US5226060A
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US
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Modem receiver with nonlinear equalization
Assignee: Motorola Mobility LLC
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Filing: 1992-01-08
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Granted: 1993-07-06
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Expires: 2012-01-08
Abstract
Abstract A modem with nonlinear equalization (100) receives a signal (101) that includes linear and nonlinear distortion. The modem includes a multiplier (107) that frequency shifts the signal to form a baseband signal, which is then sampled by an A/D converter (114) to provide a complex receiver input sample, R(n). A first equalizer (117) equalizes R(n) to form a first equalized result (n). A nonlinear generator (129) forms |R(n)| 2 R(n), which is then equalized by a second equalizer (133) to form a second equalized result (n). A summing device (121) combines the first equalized result (n) with the second equalized result (n) to form a composite equalized result (n). The modem includes a data recovery circuit (125) that determines a received signal point (n) based on the composite equalized result (n) and a predetermined constellation.
Inventors
- 👤 Richard L. Goodson
- 👤 Mickey C. Rushing
- 👤 Jack L. Hayes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:24
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03006; H04L25/03012; H04L25/03019; H04L25/03038; H04B; H04B3/00; H04B3/02; H04B3/04; H04B3/14
Claims Analysis
Total Claims: 44
Claim 1
Independent Claim
151 words
A modem receiver arranged for receiving a signal including a carrier signal that is modulated using a predetermined constellation having a plurality of signal points, the signal including linear and nonlinear distortion, the modem receiver further arranged for demodulating the signal to provide a received signal point (n), the modem receiver comprising: means for frequency shifting the signal to form a baseband signal; means for sampling the baseband signal to provide a complex receiver input sample, R(n); first equalizer means for equalizing R(n) to form a first equalized result (n); means for forming |R(n)| 2 R(n); second equalizer means for equalizing |R(n)| 2 R(n) to form a second equalized result (n); means for combining the first equalized result (n) with the second equalized result (n) to form a composite equalized result (n); means for determining a received signal point (n) based on the composite equalized result (n) and the predetermined constellation.
Claim 2
Dependent Claim
151 words
A modem receiver arranged for receiving a signal including a carrier signal that is modulated using a predetermined constellation having a plurality of signal points, the signal including linear and nonlinear distortion, the modem receiver further arranged for demodulating the signal to provide a received signal point (n), the modem receiver comprising: means for frequency shifting the signal to form a baseband signal; means for sampling the baseband signal to provide a complex receiver input sample, R(n); first equalizer means for equalizing R(n) to form a first equalized result (n); means for forming |R(n)| 2 R(n); second equalizer means for equalizing |R(n)| 2 R(n) to form a second equalized result (n); means for combining the first equalized result (n) with the second equalized result (n) to form a composite equalized result (n); means for determining a received signal point (n) based on the composite equalized result (n) and the predetermined constellation.
Claim 3
Dependent Claim
16 words
The modem receiver of claim 1, wherein the predetermined constellation is a quadrature amplitude modulation constellation.
Claim 4
Dependent Claim
16 words
The modem receiver of claim 2, wherein the first equalizer means is a linear adaptive type.
Claim 5
Dependent Claim
16 words
The modem receiver of claim 3, wherein the second equalizer means is a linear adaptive type.
Claim 6
Dependent Claim
28 words
The modem receiver of claim 4, further including: means for forming an error signal E(n) based on the received signal point (n) and the composite equalized result (n).
Claim 7
Dependent Claim
73 words
The modem receiver of claim 5 where the first equalizer means includes first coefficients (n) and the second equalizer means includes second coefficients (n), and where the modem receiver further includes: first update means for determining first coefficients (n+1) based on E(n) and R(n) to minimize the average squared magnitude of E(n); second update means for determining second coefficients (n+1) based on E(n) and R(n) to minimize the average squared magnitude of E(n).
Claim 8
Dependent Claim
44 words
The modem receiver of claim 6, wherein: the first coefficients (n+1) are determined so the gradient of the average squared magnitude of E(n) approaches zero, and the second coefficients (n+1) are determined so the gradient of the average squared magnitude of E(n) approaches zero.
Claim 9
Dependent Claim
48 words
The modem receiver of claim 6, wherein: the first coefficients (n+1) are determined to minimize the magnitude of the gradient of the average squared magnitude of E(n), and the second coefficients (n+1) are determined to minimize the magnitude of the gradient of the average squared magnitude of E(n).
