Commissariat &#xc0; L'&#xc9;nergie Atomique Et Aux &#xc9;nergies Alternatives

Commissariat a L'energie Atomique

Telecom Paristech

Abdelaziz Bouzegzi

Pierre Jallon

Philippe Ciblat

An OFDM signal identification method in a received signal, wherein the received signal is sampled and cut off into blocks of P samples, each block being subjected to an inverse Fourier transform to obtain a plurality of symbols at a plurality of frequencies. For each frequency of the plurality, the kurtosis of the set of symbols thus obtained at this frequency is calculated, and then it is determined whether the kurtosis has a periodicity in frequency domain from kurtosis values calculated for the frequencies of the plurality, and the presence of an OFDM signal in the received signal is identified if the kurtosis has such a periodicity.

Identification method of an OFDM signal

A method of estimating at least one modulation parameter of an OFDM signal, the signal being sampled during a time window in order to provide a sequence of samples, the method including: (a) grouping together consecutive samples of the sequence according to a tested value of the parameter, in order to form a plurality of vectors; (b) estimating a covariance matrix of the vectors; (c) calculating a theoretical covariance matrix that would be obtained using an OFDM signal of which the modulation parameter would have the tested value; (d) measuring a distance between the covariance matrix and the theoretical covariance matrix; and iterating the steps (a), (b), (c) and (d), wherein the estimated value of the parameter is that achieving a shortest distance in the step (d).

Method for the estimation of OFDM parameters by adaptation of covariance

The present invention relates to a method for blind estimation of at least one parameter of an OFDM signal according to a maximum likelihood (ML) criterion. In one embodiment, the estimation method uses a deterministic maximum likelihood criterion. In another embodiment, the estimation method assumes that the modulation symbols modulating the sub-carriers of the OFDM multiplex are i.i.d. and Gaussian random variables. The estimation of said parameter is carried out while minimizing a cost function depending on the chosen criterion.

Method for the blind estimation of OFDM modulation parameters according to a maximum likelihood criterion

The present invention relates to a method for the blind estimation of at least one parameter of an OFDM signal by maximizing an objective function depending on said parameter. The objective function implements a parameterized model of the OFDM modulation and a matched filtering corresponding to that model. The OFDM signal, baseband demodulated and then sampled in an observation window, is the object of the adapted filtering to calculate the objective function. It is also proposed to include, in the parameterized model, the temporal offset between the observation window and an OFDM symbol as well as the frequency offset between the frequency of the OFDM signal carrier and the baseband demodulation frequency.

Method for the blind estimation of OFDM signal parameters by adapted filtering

The present invention concerns a blind estimation method of at least one temporal modulation parameter of an OFDM signal, in which a plurality of demodulation attempts of said OFDM signal are carried out using a plurality of respective values of this temporal parameter and, for each demodulation attempt, a cost function representative of the entropy of the demodulated signal is calculated, the estimate of said temporal parameter then being obtained as the value of this parameter minimizing said cost function.

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Grenoble, France

Abdelaziz Bouzegzi