Waveform and receiver design for QAM-FBMC using non-orthogonal prototype filtering

Abstract

Cyclic prefixed orthogonal frequency division multiplexing (CP-OFDM) has been used as a waveform for mobile communications, but CP-OFDM has weaknesses in an asynchronous heterogeneous network scenario. To overcome the disadvantage of CP-OFDM, the new waveform is suggested for the next generation of the wireless communications. This dissertation deals with quadrature amplitude modulated filter bank multi-carrier (QAM-FBMC), one of the new waveform candidates that emerged after 5G standardization. To solve the problem of intrinsic interference caused by the conventional FBMC scheme, the QAM-FBMC system uses a non-orthogonal prototype filter. In this non-orthogonal structure, this dissertation studies techniques to solve the problems caused by non-orthogonality. Earlier in this dissertation, we summarize the various expressions of the system model through mathematical expressions of the QAM-FBMC system. After the formulating the system model, we aim to solve the problems of QAM-FBMC, which are occurred by the non-orthogonality. Next, we propose 1) studies on how the non-orthogonal filter of the system is designed to have high signal-to-interference ratio and good frequency limiting characteristics at the same time, 2) studies on how to compensate for performance degradation caused by non-orthogonal filters through interference mitigation, 3) methods of estimating the carrier frequency offset, and compare and analyze the performance mathematically. This studies is expected to increase the possibility that QAM-FBMC will be considered realistic candidate of new waveform.