Claim 10
Dependent Claim
26 words
The modem receiver of claim 6, wherein the second update means includes means for determining the second coefficients (n+1) based on E(n) and |R(n)| 2 R(n).
Claim 11
Dependent Claim
81 words
The modem receiver of claim 9, wherein: the first equalizer means is based on a least-means-squared algorithm and includes tap coefficients, A i , and wherein A i (n+1) is based on A i (n)-∂(n)R*(n-i)E(n), and, the second equalizer means is based on a least-means-squared algorithm and includes tap coefficients, B i , and wherein B i (n+1) is based on B i (n)-ƒ(n)|R(n-i)| 2 R*(n-i)E(n). where R*(n-i) is the complex conjugate of R(n-i) and ∂(n) and ƒ(n) are scaling factors.
Claim 12
Dependent Claim
169 words
An equalizer arranged for use with a modem receiver, the modem receiver arranged for receiving a signal including a carrier signal that is modulated using a predetermined constellation having a plurality of signal points, the signal including linear and nonlinear distortion, the modem receiver further arranged for demodulating the signal to provide a received signal point (n), the modem receiver comprising: means for frequency shifting the signal to form a baseband signal; means for sampling the baseband signal to provide a complex receiver input sample, R(n); the equalizer including: first equalizer means for equalizing R(n) to form a first equalized result (n); means for forming |R(n)| 2 R(n); second equalizer means for equalizing |R(n)| 2 R(n) to form a second equalized result (n); and, means for combining the first equalized result (n) with the second equalized result (n) to form a composite equalized result (n); the modem receiver further comprising means for determining a received signal point (n) based on the composite equalized result (n) and the predetermined constellation.
Claim 13
Dependent Claim
169 words
An equalizer arranged for use with a modem receiver, the modem receiver arranged for receiving a signal including a carrier signal that is modulated using a predetermined constellation having a plurality of signal points, the signal including linear and nonlinear distortion, the modem receiver further arranged for demodulating the signal to provide a received signal point (n), the modem receiver comprising: means for frequency shifting the signal to form a baseband signal; means for sampling the baseband signal to provide a complex receiver input sample, R(n); the equalizer including: first equalizer means for equalizing R(n) to form a first equalized result (n); means for forming |R(n)| 2 R(n); second equalizer means for equalizing |R(n)| 2 R(n) to form a second equalized result (n); and, means for combining the first equalized result (n) with the second equalized result (n) to form a composite equalized result (n); the modem receiver further comprising means for determining a received signal point (n) based on the composite equalized result (n) and the predetermined constellation.
Claim 14
Dependent Claim
15 words
The equalizer of claim 11, wherein the predetermined constellation is a quadrature amplitude modulation constellation.
Claim 15
Dependent Claim
15 words
The equalizer of claim 12, wherein the first equalizer means is a linear adaptive type.
Claim 16
Dependent Claim
15 words
The equalizer of claim 13, wherein the second equalizer means is a linear adaptive type.
Claim 17
Dependent Claim
27 words
The equalizer of claim 14, further including: means for forming an error signal E(n) based on the received signal point (n) and the composite equalized result (n).
Claim 18
Dependent Claim
68 words
The equalizer of claim 15 where the first equalizer means includes first coefficients (n) and the second equalizer means includes second coefficients (n), and further including: first update means for determining first coefficients (n+1) based on E(n) and R(n) to minimize the average squared magnitude of E(n); second update means for determining second coefficients (n+1) based on E(n) and R(n) to minimize the average squared magnitude of E(n).
Claim 19
Dependent Claim
43 words
The equalizer of claim 16, wherein: the first coefficients (n+1) are determined so the gradient of the average squared magnitude of E(n) approaches zero, and the second coefficients (n+1) are determined so the gradient of the average squared magnitude of E(n) approaches zero.
Claim 20
Dependent Claim
47 words
The equalizer of claim 16, wherein: the first coefficients (n+1) are determined to minimize the magnitude of the gradient of the average squared magnitude of E(n), and the second coefficients (n+1) are determined to minimize the magnitude of the gradient of the average squared magnitude of E(n).
Claim 21
Dependent Claim
25 words
The equalizer of claim 16, wherein the second update means includes means for determining the second coefficients (n+1) based on E(n) and |R(n)| 2 R(n).
