A synchronization processing method performed by a base station, the method comprising the steps of: a.) sending a first primary synchronization signal, PSS1, to a terminal device in a plurality of subsequent and adjacent time slots of a first subframe by using in each time slot a different transmit beam, the different transmit beams forming together a plurality of transmit beams, and sending a second primary synchronization signal, PSS2, different to PSS1, to the terminal device in a plurality of subsequent and adjacent time slots of a second subframe by using in each time slot a different transmit beam among the plurality of transmit beams, the second subframe being adjacent to the first subframe, and the first and second subframes are contained in one downlink frame, ∘ wherein the transmit beams for sending the PSS1 in the time slots of the first subframe follow a first transmit beam time sequence and the transmit beams for sending the PSS2 in the time slots of the second subframe follow a second transmit beam time sequence having a reverse time order compared to the first transmit beam time sequence, and each different transmit beam among the plurality of transmit beams corresponds to a different direction, ∘ wherein different time offsets are applied for all transmit beams used for sending the PSS1 and the PSS2, wherein the time offset is a difference between a time of sending the PSS1 using a transmit beam in the first subframe and a time of sending the PSS2 in the second subframe using the same transmit beam; b.) switching in a same time order of switching the transmits beams for sending the PSS1 and the PSS2, a direction of a receive beam; and c.) receiving, from the terminal device, a preamble sequence in a time slot in which the receive beam has a certain direction, whereby the time slot in which the preamble sequence is received is the one time slot corresponding to the optimal transmit beam for the base station to transmit to the terminal device, selected by the terminal device, such that the base station receives an implicit indication of said optimal transmit beam by receiving said preamble sequence in said time slot. a.) sending a first primary synchronization signal, PSS1, to a terminal device in a plurality of subsequent and adjacent time slots of a first subframe by using in each time slot a different transmit beam, the different transmit beams forming together a plurality of transmit beams, and sending a second primary synchronization signal, PSS2, different to PSS1, to the terminal device in a plurality of subsequent and adjacent time slots of a second subframe by using in each time slot a different transmit beam among the plurality of transmit beams, the second subframe being adjacent to the first subframe, and the first and second subframes are contained in one downlink frame, ∘ wherein the transmit beams for sending the PSS1 in the time slots of the first subframe follow a first transmit beam time sequence and the transmit beams for sending the PSS2 in the time slots of the second subframe follow a second transmit beam time sequence having a reverse time order compared to the first transmit beam time sequence, and each different transmit beam among the plurality of transmit beams corresponds to a different direction, ∘ wherein different time offsets are applied for all transmit beams used for sending the PSS1 and the PSS2, wherein the time offset is a difference between a time of sending the PSS1 using a transmit beam in the first subframe and a time of sending the PSS2 in the second subframe using the same transmit beam; ∘ wherein the transmit beams for sending the PSS1 in the time slots of the first subframe follow a first transmit beam time sequence and the transmit beams for sending the PSS2 in the time slots of the second subframe follow a second transmit beam time sequence having a reverse time order compared to the first transmit beam time sequence, and each different transmit beam among the plurality of transmit beams corresponds to a different direction, ∘ wherein different time offsets are applied for all transmit beams used for sending the PSS1 and the PSS2, wherein the time offset is a difference between a time of sending the PSS1 using a transmit beam in the first subframe and a time of sending the PSS2 in the second subframe using the same transmit beam; b.) switching in a same time order of switching the transmits beams for sending the PSS1 and the PSS2, a direction of a receive beam; and c.) receiving, from the terminal device, a preamble sequence in a time slot in which the receive beam has a certain direction, whereby the time slot in which the preamble sequence is received is the one time slot corresponding to the optimal transmit beam for the base station to transmit to the terminal device, selected by the terminal device, such that the base station receives an implicit indication of said optimal transmit beam by receiving said preamble sequence in said time slot.