Spectrally efficient GFDM and low complexity receiver design

Abstract

High spectral efficiency is one of the most important requirements in the 5th generation communication system. To achieve higher spectral efficiency than 4G standard OFDM, Generalized Frequency Division Multiplexing (GFDM) uses less number of cyclic prefixes (CP) to increase time efficiency. Spectrally Efficient Frequency Division Multiplexing (SEFDM) increases frequency domain efficiency by compressing subcarrier spacing. Both modulation schemes, however, need a complex receiver to cancel out induced inter-carrier interference (ICI). In this paper, Spectrally Efficient GFDM (SEGFDM) scheme is proposed to achieve higher spectral efficiency than GFDM or SEFDM. By investigating minimum distance property, this paper shows that SEGFDM’s subcarrier spacing can be squeezed into 0.94 (called Mazo limit) without performance degradation. However, SEGFDM subcarriers higher ICI due to compact data allocation in the transmission spectrum. So, design good equalizer to deal with interference with low complexity becomes a more critical issue. This paper suggests low complexity receiver for both coded and uncoded system speci？ed for SEGFDM using waveform characteristics. In symbol-level detection scheme, proposed receiver shows similar performance compared to an optimal receiver with low complexity. In bit-level detection scheme, proposed receiver not only has low complexity but also shows performance improvement with over-Mazo limit squeezing. Finally, spectral efficiency is compared to GFDM and SEFDM and SEGFDM shows that there’s transmission rate increase without performance degradation.