1. A method used in UE, comprising:generating a discovery signal (DS) including configured information, wherein the configured information includes both of the following:
first information: whether U1 is in the coverage of a service cell or not; and
fourth information: an index of a time frequency resource block R1-included subframe among S candidate subframes, which are within a current time window and are used for the DS transmission;
transmitting the DS to another UE on the time-frequency resource block R1, so as to establish a Device-to-Device (D2D) communication connection;
wherein the U1 is the transmitter of the DS, or the U1 is the head of a D2D group in which the transmitter of the DS camps, the time window is a periodic and continuous time window which is maintained by the U1, the indexes of frames in the time window are from 0 to L?1, L is the maximum value of System Frame Number (SFN) plus 1, S is a positive integer not greater than 10 times of L, and the G_ID is an integer of the D2D group.