A method of extracting a random access channel, RACH, preamble from a signal received in a base station from a user device, in a radio communication system, wherein the base station has removed an initial cyclic prefix, symbol CP, portion of the signal, and has performed a Fast Fourier Transformation, FFT, on time portions of the signal, the method comprising: for a predetermined number of successive time portions of the signal (S505, S562, S564) after the symbol CP portion has been removed: receiving a Fast Fourier Transformation, FFT, of a portion of the signal, generating, from the FFT of the portion, a baseband signal corresponding to selected subcarriers all other non-RACH frequency bins having been set to zero, performing an inverse FFT, IFFT, on the baseband signal to yield a time domain signal, adjusting a phase of the time domain signal, to compensate for group delays of symbol CP gaps occurring during the generating, wherein a phase adjustment is determined individually for each portion of the signal, padding zeros in the phase-adjusted time domain signal to account for the initial symbol CP portion that was removed, and storing the phase-adjusted time domain signal with inserted zeros to form a time sequence up to the predetermined number of successive portions; selecting the RACH preamble from the stored sequence; and performing a FFT on the selected RACH preamble, wherein the FFT of the RACH preamble is further used for identifying and synchronizing the user device with the base station. for a predetermined number of successive time portions of the signal (S505, S562, S564) after the symbol CP portion has been removed: receiving a Fast Fourier Transformation, FFT, of a portion of the signal, generating, from the FFT of the portion, a baseband signal corresponding to selected subcarriers all other non-RACH frequency bins having been set to zero, performing an inverse FFT, IFFT, on the baseband signal to yield a time domain signal, adjusting a phase of the time domain signal, to compensate for group delays of symbol CP gaps occurring during the generating, wherein a phase adjustment is determined individually for each portion of the signal, padding zeros in the phase-adjusted time domain signal to account for the initial symbol CP portion that was removed, and storing the phase-adjusted time domain signal with inserted zeros to form a time sequence up to the predetermined number of successive portions; receiving a Fast Fourier Transformation, FFT, of a portion of the signal, generating, from the FFT of the portion, a baseband signal corresponding to selected subcarriers all other non-RACH frequency bins having been set to zero, performing an inverse FFT, IFFT, on the baseband signal to yield a time domain signal, adjusting a phase of the time domain signal, to compensate for group delays of symbol CP gaps occurring during the generating, wherein a phase adjustment is determined individually for each portion of the signal, padding zeros in the phase-adjusted time domain signal to account for the initial symbol CP portion that was removed, and storing the phase-adjusted time domain signal with inserted zeros to form a time sequence up to the predetermined number of successive portions; selecting the RACH preamble from the stored sequence; and performing a FFT on the selected RACH preamble, wherein the FFT of the RACH preamble is further used for identifying and synchronizing the user device with the base station.