Claim 22
Dependent Claim
80 words
The equalizer of claim 19, wherein: the first equalizer means is based on a least-means-squared algorithm and includes tap coefficients, A i , and wherein A i (n+1) is based on A i (n)-∂(n)R*(n-i)E(n), and, the second equalizer means is based on a least-means-squared algorithm and includes tap coefficients, B i , and wherein B i (n+1) is based on B i (n)-ƒ(n)|R(n-i)| 2 R*(n-i)E(n), where R*(n-i) is the complex conjugate of R(n-i) and ∂(n) and ƒ(n) are scaling factors.
Claim 23
Dependent Claim
148 words
In a modem receiver arranged for receiving a signal including a carrier signal that is modulated using a predetermined constellation having a plurality of signal points, the signal including linear and nonlinear distortion, a method for demodulating the signal to provide a received signal point (n), the method comprising the following steps: (a) frequency shifting the signal to form a baseband signal; (b) sampling the baseband signal to provide a complex receiver input sample, R(n); (c) equalizing R(n) with a first equalizer to form a first equalized result (n); (d) forming |R(n)| 2 R(n); (e) equalizing |R(n)| 2 R(n) with a second equalizer to form a second equalized result (n); (f) combining the first equalized result (n) with the second equalized result (n) to form a composite equalized result (n); (g) determining a received signal point (n) based on the composite equalized result (n) and the predetermined constellation.
Claim 24
Dependent Claim
148 words
In a modem receiver arranged for receiving a signal including a carrier signal that is modulated using a predetermined constellation having a plurality of signal points, the signal including linear and nonlinear distortion, a method for demodulating the signal to provide a received signal point (n), the method comprising the following steps: (a) frequency shifting the signal to form a baseband signal; (b) sampling the baseband signal to provide a complex receiver input sample, R(n); (c) equalizing R(n) with a first equalizer to form a first equalized result (n); (d) forming |R(n)| 2 R(n); (e) equalizing |R(n)| 2 R(n) with a second equalizer to form a second equalized result (n); (f) combining the first equalized result (n) with the second equalized result (n) to form a composite equalized result (n); (g) determining a received signal point (n) based on the composite equalized result (n) and the predetermined constellation.
Claim 25
Dependent Claim
15 words
The method of claim 21, wherein the predetermined constellation is a quadrature amplitude modulation constellation.
Claim 26
Dependent Claim
14 words
The method of claim 22, wherein the first equalizer is a linear adaptive type.
Claim 27
Dependent Claim
14 words
The method of claim 23, wherein the second equalizer is a linear adaptive type.
Claim 28
Dependent Claim
28 words
The method of claim 24 including the step of: (h) forming an error signal E(n) based on the received signal point (n) and the composite equalized result (n).
Claim 29
Dependent Claim
62 words
The method of claim 25 where the first equalizer includes first coefficients (n) and the second equalizer includes second coefficients (n) and including the steps of: (i) based on E(n) and R(n), determining first coefficients (n+1) to minimize the average squared magnitude of E(n); (j) based on E(n) and R(n), determining second coefficients (n+1) to minimize the average squared magnitude of E(n).
Claim 30
Dependent Claim
43 words
The method of claim 26, wherein: the first coefficients (n+1) are determined so the gradient of the average squared magnitude of E(n) approaches zero, and the second coefficients (n+1) are determined so the gradient of the average squared magnitude of E(n) approaches zero.
Claim 31
Dependent Claim
47 words
The method of claim 26, wherein: the first coefficients (n+1) are determined to minimize the magnitude of the gradient of the average squared magnitude of E(n), and the second coefficients (n+1) are determined to minimize the magnitude of the gradient of the average squared magnitude of E(n).
Claim 32
Dependent Claim
24 words
The method of claim 26, wherein step (j) includes a step of determining the second coefficients (n+1) based on E(n) and |R(n)| 2 R(n).
Claim 33
Dependent Claim
78 words
The method of claim 29, wherein: the first equalizer is based on a least-means-squared algorithm and includes tap coefficients, A i , and wherein A i (n+1) is based on A i (n)-∂(n)R*(n-i)E(n), and, the second equalizer is based on a least-means-squared algorithm and includes tap coefficients, B i , and wherein B i (n+1) is based on B i (n)-ƒ(n)|R(n-i)| 2 R*(n-i)E(n), where R*(n-i) is the complex conjugate of R(n-i) and ∂(n) and ƒ(n) are scaling factors.
