Methods and apparatuses for signaling with geometric constellations in a rayleigh fading channel
Communication systems are described that use signal constellations, which have unequally spaced (i.e. ‘geometrically’ shaped) points. In many embodiments, the communication systems use specific geometric constellations that are capacity optimized at a specific SNR, over the Rayleigh fading channel. In addition, ranges within which the constellation points of a capacity optimized constellation can be perturbed and are still likely to achieve a given percentage of the optimal capacity increase compared to a constellation that maximizes d min , are also described. Capacity measures that are used in the selection of the location of constellation points include, but are not limited to, parallel decode (PD) capacity and joint capacity.
1. A communication system, comprising:
a transmitter capable of transmitting signals to a receiver via a communication channel;
wherein the transmitter comprises:
a coder capable of receiving user bits and output encoded bits using a code having a specific code rate;
a mapper capable of mapping encoded bits to symbols in a non-uniform quadrature amplitude modulation 1024-point symbol constellation (NU-QAM 1024);
a modulator capable of generating a signal for transmission via the communication channel using symbols generated by the mapper;
wherein the receiver comprises:
a demodulator capable of demodulating a signal received via the communication channel;
a demapper capable of estimating likelihoods from a demodulated signal based upon the NU-QAM 1024; and
a decoder capable of estimating decoded bits from likelihoods generated by the demapper based upon the code;
wherein the NU-QAM 1024 comprises an in-phase component and a quadrature component, where each component comprises 32 levels of amplitude such that the amplitudes scaled by a scaling factor are within 1.289 from the following set of amplitudes:
−38.8088, −31.7370, −26.1892, −25.0630, −18.4668, −18.4668, −16.6894, −16.6675, −9.2115, −9.2115, −9.0888, −9.0480, −3.7549, −3.7549, −3.7549, −3.7549, 3.7539, 3.7539, 3.7539, 3.7539, 9.0476, 9.0509, 9.2107, 9.2107, 16.6677, 16.6875, 18.4662, 18.4662, 25.0617, 26.1893, 31.7383, and 38.8190.
2. The communication system of claim 1 , wherein each component comprises 32 levels of amplitude such that the amplitudes scaled by a scaling factor are within 0.602 from the following set of amplitudes:
−38.8088, −31.7370, −26.1892, −25.0630, −18.4668, −18.4668, −16.6894, −16.6675, −9.2115, −9.2115, −9.0888, −9.0480, −3.7549, −3.7549, −3.7549, −3.7549, 3.7539, 3.7539, 3.7539, 3.7539, 9.0476, 9.0509, 9.2107, 9.2107, 16.6677, 16.6875, 18.4662, 18.4662, 25.0617, 26.1893, 31.7383, and 38.8190.
3. The communication system of claim 1 , wherein each component comprises 32 levels of amplitude such that the amplitudes scaled by a scaling factor are:
−38.8088, −31.7370, −26.1892, −25.0630, −18.4668, −18.4668, −16.6894, −16.6675, −9.2115, −9.2115, −9.0888, −9.0480, −3.7549, −3.7549, −3.7549, −3.7549, 3.7539, 3.7539, 3.7539, 3.7539, 9.0476, 9.0509, 9.2107, 9.2107, 16.6677, 16.6875, 18.4662, 18.4662, 25.0617, 26.1893, 31.7383, and 38.8190.
4. The communication system of claim 1 , wherein the receiver is capable of selecting the NU-QAM 1024 constellation from a plurality of constellations including a plurality of NU-QAM 1024 constellations.
5. The communication system of claim 1 , wherein the receiver is capable of selecting a code rate and the NU-QAM 1024 constellation from a plurality of combinations of code rates and NU-QAM 1024 constellations.
6. The communication system of claim 1 , wherein:
the coder is capable of encoding bits using a low-density parity check (LDPC) code; and
the decoder is capable of decoding bits using the LDPC code.
7. The communication system of claim 6 , wherein:
the receiver is capable of measuring the quality of the communication channel; and
the receiver is capable of selecting an LDPC code rate and symbol constellation pair from a plurality of predetermined LDPC code rate and symbol constellation pairs based at least in part on a quality measurement.
8. The communication system of claim 7 , wherein the receiver is capable of measuring the quality of the communication channel by obtaining at least one quality measurement selected from the group consisting of:
estimating the channel signal-to-noise ratio; and
determining an error rate at the receiver.
9. The communication system of claim 1 , wherein the symbols in the NU-QAM 1024 are labelled using gray labels.
10. The communication system of claim 1 , wherein the symbols in the NU-QAM 1024 are labelled using binary reflective gray labels.
11. A communication system, comprising:
a transmitter capable of transmitting signals via a communication channel;
wherein the transmitter comprises:
a coder capable of receiving user bits and output encoded bits using a code having a specific code rate;
a mapper capable of mapping encoded bits to symbols in a non-uniform quadrature amplitude modulation 1024-point symbol constellation (NU-QAM 1024);
a modulator capable of generating a signal for transmission via the communication channel using symbols generated by the mapper;
wherein the NU-QAM 1024 comprises an in-phase component and a quadrature component, where each component comprises 32 levels of amplitude such that the amplitudes scaled by a scaling factor are within 1.289 from the following set of amplitudes:
−38.8088, −31.7370, −26.1892, −25.0630, −18.4668, −18.4668, −16.6894, −16.6675, −9.2115, −9.2115, −9.0888, −9.0480, −3.7549, −3.7549, −3.7549, −3.7549, 3.7539, 3.7539, 3.7539, 3.7539, 9.0476, 9.0509, 9.2107, 9.2107, 16.6677, 16.6875, 18.4662, 18.4662, 25.0617, 26.1893, 31.7383, and 38.8190.
