A method performed by a position-estimating node for determining a position estimate for a first base station transceiver node in a wireless communication system, wherein the method comprises: maintaining a database of time-difference-of-arrival, TDOA, measurements stored along with corresponding known positions for measuring mobile stations, wherein each TDOA measurement involves a pair of base station transceiver nodes, and wherein the database being built by performing a mobile station assisted observed time-difference-of-arrival, OTDOA, procedures in parallel or in sequence with A-GPS and / or GPS-based positioning requests; evaluating the database of TDOA measurements to identify a subset of TDOA measurements involving the first base station transceiver node, wherein the subset of TDOA measurements is taken within a time window of a predetermined duration; evaluating the subset of TDOA measurements to identify a second base station transceiver node by determining that the second base station transceiver node is involved in at least as many of the identified subset of TDOA measurements involving the first base station transceiver node as any other base station transceiver node; computing an estimated position for the first base station transceiver node as a function of the corresponding known positions for the measuring mobile stations and the measurements involving the second base station transceiver node of the subset of TDOA measurements involving the first base station transceiver node, wherein if no suitable subset of TDOA measurements meeting the time window of the predetermined duration is identified, sending positioning requests to several mobile stations in vicinity of the first base station transceiver node; and storing in a database of base station positions the estimated position for the first base station transceiver node. maintaining a database of time-difference-of-arrival, TDOA, measurements stored along with corresponding known positions for measuring mobile stations, wherein each TDOA measurement involves a pair of base station transceiver nodes, and wherein the database being built by performing a mobile station assisted observed time-difference-of-arrival, OTDOA, procedures in parallel or in sequence with A-GPS and / or GPS-based positioning requests; evaluating the database of TDOA measurements to identify a subset of TDOA measurements involving the first base station transceiver node, wherein the subset of TDOA measurements is taken within a time window of a predetermined duration; evaluating the subset of TDOA measurements to identify a second base station transceiver node by determining that the second base station transceiver node is involved in at least as many of the identified subset of TDOA measurements involving the first base station transceiver node as any other base station transceiver node; computing an estimated position for the first base station transceiver node as a function of the corresponding known positions for the measuring mobile stations and the measurements involving the second base station transceiver node of the subset of TDOA measurements involving the first base station transceiver node, wherein if no suitable subset of TDOA measurements meeting the time window of the predetermined duration is identified, sending positioning requests to several mobile stations in vicinity of the first base station transceiver node; and storing in a database of base station positions the estimated position for the first base station transceiver node. <EOS>