Method and system for multi-carrier multiple access reception in the presence of imperfections
First Claim
1. A receiver for receiving and decoding a signal received from a communication channel, wherein the signal transmitted on the communication channel includes modulated signals on multiple subcarriers at different selected frequencies that encodes data having a selected bit length, comprising:
- (a) means for projecting the received signal onto each subcarrier and onto one or more selected adjacent subcarriers for each subcarrier, and means for combining and decoding the signals resulting from the projection to provide a decision statistic signal for each bit length; and
(b) means for evaluating the decision statistic signal to determine an estimated bit value over each bit length.
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Abstract
A multi-carrier receiver, which may be utilized for receiving MC-CDMA signals, projects the received signal onto each subcarrier and onto a selected number of adjacent subcarriers. The signals resulting from the projection are combined and decoded to provide a decision statistic signal. The decision statistic signal is evaluated to determine an estimated bit value over each bit length in the transmitted signal. The receiver exploits the effects of imperfections in the communications channel such as fast fading, Doppler and frequency offsets and phase noise, to account for the dispersion of signal energy from a subcarrier to one or more adjacent subcarriers.
160 Citations
30 Claims
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1. A receiver for receiving and decoding a signal received from a communication channel, wherein the signal transmitted on the communication channel includes modulated signals on multiple subcarriers at different selected frequencies that encodes data having a selected bit length, comprising:
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(a) means for projecting the received signal onto each subcarrier and onto one or more selected adjacent subcarriers for each subcarrier, and means for combining and decoding the signals resulting from the projection to provide a decision statistic signal for each bit length; and
(b) means for evaluating the decision statistic signal to determine an estimated bit value over each bit length. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
where T is the bit length of a bit in the transmitted signal, and wherein the decoder determines where ci,n,k are channel estimators for the communications channels corresponding to the subcarrier frequencies fi,n,k and {an} is the code sequence for a particular user, the decision statistic signal ζ
i for each bit bi in the transmittal signal iswhere N is the total number of subcarriers, and the bit decision {circumflex over (b)}i for the bit bi is determined in accordance with {circumflex over (b)}i=sign (real(ζ
i)), i≧
1.
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13. The receiver of claim 12 including means for estimating the channel coefficients ci,n,k utilizing pilot subcarriers.
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14. The receiver of claim 1 wherein the signal transmitted on the communications channel is a multicarrier code division multiple access signal.
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15. The receiver of claim 1 wherein the signal transmitted on the communications channel is a multicarrier time division multiple access signal.
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16. A method of receiving and decoding a signal received from a communication channel on which a signal is transmitted that includes modulated signals on multiple subcarriers at different selected frequencies that encode data having a selected bit length comprising:
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(a) receiving the signal from the communications channel;
(b) for each selected subcarrier frequency in the received signal, projecting the received signal onto such subcarrier and onto one or more selected adjacent subcarriers;
(c) combining and decoding the signals resulting from the projections to provide a decision statistic signal for each bit length; and
(d) evaluating the decision statistic signal to determine an estimated bit value over each bit length. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
where T is the bit length of a bit in the transmitted signal, and wherein the decoder determines where ci,n,k, are channel estimators for the communications channels corresponding to the subcarrier frequencies fi,n,k,, and {an} is the code sequence for a particular user, the decision statistic signal ζ
i for each bit bi in the transmittal signal iswhere N is the total number of subcarriers, and the bit decision {circumflex over (b)}i for the bit bi is determined in accordance with {circumflex over (b)}i=sign(real(ζ
i)), i≧
1.
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28. The method of claim 27 further including estimating the channel coefficients ci,n,k utilizing pilot subcarriers.
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29. The method of claim 16 wherein the transmitted signal is a multicarrier code division multiple access signal.
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30. The method of claim 16 wherein the transmitted signal is a multicarrier time division multiple access signal.
Specification