An approach for estimating Round Trip Time (RTT) such as used for estimating a location of mobile User Equipment (UE) devices, particularly adapted for Open Radio Access Networks (O-RANs) that disaggregate basestation functions into a Radio Unit (RU) and a Distributed Unit (DU) or Central Unit (CU). A Positioning Reference Signal (PRS) is transmitted by the RU according to schedule determined by the DU or CU. A Sounding Reference Signal (SRS) is returned by the UE to the DU or CU, with an estimate by the UE of its internal delay. The RU reports an estimate of the difference seen between a time of transmission of the PRS and time of reception of the SRS. The RTT is then estimated by subtracting the UE's internal delay from this difference. RTTs taken between the UE and two or more RU's may further determine a location of the UE.