US6092122A — xDSL DMT modem using sub-channel selection to ach…

Claim 1

Independent Claim 265 words

A high speed communications system for receiving transmitted data from a remote transceiver, which transceiver is capable of transmitting an analog signal using up to M separate subchannels within a bandwidth F through a channel to said system, said system being configured to operate within a personal computer system including a host processing device for executing user application programs, said system comprising: a channel interface circuit for coupling to and receiving said analog signal from the channel; and a front end receiving circuit for sampling the analog signal and generating a digital signal based on such analog signal; a digital signal processing circuit for processing the digital signal, said digital signal processing circuit being implemented at least in part by signal processing software executed by the host processing device, the digital signal including data from a first frequency bandwidth portion f1 of said bandwidth F containing N separate subchannels, which N separate sub-channels are a subset of said M separate subchannels; and a bus interface circuit for transmitting said digital signal to the host processing device through a data bus associated with said personal computer system so that said signal processing software can also process such digital signal; and wherein the transmitted data is extracted based on an evaluation by the digital signal processing circuit of performance characteristics of said data carrying signals; and further wherein said system supports a maximum number of said N separate sub-channels, which maximum number is based on transmission characteristics of said channel, signal processing power of said host processing device, and loading conditions experienced by said host processing device.

Claim 2

Dependent Claim 265 words

A high speed communications system for receiving transmitted data from a remote transceiver, which transceiver is capable of transmitting an analog signal using up to M separate subchannels within a bandwidth F through a channel to said system, said system being configured to operate within a personal computer system including a host processing device for executing user application programs, said system comprising: a channel interface circuit for coupling to and receiving said analog signal from the channel; and a front end receiving circuit for sampling the analog signal and generating a digital signal based on such analog signal; a digital signal processing circuit for processing the digital signal, said digital signal processing circuit being implemented at least in part by signal processing software executed by the host processing device, the digital signal including data from a first frequency bandwidth portion f1 of said bandwidth F containing N separate subchannels, which N separate sub-channels are a subset of said M separate subchannels; and a bus interface circuit for transmitting said digital signal to the host processing device through a data bus associated with said personal computer system so that said signal processing software can also process such digital signal; and wherein the transmitted data is extracted based on an evaluation by the digital signal processing circuit of performance characteristics of said data carrying signals; and further wherein said system supports a maximum number of said N separate sub-channels, which maximum number is based on transmission characteristics of said channel, signal processing power of said host processing device, and loading conditions experienced by said host processing device.

Claim 3

Dependent Claim 46 words

The system of claim 1, wherein a sampling rate required by the front end circuit to generate the digital signal from the N sub-channels is reduced by an integer factor k from that required to generate a digital signal from the M sub-channels, and where k=M/N.

Claim 4

Dependent Claim 31 words

The system of claim 2, wherein the N subchannels can be selected during an initialization process setting up a data link to the remote transceiver, from a set of M/k sub-channels.

Claim 5

Dependent Claim 50 words

The system of claim 1, wherein an additional number of data carrying signals P from the M data carrying signals (N+P<M) can be processed if transmission characteristics of said channel, signal processing power of said host processing device, and loading conditions experienced by said host processing device permit such processing.

Claim 6

Dependent Claim 23 words

The system of claim 4, further including one or more anti-aliasing filters for passing the N+P subchannels and an analog to digital converter.

Claim 7

Dependent Claim 53 words

The system of claim 1, wherein the front end receiving circuit includes: (I) a bandpass filter for passing the first frequency bandwidth portion f1 of said bandwidth F; (ii) and an analog to digital converter; and wherein the digital signal processing circuit also includes a digital signal processor coupled to a programmable memory.

Claim 8

Dependent Claim 61 words

The system of claim 1, wherein a data received rate of the system can be increased by modularly augmenting either or both of: (i) the front end receiving circuit to include additional bandwidth and analog to digital conversion capacity; (ii) the digital signal processing circuit, such that an additional number of subchannels P from the M subchannels (N+P<M) can be processed.

Claim 9

Dependent Claim 16 words

The system of claim 7, wherein the front end receiving circuit has a programmable frequency response.

Claim 10

Dependent Claim 56 words

The system of claim 1, further including a front end transmitting circuit for transmitting control information to cause said remote transceiver to transmit downstream data only using the N sub-channels, so that selection of said N sub-channels, and control of a data rate in the channel, is controlled by the system, and not the remote transceiver.

Claim 11

Dependent Claim 52 words

The system of claim 9, wherein the control information transmitted to the remote transceiver includes feedback information from the digital signal processing circuit indicating that only N of the M sub-channels are to be loaded with data for data transmission, even if said channel is capable of supporting more than N sub-channels.

