TDOA, Frequency and Phase Offsets Estimation Taking Into Account Carrier Phase of Arrival

Abstract

This paper deals with estimation of time difference of arrival (TDOA) and phase and frequency offsets between the channels in a receiving system with two distributed time synchronized, but phase and frequency unlocked channels. The system receives a radio signal with a known waveform. We analyze the impacts of using the carrier phase of arrival (CPOA) on parameter estimation accuracy. Depending on which of the parameters are unknown, three cases are considered. For the case when phase, frequency, and time shifts are all unknown, we derive the Fisher Information Matrix (FIM) in closed form, and Cramer-Rao bound (CRB) closed form expressions for the unknown phase and frequency offsets case, and the unknown TDOA case. Two maximum likelihood type (ML) statistically efficient estimation algorithms are proposed. The CRBs and simulation results show that in the unknown TDOA case the accuracy of TDOA estimation can be significantly increased by using CPOA.