1. A method for processing an input signal for application to an amplifier to generate an amplified output signal, comprising:
generating an index into a look-up table based on the input signal;
adjusting the index to compensate for changes in operating characteristics of the amplifier over time;
retrieving one or more pre-distortion parameters from the look-up table based on the adjusted index; and
pre-distorting the input signal based on the one or more pre-distortion parameters to generate a pre-distorted input signal for application to the amplifier, wherein:
the index is adjusted based on a measure of distortion in the amplified output signal; and
the measure of distortion is based on a narrow-band power level in the amplified output signal.
2. The method of claim 1, further comprising amplifying the pre-distorted input signal with the amplifier to generate the amplified output signal.
3. The method of claim 2, wherein amplifying the pre-distorted input signal comprises controlling overall gain of the amplifier to compensate for the changes in the operating characteristics of the amplifier.
4. The method of claim 3, wherein the overall gain is controlled based on a comparison of power of the pre-distorted input signal and power of the amplified output signal.
5. The method of claim 3, wherein the overall gain is controlled to keep the overall gain substantially constant over time.
6. The method of claim 5, wherein the overall gain is further controlled to reduce distortion in the amplified output signal.
7. The method of claim 3, wherein the overall gain is controlled to reduce distortion in the amplified output signal.
8. The method of claim 3, wherein amplifying the pre-distorted input signal further comprises controlling bias applied to one or more amplifier stages of the amplifier.
9. The method of claim 8, wherein the bias is controlled based on a measure of distortion in the amplified output signal.
10. The method of claim 9, wherein the measure of distortion is based on a narrow-band power level in the amplified output signal.
11. The method of claim 2, wherein amplifying the pre-distorted input signal comprises controlling bias applied to one or more amplifier stages of the amplifier.
12. The method of claim 11, wherein the bias is controlled based on a measure of distortion in the amplified output signal.
13. The method of claim 12, wherein the measure of distortion is based on a narrow-band power level in the amplified output signal.
14. The method of claim 1, wherein the look-up table corresponds to frequency-independent pre-distortion processing.
15. The method of claim 1, wherein the look-up table corresponds to frequency-dependent pre-distortion processing.
16. The method of claim 1, further comprising:
retrieving one or more other pre-distortion parameters from a different look-up table based on the input signal; and
pre-distorting the input signal based on the one or more other pre-distortion parameters to generate a different pre-distortion component for the pre-distorted input signal, wherein the different look-up table is automatically updated by:
generating a measure based on current operations of the amplifier;
applying the measure to one or more algebraic equations to generate one or more parameter values; and
applying the one or more parameter values to one or more polynomials to update the different look-up table.
17. The method of claim 1, wherein the look-up table is automatically updated by:
generating a measure based on current operations of the amplifier;
applying the measure to one or more algebraic equations to generate one or more parameter values; and
applying the one or more parameter values to one or more polynomials to update the look-up table.
18. The method of claim 1, wherein the look-up table is generated during training of the amplifier and always kept fixed after training is complete.
19. The method of claim 1, wherein the index is based on power of the input signal.
20. Apparatus for processing an input signal for application to an amplifier to generate an amplified output signal, comprising:
an index generator adapted to generate an index into a look-up table based on the input signal;
an index adjuster adapted to adjust the index to compensate for changes in operating characteristics of the amplifier over time;
the look-up table adapted to provide one or more pre-distortion parameters based on the adjusted index; and
a pre-distorter adapted to pre-distort the input signal based on the one or more pre-distortion parameters to generate a pre-distorted input signal for application to the amplifier, wherein:
the index adjuster is adapted to adjust the index based on a measure of distortion in the amplified output signal; and
the measure of distortion is based on a narrow-band power level in the amplified output signal.
21. The apparatus of claim 20, further comprising the amplifier adapted to amplify the pre-distorted input signal to generate the amplified output signal.
22. The apparatus of claim 21, wherein the amplifier is adapted to control overall gain of the amplifier to compensate for the changes in the operating characteristics of the amplifier.
23. The apparatus of claim 22, wherein the amplifier is adapted to control the overall gain based on a comparison of power of the pre-distorted input signal and power of the amplified output signal.