Claim 12

Dependent Claim 53 words

The system of claim 10, wherein the control information transmitted to the remote transceiver further includes feedback information indicating that: (i) the system and remote transceiver have compatible transmission signal protocol characteristics; and (ii) that they are connected through a channel having substantial signal attenuation characteristics for sub-channels other than the N sub-channels.

Claim 13

Dependent Claim 33 words

The system of claim 1, further including a front end transmitting circuit for transmitting a data transmission to the remote transceiver using a second frequency bandwidth F2 different from F, and L sub-channels.

Claim 14

Dependent Claim 228 words

A high speed communications system for receiving selected data contained in N Discrete Multi-Tone (DMT) modulated sub-channels from a remote transceiver capable of transmitting an analog signal containing up to M DMT modulated sub-channels through a channel to said system, said system comprising: a channel interface circuit for coupling to and receiving said analog signal from the channel; an analog front end circuit for sampling the analog signal and converting it to a digital signal, the front end circuit including an anti-aliasing filter and an analog to digital converter; a digital signal processing circuit for extracting said selected data by demodulating sub-channels in said digital signal, said demodulating being performed by signal processing software executing on a host processing device the digital signal including data only from said N DMT sub-channels, where N is a subset of the M DMT modulated sub-channels, such that N<=M; an interface circuit for coupling said analog front end circuit to a data bus within a personal computer system associated with said host processing device so that said demodulating of said digital signal can be performed by said signal processing software; and wherein said system supports a maximum number of said N separate DMT sub-channels, which maximum number is based on transmission characteristics of said channel, signal processing power of said host processing device, and loading conditions experienced by said host processing device.

Claim 15

Dependent Claim 228 words

A high speed communications system for receiving selected data contained in N Discrete Multi-Tone (DMT) modulated sub-channels from a remote transceiver capable of transmitting an analog signal containing up to M DMT modulated sub-channels through a channel to said system, said system comprising: a channel interface circuit for coupling to and receiving said analog signal from the channel; an analog front end circuit for sampling the analog signal and converting it to a digital signal, the front end circuit including an anti-aliasing filter and an analog to digital converter; a digital signal processing circuit for extracting said selected data by demodulating sub-channels in said digital signal, said demodulating being performed by signal processing software executing on a host processing device the digital signal including data only from said N DMT sub-channels, where N is a subset of the M DMT modulated sub-channels, such that N<=M; an interface circuit for coupling said analog front end circuit to a data bus within a personal computer system associated with said host processing device so that said demodulating of said digital signal can be performed by said signal processing software; and wherein said system supports a maximum number of said N separate DMT sub-channels, which maximum number is based on transmission characteristics of said channel, signal processing power of said host processing device, and loading conditions experienced by said host processing device.

Claim 16

Dependent Claim 47 words

The system of claim 13, wherein a sampling rate required by the analog front end circuit to generate the digital signal from the N sub-channels is reduced by an integer factor k from that required to generate a digital signal from the M sub-channels, and where k=M/N.

Claim 17

Dependent Claim 25 words

The system of claim 14, wherein the N sub-channels can be selected during an initialization process setting up a data link to the remote transceiver.

Claim 18

Dependent Claim 76 words

The system of claim 13, wherein the selected data can be altered to further include data obtained from an additional second number of sub-channels P taken from the set of M subchannels, so that an additional number of sub-channels (N+P<M) can be demodulated if transmission characteristics of said channel, signal processing power of said host processing device, and loading conditions experienced by said host processing device permit processing of said additional second number of subchannels P.

Claim 19

Dependent Claim 25 words

The system of claim 16, further including one or more anti-aliasing filters for passing the first number N and second number P of said sub-channels.

Claim 20

Dependent Claim 47 words

The system of claim 13, wherein the front end receiving circuit includes: (i) a bandpass filter for passing the N sub-channels; and (ii) and an analog to digital converter; and wherein the digital signal processing circuit further includes a digital signal processor coupled to a programmable memory.

Claim 21

Dependent Claim 85 words

The system of claim 13, wherein a data received rate of the system can be increased by modularly augmenting either or both of: (i) the front end circuit to include additional bandwidth and analog to digital conversion capacity; (ii) the digital signal processing circuit, such that an additional second number of sub-channels P taken from the M sub-channels (N+P<M) can be demodulated when said host processing device is upgraded to have a signal processing performance sufficient to process said additional second number of subchannels P.

Claim 22

Dependent Claim 16 words

The system of claim 19, wherein the front end receiving circuit has a programmable frequency response.

