Process for suppressing intercarrier interference in a OFDM receiver

摘要

Process for canceling Intercarrier Interference in a OFDM receiver receiving OFDM blocks in presence of Doppler, comprising the steps of: receiving a OFDM block comprising N samples; applying a FFT for the purpose of generating N frequency domain representations composing the received signal (R); multiplying said received signal (R) by the hermitian value of the channel (HH), with H being the channel estimate; applying on said received signal a preconditioned conjugate gradient algorithm based on a N×N P preconditioner matrix; Characterized in that said preconditioner matrix is computed at follows: Formula (19) and formula (20), where formula (I) is a LFIR×PN selection matrix obtained by extracting a predetermined number (LFIR) of rows from the identity matrix IPN, LFIR being a predetermined integer inferior to PN, with p corresponding to the basis expansion order chosen and N is the FFT size; formula (II) is equal to HFH, with H being the frequency-domain channel matrix and F being the N×N discrete-Fourier transform unitary matrix F; formula (III) is the N×N identity matrix; formula (IV) is the varience of the noise; formula (V) is being the 1×N vector containing 1 in n-th position and 0 elsewhere.;Sn(I)ℋ(II)I(III)σ(IV)1n⁢(V)fnT=1n⁢ℋH⁢ℋ⁢⁢SnT⁡[Sn⁢ℋH⁡(ℋℋH+σz2⁢I)⁢ℋ⁢⁢SnT]-1(19)G˘=[f0T⁢S0f1T⁢S1⋮fN-1T⁢SN-1](20)

主权项

1. A process for canceling Intercarrier Interference in a OFDM receiver comprising digital signal processing circuits, said OFDM receiver receiving OFDM blocks in presence of Doppler, said process comprising the steps of:
receiving a OFDM block, said OFDM block comprising N samples; applying, by said digital signal processing circuits, a Fast Fourier Transform (FFT) on said OFDM block for the purpose of generating N frequency domain representations composing the received signal; multiplying said received signal by the hermitian value of the channel by said digital signal processing circuits, with H being the channel estimate; and applying on said received signal a preconditioned conjugate gradient algorithm based on a N×N P preconditioner matrix by said digital signal processing circuits; wherein said preconditioning matrix is computed as follows:
fnT=1nHSnT[SnH(H+σz2I)SnT]−1 AndP=G˘=[f0T⁢S0f1T⁢S1⋮fN-1T⁢SN-1] Where Sn is a LFIR×PN selection matrix obtained by extracting a predetermined number (LFIR) of rows from the identity matrix IPN; LFIR being a predetermined integer inferior to PN, with p corresponding to the basis expansion order chosen and N is the FFT size; is equal to HFH, with H being the frequency-domain channel matrix and F being the N×N discrete-Fourier transform unitary matrix F; I is the N×N identity matrix; σ is the varience of the noise; and 1n is being the 1×N vector containing 1 in n-th position and 0 elsewhere.