24. The apparatus of claim 22, wherein the amplifier is adapted to control the overall gain to keep the overall gain substantially constant over time.
25. The apparatus of claim 24, wherein the overall gain is further controlled to reduce distortion in the amplified output signal.
26. The apparatus of claim 22, wherein the overall gain is controlled to reduce distortion in the amplified output signal.
27. The apparatus of claim 22, wherein the amplifier is further adapted to control bias applied to one or more amplifier stages of the amplifier.
28. The apparatus of claim 27, wherein the amplifier is adapted to control the bias based on a measure of distortion in the amplified output signal.
29. The apparatus of claim 28, wherein the measure of distortion is based on a narrow-band power level in the amplified output signal.
30. The apparatus of claim 21, wherein the amplifier is adapted to control bias applied to one or more amplifier stages of the amplifier.
31. The apparatus of claim 30, wherein the amplifier is adapted to control the bias based on a measure of distortion in the amplified output signal.
32. The apparatus of claim 31, wherein the measure of distortion is based on a narrow-band power level in the amplified output signal.
33. The apparatus of claim 21, further comprising:
a first power detector adapted to detect power of the pre-distorted input signal;
a second power detector adapted to detect power of the amplified output signal;
a receiver adapted to detect narrow-band power of the amplified output signal at a selected frequency; and
a controller adapted to process the detected powers from the first and second power detectors and from the receiver to generate one or more control signals used to control operations within the apparatus.
34. The apparatus of claim 33, wherein the one or more control signals control the index adjuster, a variable attenuator in the amplifier, and bias levels applied to one or more amplifier stages in the amplifier.
35. The apparatus of claim 33, wherein the first and second power detectors are wide-band power detectors.
36. The apparatus of claim 33, wherein the controller is adapted to change the selection of the frequency of the receiver.
37. The apparatus of claim 20, wherein the look-up table corresponds to frequency-independent pre-distortion processing.
38. The apparatus of claim 20, wherein the look-up table corresponds to frequency-dependent pre-distortion processing.
39. The apparatus of claim 20, further comprising:
a different look-up table adapted to provide one or more other pre-distortion parameters based on the input signal, wherein the pre-distorter is further adapted to pre-distort the input signal based on the one or more other pre-distortion parameters to generate a different pre-distortion component for the pre-distorted input signal; and
a controller adapted to automatically update the different look-up table by:
generating a measure based on current operations of the amplifier;
applying the measure to one or more algebraic equations to generate one or more parameter values; and
applying the one or more parameter values to one or more polynomials to update the different look-up table.
40. The apparatus of claim 20, further comprising a controller adapted to automatically update the look-up table by:
generating a measure based on current operations of the amplifier;
applying the measure to one or more algebraic equations to generate one or more parameter values; and
applying the one or more parameter values to one or more polynomials to update the look-up table.
41. The apparatus of claim 20, wherein the look-up table is generated during training of the amplifier and always kept fixed after training is complete.
42. The apparatus of claim 20, wherein the index is based on power of the input signal.
43. A method for processing an input signal for application to an amplifier to generate an amplified output signal, comprising:
retrieving one or more pre-distortion parameters from a look-up table based on the input signal; and
pre-distorting the input signal based on the one or more pre-distortion parameters to generate a pre-distorted input signal for application to the amplifier, wherein the look-up table is automatically updated by:
generating a measure based on current operations of the amplifier;
applying the measure to one or more algebraic equations to generate one or more parameter values; and
applying the one or more parameter values to one or more polynomials to update the look-up table.
44. The method of claim 43, wherein the measure is average power of the input signal.
45. The method of claim 43, wherein each algebraic equation is a piecewise linear curve.
46. The method of claim 43, wherein:
the measure is applied to four algebraic equations to generate four parameter values; and
the four parameter values are applied to two second-order polynomials to update two pre-distortion parameters in the look-up table.
47. The method of claim 43, wherein the pre-distortion parameters are frequency-dependent pre-distortion parameters.
48. The method of claim 43, wherein the pre-distortion parameters are frequency-independent pre-distortion parameters.
49. The method of claim 43, wherein the look-up table is updated at a specified periodic rate.
50. The method of claim 43, wherein the look-up table is updated based on a detected change in operating conditions of the amplifier.