Claim 23

Dependent Claim 56 words

The system of claim 13, further including a front end transmitting circuit for transmitting control information to cause said upstream transceiver to transmit downstream data only using the N sub-channels, such that selection of said N subchannels, and control of a data rate in the channel, is controlled by the system, and not the remote transceiver.

Claim 24

Dependent Claim 49 words

The system of claim 21, wherein the control information transmitted to the remote transceiver includes feedback information indicating that only N of the M sub-channels are to be loaded with data for downstream data transmission, even during times when said channel is capable of supporting more than N sub-channels.

Claim 25

Dependent Claim 56 words

The system of claim 22, wherein the control information transmitted to the remote transceiver further includes feedback information indicating that: (i) the system and transceiver have compatible transmission signal protocol characteristics; and (ii) that the system and remote transceiver are connected through a channel with substantial signal attenuation characteristics for sub-channels other than the N sub-channels.

Claim 26

Dependent Claim 17 words

The system of claim 13, wherein the channel supports T1.413 asymmetric digital subscriber loop (ADSL) transmission standards.

Claim 27

Dependent Claim 36 words

The system of claim 13, further including a front end transmitting circuit for transmitting data transmission to the remote transceiver using a second set of modulated sub-channels L separate from the M sub-channels, and where L<M.

Claim 28

Dependent Claim 252 words

A high speed T.413 capable communications data receiver for receiving data through a channel at a first data rate X from a remote T1.413 capable transmitter, which remote transmitter is capable of transmitting an analog signal carrying a data stream at a rate Y, where Y is a rate achievable by a full rate T1.413 capable transmitter, and Y>X, the receiver comprising: a channel interface circuit for coupling to and receiving said data stream; an analog front end circuit for data sampling the analog signal and converting it to a digital signal; a processing circuit for extracting selected data from the digital signal, and for generating a transmission control signal for causing said remote transmitter to transmit at a data rate substantially equal to said data rate X during a data stream transmission, and using an initialization and transmission protocol in conformance with T1.413 ADSL transmission standards; an interface circuit for coupling said analog front end circuit to said personal computer system data bus; wherein data sampling circuitry requirements of the analog front end circuit and extracting circuitry requirements of the processing circuit reduced from that otherwise required to support data rate Y because data sampling and extracting is only performed for a fractional portion of the total data stream that can be transmitted by said remote transmitter; and further wherein a maximum value of said data rate X achievable by said receiver is limited according to availability of signal processing resources to said processing circuit and transmission conditions of the channel.

Claim 29

Dependent Claim 252 words

A high speed T.413 capable communications data receiver for receiving data through a channel at a first data rate X from a remote T1.413 capable transmitter, which remote transmitter is capable of transmitting an analog signal carrying a data stream at a rate Y, where Y is a rate achievable by a full rate T1.413 capable transmitter, and Y>X, the receiver comprising: a channel interface circuit for coupling to and receiving said data stream; an analog front end circuit for data sampling the analog signal and converting it to a digital signal; a processing circuit for extracting selected data from the digital signal, and for generating a transmission control signal for causing said remote transmitter to transmit at a data rate substantially equal to said data rate X during a data stream transmission, and using an initialization and transmission protocol in conformance with T1.413 ADSL transmission standards; an interface circuit for coupling said analog front end circuit to said personal computer system data bus; wherein data sampling circuitry requirements of the analog front end circuit and extracting circuitry requirements of the processing circuit reduced from that otherwise required to support data rate Y because data sampling and extracting is only performed for a fractional portion of the total data stream that can be transmitted by said remote transmitter; and further wherein a maximum value of said data rate X achievable by said receiver is limited according to availability of signal processing resources to said processing circuit and transmission conditions of the channel.

Claim 30

Dependent Claim 35 words

The system of claim 26, wherein the analog front end circuit further includes anti-aliasing filter for filtering the analog signal to generate the fractional portion of the data stream that requires data sampling and extracting.

Claim 31

Dependent Claim 60 words

The system of claim 26, further including a front end transmitting circuit for transmitting the transmission control signal from the processing circuit to cause said remote transceiver to transmit downstream data only at said data rate X so that selection and control of said data rate X in the channel is controlled by the system, and not the remote transceiver.

Claim 32

Dependent Claim 43 words

The system of claim 26, further including a front end transmitting circuit for transmitting a data transmission to the remote transceiver using a transmit data rate intentionally constrained by the system to be less than a maximum receive rate of the remote transceiver.

Claim 33

Dependent Claim 35 words

The system of claim 26, wherein the ratio of X to Y is approximately 0.5 or less, and this ratio can be varied by allocating different amounts of signal processing resources to said processing circuit.

