... several reference -free localization estimators based on TOA measurements for a scenario, where anchor nodes are synchronized, and the clock of the target node runs freely The reference -free LS ... existing closed-form localization solutions is reference dependency The reference here indicates the time associated with the reference anchor For instance, in order to measure TDOAs, a reference anchor ... proposed reference -free localization estimators based on TOA measurements for a scenario, where anchors are synchronized, and the clock of the target node runs freely The reference -free estimators...