Acoustic Backscatter: Enabling Ultra-Low Power, Precise Indoor Positioning

Cox, Bert; Strycker, Lieven De; Perre, Liesbet Van der

doi:10.1109/upinlbs.2018.8559762

Cited by 6 publications

(6 citation statements)

References 13 publications

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“…After all, a very low energy consumption at the tracked device limits the battery cost and/or prolongs the device's autonomy. We performed experimental measurements in a reverberant room using the aforementioned ultra-low-power chirp-based ranging technique and made three main observations [31]: (I) the error increased with distance, which could be attributed to signal attenuation and lower signal-to-noise ratios; (II) larger errors could be found closer to the edges of the room, which was potentially attributed to the high reverberation time of the room; and (III) low ranging errors could be observed within the area covered via the directional speaker pattern. These observations suggest that transducer arrays and beamforming techniques can be employed to further improve the ranging accuracy, as will be shown in this work.…”

Section: Outlining Previous Work and The Research Gapmentioning

confidence: 99%

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Accurate and Low-Power Ultrasound–Radiofrequency (RF) Indoor Ranging Using MEMS Loudspeaker Arrays

Buyle,

De Strycker,

Van der Perre

2023

Sensors

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Accurately positioning energy-constrained devices in indoor environments is of great interest to many professional, care, and personal applications. Hybrid RF–acoustic ranging systems have shown to be a viable technology in this regard, enabling accurate distance measurements at ultra-low energy costs. However, they often suffer from self-interference due to multipaths in indoor environments. We replace the typical single loudspeaker beacons used in these systems with a phased loudspeaker array to promote the signal-to-interference-plus-noise ratio towards the tracked device. Specifically, we optimize the design of a low-cost uniform planar array (UPA) through simulation to achieve the best ranging performance using ultrasonic chirps. Furthermore, we compare the ranging performance of this optimized UPA configuration to a traditional, single-loudspeaker system. Simulations show that vertical phased-array configurations guarantee the lowest ranging errors in typical shoe-box environments, having a limited height with respect to their length and width. In these cases, a P50 ranging error of around 3 cm and P95 ranging error below 30 cm were achieved. Compared to a single-speaker system, a 10 × 2 vertical phased array was able to lower the P80 and P95 up to an order of magnitude.

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Section: Outlining Previous Work and The Research Gapmentioning

confidence: 99%

“…While the additional RF channel increases the hardware complexity of the tracked device, it can also provide a means for high-speed data transfer if needed. In this context, RF backscatter approaches have been proposed to further enhance the nodes’ autonomy [ 3 , 4 ].…”

Section: Introductionmentioning

confidence: 99%

Accurate and Low-Power Ultrasound–Radiofrequency (RF) Indoor Ranging Using MEMS Loudspeaker Arrays

Buyle,

De Strycker,

Van der Perre

2023

Sensors

Self Cite

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“…RFID, although being passive and making use of energy harvesting, also has a limited reading range for communication [28,35] or synchronization [29]. A promising hybrid method makes use of the backscattering technology refined in RFID systems, and directly communicates the received acoustic signals back [41]. In [27], the acoustic signal coming from a CMUT transceiver is modulated around the carrier, making it vulnerable to self-interference and prohibiting multiple access when several mobile nodes are present.…”

Section: Indoor Positioning Technologiesmentioning

confidence: 99%

Positioning Energy-Neutral Devices: Technological Status and Hybrid RF-Acoustic Experiments

et al. 2022

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The digital transformation is exciting the uptake of Internet-of-Things technologies, and raises the questions surrounding our knowledge of the positions of many of these things. A review of indoor localization technologies summarized in this paper shows that with conventional RF-based techniques, a significant challenge exists in terms of achieving good accuracy with a low power consumption at the device side. We present hybrid RF-acoustic approaches as an interesting alternative: the slow propagation speed of sound allows for accurate distance measurements, while RF can easily provide synchronization, data, and power to the devices. We explain how the combination of adequate signaling realizing a late wake-up of the devices with backscattering could position energy-neutral devices. Experiments in a real-life testbed confirmed the potential 10 cm-accuracy based on RF-harvested energy. Nonetheless, these also expose open challenges to be resolved in order to achieve accurate 3D positioning.

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“…Due to reverberation, it is possible that no unambiguously correct peak can be determined, which means that the estimate may give incorrect results. In addition to peak selection methods as described in [12], we here investigate the hypothesis that more redundancy can also be created when multiple distributed anchors are deployed, allowing for more accurate position estimates. To validate the latter, we focus for the ranging estimate on the maximum LPF value.…”

Section: Ultrasonic Indoor Positioning Systemmentioning

confidence: 99%

Techtile: a Flexible Testbed for Distributed Acoustic Indoor Positioning and Sensing

Delabie

Cox

Strycker

et al. 2022

2022 IEEE Sensors Applications Symposium (SAS)

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Indoor positioning applications are craving for ever higher precision and accuracy across the entire coverage zone. Optimal anchor placement and the deployment of multiple distributed anchor nodes could have a major impact in this regard. This paper examines the influences of these two difficult to approach hypotheses by means of a straightforward ultrasonic 3D indoor positioning system deployed in a real-life scenario via a geometric based simulation framework. To obtain an optimal anchor placement, a particle swarm optimization (PSO) algorithm is introduced and consequently performed for setups ranging from 4 to 10 anchors. In this way, besides the optimal anchor placement layout, the influence of deploying several distributed anchor nodes is investigated. In order to theoretically compare the optimization progress, a system model and Cramér-Rao lower bound (CRLB) are established and the results are quantified based on the simulation data. With limited anchors, the placement is crucial to obtain a high precision high reliability (HPHR) indoor positioning system (IPS), while the addition of anchors, to a lesser extent, gives a supplementary improvement.

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Acoustic Backscatter: Enabling Ultra-Low Power, Precise Indoor Positioning

Cited by 6 publications

References 13 publications

Accurate and Low-Power Ultrasound–Radiofrequency (RF) Indoor Ranging Using MEMS Loudspeaker Arrays

Accurate and Low-Power Ultrasound–Radiofrequency (RF) Indoor Ranging Using MEMS Loudspeaker Arrays

Positioning Energy-Neutral Devices: Technological Status and Hybrid RF-Acoustic Experiments

Techtile: a Flexible Testbed for Distributed Acoustic Indoor Positioning and Sensing

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