Method and system for multirate multiuser modulation
First Claim
1. A method of modulating a signal, comprising:
- determining a data rate from a plurality of data rates;
modulating the signal using an interleaved frequency division multiple access (IFDMA) modulation scheme wherein the modulated signal is characterized by having an IFDMA block repetition value dependent on the data rate;
transmitting the IFDMA modulated signal; and
applying a modulation code for the signal, wherein the modulation code is one of a block modulation code based on an L-dimensional discrete Fourier transform (DFT) matrix defining a channelization code, and a phase ramp modulation code.
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Accused Products
Abstract
A multi-rate interleaved frequency division multiple access (IFDMA) modulation scheme permits users to transmit at different data rates or to vary their data rates while providing frequency diversity and preserving low peak-to-average power ratios and orthogonality between users at different data rates. The modulation scheme allows user-specific data block and repetition sizes, as well as user-specific modulation codes. Code assignment rules are provided for maintaining orthogonality between users having different data rates. Block and phase ramp modulation codes can be used. Asynchronous transmissions by users are supported by ensuring that the length of the cyclic extension is sufficiently long to tolerate worst case relative signal arrival delays between users and the channel pulse response duration over the communication medium. The modulation scheme can be employed in wireless communication systems, such as cellular or paging systems.
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Citations
43 Claims
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1. A method of modulating a signal, comprising:
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determining a data rate from a plurality of data rates; modulating the signal using an interleaved frequency division multiple access (IFDMA) modulation scheme wherein the modulated signal is characterized by having an IFDMA block repetition value dependent on the data rate; transmitting the IFDMA modulated signal; and applying a modulation code for the signal, wherein the modulation code is one of a block modulation code based on an L-dimensional discrete Fourier transform (DFT) matrix defining a channelization code, and a phase ramp modulation code. - View Dependent Claims (2, 3, 4, 34, 35)
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5. An apparatus, comprising:
a transmitter modulating a signal at a selected one of a plurality of data rates using an interleaved frequency division multiple access (IFDMA) modulation scheme, wherein the transmitter includes, means for applying a user-specific symbol block repetition value in the IFDMA modulation scheme;
wherein the transmitter includes means for adding a cyclic extension to the signal, and wherein the cyclic extension has a length greater than the sum of a relative signal arrival delay between a plurality of users and the channel pulse response duration.- View Dependent Claims (6, 36, 37, 38)
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7. A method of demodulating a signal, comprising:
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equalizing the signal; correlating the equalized signal with a predetermined modulation code; combining block repetitions of the correlated signal; and detecting one or more symbols based on the combined block repetitions. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method of demodulating a signal, comprising:
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correlating the signal with a predetermined modulation code; combining block repetitions of the correlated signal; and detecting one or more symbols based on the combined block repetitions. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A receiver, comprising:
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an equalizer for equalizing an input signal; a correlator, operatively couple to the equalizer, for correlating the equalized signal using a predetermined modulation code; and a block combiner, operatively coupled to the correlator, for combining block repetitions of the correlated signal. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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27. A receiver, comprising:
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a correlator for correlating a signal using a predetermined modulation code; a block combiner, operatively coupled to the correlator, for combining block repetitions of the correlated signal; and an equalizer, operatively coupled to the block combiner, for equalizing the output of the block combiner. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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39. An apparatus, comprising:
a transmitter modulating a signal at a selected one of a plurality of data rates using an interleaved frequency division multiple access (IFDMA) modulation scheme, wherein the transmitter includes, means for applying a user-specific symbol block repetition value in the IFDMA modulation scheme, wherein the transmitter includes, means for applying a user-specific modulation code in the IFDMA modulation scheme; and
wherein the user-specific modulation code is one of a block modulation code based on an L-dimensional discrete Fourier transform (DFT) matrix defining a channelization code, or a phase ramp modulation code.- View Dependent Claims (40, 41, 42, 43)
Specification