Joint Positioning and Synchronization Based on Multi-Epoch Measurements in Imperfectly-Synchronous 5G mmWave Systems

The inter-base station (BS) synchronization error poses a serious challenge to high-precision 5G localization. This letter proposes a joint positioning and synchronization method in an imperfectly-synchronous 5G mmWave system. First, the temporal correlation model of the synchronization error over adjacent epochs is established. Then, the conventional single-epoch Taylor-weighted least squares method is improved and extended to a multi-epoch time of arrival (TOA)-angle of departure (AOD) hybrid positioning scheme. Based on this scheme, a multi-epoch-based joint positioning and synchronization method is proposed, which minimizes state quantities related to the BS clock offsets by employing the temporal correlation model. Finally, the Cramer Rao Lower Bound of positioning error is derived to show the fundamental performance. Results show that the proposed method significantly reduces the positioning error compared with three baseline methods in an imperfectly-synchronous 5G network.