Hybrid GPS/TDOA location algorithm in non-line-of-sight environment

Under certain bad conditions, the number of observed GPS satellites is less than 4 for location determination, and TDOA location method in cellular networks can´t get enough TDOA measurements to position the mobile. Steepest decent method used to fuse GPS pseudo-range and TDOA Observations to resolve the problem is introduced. Then Kaiman filter is proposed to deep process the location data. Field experiment is conducted to verify the algorithms. Results show that GPS/TDOA Kaiman Filter integrated navigation algorithm can achieve higher accurate location.