Equalization for zero prefix OFDM systems
AssigneeKoninklijke Philips Electronics N.V.
InventorMonisha Ghosh
Life of this patent
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Abstract
The system, apparatus, and method (300) of the present invention provide sub-optimal channel equalization techniques for zero-prefixed orthogonal frequency division modulation (OFDM) systems that retain the performance of least-squares equalization but are not as complex. The technique of the present invention improves equalization performance with less complexity than required by minimum-mean-squared-error (MMSE) equalization as well. The channel matrix is rendered circulant and then truncated where the eigenvalues are small.
Claims21
A method of estimating a transmitted data vector a=[a0a1 . . . aN]T of length N, comprising:
- receiving a transmission over a channel HC of a data vector R as a zero-prefixed OFDM symbol A=[A0 A1 . . . AN 0 . . . 0]T having NG zeros, where NG is the length of a guard interval;
- computing eigenvalues of the channel HC with an M-point FFT where M=N+NG;
- removing smallest frequency values from the received vector based on the computed eigenvalues to obtain truncated received data vector RT;
- performing symbol estimation based on the truncated received data vector RT;
- and
- decoding the estimated symbol.
A symbol determination apparatus for a zero-prefixed OFDM systems, comprising:
- a receiver configured to receive a data vector R as a transmission over a channel HC as a zero-prefixed OFDM symbol A=[A0 A1 . . . AN 0 . . . 0]T having NG zeros, where NG is the length of a guard interval, the data vector R corresponds to a transmitted data vector a=[a0 a1 . . . aN]T of length N;
- a frequency removal module configured to
- i. compute eigenvalues of the channel HC with an M-point FFT where M=N+NG, and
- ii. remove smallest frequency values from the received vector based on the computed eigenvalues to obtain truncated received data vector RT;
- a symbol estimation module that estimates a transmitted symbol corresponding to the received data vector R from the truncated received data vector RT using a predetermined estimation means;
- and
- a decoder to decode the estimated symbol.
A symbol determination apparatus for zero-prefixed OFDM systems comprising:
- circuitry configured to perform
- receiving a transmission over a channel HC of a data vector R as a zero-prefixed OFDM symbol A=[A0 A1 . . . AN 0 . . . 0]T having NG zeros, where NG is the length of a guard interval;
- computing eigenvalues of the channel HC with an M-point FFT where M=N+NG;
- removing smallest frequency values from the received vector based on the computed eigenvalues to obtain truncated received data vector RT;
- performing symbol estimation based on the truncated received data vector RT;
- and
- decoding the estimated symbol.
Dependencies are inferred from the claim text.