Fast-convolution filtered OFDM waveforms with adjustable CP length

This paper investigates the application of flexible and effective fast-convolution (FC) filtering scheme for multiplexing OFDM physical resource blocks (PRBs) in a spectrally well-localized manner. The scheme is able to suppress interference leakage between adjacent PRBs, thus supporting independent waveform parametrization for different PRBs, as well as asynchronous multiuser operation. These are considered as important features in the 5G waveform development. This contribution focuses on the parametrization alternatives and constraints, which are mostly due to the forward and inverse discrete Fourier transform (DFT/IDFT) lengths feasible for practical implementation. Special attention is on cyclic prefix (CP) OFDM system dimensioning with adjustable CP length while the overall symbol duration is fixed. It is demonstrated that a wide range of alternative CP-lengths are usually available through the FC-filtered OFDM scheme.