TDOA Localization Scheme with NLOS Mitigation

It is important to deploy the capability to locate a User Equipment (UE) using the Time-Difference-of-Arrival (TDOA) measurements. One of the sources of error is the presence of Non-Line-of-Sight (NLOS) errors in the localization problem, which leads to severe degradation in the localization performance using conventional localization algorithms such as the two-step weighted least squares (2WLS) method. In this work, a TDOA localization scheme with NLOS mitigation is proposed. The scheme uses the multidimensional scaling (MDS) framework and it contains three steps. Firstly, the set of all the TDOA measurements is used to form a scalar product matrix in the MDS framework. Secondly, the deletion diagnostics approach is applied to the scalar product matrix to find a subset of the TDOA measurements which forms a submatrix whose eigenvalues satisfy a specific distribution. Finally, the above subset of TDOA measurements is used to compute the estimate of the UE position using 2WLS method. Simulation results show that the proposed scheme successfully eliminates the adverse effects of the NLOS errors.