Claim 34

Dependent Claim 239 words

A high speed communications system for communicating data to a host processing device from a remote transceiver capable of transmitting M Discrete Multi-Tone (DMT) modulated subchannels embodied in an analog data transmission signal using up to a bandwidth F in a channel coupled to said system, said system comprising: a channel interface circuit for coupling to and receiving said analog data signal from the channel; and a front end receiving circuit for processing the analog data signal and converting it to a digital signal; and a digital signal processing circuit for extracting selected data from the digital signal, the digital signal including data from a first frequency bandwidth portion f1 of said bandwidth F, and which data corresponds to a number N of said M DMT modulated subchannels, where N<=M/k, and where k is an integer >=2; said digital signal processing circuit also generating feedback information indicating to the remote transceiver that the bandwidth other than f1 is unsuitable for data transmission even when said channel can support said bandwidth F, and for indicating to said remote transceiver that said system is a reduced rate but otherwise fully compliant T.1413 transceiver; and a bus interface circuit for transmitting said selected data to the host processing device; and wherein a maximum value of subchannels N supported by said system is limited according to availability of signal processing resources to said digital signal processing circuit and transmission conditions of the channel.

Claim 35

Dependent Claim 239 words

A high speed communications system for communicating data to a host processing device from a remote transceiver capable of transmitting M Discrete Multi-Tone (DMT) modulated subchannels embodied in an analog data transmission signal using up to a bandwidth F in a channel coupled to said system, said system comprising: a channel interface circuit for coupling to and receiving said analog data signal from the channel; and a front end receiving circuit for processing the analog data signal and converting it to a digital signal; and a digital signal processing circuit for extracting selected data from the digital signal, the digital signal including data from a first frequency bandwidth portion f1 of said bandwidth F, and which data corresponds to a number N of said M DMT modulated subchannels, where N<=M/k, and where k is an integer >=2; said digital signal processing circuit also generating feedback information indicating to the remote transceiver that the bandwidth other than f1 is unsuitable for data transmission even when said channel can support said bandwidth F, and for indicating to said remote transceiver that said system is a reduced rate but otherwise fully compliant T.1413 transceiver; and a bus interface circuit for transmitting said selected data to the host processing device; and wherein a maximum value of subchannels N supported by said system is limited according to availability of signal processing resources to said digital signal processing circuit and transmission conditions of the channel.

Claim 36

Dependent Claim 15 words

The system of claim 31, wherein the feedback information contains intentionally altered channel characteristic information.

Claim 37

Dependent Claim 54 words

The system of claim 32, wherein the feedback information, including the size and center of first frequency bandwidth portion f1, can be controlled by the host processing device, such that selection of said N subchannels, and control of a data rate in the channel, is controlled by the system, and not the remote transceiver.

Claim 38

Dependent Claim 37 words

The system of claim 33, wherein the ratio of f1 to F is approximately 0.5 or less, and this ratio can be increased through modular additions to the front end receiving circuit and/or to the processing circuit.

Claim 39

Independent Claim 269 words

A method of operating a high speed communications system that is coupled through a channel to a remote transceiver, said transceiver capable of supporting an analog data transmission signal having up to a bandwidth F, said method comprising: (a) configuring said system to achieve a data receive rate X; and (b) receiving an analog initialization signal from the remote transceiver through the channel; and (c) generating a digital signal based on a first frequency bandwidth portion f1 sufficient to meet data receive rate X; and (d) transmitting said digital signal across a digital data bus to a host processing device which is located within a computer system incorporating the high speed communications system; and (e) executing a signal processing routine using said host processing device so as to process the digital signal to extract information relating to characteristics of data carrying signals contained within first frequency bandwidth portion f1; and (f) executing an initialization routine using said host processing device for generating feedback information indicating to the remote transceiver that bandwidth other than the first frequency bandwidth f1 should not be used for data transmission; and (g) receiving an analog data transmission signal having a bandwidth f1 from said remote transceiver; and (h) generating a digital data transmission signal based on sampling the analog data transmission signal; and (i) repeating step (e) above for said digital data transmission signal, and for every other digital data transmission signal received thereafter by the system; and wherein a maximum data receive rate is limited according to availability of signal processing resources to said host processing device and transmission conditions of the channel.

