most of the localization system based on TDOA cannot handle NLOS situation in Outdoor Urban scenario.
the idea is to use a ray tracing simulator to extract a “Multipath Fingerprint”, and based on the Channel Impulse Response of the signal received I try to use the fingerprint and “match” the position of the RF target in an urban scenario.
so the problem should define an emitter in NLOS situation and the bad performance of the TDoA localization system.
then this fingerprinting method is applied and there is an improvement.
Machine Learning can be used as well and also there is a commercial Ray trace simulator that can be downloaded and used for one month