A method of determining a device-to-device, D2D, data transmission resource for a user equipment , the method comprising: receiving, at a user equipment , configuration information associated with a D2D data transmission resource, the configuration information comprising information of a D2D data allocation period and being transmitted from an evolved NodeB, eNB; executing a discovery process for communicating between user equipments; for D2D data communication, determining an initial start point of the D2D data allocation period; determining, in each D2D data allocation period, a D2D data transmission resource offset and a period associated with a D2D data transmission resource bitmap, the D2D data transmission resource bitmap comprising at least one bit corresponding to bit value "1"; and determining a pool of subframes corresponding to the bit value "1" of the D2D data transmission resource bitmap, the period associated with the D2D data transmission resource bitmap comprising the pool of subframes, the pool of subframes corresponding to D2D data transmission resources through which a D2D data transmission is capable, wherein information of the D2D data transmission resource offset and information of the D2D data transmission resource bitmap are transmitted from the eNB, wherein in each D2D data allocation period, the D2D data transmission resource offset precedes the period associated with the D2D data transmission resource bitmap, and wherein in each D2D data allocation period, a start point of the period associated with the D2D data transmission resource bitmap is determined based on a start point of the D2D data allocation period and the D2D data transmission resource offset. receiving, at a user equipment , configuration information associated with a D2D data transmission resource, the configuration information comprising information of a D2D data allocation period and being transmitted from an evolved NodeB, eNB; executing a discovery process for communicating between user equipments; for D2D data communication, determining an initial start point of the D2D data allocation period; determining, in each D2D data allocation period, a D2D data transmission resource offset and a period associated with a D2D data transmission resource bitmap, the D2D data transmission resource bitmap comprising at least one bit corresponding to bit value "1"; and determining a pool of subframes corresponding to the bit value "1" of the D2D data transmission resource bitmap, the period associated with the D2D data transmission resource bitmap comprising the pool of subframes, the pool of subframes corresponding to D2D data transmission resources through which a D2D data transmission is capable, wherein information of the D2D data transmission resource offset and information of the D2D data transmission resource bitmap are transmitted from the eNB, wherein in each D2D data allocation period, the D2D data transmission resource offset precedes the period associated with the D2D data transmission resource bitmap, and wherein in each D2D data allocation period, a start point of the period associated with the D2D data transmission resource bitmap is determined based on a start point of the D2D data allocation period and the D2D data transmission resource offset. <EOS>