arXiv:2611.13828v1 Announce Type: new Abstract: Indoor user localization is essential for applications such as asset tracking, robotic navigation, and smart-building automation where satellite-based positioning is unavailable. Bistatic MIMO radar exploits bistatic range measurements and geometric diversity from distributed antennas, but low-SNR conditions make the resulting estimation ill-conditioned. We formulate indoor localization as a Tikhonov-regularized nonlinear least-squares problem and solve it with a damped Gauss-Newton (DGN) algorithm, in which each iteration reduces to a closed-form 3x3 linear solve followed by an Armijo backtracking line search. Simulations show accuracy on par with, and runtime far faster than, an SDP-based benchmark.