ESTIMATING FREQUENCY-OFFSETS AND MULTI-ANTENNA CHANNELS IN MIMO OFDM SYSTEMS
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Accused Products
Abstract
Techniques are described for carrier frequency offset (CFO) and channel estimation of orthogonal frequency division multiplexing (OFDM) transmissions over multiple-input multiple-output (MIMO) frequency-selective fading channels. A wireless transmitter forms blocks of symbols by inserting training symbols within two or more blocks of information-bearing symbols. The transmitter appliex a hopping code to each of the blocks of symbols to insert a null subcarrier at a different position within each of the blocks of symbols, and a modulator outputs a wireless signal in accordance with the blocks of symbols. A receiver receives the wireless signal and estimates the CFO, and outputs a stream of estimated symbols based on the estimated CFO.
1 Citation
49 Claims
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1-20. -20. (canceled)
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21. A method comprising:
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forming two or more blocks of output symbols for orthogonal frequency division multiplexing (OFDM) transmissions over a multiple-input multiple-output (MIMO) channel, wherein the forming comprises inserting, based on a hopping code, training symbols and null subcarriers within two or more blocks of information-bearing symbols, the hopping code directing at least a portion of the null subcarriers to be inserted at different positions within the two or more blocks of output symbols; and transmitting, via two or more antennas, transmission signals in accordance with the two or more blocks of output symbols. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29)
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30. A system, comprising:
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two or more antennas; and a base station configured to (i) form two or more blocks of output symbols for orthogonal frequency division multiplexing (OFDM) transmissions over a multiple-input multiple-output (MIMO) channel by inserting, based on a hopping code, training symbols and null subcarriers within two or more blocks of information-bearing symbols, the hopping code directing at least a portion of the null subcarriers to be inserted at different positions within the two or more blocks of output symbols, and (ii) transmit, via the two or more antennas, transmission signals in accordance with the two or more blocks of output symbols. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39)
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40. A system comprising:
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two or more antennas; means for forming two or more blocks of output symbols for orthogonal frequency division multiplexing (OFDM) transmissions over a multiple-input multiple-output (MIMO) channel via the two or more antennas, wherein the means for forming comprises means for inserting training symbols and null subcarriers within two or more blocks of information-bearing symbols using a hopping code, the hopping code directing at least a portion of the null subcarriers to be inserted at different positions within the two or more blocks of output symbols; and means for transmitting, via the two or more antennas, transmission signals in accordance with the two or more blocks of output symbols. - View Dependent Claims (41, 42, 43, 44, 45, 46, 47, 48, 49)
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Specification