51. The method of claim 50, wherein the detected change in the amplifier operating conditions corresponds to a change in a parameter value greater than a specified threshold value.
52. The method of claim 43, wherein the one or more parameter values are fine-tuned based on output spectrum of the amplifier.
53. Apparatus for processing an input signal for application to an amplifier to generate an amplified output signal, comprising:
a look-up table adapted to provide one or more pre-distortion parameters based on the input signal;
a pre-distorter adapted to pre-distort the input signal based on the one or more pre-distortion parameters to generate a pre-distorted input signal for application to the amplifier; and
a controller adapted to automatically update the look-up table by:
generating a measure based on current operations of the amplifier;
applying the measure to one or more algebraic equations to generate one or more parameter values; and
applying the one or more parameter values to one or more polynomials to update the look-up table.
54. The apparatus of claim 53, wherein:
the measure is average power of the input signal; and
further comprising an envelope detector adapted to detect current power of the input signal, wherein the controller uses the current input signal power to generate the average input signal power.
55. The apparatus of claim 53, wherein each algebraic equation is a piecewise linear curve.
56. The apparatus of claim 53, wherein:
the controller is adapted to apply the measure to four algebraic equations to generate four parameter values; and
the controller is adapted to apply the four parameter values to two second-order polynomials to update two pre-distortion parameters in the look-up table.
57. The apparatus of claim 53, wherein the pre-distortion parameters are frequency-dependent pre-distortion parameters.
58. The apparatus of claim 53, wherein the pre-distortion parameters are frequency-independent pre-distortion parameters.
59. The apparatus of claim 53, wherein the controller is adapted to update the look-up table at a specified periodic rate.
60. The apparatus of claim 53, wherein the controller is adapted to update the look-up table based on a detected change in operating conditions of the amplifier.
61. The apparatus of claim 60, wherein the detected change in the amplifier operating conditions corresponds to a change in a parameter value greater than a specified threshold value.
62. The apparatus of claim 53, wherein the controller is adapted to fine-tune the one or more parameter values based on output spectrum of the amplifier.
63. A method for processing an input signal for application to an amplifier to generate an amplified output signal, comprising:
generating an index into a look-up table based on the input signal;
adjusting the index to compensate for changes in operating characteristics of the amplifier over time;
retrieving one or more pre-distortion parameters from the look-up table based on the adjusted index;
pre-distorting the input signal based on the one or more pre-distortion parameters to generate a pre-distorted input signal for application to the amplifier; and
amplifying the pre-distorted input signal with the amplifier to generate the amplified output signal, wherein amplifying the pre-distorted input signal comprises controlling overall gain of the amplifier to compensate for the changes in the operating characteristics of the amplifier.
64. The method of claim 63, wherein the overall gain is controlled based on a comparison of power of the pre-distorted input signal and power of the amplified output signal.
65. The method of claim 63, wherein the overall gain is controlled to reduce distortion in the amplified output signal.
66. The method of claim 63, wherein amplifying the pre-distorted input signal further comprises controlling bias applied to one or more amplifier stages of the amplifier.
67. Apparatus for processing an input signal for application to an amplifier to generate an amplified output signal, comprising:
an index generator adapted to generate an index into a look-up table based on the input signal;
an index adjuster adapted to adjust the index to compensate for changes in operating characteristics of the amplifier over time;
the look-up table adapted to provide one or more pre-distortion parameters based on the adjusted index;
a pre-distorter adapted to pre-distort the input signal based on the one or more pre-distortion parameters to generate a pre-distorted input signal for application to the amplifier; and
the amplifier adapted to amplify the pre-distorted input signal to generate the amplified output signal, wherein the amplifier is adapted to control overall gain of the amplifier to compensate for the changes in the operating characteristics of the amplifier.
68. The apparatus of claim 67, wherein the amplifier is adapted to control the overall gain based on a comparison of power of the pre-distorted input signal and power of the amplified output signal.
69. The apparatus of claim 67, wherein the overall gain is controlled to reduce distortion in the amplified output signal.
70. The apparatus of claim 67, wherein the amplifier is further adapted to control bias applied to one or more amplifier stages of the amplifier.
