A method executed at a network side for determining a preamble sequence on a Physical Random Access Channel, PRACH, characterized in that, the method comprising: in a first stage, eceiving, from a plurality of user equipment, UEs, preamble sub-sequences of the first stage, and determining instances of time of the first stage at which the preamble sub-sequences of the first stage are detected in a detection window of the first stage; in a second stage, receiving, from the plurality of UEs, preamble sub-sequences of the second stage, and determining instances of time of the second stage at which the preamble sub-sequences of the second stage are detected in a detection window of the second stage; and determining that a preamble sub-sequence of the first stage and a preamble sub-sequence of the second stage belong to a same preamble sequence according to the instances of time of the first stage at which said preamble sub-sequence of the first stage is detected in the first stage, and the instances of time of the second stage at which the preamble sub-sequence of the second stage is detected in the second stage; wherein said determining comprises: determining an instance of time of the first stage at which said preamble sub-sequence of the first stage is detected in the first stage, and an instance of time of the second stage at which said preamble sub-sequence of the second stage is detected in the second stage characterized by if a difference between said instance of time of the first stage and said instance of time of the second stage is below a present difference threshold; determining that said preamble sub-sequence of the first stage and said preamble sub-sequence of the second stage belong to the same preamble sequence. in a first stage, eceiving, from a plurality of user equipment, UEs, preamble sub-sequences of the first stage, and determining instances of time of the first stage at which the preamble sub-sequences of the first stage are detected in a detection window of the first stage; in a second stage, receiving, from the plurality of UEs, preamble sub-sequences of the second stage, and determining instances of time of the second stage at which the preamble sub-sequences of the second stage are detected in a detection window of the second stage; and determining that a preamble sub-sequence of the first stage and a preamble sub-sequence of the second stage belong to a same preamble sequence according to the instances of time of the first stage at which said preamble sub-sequence of the first stage is detected in the first stage, and the instances of time of the second stage at which the preamble sub-sequence of the second stage is detected in the second stage; wherein said determining comprises: determining an instance of time of the first stage at which said preamble sub-sequence of the first stage is detected in the first stage, and an instance of time of the second stage at which said preamble sub-sequence of the second stage is detected in the second stage characterized by if a difference between said instance of time of the first stage and said instance of time of the second stage is below a present difference threshold; determining that said preamble sub-sequence of the first stage and said preamble sub-sequence of the second stage belong to the same preamble sequence. determining an instance of time of the first stage at which said preamble sub-sequence of the first stage is detected in the first stage, and an instance of time of the second stage at which said preamble sub-sequence of the second stage is detected in the second stage characterized by if a difference between said instance of time of the first stage and said instance of time of the second stage is below a present difference threshold; determining that said preamble sub-sequence of the first stage and said preamble sub-sequence of the second stage belong to the same preamble sequence.