Claim 40

Independent Claim 269 words

A method of operating a high speed communications system that is coupled through a channel to a remote transceiver, said transceiver capable of supporting an analog data transmission signal having up to a bandwidth F, said method comprising: (a) configuring said system to achieve a data receive rate X; and (b) receiving an analog initialization signal from the remote transceiver through the channel; and (c) generating a digital signal based on a first frequency bandwidth portion f1 sufficient to meet data receive rate X; and (d) transmitting said digital signal across a digital data bus to a host processing device which is located within a computer system incorporating the high speed communications system; and (e) executing a signal processing routine using said host processing device so as to process the digital signal to extract information relating to characteristics of data carrying signals contained within first frequency bandwidth portion f1; and (f) executing an initialization routine using said host processing device for generating feedback information indicating to the remote transceiver that bandwidth other than the first frequency bandwidth f1 should not be used for data transmission; and (g) receiving an analog data transmission signal having a bandwidth f1 from said remote transceiver; and (h) generating a digital data transmission signal based on sampling the analog data transmission signal; and (i) repeating step (e) above for said digital data transmission signal, and for every other digital data transmission signal received thereafter by the system; and wherein a maximum data receive rate is limited according to availability of signal processing resources to said host processing device and transmission conditions of the channel.

Claim 41

Dependent Claim 40 words

The method of claim 35, further including a step: determining an optimal size and location of first frequency bandpass portion f1 in response to a determination of an amount of processing required to extract the data from the digital signal.

Claim 42

Dependent Claim 17 words

The method of claim 35, wherein the system transmits feedback information containing intentionally altered channel characteristic information.

Claim 43

Dependent Claim 33 words

The method of claim 35, wherein the analog data transmission is comprised of M separately modulated sub-channels, and the selected data is contained in a subset N of the M sub-channels, where N<M.

Claim 44

Dependent Claim 36 words

The method of claim 38, further including a step: determining an optimal set of said N sub-channels based on the channel characteristics and an amount of processing required to extract the data from the digital signal.

Claim 45

Dependent Claim 41 words

The method of claim 39, further including a step wherein protocol information pertaining to standards applicable to Asymmetric Digital Subscriber Loops is transmitted between the remote data transceiver and the system so as to set up a T1.413 compatible data link.

Claim 46

Dependent Claim 209 words

A software based modem for use in a personal computer system, comprising: a channel interface circuit for coupling to and receiving an analog signal from the channel, said analog signal being comprised of N separately modulated sub-carriers; and a front end receiving circuit for sampling the analog signal and generating a digital signal based on such analog signal, the digital signal including received data from said N separately modulated sub-carriers; a bus interface coupled to said front end receiving circuit, and configured for transmitting said received data across a data bus within the personal computer system to a host processing device; a software digital signal processing routine adapted for execution on the host processing device and for generating an extracted data stream by processing said received data, said software digital signal processing routine processing said received data at a rate related to a maximum amount of signal processing resources available to said software digital signal processing routine during a transmission session; and wherein the software modem can achieve a receive data rate during said transmission session that exceeds 500 Kb/s in said channel when said maximum amount of signal processing resources are available to said host processing device and transmission conditions in the channel support such receive data rate.

Claim 47

Dependent Claim 209 words

A software based modem for use in a personal computer system, comprising: a channel interface circuit for coupling to and receiving an analog signal from the channel, said analog signal being comprised of N separately modulated sub-carriers; and a front end receiving circuit for sampling the analog signal and generating a digital signal based on such analog signal, the digital signal including received data from said N separately modulated sub-carriers; a bus interface coupled to said front end receiving circuit, and configured for transmitting said received data across a data bus within the personal computer system to a host processing device; a software digital signal processing routine adapted for execution on the host processing device and for generating an extracted data stream by processing said received data, said software digital signal processing routine processing said received data at a rate related to a maximum amount of signal processing resources available to said software digital signal processing routine during a transmission session; and wherein the software modem can achieve a receive data rate during said transmission session that exceeds 500 Kb/s in said channel when said maximum amount of signal processing resources are available to said host processing device and transmission conditions in the channel support such receive data rate.

Claim 48

Dependent Claim 29 words

The software modem of claim 41, further wherein said software digital signal processing routine performs data pump operations associated with extracting a data stream from an T1.413 modulated signal.

Claim 49

Dependent Claim 25 words

The software modem of claim 42, wherein said software digital signal processing routine also performs initialization operations associated with establishing a T1.413 compatible data link.

Claim 50

Dependent Claim 43 words

The software modem of claim 41, further wherein a maximum number of subchannels M are supportable in the channel, and said N subchannels are selected from a reduced set of said subchannels M, such that N<=M/k, where k is an integer scaling factor.

Claim 51

Dependent Claim 34 words

The software modem of claim 41, further wherein said maximum amount of signal processing resources available to said software digital signal processing routine can be allocated by a user of said personal computer system.

