An OFDM-modulator for operating in a radio device (BS; UE) of a cellular radio communications network (RCN), wherein the OFDM-modulator comprises a processor (P1; P2) and a memory (M1; M2) being configured to: - receive a first and second ingress modulation-symbol stream (a 0 ,...,a N-1 , b 0 ,...,b M-1 ); - determine a first and second inverse Fast Fourier Transform (IFFT A , IFFT B ) of different block lengths (A, B) in dependence on the first and second ingress modulation-symbol stream (a 0 ,...,a N-1 , b 0 ,...,b M-1 ), respectively, wherein the second block length (B) of the second inverse Fast Fourier Transform (IFFT B ) multiplied with an integer factor (K) equals the first block length (A) of the first inverse Fast Fourier Transform (IFFT A ); - determine first and second frequency-shifted samples (Sa; Sb) of different frequency offsets to a subcarrier frequency (DC) in dependence on the first and second inverse Fast Fourier Transform (IFFT A , IFFT B ), respectively; - determine a first and second egress sample stream (d 0 ,...,d A-1 , e 0 ,...,e B-1 ) in dependence on the first and second frequency-shifted samples (Sa; Sb), respectively; - determine a joined sample stream (g 0 ,...,g A-1 ) in dependence on the first and second frequency-shifted sample streams (d 0 ,...,d A-1 , e 0 ,...,e B-1 ) for up-converting the joined sample stream (g 0 ,...,g A-1 ) to a carrier frequency higher than respective subcarrier frequencies; - determine an inverse Fast Fourier Transform of a synchronization sequence (SS) with the first block length (A); and - repeat the synchronization sequence (SS) across the available bandwidth as a synchronization signal (PSS; SSS) for different block lengths and different frequency offsets such that for the second inverse Fast Fourier Transform (IFFT B ) of the second block length with the integer factor (K) being larger than one a synchronization symbol is split in symbols of reduced length. - receive a first and second ingress modulation-symbol stream (a 0 ,...,a N-1 , b 0 ,...,b M-1 ); - determine a first and second inverse Fast Fourier Transform (IFFT A , IFFT B ) of different block lengths (A, B) in dependence on the first and second ingress modulation-symbol stream (a 0 ,...,a N-1 , b 0 ,...,b M-1 ), respectively, wherein the second block length (B) of the second inverse Fast Fourier Transform (IFFT B ) multiplied with an integer factor (K) equals the first block length (A) of the first inverse Fast Fourier Transform (IFFT A ); - determine first and second frequency-shifted samples (Sa; Sb) of different frequency offsets to a subcarrier frequency (DC) in dependence on the first and second inverse Fast Fourier Transform (IFFT A , IFFT B ), respectively; - determine a first and second egress sample stream (d 0 ,...,d A-1 , e 0 ,...,e B-1 ) in dependence on the first and second frequency-shifted samples (Sa; Sb), respectively; - determine a joined sample stream (g 0 ,...,g A-1 ) in dependence on the first and second frequency-shifted sample streams (d 0 ,...,d A-1 , e 0 ,...,e B-1 ) for up-converting the joined sample stream (g 0 ,...,g A-1 ) to a carrier frequency higher than respective subcarrier frequencies; - determine an inverse Fast Fourier Transform of a synchronization sequence (SS) with the first block length (A); and - repeat the synchronization sequence (SS) across the available bandwidth as a synchronization signal (PSS; SSS) for different block lengths and different frequency offsets such that for the second inverse Fast Fourier Transform (IFFT B ) of the second block length with the integer factor (K) being larger than one a synchronization symbol is split in symbols of reduced length. <EOS>