A method for determining a delay difference, comprising: a base station of a serving cell receiving (101, 403) from a base station of a neighboring cell information of time which is measured by the base station of the neighboring cell and at which uplink channel/signal information of User Equipment, UE, for determining a synchronization delay is received by the base station of the neighboring cell; and the base station of the serving cell determining (102, 404) a synchronization delay difference between the UE to the base station of the serving cell itself and the UE to the base station of the neighboring cell according to information of time which is measured by the base station of the serving cell itself and at which the uplink channel/signal information of the UE for determining the synchronization delay is received, and the information of time which is measured by the base station of the neighboring cell and at which the uplink channel/signal information of the UE for determining the synchronization delay is received; wherein the uplink channel/signal information, which is measured by the base station of the serving cell, of the UE for determining the synchronization delay is the same as the uplink channel/signal information, which is measured by the base station of the neighboring cell, of the UE for determining the synchronization delay; the serving cell is a macro cell; the neighboring cell is a small cell deployed in an area covered by the macro cell; characterized in that, when a state of the neighboring cell is an off state, before said a base station of a serving cell receiving from a base station of a neighboring cell information of time which is measured by the base station of the neighboring cell and at which uplink channel/signal information of UE for determining a synchronization delay is received, the method further comprises: the base station of the serving cell informing the UE of patterns and measurement indications of a Discontinuous Transmission ON, DTX ON, state and a Discontinuous Reception ON, DRX_ON, state of the neighboring cell during a sleep period. a base station of a serving cell receiving (101, 403) from a base station of a neighboring cell information of time which is measured by the base station of the neighboring cell and at which uplink channel/signal information of User Equipment, UE, for determining a synchronization delay is received by the base station of the neighboring cell; and the base station of the serving cell determining (102, 404) a synchronization delay difference between the UE to the base station of the serving cell itself and the UE to the base station of the neighboring cell according to information of time which is measured by the base station of the serving cell itself and at which the uplink channel/signal information of the UE for determining the synchronization delay is received, and the information of time which is measured by the base station of the neighboring cell and at which the uplink channel/signal information of the UE for determining the synchronization delay is received; wherein the uplink channel/signal information, which is measured by the base station of the serving cell, of the UE for determining the synchronization delay is the same as the uplink channel/signal information, which is measured by the base station of the neighboring cell, of the UE for determining the synchronization delay; the serving cell is a macro cell; the neighboring cell is a small cell deployed in an area covered by the macro cell; characterized in that, when a state of the neighboring cell is an off state, before said a base station of a serving cell receiving from a base station of a neighboring cell information of time which is measured by the base station of the neighboring cell and at which uplink channel/signal information of UE for determining a synchronization delay is received, the method further comprises: the base station of the serving cell informing the UE of patterns and measurement indications of a Discontinuous Transmission ON, DTX ON, state and a Discontinuous Reception ON, DRX_ON, state of the neighboring cell during a sleep period.