Scattered Reference Symbol-Based Channel Estimation and Equalization for FBMC-QAM Systems

In this paper, we derive the closed forms of residual interference that occurs over a multipath channel of a filter bank multicarrier-quadrature amplitude modulation (FBMC-QAM) system, in which the system adopts two different prototype filters to guarantee that the orthogonality condition is met for both even and odd subcarriers without using a guard interval. The filter coefficients of the two filters are designed differently to meet the orthogonality condition, and thus, their degrees of robustness are different over the multipath channel. In order to clarify the influence of the multipath channel on the performance of the FBMC-QAM, we both derive an effective channel frequency response that includes the filter response and analyze the residual interference over the multipath channel. Based on this analysis, we propose a unique scheme for both even-biased reference symbol mapping and symbol/signal-level channel estimation and equalization that is suitable for the FBMC-QAM system transceiver structure. The simulation results show that the performance of the proposed scheme is comparable to that of a conventional orthogonal frequency division multiplexing-quadrature amplitude modulation system in terms of the mean squared error, bit error rate, and effective data rate.