In cellular systems, network re-planning aims to update network configuration to cope with permanent changes in the environment. In this task, terminal measurements are often used to calibrate performance models integrated in radio network planning tools. In Release 10 of the 3GPP standard, the Minimization of Drive Test (MDT) feature allows the collection
of user position correlated to performance statistics or radio events. In practice, positioning errors severely limit the potential
of MDT measurements. In this work, a preliminary analysis of a large MDT dataset taken from a commercial Long-Term
Evolution (LTE) network shows for the first time several sources of positioning errors not previously reported in the literature.
Then, a heuristic filtering algorithm is proposed to discard samples with inaccurate location data. Method assessment is
done by checking the impact of filtering on the coverage map built with a real MDT dataset. Results show that the proposed
method significantly improves the accuracy of coverage maps by filtering unreliable measurements.
