Pairwise Node Localization From Differences in Their UWB Channels to Observer Nodes

Abstract

We consider the problem of localization and distance estimation between a pair of wireless nodes in a multipath propagation environment, but not the usual way of processing a channel measurement between them. We propose a novel paradigm which compares the two nodes' ultra-wideband (UWB) channels to other nodes, called observers. The main idea is that the dissimilarity between the channel impulse responses (CIRs) increases with d and allows for an estimate d. Our approach relies on extracting common multipath components (MPCs) from the CIRs. This is realistic in indoor or urban scenarios and if d is considerably smaller than the distances to the observers.We present distance estimators which utilize the rich location information contained in MPC delay differences. Likewise, we present estimators for the relative position vector which process both MPC delays and MPC directions. We do so for various important cases: with and without time synchronization, delay measurement errors, and knowledge of the MPC association between the two CIRs. The estimators exhibit great technological advantages: they do not require line-of-sight conditions or knowledge about the observer locations or the environment.We study the estimation accuracy with a numerical evaluation based on random sampling and, additionally, with an experimental evaluation based on measurements in an indoor environment. The proposal shows the potential for great accuracy in theory and practice. We describe how the paradigm could be incorporated into established cooperative localization frameworks to provide them with novel inter-and intra-node measurements for spatiotemporal tracking. This could enable low-cost localization of wireless users or networks in dynamic multipath settings.

Multistate Constraint Multipath-Assisted Positioning and Mismatch Alleviation

“…The dimension of the observation matrix H of ( 17) is T (M + K) × 2(M + T ). Clearly, (17) has one and only one solution because the calculated UE's and VAs' positions are unique, meaning that the observation matrix is full column rank:…”

“…The above formula provides the MOC for solving (17). For example, when K = 0 and M = 5, T ≥ 4 can guarantee that (17) has a solution.…”

“…It should be noted that the least square is used to explore the distinct constraint of the observation epoch during realtime state estimation. Upon adding the kinematic model of the UE to the linearized observation model (17), joint position estimation can be easily extended to some filter methods; this topic is beyond the scope of this paper.…”

On Indoor Localization Using WiFi, BLE, UWB, and IMU Technologies

“…To address this, the detection of the NLoS condition [11,65] and mitigation of the resulting ranging errors [65] have become active areas of research. Other studies have focused on channel impulse responses between anchors and receivers [66,67]. The theory behind this approach is to utilize the Multi-Path Components (MPCs) of the signal to enhance localization accuracy [67] in a manner similar to WiFi CSI.…”

Improved Detection Schemes for Non-coherent Pulse-Position Modulation

“…Also, Apple iPhones are equipped with a UWB chip for spatial awareness to accurately locate one another [ 8 ]. UWB ranging has been used for social distancing and contact tracing, especially during the COVID-19 pandemic [ 15 ]. Moreover, car manufacturers like Audi and BMW use UWB systems for keyless entry and hands-free access control [ 8 ].…”