A method, in a macro base station of a macro cell of a heterogeneous communication network, of assisting a user equipment (20, 30) in discovering small cells (PC1, PC2, PC3), the method comprising the steps of: B. judging whether the user equipment (20, 30) has approached to a target region that includes one or more candidate small cells (PC1, PC2, PC3) based upon stored location range information of all candidate small cells (PC1, PC2, PC3) in the macro cell and estimated position information of the user equipment (20, 30); C. judging based upon a result of the judgment in the step B whether to instruct the user equipment (20, 30) to perform a periodical measurement on the one or more candidate small cells (PC1, PC2, PC3) in the target region to discover small cells (PC1, PC2, PC3); and D. when a result of the judgment in the step C is to instruct the user equipment (20, 30) to perform the periodical measurement, performing the steps of: D1. obtaining density information that indicates a density of the candidate small cells (PC1, PC2, PC3) in the target region; D2. determining an interval for the periodical measurement of the user equipment (20, 30) based upon the obtained density information; and D3. transmitting a first signaling to the user equipment (20, 30) to instruct the user equipment (20, 30) to perform the periodical measurement, wherein the first signaling includes cell identifiers of the one or more candidate small cells (PC1, PC2, PC3) in the target region and the determined interval. B. judging whether the user equipment (20, 30) has approached to a target region that includes one or more candidate small cells (PC1, PC2, PC3) based upon stored location range information of all candidate small cells (PC1, PC2, PC3) in the macro cell and estimated position information of the user equipment (20, 30); C. judging based upon a result of the judgment in the step B whether to instruct the user equipment (20, 30) to perform a periodical measurement on the one or more candidate small cells (PC1, PC2, PC3) in the target region to discover small cells (PC1, PC2, PC3); and D. when a result of the judgment in the step C is to instruct the user equipment (20, 30) to perform the periodical measurement, performing the steps of: D1. obtaining density information that indicates a density of the candidate small cells (PC1, PC2, PC3) in the target region; D2. determining an interval for the periodical measurement of the user equipment (20, 30) based upon the obtained density information; and D3. transmitting a first signaling to the user equipment (20, 30) to instruct the user equipment (20, 30) to perform the periodical measurement, wherein the first signaling includes cell identifiers of the one or more candidate small cells (PC1, PC2, PC3) in the target region and the determined interval. D1. obtaining density information that indicates a density of the candidate small cells (PC1, PC2, PC3) in the target region; D2. determining an interval for the periodical measurement of the user equipment (20, 30) based upon the obtained density information; and D3. transmitting a first signaling to the user equipment (20, 30) to instruct the user equipment (20, 30) to perform the periodical measurement, wherein the first signaling includes cell identifiers of the one or more candidate small cells (PC1, PC2, PC3) in the target region and the determined interval.