Methods and apparatuses for signaling with geometric constellations

• US 9,887,870 B2
• Filed: 09/10/2012
• Issued: 02/06/2018
• Est. Priority Date: 06/05/2007
• Status: Active Grant

• Current Assignee: Constellation Designs, LLC (SoftBank Group Corp.)
• Original Assignee: Constellations Designs, Inc.
• Inventors: Barsoum, Maged F., Jones, Christopher R.
• Primary Examiner(s): Paulson, Sheetal R
• Application Number:
  US13/608,838
• Publication Number:
  US 20130170571A1
• Time in Patent Office: 1,975 Days
• Field of Search: 382128
• CPC Class Codes: A61B 2017/00703 correcting for movement of heart, e.g. ECG-triggered
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2090/376 using X-rays, e.g. fluoroscopy
• CPC Class Codes: A61B 2090/3983 Reference marker arrangements for use with image guided surgery
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61B 6/12 Arrangements for detecting or locating foreign bodies
• CPC Class Codes: A61B 6/503 for diagnosis of the heart
• CPC Class Codes: A61B 6/5235 combining images from the same or different ionising radiation imaging techniques, e.g. PET and CT
• CPC Class Codes: A61B 6/5264 due to motion
• CPC Class Codes: A61B 6/527 using data from a motion artifact sensor
• CPC Class Codes: G06T 2207/10121 Fluoroscopy
• CPC Class Codes: G06T 2207/30021 Catheter; Guide wire
• CPC Class Codes: G06T 2207/30048 Heart; Cardiac
• CPC Class Codes: G06T 7/33 using feature-based methods
• CPC Class Codes: H04B 14/023 using pulse amplitude modulation
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 27/3405 Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power

Abstract

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. 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.

Claims

1. A digital communication system, comprising:

a transmitter configured to transmit signals to a receiver via a communication channel using quadrature amplitude modulation (QAM);

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 geometrically spaced symbol constellation that provides a given capacity at a reduced signal-to-noise ratio compared to a signal constellation that maximizes the minimum distance (d_min);

wherein the symbol constellation provides an increase in capacity at a predetermined SNR that is at least 5% of the gain in capacity achieved by a constellation optimized for joint capacity at the predetermined SNR relative to a signal constellation that maximizes the minimum distance (d_min) between constellation points.

2. The communication system of claim 1, wherein the code is a Turbo code.

3. The communication system of claim 1, wherein the code is a LDPC code.

4. The communication system of claim 1, wherein the constellation provides an increase in capacity at a predetermined SNR that is at least 15% of the gain in capacity achieved by a constellation optimized for joint capacity at the predetermined SNR.

5. The communication system of claim 1, wherein the constellation provides an increase in capacity at a predetermined SNR that is at least 30% of the gain in capacity achieved by a constellation optimized for joint capacity at the predetermined SNR.

6. The communication system of claim 1, wherein the constellation provides an increase in capacity at a predetermined SNR that is at least 45% of the gain in capacity achieved by a constellation optimized for joint capacity at the predetermined SNR.

7. The communication system of claim 1, wherein the constellation provides an increase in capacity at a predetermined SNR that is at least 60% of the gain in capacity achieved by a constellation optimized for joint capacity at the predetermined SNR.

8. The communication system of claim 1, wherein the constellation provides an increase in capacity at a predetermined SNR that is at least 100% of the gain in capacity achieved by a constellation optimized for joint capacity at the predetermined SNR.

9. The communication system of claim 1, wherein the symbol constellation is a Quadrature Amplitude Modulation 256 point (QAM-256) symbol constellation.

10. The communication system of claim 9, wherein the constellation provides an increase in capacity at a predetermined SNR that is at least 60% of the gain in capacity achieved by a constellation optimized for joint capacity at the predetermined SNR.

11. The communication system of claim 1, wherein the symbol constellation is a Quadrature Amplitude Modulation 1024 point (QAM-1024) symbol constellation.

12. The communication system of claim 11, wherein the constellation provides an increase in capacity at a predetermined SNR that is at least 60% of the gain in capacity achieved by a constellation optimized for joint capacity at the predetermined SNR.

13. A digital communication system, comprising:

a transmitter configured to transmit signals to a receiver via a communication channel using quadrature amplitude modulation (QAM);

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 geometrically spaced symbol constellation that provides a given capacity at a reduced signal-to-noise ratio compared to a signal constellation that maximizes a minimum distance (d_min); and

wherein the symbol constellation provides an increase in capacity at a predetermined SNR that is at least 5% of the gain in capacity achieved by a constellation optimized for parallel decode (PD) capacity at the predetermined SNR relative to a signal constellation that maximizes the minimum distance (d_min) between constellation points.

14. The communication system of claim 13, wherein the code is a Turbo code.

15. The communication system of claim 13, wherein the code is a LDPC code.

16. The communication system of claim 13, wherein the constellation provides an increase in capacity at a predetermined signal to noise ratio (SNR) that is at least 15% of the gain in capacity achieved by a constellation optimized for parallel decode (PD) capacity at the predetermined SNR.

17. The communication system of claim 13, wherein the constellation provides an increase in capacity at a predetermined signal to noise ration (SNR) that is at least 30% of the gain in capacity achieved by a constellation optimized for parallel decode (PD) capacity at the predetermined SNR.

18. The communication system of claim 13, wherein the constellation provides an increase in capacity at a predetermined signal to noise ratio (SNR) that is at least 45% of the gain in capacity achieved by a constellation optimized for parallel decode (PD) capacity at the predetermined SNR.

19. The communication system of claim 13, wherein the constellation provides an increase in capacity at a predetermined signal to noise ratio (SNR) that is at least 60% of the gain in capacity achieved by a constellation optimized for parallel decode (PD) capacity at the predetermined SNR.

20. The communication system of claim 13, wherein the constellation provides an increase in capacity at a predetermined signal to noise ratio (SNR) that is at least 100% of the gain in capacity achieved by a constellation optimized for parallel decode (PD) capacity at the predetermined SNR.

21. The communication system of claim 13, wherein the symbol constellation is a Quadrature Amplitude Modulation 64 point (QAM-64) symbol constellation.

22. The communication system of claim 21, wherein the constellation provides an increase in capacity at a predetermined SNR that is at least 60% of the gain in capacity achieved by a constellation optimized for parallel decode (PD) capacity at the predetermined SNR.

23. The communication system of claim 13, wherein the symbol constellation is a Quadrature Amplitude Modulation 256 point (QAM-256) symbol constellation.

24. The communication system of claim 23, wherein the constellation provides an increase in capacity at a predetermined SNR that is at least 60% of the gain in capacity achieved by a constellation optimized for parallel decode (PD) capacity at the predetermined SNR.

25. The communication system of claim 13, wherein the symbol constellation is a Quadrature Amplitude Modulation 1024 point (QAM-1024) symbol constellation.

26. The communication system of claim 25, wherein the constellation provides an increase in capacity at a predetermined SNR that is at least 60% of the gain in capacity achieved by a constellation optimized for parallel decode (PD) capacity at the predetermined SNR.