Claim 52

Dependent Claim 220 words

A high speed system for communicating with an ANSI T1.413 compatible remote transceiver, which remote transceiver is capable of transmitting a first analog signal using up to M discrete multi-tone (DMT) modulated subchannels within an available bandwidth F through a channel to said system, said system comprising: a digital processing circuit, said digital processing circuit being configured: (i) for receiving a first digital signal from a channel interface circuit coupled to the remote transceiver, said first digital signal being derived from said first analog signal; (ii) for extracting a data stream from the first digital signal, the first digital signal including data from N variable DMT modulated sub-channels located within a receive frequency bandwidth portion f1 of the bandwidth F, where N<=M/k, and where k is an integer >=1; (iii) for setting up a data link with the ANSI T1.413 compatible remote transceiver which complies with T1.413 signal protocols; wherein the system can set up a bi-directional data link with the ANSI T1.413 compatible remote transceiver, such that both a transmit and receive data rate in said bi-directional data link is configured by said system and not the ANSI T1.413 compatible remote transceiver; and further wherein the bi-directional data link is intentionally constrained by the system to use less than the available transmit bandwidth F available to the remote transceiver.

Claim 53

Dependent Claim 220 words

A high speed system for communicating with an ANSI T1.413 compatible remote transceiver, which remote transceiver is capable of transmitting a first analog signal using up to M discrete multi-tone (DMT) modulated subchannels within an available bandwidth F through a channel to said system, said system comprising: a digital processing circuit, said digital processing circuit being configured: (i) for receiving a first digital signal from a channel interface circuit coupled to the remote transceiver, said first digital signal being derived from said first analog signal; (ii) for extracting a data stream from the first digital signal, the first digital signal including data from N variable DMT modulated sub-channels located within a receive frequency bandwidth portion f1 of the bandwidth F, where N<=M/k, and where k is an integer >=1; (iii) for setting up a data link with the ANSI T1.413 compatible remote transceiver which complies with T1.413 signal protocols; wherein the system can set up a bi-directional data link with the ANSI T1.413 compatible remote transceiver, such that both a transmit and receive data rate in said bi-directional data link is configured by said system and not the ANSI T1.413 compatible remote transceiver; and further wherein the bi-directional data link is intentionally constrained by the system to use less than the available transmit bandwidth F available to the remote transceiver.

Claim 54

Dependent Claim 41 words

The system of claim 46, further wherein M is >200, k>=2, and N can be varied between 1 and a value >100 depending on processing characteristics of said digital processing circuit, loading on said digital processing circuit, and channel transmission conditions.

Claim 55

Dependent Claim 19 words

The system of claim 46, wherein said system operates as a full rate or reduced rate T1.413 compliant transceiver.

Claim 56

Dependent Claim 30 words

The system of claim 46, further wherein portions of said digital processing circuit are implemented by a software routine executed by a host processing device within a personal computer system.

Claim 57

Dependent Claim 28 words

The system of claim 49, further wherein said channel interface circuit is physically separated from said host processing device but electrically connected through a personal computer system bus.

Claim 58

Dependent Claim 260 words

A high speed system for communicating with a remote transceiver, which remote transceiver supports a T1.413 ADSL data link by transmitting a first analog signal using up to a number M discrete multi-tone (DMT) modulated subchannels within an available bandwidth F through a channel to said system, said high speed system comprising: a channel interface circuit for receiving said analog signal from the channel; and a front end receiving circuit coupled to said channel interface circuit, said front end circuit being adapted for: (i) sampling the first analog signal; and (ii) generating a first received digital signal based on such first analog signal; and a digital signal processing circuit coupled to said front end receiving circuit, said digital signal processing circuit being configured: (i) for extracting a data stream from the first digital signal, the first digital signal including data from N DMT subchannels located within a receive frequency bandwidth portion f1 of the bandwidth F (f1<=F), where N is a variable subset of the M subchannels, and N can be configured by the high speed system to have a value between 1 and M; and (ii) for signaling to said remote transceiver that the high speed system supports only a reduced data rate, said reduced data rate being only a fractional portion of that of a full rate T1.413 ADSL transceiver; and (iii) for adjusting said reduced data rate depending on computational resources available to said digital signal processing circuit for extracting said data stream from said first digital signal and depending on signal transmission conditions in the channel.

