Patent US6512739B1 successfully refreshed from Google Patents.
US6512739B1
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Method and apparatus for down conversion within an X-DSL receiver
Assignee: Ikanos Communications Inc
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Filing: 2001-02-07
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Granted: 2003-01-28
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Expires: 2021-02-07
Abstract
Abstract The current invention provides a method and apparatus for downconverting received digital data from the elevated frequencies at which the data is modulated. Various multi-tone communications systems (such as DMT in wire-line communication or OFDM in wireless communication) operate by up-converting output of the modulated signal at the output of the IFFT from baseband to a higher center frequency. Therefore, at the receiver, the inverse operation is required. At the receiver the signal must be down-converted to baseband before being available for processing by the FFT. In this invention, a simplified converter is provided, where the complex multiplication required by prior art downconverters is avoided, thus simplify the downconversion process and reducing power requirements. The apparatus and method may be implemented on a physical modem or a logical modem with the logical modem including a digital signal processor (DSP) coupled to an analog front end (AFE). The communication medium may include: wired, wireless and optical. The present invention provides a signal processing architecture that supports scalability of CO/DLC/ONU resources, and allows a significantly more flexible hardware response to the evolving X-DSL standards without over committing of hardware resources. As standards evolve hardware may be reconfigured to support the new standards.
Inventors
- 👤 Sam Heidari
- 👤 Behrooz Rezvani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 12:59
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/26; H04L27/2601; H04L27/2647; H04L5/00; H04L5/14
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
213 words
A communication device for coupling to a communication medium and receiving therefrom an analog signal with a multi-tone communication channel modulated thereon; and the communication device comprising: a converter with an input coupled to the analog signal and an output, and the converter for converting the analog signal to discrete digital samples at the output, at a sampling rate equivalent to twice a highest frequency exhibited by the multi-tone communication channel; a downconverter with an input coupled to the output of the converter and an output, and the downconverter to downconvert the communication channel to a zero center frequency and the downconversion corresponding with a multiplication of the discrete digital samples by a sequence exp (jπn) where n is a time index; a decimator with an output and an input coupled to the output of the downconverter to decimate the discrete digital samples output therefrom to a sampling rate corresponding with twice the highest frequency exhibited after downconversion by the downconverter; a fourier transform engine coupled to the output of the decimator for converting the communication channel from a time to a frequency domain and outputting an ordered set of tones corresponding thereto; and a tone re-orderer to re-order in a reverse order the ordered set of tones from the fourier transform engine.
Claim 2
Dependent Claim
213 words
A communication device for coupling to a communication medium and receiving therefrom an analog signal with a multi-tone communication channel modulated thereon; and the communication device comprising: a converter with an input coupled to the analog signal and an output, and the converter for converting the analog signal to discrete digital samples at the output, at a sampling rate equivalent to twice a highest frequency exhibited by the multi-tone communication channel; a downconverter with an input coupled to the output of the converter and an output, and the downconverter to downconvert the communication channel to a zero center frequency and the downconversion corresponding with a multiplication of the discrete digital samples by a sequence exp (jπn) where n is a time index; a decimator with an output and an input coupled to the output of the downconverter to decimate the discrete digital samples output therefrom to a sampling rate corresponding with twice the highest frequency exhibited after downconversion by the downconverter; a fourier transform engine coupled to the output of the decimator for converting the communication channel from a time to a frequency domain and outputting an ordered set of tones corresponding thereto; and a tone re-orderer to re-order in a reverse order the ordered set of tones from the fourier transform engine.
Claim 3
Dependent Claim
59 words
The communication device of claim 1 , wherein the converter comprises: an analog-to-digital converter for sampling the analog signal at a sampling rate greater than twice the highest frequency exhibited by the multi-tone communication channel; and an accompanying decimator to decimate the samples provided by the analog-to-digital converter to twice the highest frequency exhibited by the multi-tone communication channel.
Claim 4
Dependent Claim
39 words
The communication device of claim 1 , wherein the downconverter comprises: binary logic for inverting a sign of alternating ones of the discrete digital samples to effect the multiplying of the discrete digital samples by the sequence exp (jπn).
