The paper deals with the transmission over multiple-input/multiple-output channels exhibiting time-dispersion. A minimum mean-square error equalizer based on widely linear processing combined with the decision-feedback (DF) strategy is implemented via finite-impulse-response filters. The proposed equalizer provides considerable performance gain at the expense of a limited increase in computational complexity. The performance analysis has been carried out accounting for mismatch conditions always present in practice. The results confirm the stronger sensitivity of the DF-based equalizers with respect to the feedforward-based ones when system parameters are not accurately known
The paper deals with the problem of blind synchronization for OFDM/OQAM systems. Specifically, by exploiting the approximate conjugate-symmetry property of the beginning of a burst of OFDM/OQAM symbols, due to the presence of the time offset, a new procedure for blind symbol timing and CFO estimation is proposed. The performance of the derived blind estimators is analyzed by computer simulations; the results show that the proposed methods may provide acceptable performance for reasonable values of the signal-to-noise ratio
Abstract-We consider overloaded CDMA systems where detection is performed with linear receivers and we find that in such systems it is possible to detect only a fraction of all users simultaneously, at most the spreading factor, with a probability of error that vanishes to zero as the channel noise goes to zero. To overcome this problem nonlinear detectors are required and we propose a simple iterative detector (that we call conditional conventional detector), based on filters matched to users' signatures. Simulations show that indeed the proposed detector can be asymptotically efficient for all users at the same time.
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