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A system and method are provided for removing quadrature imbalance errors in received data. The method accepts an unbiased training sequence in a quadrature demodulation receiver. An unbiased training sequence has a uniform accumulated power evenly distributed in a complex plane, and includes predet

A system and method are provided for removing quadrature imbalance errors in received data. The method accepts an unbiased training sequence in a quadrature demodulation receiver. An unbiased training sequence has a uniform accumulated power evenly distributed in a complex plane, and includes predetermined reference signals (p) at frequency +f and predetermined mirror signals (pm) at frequency −f. The unbiased training sequence is processed, generating a sequence of processed symbols (y) at frequency +f, representing complex plane information in the unbiased training sequence. Each processed symbol (y) is multiplied by the mirror signal (pm), and an unbiased quadrature imbalance estimate Bm is obtained at frequency (−f). Using quadrature imbalance estimates, channel estimates, and processed symbols, an imbalance-corrected symbol can be generated.

대표청구항 ▼

1. A method of communication, the method comprising: receiving a training signal at a quadrature demodulation receiver, the training signal representing a plurality of predetermined reference values at a frequency +f or a frequency adjacent to the frequency +f and a plurality of corresponding predet

1. A method of communication, the method comprising: receiving a training signal at a quadrature demodulation receiver, the training signal representing a plurality of predetermined reference values at a frequency +f or a frequency adjacent to the frequency +f and a plurality of corresponding predetermined mirror values at a frequency −f or a frequency adjacent to the frequency −f, wherein the sum of the products of each predetermined reference value and the corresponding predetermined mirror value is zero;generating a plurality of received values based on the received portion of the training signal representing the predetermined reference values at the frequency +f or the frequency adjacent to the frequency +f;generating a plurality of derotation values by multiplying each received value by the corresponding predetermined mirror value; andaveraging the derotation values so as to obtain a quadrature imbalance estimate for the frequency −f or the frequency adjacent to the frequency −f. 2. The method of claim 1, wherein the received training signal represents at least a first predetermined reference value at the frequency +f, a second predetermined reference value at the frequency adjacent to the frequency +f, a first corresponding predetermined mirror value at the frequency −f, and a second corresponding predetermined mirror value at the frequency adjacent to the frequency −f and wherein the sum of the first predetermined reference value multiplied by the first corresponding predetermined mirror value and the second predetermined reference value multiplied by the second corresponding predetermined mirror value is zero. 3. The method of claim 1, wherein the received training signal represents at least a first predetermined reference value at the frequency +f received at a first time, a second predetermined reference value at the frequency +f received at a second time after the first time, a first corresponding predetermined mirror value at the frequency −f received at the first time, and a second corresponding predetermined mirror value at the frequency −f received at the second time and wherein the sum of the first predetermined reference value multiplied by the first corresponding predetermined mirror value and the second predetermined reference value multiplied by the second corresponding predetermined mirror value is zero. 4. The method of claim 1, further comprising: generating a plurality of second derotation values by multiplying each received value by the conjugate of the corresponding predetermined reference value; andaveraging the second derotation values so as to obtain a channel estimate for the frequency +f or the frequency adjacent to the frequency +f. 5. The method of claim 1, further comprising: generating a plurality of second received values based on the received portion of the training signal representing the predetermined mirror values at the frequency −f or the frequency adjacent to the frequency −f;generating a plurality of third derotation values by multiplying each second received value by the corresponding predetermined reference value; andaveraging the third derotation values so as to obtain a quadrature imbalance estimate for the frequency +f or the frequency adjacent to the frequency +f. 6. The method of claim 1, further comprising: generating a plurality of second received values based on the received portion of the training signal representing the predetermined mirror values at the frequency −f or the frequency adjacent to the frequency −f;generating a plurality of fourth derotation values by multiplying each second received value by the conjugate of the predetermined mirror value; andaveraging the fourth derotation values so as to obtain a channel estimate for the frequency −f or the frequency adjacent to the frequency −f. 7. The method of claim 1, further comprising: receiving a data signal at the quadrature demodulation receiver, the data signal representing at least a plurality of data values at frequency +f;generating a plurality of received data values based on the received portion of the data signal representing the data values at the frequency +f; andgenerating a plurality of compensated data values based on the received data values and the quadrature imbalance estimate. 8. The method of claim 7, wherein: receiving a data signal comprises receiving data signal representing a plurality of data values at frequency +f and a plurality of corresponding mirror data values at frequency −f;generating a plurality of received data values further comprises generating a plurality of received corresponding mirror data values based on the received portion of the data signal representing the corresponding mirror data values at frequency −f; andgenerating a plurality of compensated data values comprises subtracting, from each received data value, a value proportional to the quadrature imbalance estimate and the received corresponding mirror data value. 9. The method of claim 7, further comprising determining that signal-to-noise ratio is greater than a threshold, wherein generating a plurality of compensated data values comprises generating a plurality of compensated data values in response to the determination. 