Robust Filter Design for Multicarrier Communication over Doubly Dispersive Channels

Although orthogonal frequency division multiplexing (OFDM) has been the dominant technology for broadband communications in the past, a number of researchers have noted the shortcomings of OFDM in timevarying channels. Hence, alternative systems that use filter banks for multicarrier modulation have been proposed. Filter bank multicarrier (FBMC) systems use offset quadrature amplitude modulation (OQAM) or cosine modulated filter bank (CMFB) to maximize the transmission efficiency by maximizing the number of subcarriers in the available band. Moreover, the use of isotropic pulses for prototype filters will allow one to strike a balance between the time and frequency dispersion of the channel. However, unfortunately, such systems are not extendable to transmission over multipleinput multiple-output (MIMO) channels. The emphasis of this paper is on a class of FBMC systems in which data symbols are conventional QAM and, thus, support MIMO channels. Unlike OQAM/CMFB-based systems, the FBMC systems considered in this paper suffer some bandwidth loss. We develop a novel filter design that minimizes this bandwidth loss.