Claim 5
Dependent Claim
111 words
The communication device of claim 3 , wherein the binary logic comprises for digital samples expressed in a sign magnitude format: a binary counter outputting a binary stream alternating between “0” and “1” for each successive one of the digital samples; and an “XOR” logic gate with a first and a second input and an output, and with the first input coupled to receive a sign bit of successive ones of the digital samples and the second input coupled to the binary counter and with the down-conversion effected by an inversion of the sign bit of alternating ones of the discrete digital samples as effected at the output of the XOR.
Claim 6
Dependent Claim
63 words
The communication device of claim 3 , wherein the binary logic comprises for digital samples expressed in a two's compliment format: a binary counter outputting a binary stream alternating between “0” and “1” for each successive one of the digital samples; and an inverter coupled to binary counter to invert a sign of the digital samples when the binary counter output equals “1”.
Claim 7
Dependent Claim
18 words
The communication device of claim 1 , wherein the multi-tone communication channel exhibits a discrete multi-tone (DMT) modulation.
Claim 8
Dependent Claim
22 words
The communication device of claim 1 , with the various elements thereof configured to form a receive path of a physical modem.
Claim 9
Dependent Claim
22 words
The communication device of claim 1 , with the various elements thereof configured to form a receive path of a logical modem.
Claim 10
Dependent Claim
25 words
The communication device of claim 1 , wherein the communication medium includes at least one of a wired communication medium and a wireless communication medium.
Claim 11
Independent Claim
153 words
A method for receiving an analog signal with a multi-tone communication channel modulated thereon; and the method comprising: converting the analog signal to discrete digital samples at a sampling rate equivalent to twice a highest frequency exhibited by the multi-tone communication channel; down-converting the discrete digital samples converted in said converting act to a zero center frequency for the communication channel and the downconversion corresponding with a multiplication of the discrete digital samples by a sequence exp (jπn) where n is a time index; decimating the down-converted discrete digital samples down-converted in the down-converting act to a sampling rate corresponding with twice the highest frequency exhibited by the communication channel after down conversion in the down converting act; converting the decimated digital samples decimated in the decimating to an ordered set of tones in a frequency domain; and re-ordering in a reverse order the ordered set of tones converted in the converting act.
Claim 12
Independent Claim
153 words
A method for receiving an analog signal with a multi-tone communication channel modulated thereon; and the method comprising: converting the analog signal to discrete digital samples at a sampling rate equivalent to twice a highest frequency exhibited by the multi-tone communication channel; down-converting the discrete digital samples converted in said converting act to a zero center frequency for the communication channel and the downconversion corresponding with a multiplication of the discrete digital samples by a sequence exp (jπn) where n is a time index; decimating the down-converted discrete digital samples down-converted in the down-converting act to a sampling rate corresponding with twice the highest frequency exhibited by the communication channel after down conversion in the down converting act; converting the decimated digital samples decimated in the decimating to an ordered set of tones in a frequency domain; and re-ordering in a reverse order the ordered set of tones converted in the converting act.
Claim 13
Dependent Claim
52 words
The method of claim 10 , wherein the converting act further comprises: sampling the analog signal at a sampling rate greater than twice the highest frequency exhibited by the multi-tone communication channel; and decimating the samples provided by the sampling act to twice the highest frequency exhibited by the multi-tone communication channel.
Claim 14
Dependent Claim
38 words
The method of claim 10 , wherein the down converting act further comprises: inverting a sign of alternating ones of the discrete digital samples to effect the multiplying of the discrete digital samples by the sequence exp (jπn).
Claim 15
Dependent Claim
94 words
The method of claim 10 , with the digital samples expressed in a sign magnitude format and wherein the inverting act further comprises the acts of: generating a binary stream alternating between “0” and “1” for each successive one of the digital samples; and performing an “XOR” logic operation on a pair of inputs comprising the binary stream generated in the generating act and a sign bit of successive ones of the digital samples to effect the down conversion by an inversion of the sign bit of alternating ones of the discrete digital samples.
