Carrier Phase-Based Localization Method for TDD Systems via Extended Kalman Filter

In time-division duplex (TDD) systems, where uplink and downlink channels alternate during transmission process, the continuity of carrier phase measurements becomes challenging to maintain. This leads to periodic lock-loss in the phase-locked loop (PLL), rendering the integer ambiguity non-constant. To address this issue, a carrier phase-based localization method for TDD systems via extended Kalman filtering is proposed in this study. The proposed method modifies the one-step predicted state within each TDD cycle based on extended Kalman filtering (EKF) to overcome the effects of PLL lock-loss in TDD. Simulation results verificate that the proposed method can overcome the problem of discontinuous measurement in TDD system, accurately solve integer ambiguities and achieve high-precision positioning.