Cooperative Carrier Phase Positioning for Asynchronous Narrowband Positioning Systems

Abstract

Carrier phase positioning (CPP) is crucial for precise positioning in Global Satellite Navigation Systems and has gradually been applied to ground-based narrowband positioning systems such as cellular networks and pseudolites. Existing research mainly focuses on single point positioning (SPP) or double difference positioning (DDP) modes. SPP is non-cooperative, and DDP is considered to be a dual-user cooperation requiring the deterministic model of a static reference station. In this paper, we develop a cooperative CPP (CoCPP) mode for asynchronous systems. CoCPP enables multi-user cooperation and allows both static and mobile users to participate in the cooperation. Specifically, we present the principle and algorithm of CoCPP and discuss practical considerations associated with the test of ambiguity fixing. CoCPP makes the carrier phase ambiguities become integers by double differencing and then enables cooperation gains based on ambiguity fixing. We prove that CoCPP has lower Cramer-Rao Lower Bound than SPP if the ambiguities are correctly fixed. We demonstrate that the single difference matrices and cooperating sequences are non-trivial in the case of partial ambiguity fixing for CoCPP. Simulations show that CoCPP outperforms SPP in positioning accuracy.