Joint ranging and synchronization for an anchorless network of mobile nodes

TL;DR

This paper introduces a joint model for ranging and synchronization in mobile wireless networks, proposing algorithms that estimate clock parameters and distances simultaneously, and demonstrating near-optimal performance through simulations.

Contribution

It presents a novel joint time-range model for mobile nodes and develops a global least squares algorithm with a constrained CCRB analysis, advancing synchronization and localization methods.

Findings

Proposed algorithms approach theoretical performance limits.

Joint estimation improves synchronization and ranging accuracy.

Simulations validate the effectiveness of the proposed methods.

Abstract

Synchronization and localization are critical challenges for the coherent functioning of a wireless network, which are conventionally solved independently. Recently, various estimators have been proposed for pairwise synchronization between immobile nodes, based on time stamp exchanges via two-way communication. In this paper, we consider a \textit{network of mobile nodes} for which a novel joint time-range model is presented, treating both unsynchronized clocks and the pairwise distances as a polynomial function of \textit{true} time. For a set of nodes, a pairwise least squares solution is proposed for estimating the pairwise range parameters between the nodes, in addition to estimating the clock offsets and clock skews. Extending these pairwise solutions to network-wide ranging and clock synchronization, we present a central data fusion based global least squares algorithm. A unique solution is non-existent without a constraint on the cost function (\eg clock reference node). Ergo, a constrained framework is proposed and a new Constrained \Cramer\ Rao Bound (CCRB) is derived for the joint time-range model. In addition, various constraints are proposed and their effects on the proposed algorithms are studied. Simulations are conducted and the proposed algorithm is shown to approach the theoretical limits.