71. A method for processing an input signal for application to an amplifier to generate an amplified output signal, comprising:
generating an index into a look-up table based on the input signal;
adjusting the index to compensate for changes in operating characteristics of the amplifier over time;
retrieving one or more pre-distortion parameters from the look-up table based on the adjusted index;
pre-distorting the input signal based on the one or more pre-distortion parameters to generate a pre-distorted input signal for application to the amplifier; and
amplifying the pre-distorted input signal with the amplifier to generate the amplified output signal, wherein amplifying the pre-distorted input signal comprises controlling bias applied to one or more amplifier stages of the amplifier.
72. The method of claim 71, wherein the bias is controlled based on a measure of distortion in the amplified output signal.
73. The method of claim 72, wherein the measure of distortion is based on a narrow-band power level in the amplified output signal.
74. Apparatus for processing an input signal for application to an amplifier to generate an amplified output signal, comprising:
an index generator adapted to generate an index into a look-up table based on the input signal;
an index adjuster adapted to adjust the index to compensate for changes in operating characteristics of the amplifier over time;
the look-up table adapted to provide one or more pre-distortion parameters based on the adjusted index;
a pre-distorter adapted to pre-distort the input signal based on the one or more pre-distortion parameters to generate a pre-distorted input signal for application to the amplifier; and
the amplifier adapted to amplify the pre-distorted input signal to generate the amplified output signal, wherein the amplifier is adapted to control bias applied to one or more amplifier stages of the amplifier.
75. The apparatus of claim 74, wherein the amplifier is adapted to control the bias based on a measure of distortion in the amplified output signal.
76. The apparatus of claim 75, wherein the measure of distortion is based on a narrow-band power level in the amplified output signal.
77. Apparatus for processing an input signal for application to an amplifier to generate an amplified output signal, comprising:
an index generator adapted to generate an index into a look-up table based on the input signal;
an index adjuster adapted to adjust the index to compensate for changes in operating characteristics of the amplifier over time;
the look-up table adapted to provide one or more pre-distortion parameters based on the adjusted index;
a pre-distorter adapted to pre-distort the input signal based on the one or more pre-distortion parameters to generate a pre-distorted input signal for application to the amplifier;
the amplifier adapted to amplify the pre-distorted input signal to generate the amplified output signal;
a first power detector adapted to detect power of the pre-distorted input signal;
a second power detector adapted to detect power of the amplified output signal;
a receiver adapted to detect narrow-band power of the amplified output signal at a selected frequency; and
a controller adapted to process the detected powers from the first and second power detectors and from the receiver to generate one or more control signals used to control operations within the apparatus.
78. The apparatus of claim 77, wherein the one or more control signals control the index adjuster, a variable attenuator in the amplifier, and bias levels applied to one or more amplifier stages in the amplifier.
79. The apparatus of claim 77, wherein the first and second power detectors are wide-band power detectors.
80. The apparatus of claim 77, wherein the controller is adapted to change the selection of the frequency of the receiver.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A computer-implemented method for digitally signing data, comprising:
generating a lattice having at least one short basis establishing a private key and at least one long basis establishing a public key;
mapping at least the message \u03bc or a concatenation thereof to a message point \u201cx\u201d in n-dimensional space using a function \u201cf\u201d rendering infeasible the possibility of mapping two messages together in the space; and
using the short basis, finding a lattice point \u201cy\u201d of the lattice that is close to the message point \u201cx\u201d and
using at least the message point \u201cx\u201d and lattice point \u201cy\u201d, digitally signing an entity, wherein the function \u201cf\u201d maps the message \u03bc to a point on a grid and is collision intractable.
2. The method of claim 1, further comprising randomizing the function \u201cf\u201d.
3. The method of claim 2, wherein the function \u201cf\u201d is randomized by concatenating the message \u03bc with a random number \u03c1.
4. The method of claim 1, wherein the collision intractability of the function \u201cf\u201d is derived from the hardness of lattice problems.
5. The method of claim 1, wherein the function \u201cf\u201d maps at least the message to a point on an auxiliary lattice.
6. The method of claim 1, further comprising verifying a digital signature at least in part by determining whether a difference between the lattice point \u201cy\u201d and the message point \u201cx\u201d is no more than a predetermined distance.
