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.
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ABSTRACT: This paper presents a fully integrated flexible ultra-low power UWB impulse radio receiver, capable of cm-accurate ranging. Ultra-low-power consumption is achieved by employing the quadrature analog correlating receiver architecture, by exploiting the duty-cycled nature of the system, by operating in the sub-1 GHz band as well as by careful circuit design. Two pulse rates, 39.0625 Mpulses per second (Mpps) and 19.531 Mpps, and a wide range of processing gains (0-18 dB) are supported. Also, the acquisition algorithm and accuracy can be adapted at run time. This flexible implementation allows to dynamically trade power consumption for performance depending on the operating conditions and the application requirements. The receiver prototype was manufactured in 130 nm CMOS and the active circuit area measures 4.52 mm<sup>2</sup>. The IC contains a complete analog front-end, digital backend and implements the algorithms necessary for acquisition, synchronization, data reception and ranging. Consuming 4.2 mW when operating at 39.0625 Mpps, it achieves an energy efficiency of 108 pJ/pulse. A 1.3 Mb/s wireless link over more than 10 m in an office-like environment has been demonstrated under direct line-of-sight (LOS) conditions with a raw packet-error-rate (PER) less than 10% and cm-accurate ranging.IEEE Journal of Solid-State Circuits 02/2010; · 3.06 Impact Factor
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ABSTRACT: In RFID-tags with pulse-based UWB communication, accurate supply-independent low-power oscillators are required. The 24 MHz oscillator presented was realized in a 130 nm CMOS technology. It has an ultra-low supply voltage dependency of 104 ppm/V over a voltage range of 1.4 V to 0.4 V. This was achieved by the use of two nested ultra-low-power voltage regulators and a novel circuit technique based on the attraction of two oscillator frequencies. The mean power consumption is 33 muW over the 1 V voltage span. No external biasing and no trimming or calibration was used.ESSCIRC, 2009. ESSCIRC '09. Proceedings of; 10/2009
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