Effect of Inaccurate Range Measurements on Hybrid TOA/RSS Linear Least Squares Localization

Linear least squares (LLS) estimation is a sub-optimum but low-complexity localization method based on measurements of location-related parameters. It has been proved that hybridization of different types of measurements can enhance localization accuracy from Cramer-Rao lower bound (CRLB) analysis. In this paper, a hybrid time-of-arrival and received-signal-strength (TOA/RSS) LLS localization algorithm is derived, where TOA-based ranging has higher accuracy than RSS-based ranging. In many situations such as the case investigated in this paper, accuracies of different measurements are difficult to obtain, and hence no weighting factors are applied to different ranging measurements. In this case, incorporating extra inaccurate measurements into hybrid TOA/RSS LLS localization may degrade its original localization accuracy in some scenarios. Simulation results confirm the theoretical analysis and show that signal-to-noise ratio, path-loss exponent, anchors placement, as well as geometric relation between the agent and anchors all affect the hybrid TOA/RSS LLS localization accuracy in different ways.