7. The method of claim 6, wherein the predetermined distance is related to the number of dimensions in the lattice .
8. A computer program storage device including a program of instructions for generating a digital signature for a message, the program of instructions including:
computer readable code means for mapping a message \u03bc or a concatenation thereof to a message point \u201cx\u201d in n-dimensional space, the message point \u201cx\u201d being a point of a grid or a point of an auxiliary lattice;
computer readable code means for finding a point \u201cy\u201d of a key lattice that is not the same as the auxiliary lattice; and
computer readable code means for establishing a digital signature, based at least on the points \u201cx\u201d and \u201cy\u201d.
9. The computer program storage device of claim 8, wherein the means for mapping uses a function \u201cf\u201d rendering infeasible the possibility of mapping two messages close together in the space, and wherein the means for finding includes using a hard to find short basis of the key lattice .
10. The computer program storage device of claim 9, further comprising means for randomizing the function \u201cf\u201d.
11. The computer program storage device of claim 10, wherein the function \u201cf\u201d is randomized by concatenating the message \u03bc with a random number \u03c1.
12. The computer program storage device of claim 9, wherein the function \u201cf\u201d maps at least the message to a point on an auxiliary lattice.
13. The computer program storage device of claim 8, wherein the function \u201cf\u201d maps the message \u03bc to a point on a grid, and wherein the function \u201cf\u201d is collision intractable, the collision intractability being derived from the hardness of lattice problems.
14. The computer program storage device of claim 8, wherein the function \u201cf\u201d is not collision intractable.
15. A computer system for generating a digital signature of a message \u03bc, comprising:
at least one sender computer including logic for executing method steps including:
mapping the message \u03bc to a message point \u201cx\u201d at which it is not feasible to map any other message;
finding a lattice point \u201cy\u201d; and
transmitting at least the message \u03bc and the points \u201cx\u201d and \u201cy\u201d;
at least one receiver computer receiving the message \u03bc and points \u201cx\u201d and \u201cy\u201d and including logic for executing method steps including:
determining whether a distance between the points \u201cx\u201d and \u201cy\u201d is related in a predetermined way to a predetermined distance, and based thereon determining whether the message \u03bc has been properly signed.
16. The system of claim 15, wherein the mapping act is undertaken using a function \u201cf\u201d that maps the message point \u201cx\u201d to a point of a grid or of an auxiliary lattice, and further wherein the lattice point \u201cy\u201d is a member of a lattice , and the finding act is undertaken using a hard-to-find short basis of the lattice .
17. The system of claim 16, wherein the acts undertaken by the logic of the sender computer further comprise randomizing the function \u201cf\u201d by concatenating the message \u03bc with a random number \u03c1.
18. The system of claim 16, wherein the function \u201cf\u201d is collision intractable.
19. The system of claim 18, wherein the collision intractability of the function \u201cf\u201d is derived from the hardness of lattice problems.
20. The system of claim 16, wherein the function \u201cf\u201d is not collision intractable.
21. The system of claim 16, wherein the predetermined distance is related to the number \u201cr\u201d of dimensions in the lattice .
22. A computer-implemented method for digitally signing data, comprising:
generating a lattice having at least one short basis and at least one long basis;
mapping at least the message \u03bc or a concatenation thereof to a message point \u201cx\u201d in n-dimensional space, the message point \u201cx\u201d being an element of a set of spaced-apart points not on the lattice; and
using the short basis, finding a lattice point \u201cy\u201d of the lattice ; and
using at least the message point \u201cx\u201d and lattice point \u201cy\u201d, digitally signing an entity, wherein the mapping is undertaken using a function \u201cf\u201d that is not collision intractable.
23. The method of claim 22, further comprising randomizing the function \u201cf\u201d by concatenating the message \u03bc with a random number \u03c1.
24. The method of claim 22, wherein the function \u201cf\u201d maps the message \u03bc to a point on a grid.
25. The method of claim 22, wherein the function \u201cf\u201d maps at least the message to a point on an auxiliary lattice.
26. The method of claim 22, further comprising verifying a digital signature at least in part by determining whether a difference between the lattice point \u201cy\u201d and the message point \u201cx\u201d is no more than a predetermined distance.
27. The method of claim 26, wherein the predetermined distance is related to the number of dimensions in the lattice .