System Design for Ultra-Low-Power UWB-based Indoor Localization
ABSTRACT In this paper, we propose a 3-tier ultra wide-band indoor localization system for autonomously powered sensor network applications. It consists of a large number of cost-effective tags, a number of cheap and low-power hubs and few synchronized base stations. Using the UWB characteristics and the hierarchical scheme, the localization system enables ultra-low-power, autonomous tags and precise positioning. We present how ambiguous solutions (coordinates and transmission time of an unknown node) can be eliminated with the help of the proper geometry of 4 reference nodes. A method for optimizing the number and placement of hubs is proposed. Different positioning algorithms are discussed and compared based on the position accuracy a.f.o range errors. We determine the optimal algorithm for different scenarios. Simulations are conducted to investigate the performance degradation due to timing errors.
SourceAvailable from: Georges G. E. Gielen[Show abstract] [Hide abstract]
ABSTRACT: Ultra-wideband (UWB) enabled wireless sensor networks (WSNs) are capable of identification, localization and recording of sensor readings. For reasons of cost, size and above all energy consumption constraints, scavenging-based ultra-lower-power (ULP) sensor nodes (SNs) are designed with only UWB transmitters. Transmit-only SNs are unaware of each other and broadcast data packets as soon as enough energy is harvested from the environment. The trade-off is that the resulting uncoordinated multiuser access causes packet collisions so that many SNs become undetectable. In this paper, we propose several techniques to control the transmit time of SNs. These techniques help to alleviate packet collisions and improve SNs detectability. They are evaluated and compared as a function of the network density (the number of SNs per m<sup>3</sup>). We determine the effective techniques for different network density. Results obtained from simulations indicate that by adding randomness in the transmissions while introducing pause time between two consecutive transmissions, all SNs can be identified up to quite a large network density (500 SNs/m<sup>3</sup>) in this scavenging-based transmit-only scenario.Communication Systems, 2008. ICCS 2008. 11th IEEE Singapore International Conference on; 12/2008
Conference Paper: Preliminary study on noncooperative positioning using UWB impulse radio[Show abstract] [Hide abstract]
ABSTRACT: Impulse radio ultra wideband (IR UWB) is a promising technology for positioning. Many papers about UWB positioning focus on cooperative target. The study considers UWB positioning for noncooperative target, which means that the target is passive and does not transmit signal. There are few papers in the literature on the field. Existing papers place great emphasis on positioning algorithms instead of time based ranging techniques. In addition, they do not pay much attention on the propagation characteristics of the IR UWB signal in the special usage scenario, which is different from that in cooperative positioning. In the study, we present our understanding on the field. First, we point the importance of TOA estimation in noncooperative positioning. Then, we propose a novel UWB channel to explore the signal propagation characteristics. It is a two-stage cascade multipath channel. In the simulation, energy detection receiver is used to estimate the TOA of the special direct path.Ultra-Wideband (ICUWB), 2012 IEEE International Conference on; 01/2012
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ABSTRACT: We present a 3-tier UWB-based indoor localization system. It consists of a large number of energy-scavenging-based cost-effective transmit-only tags, a small number of battery powered hubs as relay stations and a few base stations. This hierarchical scheme is driven by the energy available at each node. Localization is based on the arrival time of the UWB pulses at reference nodes.We describe how the coordinates and transmit time of a tag are determined and how the ambiguous solution is eliminated with the proper geometry of 4 reference nodes. We formulate where to place the hubs as an optimization problem. The localization performance of the system is investigated as a function of several parameters such as non-ideal hub placement, hub localization error and TOA error.IEEE Transactions on Wireless Communications 07/2009; DOI:10.1109/TWC.2009.080602 · 2.76 Impact Factor