A method comprising: receiving a time-domain synchronization signal transmitted from a base station by a user equipment, UE in a mobile communication network, wherein a plurality of control beams is configured to cover an entire service area of a cell for transmitting the synchronization signal, wherein the synchronization signal carries a unique sequence with consecutive time-domain repetition, wherein the unique sequence identifies control information comprising at least one of a cell ID and a beam ID of the base station, characterized by the unique sequence having a length of N/n time-domain samples, the unique sequence being repeated for n times in one OFDM symbol, the one OFDM symbol containing N time-domain samples, and N and n being positive integers; and the method further comprising: performing a stage-1 signal detection by self-correlating the synchronization signal at different sampling points with N/n time-domain samples time distance during an observation window and deriving a coarse location of the synchronization signal and the unique sequence; and performing a stage-2 signal detection by cross-correlating the synchronization signal with each candidate sequence of a plurality of candidate sequences at sampling instances near the coarse location and thereby detecting a fine location of the synchronization signal and the unique sequence. receiving a time-domain synchronization signal transmitted from a base station by a user equipment, UE in a mobile communication network, wherein a plurality of control beams is configured to cover an entire service area of a cell for transmitting the synchronization signal, wherein the synchronization signal carries a unique sequence with consecutive time-domain repetition, wherein the unique sequence identifies control information comprising at least one of a cell ID and a beam ID of the base station, characterized by the unique sequence having a length of N/n time-domain samples, the unique sequence being repeated for n times in one OFDM symbol, the one OFDM symbol containing N time-domain samples, and N and n being positive integers; and the method further comprising: performing a stage-1 signal detection by self-correlating the synchronization signal at different sampling points with N/n time-domain samples time distance during an observation window and deriving a coarse location of the synchronization signal and the unique sequence; and performing a stage-2 signal detection by cross-correlating the synchronization signal with each candidate sequence of a plurality of candidate sequences at sampling instances near the coarse location and thereby detecting a fine location of the synchronization signal and the unique sequence. performing a stage-1 signal detection by self-correlating the synchronization signal at different sampling points with N/n time-domain samples time distance during an observation window and deriving a coarse location of the synchronization signal and the unique sequence; and performing a stage-2 signal detection by cross-correlating the synchronization signal with each candidate sequence of a plurality of candidate sequences at sampling instances near the coarse location and thereby detecting a fine location of the synchronization signal and the unique sequence.