Claim 34
Dependent Claim
161 words
A modem receiver arranged for receiving a signal including a carrier signal that is modulated using a predetermined constellation having a plurality of signal points, the signal including linear and nonlinear distortion, the modem receiver including a digital signal processor arranged for demodulating the signal to provide a received signal point (n) in accordance with a predetermined method, the predetermined method comprising the following steps: (a) frequency shifting the signal to form a baseband signal; (b) sampling the baseband signal to provide a complex receiver input sample, R(n); (c) equalizing R(n) with a first equalizer to form a first equalized result (n); (d) forming |R(n)| 2 R(n); (e) equalizing |R(n)| 2 R(n) with a second equalizer to form a second equalized result (n); (f) combining the first equalized result (n) with the second equalized result (n) to form a composite equalized result (n); (g) determining a received signal point (n) based on the composite equalized result (n) and the predetermined constellation.
Claim 35
Dependent Claim
161 words
A modem receiver arranged for receiving a signal including a carrier signal that is modulated using a predetermined constellation having a plurality of signal points, the signal including linear and nonlinear distortion, the modem receiver including a digital signal processor arranged for demodulating the signal to provide a received signal point (n) in accordance with a predetermined method, the predetermined method comprising the following steps: (a) frequency shifting the signal to form a baseband signal; (b) sampling the baseband signal to provide a complex receiver input sample, R(n); (c) equalizing R(n) with a first equalizer to form a first equalized result (n); (d) forming |R(n)| 2 R(n); (e) equalizing |R(n)| 2 R(n) with a second equalizer to form a second equalized result (n); (f) combining the first equalized result (n) with the second equalized result (n) to form a composite equalized result (n); (g) determining a received signal point (n) based on the composite equalized result (n) and the predetermined constellation.
Claim 36
Dependent Claim
16 words
The modem receiver of claim 31, wherein the predetermined constellation is a quadrature amplitude modulation constellation.
Claim 37
Dependent Claim
15 words
The modem receiver of claim 32, wherein the first equalizer is a linear adaptive type.
Claim 38
Dependent Claim
15 words
The modem receiver of claim 33, wherein the second equalizer is a linear adaptive type.
Claim 39
Dependent Claim
31 words
The modem receiver of claim 34, the method including the step of: (h) forming an error signal E(n) based on the received signal point (n) and the composite equalized result (n).
Claim 40
Dependent Claim
64 words
The modem receiver of claim 35 where the first equalizer includes first coefficients (n) and the second equalizer includes second coefficients (n), the method including the steps of: (i) based on E(n) and R(n), determining first coefficients (n+1) to minimize the average squared magnitude of E(n); (j) based on E(n) and R(n), determining second coefficients (n+1) to minimize the average squared magnitude of E(n).
Claim 41
Dependent Claim
44 words
The modem receiver of claim 36, wherein: the first coefficients (n+1) are determined so the gradient of the average squared magnitude of E(n) approaches zero, and the second coefficients (n+1) are determined so the gradient of the average squared magnitude of E(n) approaches zero.
Claim 42
Dependent Claim
48 words
The modem receiver of claim 36, wherein: the first coefficients (n+1) are determined to minimize the magnitude of the gradient of the average squared magnitude of E(n), and the second coefficients (n+1) are determined to minimize the magnitude of the gradient of the average squared magnitude of E(n).
Claim 43
Dependent Claim
26 words
The modem receiver of claim 36, wherein the step (j) includes a step of determining the second coefficients (n+1) based on E(n) and |R(n)| 2 R(n).
Claim 44
Dependent Claim
79 words
The modem receiver of claim 39, wherein: the first equalizer is based on a least-means-squared algorithm and includes tap coefficients, A i , and wherein A i (n+1) is based on A i (n)-∂(n)R*(n-i)E(n), and, the second equalizer is based on a least-means-squared algorithm and includes tap coefficients, B i , and wherein B i (n+1) is based on B i (n)-ƒ(n)|R(n-i)| 2 R*(n-i)E(n), where R*(n-i) is the complex conjugate of R(n-i) and ∂(n) and ƒ(n) are scaling factors.
References Cited (Backward Citations)
US4213095A
Cited
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