Systems and methods for adaptive bit loading in a multiple antenna orthogonal frequency division multiplexed communication system
First Claim
1. A transmitter comprising:
- a parser to parse a block of bits representing an orthogonal frequency division multiplexed symbol into groups of a variable number of coded bits;
subcarrier modulators to individually modulate the groups on orthogonal frequency division multiplexed subcarriers in accordance with spatial-frequency subcarrier modulation assignments to generate symbol-modulated subcarriers; and
IFFT circuitry to generate time domain waveforms from the symbol-modulated subcarriers for subsequent RF transmission over a plurality of spatial channels.
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Accused Products
Abstract
In an orthogonal frequency division multiplexed (OFDM) system, a transmitter and/or receiver communicate separate data streams on non-orthogonal spatial channels. Each spatial channel may use the same set of OFDM subcarriers and may take advantage of the multipath characteristics of the spatial channel allowing the communication of additional data without an increase in frequency bandwidth. Space-frequency subcarrier modulation assignments may be dynamically assigned on a per subcarrier basis as well as a per spatial channel basis to help maximize the data-carrying capacity of the channel. In some embodiments, each of the spatial channels may be associated with one of a plurality of spatially diverse antennas. In other embodiments, beamforming may be performed to allow the transmission and/or reception of signals within the spatial channels.
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Citations
30 Claims
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1. A transmitter comprising:
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a parser to parse a block of bits representing an orthogonal frequency division multiplexed symbol into groups of a variable number of coded bits;
subcarrier modulators to individually modulate the groups on orthogonal frequency division multiplexed subcarriers in accordance with spatial-frequency subcarrier modulation assignments to generate symbol-modulated subcarriers; and
IFFT circuitry to generate time domain waveforms from the symbol-modulated subcarriers for subsequent RF transmission over a plurality of spatial channels. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A receiver comprising:
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FFT circuitry to generate frequency domain representations of a symbol received over orthogonal frequency division multiplexed subcarriers of a plurality of spatial channels;
subcarrier demodulators to demodulate the frequency domain representations for each subcarrier in accordance with spatial-frequency subcarrier modulation assignments to generate groups of bits; and
a deparser to combine the groups of bits to generate a block of coded bits representing the symbol. - View Dependent Claims (15, 16, 17, 18)
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19. A method comprising:
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parsing a block of bits representing an orthogonal frequency division multiplexed symbol into groups having a variable number of coded bits;
individually modulating the groups of bits on orthogonal frequency division multiplexed subcarriers in accordance with spatial-frequency subcarrier modulation assignments to generate symbol-modulated subcarriers; and
generating time domain waveforms by performing an inverse fast Fourier transform (IFFT) on the symbol-modulated subcarriers for subsequent RF transmission over a plurality of spatial channels. - View Dependent Claims (20, 21)
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22. A method comprising:
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generating frequency domain representations of a symbol received over orthogonal frequency division multiplexed subcarriers over a plurality of spatial channels;
demodulating the frequency domain representations for the subcarriers separately for each of the antennas in accordance with spatial-frequency subcarrier modulation assignments to generate groups of bits; and
generating the symbol from the groups of bits. - View Dependent Claims (23, 24)
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25. A system comprising:
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a plurality of substantially omnidirectional spatially-diverse transmit antennas; and
a transmitter, wherein the transmitter comprises;
a parser to parse a block of bits representing a transmit orthogonal frequency division multiplexed symbol into groups;
subcarrier modulators to individually modulate the groups of bits on orthogonal frequency division multiplexed subcarriers in accordance with spatial-frequency subcarrier modulation assignments to generate symbol-modulated subcarriers; and
IFFT circuitry to generate time domain waveforms from the symbol-modulated subcarriers for subsequent RF transmission by the spatially diverse transmit antennas. - View Dependent Claims (26, 27)
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28. A machine-readable medium that provides instructions, which when executed by one or more processors, cause said processors to perform operations comprising:
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parsing a block of bits representing an orthogonal frequency division multiplexed symbol into groups having a variable number of coded bits;
individually modulating the groups of bits on orthogonal frequency division multiplexed subcarriers in accordance with spatial-frequency subcarrier modulation assignments to generate symbol-modulated subcarriers; and
generating time domain waveforms by performing an inverse fast Fourier transform (IFFT) on the symbol-modulated subcarriers for subsequent RF transmission over a plurality of spatial channels. - View Dependent Claims (29, 30)
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Specification