Method and System for Multirate Multiuser Modulation
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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 user 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 the different user 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
78 Claims
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1-55. -55. (canceled)
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56. Method for performing orthogonal single carrier multiple access, the method comprising the steps of:
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assigning a first user a first set of subcarriers comprising a first number of subcarriers, wherein spacing between neighboring subcarriers within the first set of subcarriers is uniform;
assigning a second user a second set of subcarriers comprising a second number of subcarriers, wherein spacing between neighboring subcarriers within the second set of subcarriers is uniform;
wherein the first number of subcarriers differs from the second number of subcarriers;
wherein the first and the second set of subcarriers are assigned in an orthogonal fashion; and
wherein the first and the second set of subcarriers are to be used for single carrier frequency division multiple access between the first and the second users. - View Dependent Claims (57, 58, 59, 60, 61, 62, 63, 64, 65)
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66. A method comprising the steps of:
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receiving a subcarrier assignment;
generating a signal to be transmitted by a first user, wherein the signal comprises a first set of subcarriers corresponding to the received subcarrier assignment comprising a first number of subcarriers, wherein spacing between neighboring subcarriers within the first set of subcarriers is uniform;
wherein the first number of subcarriers differs from a second number of subcarriers assigned to a second user;
wherein the first and the second set of subcarriers are assigned in an orthogonal fashion;
wherein the first set of subcarriers are to be used for single carrier frequency division multiple access; and
transmitting the single carrier frequency division multiplexed signal. - View Dependent Claims (67, 68, 69, 70, 71, 72, 73, 74, 76, 77)
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78. A method comprising the steps of:
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receiving a first subcarrier assignment at a first time instance;
generating a first single carrier signal to be transmitted, wherein the signal comprises a first set of subcarriers corresponding to the first received subcarrier assignment comprising a first number of subcarriers, wherein spacing between neighboring subcarriers within the first set of subcarriers is uniform;
transmitting the first single carrier signal;
receiving a second subcarrier assignment at a second time instance;
generating a second single carrier signal to be transmitted, wherein the signal comprises a second set of subcarriers corresponding to the second received subcarrier assignment comprising a second number of subcarriers, wherein spacing between neighboring subcarriers within the second set of subcarriers is uniform;
wherein the first number of subcarriers differs from the second number of subcarriers;
wherein the first and second set of subcarriers are used for single carrier frequency division multiple access; and
transmitting the second single carrier signal.
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Specification