Shaped signal spaces in a simultaneous voice and data system

• US 5,475,713 A
• Filed: 06/14/1993
• Issued: 12/12/1995
• Est. Priority Date: 06/14/1993
• Status: Expired due to Term

• Current Assignee: Patent Business Development LLC
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Bremer, Gordon, Ko, Kenneth D., Smithwick, Luke J.
• Primary Examiner(s): O'Shea, Sandra L.
• Assistant Examiner(s): NING, JOHN K
• Application Number:
  US08/076,530
• Time in Patent Office: 911 Days
• Field of Search: 375/37, 375/38, 375/39, 375/59
• US Class Current: 375/261
• CPC Class Codes: H04J 7/00 Multiplex systems in which the amplitudes or durations of the signals in individual channels are characteristic of those channels
• CPC Class Codes: H04L 27/3483 using a modulation of the constellation points

Abstract

In a simultaneous voice and data communications system, a voice signal is mapped into an N-dimensional signal space constellation as a vector, and added to a reference signal point, i.e., a data symbol, where the data symbol is selected from a constellation of data symbols every signaling interval as a function of a data signal. The constellation signal space is further divided into a number of shaped regions, where each region is associated with a different one of the data symbols. The shape of each region is selected as a function of the characteristics of the voice, or audio, signal. In particular, each region illustratively has a rectangular shape.

Claims

1. A method for transmitting comprising the steps of:

a) selecting a data symbol as a function of a data signal, where each data symbol represents a different one of a number of regions of an N-dimensional signal space, and each data symbol is associated with a different N-dimensional signal point in the N-dimensional signal space;

b) selecting an N-dimensional signal point as a function of an applied signal, where the signal point is selected from the N-dimensional signal space;

c) adding the signal space coordinates of the selected data symbol and the selected N-dimensional signal point to provide a resultant signal point;

where each resultant signal point is taken from the region associated with the data symbol and where each one of the number of regions has a non-square shape.

2. The method of claim 1 wherein the shape of each one of the number of regions is a function of the characteristics of the applied signal.

3. The method of claim 2 wherein the applied signal is a voice signal and each coordinate of the signal point selected in step b) is a sample of a voice signal.

4. The method of claim 1 wherein the selecting step b) includes the step of:

d) sampling the applied signal to provide a number of samples at most equal to the number of dimensions of the N-dimensional signal space;

e) scaling the number of samples to provide a number of scaled samples, where the scaling step is performed in such a way that at least one of the number of samples is scaled differently from the remaining ones of the number of samples; and

f) selecting the N-dimensional signal point as a function of the number of scaled samples.

5. A method for use in a communications system for transmitting a data signal and an applied signal, comprising the steps of:

defining a number of N-dimensional signal spaces, where each N-dimensional signal space includes a number of regions and where at least two of the N-dimensional signal spaces have a different number of regions and a size of at least one dimension of each region is identical;

selecting one of the number of N-dimensional signal spaces; and

transmitting an N-dimensional signal point from the selected N-dimensional signal space, where the N-dimensional signal point is taken from one of the number of regions of the selected N-dimensional signal space as a function of the data signal and the applied first signal,

wherein the applied signal is a voice signal and the shape of each region is proportional to the dynamic range of the voice signal.

6. The method of claim 5 wherein the number of regions in each one of the number of N-dimensional signal spaces is proportional to a data rate of the communications system.

7. A method for transmitting comprising the steps of:

processing a first signal to provide a sequence of N-dimensional first signal points, each first signal point taken from an N-dimensional signal space, where each first signal point of the sequence defines a respective first signal vector from the origin of the signal space to the first signal point;

processing a data signal to provide a sequence of data symbols, each data symbol associated with a different N-dimensional signal point from the signal space;

adding each first signal vector to a respective data symbol from the sequence of data symbols to prove a sequence of resultant signal points; and

transmitting a signal that represents the sequence of resultant signal points;

where the magnitudes of at least one of the first signal vectors is limited in one dimension more than in another dimension.

8. The method of claim 7 wherein the first signal is a voice signal.

9. Apparatus for transmitting comprising:

first selecting means for selecting an N-dimensional signal point as a function of a first signal where the signal point is selected from an N-dimensional signal space;

second selecting means for selecting a data symbol as a function of a data signal, where each data symbol represents one of a number of regions of the signal space, and each data symbol is associated with a different signal point in the N-dimensional signal space; and

means for adding in every signaling interval, T, the signal space coordinates of the two selected signal points to provide a resultant signal point;

where each resultant signal point is taken from the region associated with the data symbol occurring in a respective signaling interval, and where each one of the number of regions has a non-square shape.

10. The apparatus of claim 9 wherein the shape of each one of the number of regions is a function of the characteristics of the first signal.

11. The apparatus of claim 10 wherein the first signal is a voice signal and each coordinate of the signal point selected by the first selecting means is a sample of the voice signal.

12. The apparatus of claim 9 wherein the first selecting means includes:

means for sampling the first signal to provide a number of samples at most equal to the number of dimensions of the N-dimensional signal space;

means for scaling the number of samples to provide a number of scaled samples, where the scaling is performed in such a way that at least one of the number of samples is scaled differently from the remaining ones of the number of samples; and

third selecting means for selecting the N-dimensional signal point as a function of the number of scaled samples.

13. Apparatus for transmitting comprising:

means for processing a first signal to provide sequence of N-dimensional first signal points, each first signal point taken from an N-dimensional signal space, where each first signal point of the sequence defines a respective first signal vector from the origin of the signal space to the first signal point;

means for processing a data signal to provide a sequence of data symbols, each data symbol associated with a different N-dimensional signal point from the signal space;

means for adding each first signal vector to a respective data symbol from the sequence of data symbols to prove a sequence of resultant signal points; and

means for transmitting a signal that represents the sequence of resultant signal points;

where the magnitudes of at least one of the first signal vectors is limited in one dimension more than in another dimension.

14. The apparatus of claim 13 wherein the first signal is a voice signal.