Enhancing spectral efficiency in advanced multicarrier techniques: A challenge

Advanced multicarrier systems, like the Offset-QAM filter bank based (OQAM-FBMC) ones, are gaining importance as candidates for the physical layer of the 5-th generation of wireless communications. One of the main advantages of FBMC, when compared to traditional cyclic prefix based OFDM, is its higher spectral efficiency. However, this gain can be lost again if the problem of training based channel estimation is not tackled correctly. This is due to the memory inserted by the longer pulse shaping and the loss of orthogonality of overlapping subcarriers. In this paper we approach the problem of training based channel estimation for FBMC systems. We propose an iterative algorithm based on the expectation maximization (EM) maximum likelihood (ML) that reduces the overhead and consequently improves the spectral efficiency.