An Improved Reference Selection Method in Linear Least Squares Localization for LOS and NLOS

Linear least squares (LLS) estimation is a low complexity but sub-optimum method for estimating the location of a mobile terminal (MT) from some measured distances. It requires selecting one of the known fixed terminals (FTs) as a reference FT for obtaining a linear set of expressions. In this paper, a new method for selecting the reference FT is proposed, which selects the reference FT based on the minimum residual rather than the smallest measured distance and improves the localization accuracy significantly in Line of sight (LOS) environment. In Non-line of sight (NLOS) environment, a new residual weighting algorithm is proposed, which is based on the proposed LOS algorithm. Moreover, by making use of the interior-point optimization method which can obtain the estimation of NLOS error, a new algorithm which is also based on the proposed LOS algorithm is proposed. Simulation results show that the proposed methods improve the positioning accuracy considerably comparing with other existing methods.