Systems and methods for obtaining an optimum transmission format of reference signals to maximize capacity and minimize peak to average power ratio

1. A method for optimizing a transmission format of a reference signal, the method comprising:

providing a first matrix;

computing a second matrix from the first matrix;

defining a derivative of a function of the second matrix;

obtaining iterates of the function of the second matrix;

determining, by a processor, the function of the second matrix using the derivative of the function of the second matrix and the iterates;

calculating, by the processor, an optimum value of the first matrix using the iterates of the function of the second matrix, wherein the optimum value of the first matrix minimizes the peak-to-average power ratio (PAPR) of a transmit signal; and

transforming a plurality of data symbols to be sent contemporaneously with one or more reference signals using the optimum value of the first matrix.

2. The method of claim 1 , further comprising transmitting the plurality of data symbols and the one or more reference signals with a single antenna.

3. The method of claim 1 , further comprising transmitting the plurality of data symbols and the one or more reference signals with a multiple-input multiple-output antenna system.

4. The method of claim 1 , further comprising implementing Gaussian random matrices to represent signal constellations.

5. The method of claim 1 , further comprising implementing random M-ary phase shift keyed (M-PSK) modulation to transmit the data, wherein the data and a superposed pilot signal are optimized based on the M-PSK modulation format.

6. The method of claim 1 , further comprising implementing random M-ary quadrature amplitude modulation (M-QAM) modulation to transmit the data, wherein the data and a superposed pilot signal are optimized based on the M-QAM modulation format.

7. The method of claim 1 , further comprising implementing Gram-Schmidt procedures to format a signal to be orthogonal to the data wherein the signal is superposed on the data.

8. The method of claim 1 , further comprising obtaining the optimum value of the first matrix by implementing steepest decent methods restricted to a Stiefel manifold determined by the reference signals.

9. A method for optimizing a transmission format of a reference signal, the method comprising:

providing a first matrix;

computing a second matrix from the first matrix;

defining a derivative of a function of the second matrix;

obtaining iterates of the function of the second matrix;

determining, by a processor, the function of the second matrix using the derivative of the function of the second matrix and the iterates;

calculating, by the processor, an optimum value of the first matrix using the iterates of the function of the second matrix; and

transmitting data, by a transmitter, in the form rpmT X(p)+rdmT AX(d) wherein X(d) is a column vector which is mapped by a matrix A into a column vector of n rows, wherein n represents coherence time of the flat fading channel, wherein m represents the number of antennas, and wherein X(p) is a reference signal composed of the sum of m orthogonal reference signals.

10. The method of claim 9 , wherein the matrix A has a singular value decomposition of the form A=UΣV H , wherein a matrix Uε , wherein Σε , wherein a matrix Vε , wherein U and V are unitary matrices, and wherein Σ is a matrix of singular values on the diagonal.

11. The method of claim 10 , wherein the matrix U is an orthonormal basis which contains X(p) in the last row and column of the matrix U.

12. The method of claim 9 , wherein the matrix A is an isometry and wherein Σ has the form of all ones on the diagonal, except for the last row, wherein the last row is zero.

13. A transmitter that is configured to implement a method for optimizing a transmission format of a reference signal, the transmitter comprising:

a processor;

memory in electronic communication with the processor;

instructions stored in the memory. the instructions being executable to:

provide a first matrix;

compute a second matrix from the first matrix;

define a derivative of a function of the second matrix;

obtain iterates of the function of the second matrix;

determine the function of the second matrix using the derivative of the function of the second matrix and the iterates;

calculate an optimum value of the first matrix using the iterates of the function of the second matrix, wherein the optimum value of the first matrix minimizes the peak-to-average power ratio (PAPR) of a transmit signal; and

transforming a plurality of data symbols to he sent contemporaneously with one or more reference signals using the optimum value of the first matrix.

14. The transmitter of claim 13 , wherein the instructions are further executable to transmit the plurality of data symbols and the one or more reference signals with a single antenna.

15. The transmitter of claim 13 , wherein the instructions are further executable to transmit the plurality of data symbols and the one or more reference signals with a multiple-input multiple-output antenna system.