This paper deals with the minimum mean square error-(MMSE-) based multipath channel and noise variance estimation in the case of a pilot-aided orthogonal frequency division multiplexing/offset quadrature amplitude modulation (OFDM/OQAM) system. The theoretical expression of the LMMSE channel estimation is formulated, and a simpler closedform is derived. The MSE analysis shows that LMMSE inevitably reaches an error floor due to the interference inherent to OFDM/OQAM modulation. Furthermore, an

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... gorithm for the joint MMSE estimation of both the channel and the noise variance (J-MCNE) is proposed, and features a reduced complexity thanks to the low-rank approximation method. The noise level estimation represents a challenge as it is concealed in the intrinsic interferences generated by the OFDM/OQAM. Simulations reveal the capability of the proposed J-MCNE method to estimate the noise variance, and show that the achieved bit error rate (BER) is close to that of the perfect estimation. Index Terms-OFDM/OQAM, channel estimation, LMMSE, noise variance. 0090-6778 (c)