Claim 16
Dependent Claim
117 words
The method of claim 10 , with the digital samples expressed in a twos compliment format and wherein the inverting act further comprises: generating a binary stream alternating between “0” and “1” for each successive one of the digital samples; and performing an “XOR” logic operation on a pair of inputs comprising the binary stream generated in the generating act and a sign bit of successive ones of the digital samples to effect a portion of the down conversion by an inversion of the sign bit of alternating ones of the discrete digital samples; and inverting such additional bits of the alternating ones of the discrete digital samples as may be required by the twos compliment format.
Claim 17
Dependent Claim
17 words
The method of claim 10 , wherein the multi-tone communication channel exhibits a discrete multi-tone (DMT) modulation.
Claim 18
Dependent Claim
24 words
The method of claim 10 , wherein the communication medium includes at least one of a wired communication medium and a wireless communication medium.
Claim 19
Dependent Claim
171 words
A means for receiving an analog signal with a multi-tone communication channel modulated thereon; and the means comprising: means for converting the analog signal to discrete digital samples at a sampling rate equivalent to twice a highest frequency exhibited by the multi-tone communication channel; means for down converting the discrete digital samples converted by said means for converting act to a zero center frequency for the communication channel and the down conversion corresponding with a multiplication of the discrete digital samples by a sequence exp (jπn) where n is a time index; means for decimating the down-converted discrete digital samples down-converted by the means for down-converting to a sampling rate corresponding with twice the highest frequency exhibited by the communication channel after down conversion by the means for down conversion; means for converting the decimated digital samples decimated in the means for decimating to an ordered set of tones in a frequency domain; and means for re-ordering in a reverse order the ordered set of tones converted in the converting act.
Claim 20
Dependent Claim
171 words
A means for receiving an analog signal with a multi-tone communication channel modulated thereon; and the means comprising: means for converting the analog signal to discrete digital samples at a sampling rate equivalent to twice a highest frequency exhibited by the multi-tone communication channel; means for down converting the discrete digital samples converted by said means for converting act to a zero center frequency for the communication channel and the down conversion corresponding with a multiplication of the discrete digital samples by a sequence exp (jπn) where n is a time index; means for decimating the down-converted discrete digital samples down-converted by the means for down-converting to a sampling rate corresponding with twice the highest frequency exhibited by the communication channel after down conversion by the means for down conversion; means for converting the decimated digital samples decimated in the means for decimating to an ordered set of tones in a frequency domain; and means for re-ordering in a reverse order the ordered set of tones converted in the converting act.
Claim 21
Dependent Claim
60 words
The means for receiving of claim 17 , wherein the means for converting further comprises: means for sampling the analog signal at a sampling rate greater than twice the highest frequency exhibited by the multi-tone communication channel; and means for decimating the samples provided by the means for sampling to twice the highest frequency exhibited by the multi-tone communication channel.
Claim 22
Dependent Claim
42 words
The means for receiving of claim 17 , wherein the down converting means further comprises: means for inverting a sign of alternating ones of the discrete digital samples to effect the multiplying of the discrete digital samples by the sequence exp (jπn).
Claim 23
Dependent Claim
99 words
The means for receiving of claim 19 , with the digital samples expressed in a sign magnitude format and wherein the means for inverting further comprises: means for generating a binary stream alternating between “0” and “1” for each successive one of the digital samples; and means for performing an “XOR” logic operation on a pair of inputs comprising the binary stream generated by the means for generating and a sign bit of successive ones of the digital samples to effect the down conversion by an inversion of the sign bit of alternating ones of the discrete digital samples.
Claim 24
Dependent Claim
127 words
The means for receiving of claim 19 , with the digital samples expressed in a twos compliment format and wherein the means for inverting further comprises: means for generating a binary stream alternating between “0” and “1” for each successive one of the digital samples; and means for performing an “XOR” logic operation on a pair of inputs comprising the binary stream generated by the means for generating and a sign bit of successive ones of the digital samples to effect a portion of the down conversion by an inversion of the sign bit of alternating ones of the discrete digital samples; and means for inverting such additional bits of the alternating ones of the discrete digital samples as may be required by the twos compliment format.
References Cited (Backward Citations)
US6240150B1
Cited
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