Alamouti Coding for DFT Spreading-Based Low PAPR FBMC

Abstract

So far, the solutions for the two major issues of filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM), i.e., 1) high PAPR and 2) incompatibility with MIMO have been devised exclusive of each other; and thus, the signal formats and processings are also exclusive. Therefore, how to constructively combine their solutions into a single system is another challenging issue. As a specific solution to this, we extend the idea of DFT spreading-based low peak to average power ratio (PAPR) FBMC scheme to the ICI-free Alamouti-coded FBMC. In order to inherit the merits of the two schemes, we first provide the required modifications for combining the two schemes. A mathematical analysis confirms that even with frequency reversal Alamouti code arrangement and subblock partitioning, the proposed scheme still achieves the single carrier effect of DFT spreading. The simulation results reveal that the proposed scheme achieves substantially lower PAPR than the previous Alamouti-coded FBMC scheme. Moreover, owing to the additional frequency diversity via DFT spreading, the proposed scheme with properly chosen subblock size achieves even lower BER than the theoretical Alamouti-coded BER with a diversity order of two. Considering the PAPR, BER, and data rate loss, we conclude that the proposed scheme is a competitive solution for Alamouti-coded multicarrier system.