A method for provision of position determination assisting data in a cellular communication network comprises establishing (204) of a cell relation configuration for a user equipment. The cell relation configuration comprises cell identities of cells, in which signals fulfil a specific radio condition criterion when received. The method further comprises performing (206) of a high-precision position determination for the user equipment. The establishing and performing steps (204, 206) are repeated a plurality of times. Positioning points belonging to the same cell relation configuration are clustered (208) and a polygon is associated (212) with each result cluster. The association (212) comprises encompassing of a result cluster by a polygon, altering of the polygon corners along defined paths to improve a predetermined criterion, and counteracting that polygon corners are gathering at a minor portion of a circumference. The method finally comprises creating (212) of position determination assisting data comprising a relation between the cell relation configurations and the polygon.