TC-OFDM receiver code tracking method based on extended Kalman filter

Abstract

Accurate code phase measurement is an important research focus in high sensitivity tracking. Due to the existing time and code division-orthogonal frequency division multiplexing (TC-OFDM) receiver code tracking algorithms based on delay-locked loop (DLL) and the extended Kalman filter (EKF) without amplitude estimation are prone to loosing the loop in dynamic environments, a TC-OFDM receiver code tracking method is proposed. To improve the estimation accuracy of EKF in the environment with drastic change of signal amplitude, the algorithm estimates the phase error of PN code and signal amplitude as the state vector of EKF. Theoretical analysis and simulation results show that this algorithm takes advantage of the statistical properties of signal amplitude, overcomes the shortcomings of the traditional DLL and EKF without amplitude estimation, and effectively improves the convergence speed and tracking quality of the code loop. Thereby, the proposed algorithm can improve the tracking sensitivity of the existing TC-OFDM receiver by 2–5 dB.