10. A system for communication, the system comprising: a receiver configured to receive a training signal, the training signal representing a plurality of predetermined reference values at a frequency +f or a frequency adjacent to the frequency +f and a plurality of corresponding predetermined mirror values at a frequency −f or a frequency adjacent to the frequency −f, wherein the sum of the products of each predetermined reference value and the corresponding predetermined mirror value is zero; anda processor configured to: generate a plurality of received values based on the received portion of the training signal representing the predetermined reference values at the frequency +f or the frequency adjacent to the frequency +f,generate a plurality of derotation values by multiplying each received value by the corresponding predetermined mirror value, andaverage the derotation values so as to obtain a quadrature imbalance estimate for the frequency −f or the frequency adjacent to the frequency −f. 11. The system of claim 10, wherein the received training signal represents at least a first predetermined reference value at the frequency +f, a second predetermined reference value at the frequency adjacent to the frequency +f, a first corresponding predetermined mirror value at the frequency −f, and a second corresponding predetermined mirror value at the frequency adjacent to the frequency −f and wherein the sum of the first predetermined reference value multiplied by the first corresponding predetermined mirror value and the second predetermined reference value multiplied by the second corresponding predetermined mirror value is zero. 12. The system of claim 10, wherein the received training signal represents at least a first predetermined reference value at the frequency +f received at a first time, a second predetermined reference value at the frequency +f received at a second time after the first time, a first corresponding predetermined mirror value at the frequency −f received at the first time, and a second corresponding predetermined mirror value at the frequency −f received at the second time and wherein the sum of the first predetermined reference value multiplied by the first corresponding predetermined mirror value and the second predetermined reference value multiplied by the second corresponding predetermined mirror value is zero. 13. The system of claim 10, wherein the processor is further configured to generate a plurality of second derotation values by multiplying each received value by the conjugate of the corresponding predetermined reference value and average the second derotation values so as to obtain a channel estimate for the frequency +f or the frequency adjacent to the frequency +f. 14. The system of claim 10, wherein the processor is further configured to: generate a plurality of second received values based on the received portion of the training signal representing the predetermined mirror values at the frequency −f or the frequency adjacent to the frequency −f,generate a plurality of third derotation values by multiplying each second received value by the corresponding predetermined reference value, andaverage the third derotation values so as to obtain a quadrature imbalance estimate for the frequency +f or the frequency adjacent to the frequency +f. 15. The system of claim 10, wherein the processor is further configured to: generate a plurality of second received values based on the received portion of the training signal representing the predetermined mirror values at the frequency −f or the frequency adjacent to the frequency −f,generate a plurality of fourth derotation values by multiplying each second received value by the conjugate of the predetermined mirror value, andaverage the fourth derotation values so as to obtain a channel estimate for the frequency −f or the frequency adjacent to the frequency −f. 16. The system of claim 10, wherein the receiver is further configured to receive a data signal representing at least a plurality of data values at frequency +f and the processor is further configured to generate a plurality of received data values based on the received portion of the data signal representing the data values at the frequency +f and generate a plurality of compensated data values based on the received data values and the quadrature imbalance estimate. 17. The system of claim 16, wherein the data signal represents a plurality of data values at frequency +f and a plurality of corresponding mirror data values at frequency −f and the processor is configured to generate a plurality of received corresponding mirror data values based on the received portion of the data signal representing the corresponding mirror data values at frequency −f and to generate the plurality of compensated data values by subtracting, from each received data value, a value proportional to the quadrature imbalance estimate and the received corresponding mirror data value. 18. The system of claim 16, wherein the processor is configure to determine that signal-to-noise ratio is greater than a threshold and to generate the plurality of compensated data values in response to the determination. 19. A system for communication, the system comprising: means for receiving a training signal at a quadrature demodulation receiver, the training signal representing a plurality of predetermined reference values at a frequency +f or a frequency adjacent to the frequency +f and a plurality of corresponding predetermined mirror values at a frequency −f or a frequency adjacent to the frequency −f, wherein the sum of the products of each predetermined reference value and the corresponding predetermined mirror value is zero;means for generating a plurality of received values based on the received portion of the training signal representing the predetermined reference values at the frequency +f or the frequency adjacent to the frequency +f;means for generating a plurality of derotation values by multiplying each received value by the corresponding predetermined mirror value; andmeans for averaging the derotation values so as to obtain a quadrature imbalance estimate for the frequency −f or the frequency adjacent to the frequency −f. 20. A computer-readable non-transitory medium having instructions encoded thereon which, when executed by a computer, cause a system to perform a method of communication, the method comprising: receiving a training signal at a quadrature demodulation receiver, the training signal representing a plurality of predetermined reference values at a frequency +f or a frequency adjacent to the frequency +f and a plurality of corresponding predetermined mirror values at a frequency −f or a frequency adjacent to the frequency −f, wherein the sum of the products of each predetermined reference value and the corresponding predetermined mirror value is zero;generating a plurality of received values based on the received portion of the training signal representing the predetermined reference values at the frequency +f or the frequency adjacent to the frequency +f;generating a plurality of derotation values by multiplying each received value by the corresponding predetermined mirror value; andaveraging the derotation values so as to obtain a quadrature imbalance estimate for the frequency −f or the frequency adjacent to the frequency −f.