Claim 59

Dependent Claim 260 words

A high speed system for communicating with a remote transceiver, which remote transceiver supports a T1.413 ADSL data link by transmitting a first analog signal using up to a number M discrete multi-tone (DMT) modulated subchannels within an available bandwidth F through a channel to said system, said high speed system comprising: a channel interface circuit for receiving said analog signal from the channel; and a front end receiving circuit coupled to said channel interface circuit, said front end circuit being adapted for: (i) sampling the first analog signal; and (ii) generating a first received digital signal based on such first analog signal; and a digital signal processing circuit coupled to said front end receiving circuit, said digital signal processing circuit being configured: (i) for extracting a data stream from the first digital signal, the first digital signal including data from N DMT subchannels located within a receive frequency bandwidth portion f1 of the bandwidth F (f1<=F), where N is a variable subset of the M subchannels, and N can be configured by the high speed system to have a value between 1 and M; and (ii) for signaling to said remote transceiver that the high speed system supports only a reduced data rate, said reduced data rate being only a fractional portion of that of a full rate T1.413 ADSL transceiver; and (iii) for adjusting said reduced data rate depending on computational resources available to said digital signal processing circuit for extracting said data stream from said first digital signal and depending on signal transmission conditions in the channel.

Claim 60

Dependent Claim 10 words

The system of claim 51, further wherein M is >200.

Claim 61

Dependent Claim 19 words

The system of claim 51, wherein said system operates as a full rate or reduced rate T1.413 compliant transceiver.

Claim 62

Dependent Claim 31 words

The system of claim 51, further wherein portions of said digital signal processing circuit are implemented by a software routine executed by a host processing device within a personal computer system.

Claim 63

Dependent Claim 33 words

The system of claim 54, further wherein said channel interface circuit and analog front end circuit are physically separated from said host processing device but electrically connected through a personal computer system bus.

Claim 64

Dependent Claim 173 words

A high speed system for maintaining a data link with an ANSI T1.413 compatible remote transceiver through a data channel, said system comprising: a digital signal processing circuit, said digital signal processing circuit being configured: (i) for setting up the data link with the ANSI T1.413 compatible remote transceiver which data link complies with T1.413 data signal protocols; and (iv) for supporting a variable channel data rate which can vary from a full data rate achievable by an ANSI T1.413 compatible ADSL transceiver connected in such data channel to such system, to a fractional portion of such full data rate; (ii) for achieving said variable channel data rate by varying a number of sub-channels N used for carrying data in the data channel, where M is a maximum number of sub-channels supportable in the data channel, k is an integer >=1, and N<=M/k; wherein N is configured based on computing resources available to said digital signal processing circuit, performance characteristics of the ANSI T1.413 compatible remote transceiver, and transmission conditions in the channel.

Claim 65

Dependent Claim 173 words

A high speed system for maintaining a data link with an ANSI T1.413 compatible remote transceiver through a data channel, said system comprising: a digital signal processing circuit, said digital signal processing circuit being configured: (i) for setting up the data link with the ANSI T1.413 compatible remote transceiver which data link complies with T1.413 data signal protocols; and (iv) for supporting a variable channel data rate which can vary from a full data rate achievable by an ANSI T1.413 compatible ADSL transceiver connected in such data channel to such system, to a fractional portion of such full data rate; (ii) for achieving said variable channel data rate by varying a number of sub-channels N used for carrying data in the data channel, where M is a maximum number of sub-channels supportable in the data channel, k is an integer >=1, and N<=M/k; wherein N is configured based on computing resources available to said digital signal processing circuit, performance characteristics of the ANSI T1.413 compatible remote transceiver, and transmission conditions in the channel.

Claim 66

Dependent Claim 10 words

The system of claim 56, further wherein M is >200.

Claim 67

Dependent Claim 19 words

The system of claim 56, wherein said system operates as a full rate or reduced rate T1.413 compliant transceiver.

Claim 68

Dependent Claim 31 words

The system of claim 56, further wherein portions of said digital signal processing circuit are implemented by a software routine executed by a host processing device within a personal computer system.

Claim 69

Dependent Claim 34 words

The system of claim 59, further including a channel interface circuit and analog front end circuit that are physically separated from said host processing device but electrically connected through a personal computer system bus.

Claim 70

Dependent Claim 214 words

A high speed system for communicating with a remote transceiver, which remote transceiver operates at a data transmission sampling rate B, and can transmit a first analog signal using up to a maximum number M modulated subchannels within an available bandwidth F through a channel to said system, the high speed system comprising: a channel interface circuit for coupling to and receiving said analog signal from the channel; and a front end receiving circuit coupled to said channel interface circuit, said front end circuit being adapted for: (iii) sampling the first analog signal, said sampling being performed at a sampling rate B', where B'=B/k, and where k is an integer >=2; and (iv) generating a first received digital signal based on such first analog signal; and a digital signal processing circuit coupled to said front end receiving circuit, said digital signal processing circuit being configured: (iv) for extracting a data stream from the first digital signal, the first digital signal including data from N subchannels located within a receive frequency bandwidth portion f1 of the bandwidth F (f1<=F), where N is a subset of the maximum number of M subchannels, N<=M/k; and (v) for signaling to said remote transceiver that the high speed system supports a subset of the maximum number of subchannels M.

