Ensemble modem structure for imperfect transmission media
First Claim
1. In a high speed modem, for transmitting data over a telephone line, of the type that encodes data elements on an ensemble of carrier frequencies, a method for allocating data and power to the carrier frequencies, said method comprising the steps of:
- determining the equivalent noise component for every carrier frequency in the ensemble;
determining the marginal power requirement to increase the complexity of the data element on each carrier from n information units to n+1 information units, n being an integer between 0 and N;
ordering the marginal powers of all the carriers in the ensemble in order of increasing power;
assigning available power to the ordered marginal powers in order of increasing power;
determining the value, MP(max) at which point the available power is exhausted; and
allocating power and data to each carrier frequency where the power allocated is equal to the sum of all the marginal powers less than or equal to MP(max) for that carrier and the number of data units allocated is equal to the number of marginal powers for that carrier less than or equal to MP(max).
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Accused Products
Abstract
A high-speed modem that transmits and receives digital data on an ensemble of carrier frequencies spanning the usable band of a dial-up telephone line. The modem includes a system for variably allocating data and power among the carriers to compensate for equivalent noise and to maximize the data rate. Additionally, systems for eliminating the need for an equalization network, for adaptively allocating control of a channel, and for tracking variations in line parameters are disclosed.
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Citations
17 Claims
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1. In a high speed modem, for transmitting data over a telephone line, of the type that encodes data elements on an ensemble of carrier frequencies, a method for allocating data and power to the carrier frequencies, said method comprising the steps of:
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determining the equivalent noise component for every carrier frequency in the ensemble; determining the marginal power requirement to increase the complexity of the data element on each carrier from n information units to n+1 information units, n being an integer between 0 and N; ordering the marginal powers of all the carriers in the ensemble in order of increasing power; assigning available power to the ordered marginal powers in order of increasing power; determining the value, MP(max) at which point the available power is exhausted; and allocating power and data to each carrier frequency where the power allocated is equal to the sum of all the marginal powers less than or equal to MP(max) for that carrier and the number of data units allocated is equal to the number of marginal powers for that carrier less than or equal to MP(max). - View Dependent Claims (2, 3)
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4. A high speed modem of the type for transmitting a signal on a VF telephone line, comprising:
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means for receiving an input digital data stream and for storing said input digital data; means for generating a modulated ensemble of carriers to encode said input digital data, where each carrier has data elements of variable complexity encoded thereon; means for measuring the signal loss and noise loss of the VF telephone line for each carrier; and means for varying the complexity of the data element encoded on each carrier and the amount of power allocated to each carrier to compensate for the measured signal loss and noise level.
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5. A high speed modem of the type that encodes data elements on an ensemble of carriers of different frequency, said modem comprising:
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a digital electronic processor; a digital electronic memory; bus means for coupling said processor and said memory; means, associated with said digital electronic processor, for determining the equivalent noise component for every carrier frequency in the ensemble; determining the marginal power requirements to increase the complexity of the data element on each carrier from n information units to n+1 information units, n being an integer between 0 and N; ordering the marginal powers of all the carriers in the ensemble in order of increasing power; assigning available power to the ordered marginal powers in order of increasing power; determining the value, MP(max) at which point the available power is exhausted; and assigning power and data to each carrier frequency where the power assigned is equal to the sum of all the marginal powers less than or equal to MP(max) for that carrier and the number of data units is equal to the number of marginal powers for that carrier less than or equal to MP(max). - View Dependent Claims (6)
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7. In a high speed modem, for transmitting data in the form of a QAM ensemble of carrier frequencies on a VF telephone line, of the type that measures the magnitude of a system parameter prior to transmission, a method for tracking deviations in the magnitude of the system parameter during the receipt of data, said method comprising the steps of:
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generating QAM constellations for a plurality of carrier frequencies; constructing a demodulation template for one of said plurality of carrier frequencies comprising a plurality of first regions with one of the points of said constellation positioned within each of said first regions; forming a set of tracking regions where each first region has a first and second tracking region disposed therein; demodulating said ensemble of carriers to obtain the demodulation points positioned in said set of first and second tracking regions; counting the number of points disposed in said set of first tracking regions and the number of points disposed in said set of second tracking regions; determining the difference in the number of counts disposed in said set of first tracking regions and disposed in said tracking regions to construct an error characteristic; and utilizing said error characteristic to adjust the magnitude of said signal parameter during the receipt of data. - View Dependent Claims (8, 9)
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10. In a high speed modem for transmitting data over a telephone line of the type that encodes data elements on an ensemble of carrier frequencies, a method for allocating data and power to the carrier frequencies, said method comprising the steps of:
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determining the sum of the equivalent noise power and signal power for each carrier; and allocating in increment of available power to the carrier having this minimum sum of the equivalent noise power and signal power.
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11. In a high speed modem, for transmitting data over a telephone line, of the type that encodes data elements on an ensemble of carrier frequencies, a system for allocating data and power to the carrier frequencies, said system comprising:
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means for determining the equivalent noise component for every carrier frequency in the ensemble; means for determining the marginal power requirement to increase the complexity of the data element on each carrier from n information units to n+1 information units, n being an integer between 0 and N; means for ordering the marginal powers of all the carriers in the ensemble in order of increasing power; means for assigning available power to the ordered marginal powers in order of increasing power; means for determining the value, MP(max) at which point the available power is exhausted; and means allocating power and data to each carrier frequency where the power allocated is equal to the sum of all the marginal powers less than or equal to MP(max) for that carrier and the number of data units allocated is equal to the number of marginal powers for that carrier less than or equal to MP(max). - View Dependent Claims (12, 13)
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14. In a high speed modem, for transmitting data in the form of a QAM ensemble of carrier frequencies on a VF telephone line, of the type that measures the magnitude of a system parameter prior to transmission, a system for tracking deviations in the magnitude of the system parameter during the receipt of data, said system comprising:
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means for generating QAM constellations for a plurality of carrier frequencies; means for constructing a demodulation template for one of said plurality of carrier frequencies comprising a plurality of first regions with one of the points of said constellation positioned within each of said first regions; means for forming a set of tracking regions where each first region has a first and second tracking region disposed therein; means for demodulating said ensemble of carriers to obtain the modulation points positioned in said set of first and second tracking regions; means for counting the number of points disposed in said set of first tracking regions and the number of points disposed in said set of second tracking regions; means for determining the difference in the number of counts disposed in said set of first tracking regions and disposed in said tracking regions to construct an error characteristic; and means for utilizing said error characteristic to adjust the magnitude of said signal parameter during the receipt of data. - View Dependent Claims (15, 16)
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17. In a high speed modem for transmitting data over a telephone line of the type that encodes data elements on an ensemble of carrier frequencies, a system for allocating data and power to the carrier frequencies, said system comprising:
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means for determining the sum of the equivalent noise power and signal power for each carrier; and means for allocating in increment of available power to the carrier having this minimum sum of the equivalent noise power and signal power.
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Specification