Windowed OFDM for mixed-numerology 5G and beyond systems

Mixed numerology is considered as a promising way to support the extremely diverse service requirements of the fifth generation (5G) wireless communication systems. However, inter-numerology interference (INI) will be introduced with multiple numerologies coexisting in the same frequency band, which may degrade the system performance significantly. To solve the problem, a promising low out-of-band-emission (OoBE) waveform, i.e. windowed orthogonal frequency division multiplexing (W-OFDM), is investigated in this chapter. In addition, a theoretical model of INI is established, and the analytical expression of its power is derived as a function of the channel frequency response of the interfering subcarrier, the spectral distance separating the aggressor and the victim subcarrier, and the overlapping windows generated by the interferer's transmitter windows and the victim's receiver window. At last, simulations are performed to verify the effectiveness of the derivations.