Claim 71

Dependent Claim 214 words

A high speed system for communicating with a remote transceiver, which remote transceiver operates at a data transmission sampling rate B, and can transmit a first analog signal using up to a maximum number M modulated subchannels within an available bandwidth F through a channel to said system, the high speed system comprising: a channel interface circuit for coupling to and receiving said analog signal from the channel; and a front end receiving circuit coupled to said channel interface circuit, said front end circuit being adapted for: (iii) sampling the first analog signal, said sampling being performed at a sampling rate B', where B'=B/k, and where k is an integer >=2; and (iv) generating a first received digital signal based on such first analog signal; and a digital signal processing circuit coupled to said front end receiving circuit, said digital signal processing circuit being configured: (iv) for extracting a data stream from the first digital signal, the first digital signal including data from N subchannels located within a receive frequency bandwidth portion f1 of the bandwidth F (f1<=F), where N is a subset of the maximum number of M subchannels, N<=M/k; and (v) for signaling to said remote transceiver that the high speed system supports a subset of the maximum number of subchannels M.

Claim 72

Dependent Claim 7 words

The system of claim 61, where M>200.

Claim 73

Dependent Claim 19 words

The system of claim 61, wherein said system operates as a full rate or reduced rate T1.413 compliant transceiver.

Claim 74

Dependent Claim 31 words

The system of claim 61, further wherein portions of said digital signal processing circuit are implemented by a software routine executed by a host processing device within a personal computer system.

Claim 75

Dependent Claim 32 words

The system of claim 64, further wherein said channel interface circuit and front end circuit are physically separated from said host processing device but electrically connected through a personal computer system bus.

Claim 76

Independent Claim 173 words

A method of communicating data based on DMT modulation as specified in T1.413 between a local transceiver and a remote transceiver coupled through a data channel, the method comprising the steps of: (a) determining an amount of computing resources available for processing discrete multi-tone (DMT) modulated subchannels; and (b) determining data sampling capabilities of an analog front end circuit associated with the local transceiver; and (c) determining data capacity of the data channel, including a maximum number M of DMT modulated subchannels supported by the data channel; and (d) determining data transmission capabilities of the remote transceiver during an initialization routine, including a maximum number of DMT modulated subchannnels supported by the remote transceiver; and (e) selecting a subset of the M subchannels for data transmissions between the local transceiver and the remote transceiver, said subset constituting a number N of said M subchannels, where N<=M, and N is selected by evaluating said amount of computing resources, said data sampling capabilities, said data capacity, and said data transmission capabilities of the remote transceiver.

Claim 77

Independent Claim 173 words

A method of communicating data based on DMT modulation as specified in T1.413 between a local transceiver and a remote transceiver coupled through a data channel, the method comprising the steps of: (a) determining an amount of computing resources available for processing discrete multi-tone (DMT) modulated subchannels; and (b) determining data sampling capabilities of an analog front end circuit associated with the local transceiver; and (c) determining data capacity of the data channel, including a maximum number M of DMT modulated subchannels supported by the data channel; and (d) determining data transmission capabilities of the remote transceiver during an initialization routine, including a maximum number of DMT modulated subchannnels supported by the remote transceiver; and (e) selecting a subset of the M subchannels for data transmissions between the local transceiver and the remote transceiver, said subset constituting a number N of said M subchannels, where N<=M, and N is selected by evaluating said amount of computing resources, said data sampling capabilities, said data capacity, and said data transmission capabilities of the remote transceiver.

Claim 78

Dependent Claim 12 words

The method of claim 66, where N<=M/k, and k is an integer.

Claim 79

Dependent Claim 41 words

The method of claim 67, wherein said analog front end circuit associated with the local transceiver uses a sampling rate B that is reduced by said integer k from a sampling rate B' used by the remote transceiver, such that B=B'/k.

Claim 80

Dependent Claim 32 words

The method of claim 66, wherein during step (a), a measurement is made of signal processing capabilities of a host processor within a personal computer system used for demodulating said N subchannels.

Claim 81

Dependent Claim 20 words

The method of claim 66, wherein subchannels other than said number N are filtered by said analog front end circuit.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2003-07-18	2004-01-17	2004-07-18	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2007-07-18	2008-01-17	2008-07-18	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2011-07-18	2012-01-17	2012-07-18	$7700.00	Window Closed / Lapsed

xDSL DMT modem using sub-channel selection to achieve scaleable data rate based on available signal processing resources

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