-dimensional symbol constellation, wherein the symbol constellation is an N-dimensional capacity optimized geometrically spaced symbol constellation that provides a given capacity at a reduced signal-to-noise ratio compared to an N-dimensional signal constellation that maximizes dmin; using a modulator within the transmitter to modulate the symbols in accordance with a modulation scheme; transmitting the modulated signal via the communication channel using the transmitter; receiving a modulated signal at the receiver; using a demodulator within the receiver to demodulate the modulated signal in accordance with the modulation scheme; using a demapper within the receiver to demap the demodulated signal using the geometrically shaped signal constellation to produce likelihoods; and decoding the likelihoods using the receiver to obtain an estimate of the decoded bits.
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19. A method of selecting the points of an N-dimensional geometrically shaped symbol constellation for use in the mapper of a transmitter and the demapper of a receiver in a communication system using a computing device, comprising:
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storing in a memory of the computing device a selected constellation size; and using the computing device to iteratively optimize the location of the points of the N-dimensional constellation to maximize a capacity measure using the stored constellation size, where the iterative optimization proceeds until a predetermined termination condition is reached that results in an N-dimensional geometrically spaced symbol constellation that provides a given capacity at a reduced signal-to-noise ratio compared to a signal constellation that maximizes dmin. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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Specification