12. The communication system of claim 11 , wherein each component comprises 32 levels of amplitude such that the amplitudes scaled by a scaling factor are within 0.602 from the following set of amplitudes:
−38.8088, −31.7370, −26.1892, −25.0630, −18.4668, −18.4668, −16.6894, −16.6675, −9.2115, −9.2115, −9.0888, −9.0480, −3.7549, −3.7549, −3.7549, −3.7549, 3.7539, 3.7539, 3.7539, 3.7539, 9.0476, 9.0509, 9.2107, 9.2107, 16.6677, 16.6875, 18.4662, 18.4662, 25.0617, 26.1893, 31.7383, and 38.8190.
13. The communication system of claim 11 , wherein each component comprises 32 levels of amplitude such that the amplitudes scaled by a scaling factor are:
−38.8088, −31.7370, −26.1892, −25.0630, −18.4668, −18.4668, −16.6894, −16.6675, −9.2115, −9.2115, −9.0888, −9.0480, −3.7549, −3.7549, −3.7549, −3.7549, 3.7539, 3.7539, 3.7539, 3.7539, 9.0476, 9.0509, 9.2107, 9.2107, 16.6677, 16.6875, 18.4662, 18.4662, 25.0617, 26.1893, 31.7383, and 38.8190.
14. The communication system of claim 11 , wherein the modulator is capable of selecting the NU-QAM 1024 constellation from a plurality of constellations including a plurality of NU-QAM 1024 constellations.
15. The communication system of claim 11 , wherein the modulator is capable of selecting a code rate and the NU-QAM 1024 constellation from a plurality of combinations of code rates and NU-QAM 1024 constellations.
16. The communication system of claim 11 , wherein the coder is capable of encoding bits using a low-density parity check-code (LDPC).
17. The communication system of claim 11 , wherein the symbols in the non-uniform quadrature amplitude modulation 1024-point symbol constellation (NU-QAM 1024) are labelled using gray labels.
18. The communication system of claim 11 , wherein the symbols in the non-uniform quadrature amplitude modulation 1024-point symbol constellation (NU-QAM 1024) are labelled using binary reflective gray labels.
19. A communication system, comprising:
a receiver capable of receiving signals via a communication channel;
wherein the receiver comprises:
a demodulator capable of demodulating a signal received via the communication channel;
a demapper capable of estimating likelihoods from a demodulated signal based upon the NU-QAM 1024; and
a decoder capable of estimating decoded bits from likelihoods generated by the demapper using a code having a specific code rate; and
wherein the NU-QAM 1024 comprises an in-phase component and a quadrature component, where each component comprises 32 levels of amplitude such that the amplitudes scaled by a scaling factor are within 1.289 from the following set of amplitudes:
−38.8088, −31.7370, −26.1892, −25.0630, −18.4668, −18.4668, −16.6894, −16.6675, −9.2115, −9.2115, −9.0888, −9.0480, −3.7549, −3.7549, −3.7549, −3.7549, 3.7539, 3.7539, 3.7539, 3.7539, 9.0476, 9.0509, 9.2107, 9.2107, 16.6677, 16.6875, 18.4662, 18.4662, 25.0617, 26.1893, 31.7383, and 38.8190.
20. The communication system of claim 19 , wherein each component comprises 32 levels of amplitude such that the amplitudes scaled by a scaling factor are within 0.602 from the following set of amplitudes:
−38.8088, −31.7370, −26.1892, −25.0630, −18.4668, −18.4668, −16.6894, −16.6675, −9.2115, −9.2115, −9.0888, −9.0480, −3.7549, −3.7549, −3.7549, −3.7549, 3.7539, 3.7539, 3.7539, 3.7539, 9.0476, 9.0509, 9.2107, 9.2107, 16.6677, 16.6875, 18.4662, 18.4662, 25.0617, 26.1893, 31.7383, and 38.8190.
21. The communication system of claim 19 , wherein each component comprises 32 levels of amplitude such that the amplitudes scaled by a scaling factor are:
−38.8088, −31.7370, −26.1892, −25.0630, −18.4668, −18.4668, −16.6894, −16.6675, −9.2115, −9.2115, −9.0888, −9.0480, −3.7549, −3.7549, −3.7549, −3.7549, 3.7539, 3.7539, 3.7539, 3.7539, 9.0476, 9.0509, 9.2107, 9.2107, 16.6677, 16.6875, 18.4662, 18.4662, 25.0617, 26.1893, 31.7383, and 38.8190.
22. The communication system of claim 19 , wherein the demodulator is capable of selecting the NU-QAM 1024 from a plurality of constellations including a plurality of NU-QAM 1024 constellations.
23. The communication system of claim 19 , wherein the demodulator is capable of selecting a code rate and the NU-QAM 1024 constellation from a plurality of combinations of code rates and NU-QAM 1024 constellations.
24. The communication system of claim 19 , wherein the decoder is capable of decoding bits using a low-density parity check-code (LDPC).
25. The communication system of claim 24 , wherein:
the receiver is capable of measuring the quality of the communication channel;
the receiver is capable of selecting an LDPC code rate and symbol constellation pair from a plurality of predetermined LDPC code rate and symbol constellation pairs based at least in part on a quality measurement; and
the receiver comprises a local transmitter capable of sending a request to a remote transmitter to use a selected LDPC code rate and symbol constellation pair.
26. The communication system of claim 25 , wherein the receiver is capable of measuring the quality of the communication channel by obtaining at least one quality measurement selected from the group consisting of:
estimating the channel signal-to-noise ratio; and
determining an error rate at the receiver.
27. The communication system of claim 19 , wherein the symbols in the NU-QAM 1024 are labelled using gray labels.
28. The communication system of claim 19 , wherein the symbols in the NU-QAM 1024 are labelled using binary reflective gray labels.