A Multichannel Low-Power Wide-Area Network With High-Accuracy Synchronization Ability for Machine Vibration Monitoring

Gao, Shang; Zhang, Xuehui; Du, Cuicui; Ji, Qian

doi:10.1109/jiot.2019.2895158

Cited by 46 publications

(15 citation statements)

References 25 publications

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“…In the literature, similar MAC approaches have been considered as they typically offer higher reliability than that of Pure Aloha [ 19 ]. In [ 20 , 21 , 22 ], various time-slotted MAC strategies are used to mitigate the collisions in dense LoRa/LoRaWAN networks and, thus, improve their scalability. Similar MAC strategies are also considered in [ 23 , 24 , 25 , 26 ] to meet the requirements of soft real-time industrial applications.…”

Section: Related Researchmentioning

confidence: 99%

Optimal Data Collection Time in LoRa Networks—A Time-Slotted Approach

Zorbas

Caillouet

Abdelfadeel

et al. 2021

Sensors

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LoRa is a low-power and long range radio communication technology designed for low-power Internet of Things devices. These devices are often deployed in remote areas where the end-to-end connectivity provided through one or more gateways may be limited. In this paper, we examine the case where the gateway is not available at all times. As a consequence, the sensing data need to be buffered locally and transmitted as soon as a gateway becomes available. However, due to the Aloha-style transmission policy of current LoRa-based standards, such as the LoRaWAN, delivering a large number of packets in a short period of time by a large number of nodes becomes impossible. To avoid bursts of collisions and expedite data collection, we propose a time-slotted transmission scheduling mechanism. We formulate the data scheduling optimisation problem, taking into account LoRa characteristics, and compare its performance to low complexity heuristics. Moreover, we conduct a set of simulations to show the benefits of synchronous communications on the data collection time and the network performance. The results show that the data collection can reliably be achieved at least 10 times faster compared to an Aloha-based approach for networks with 100 or more nodes. We also develop a proof-of-concept to assess the overhead cost of communicating the schedule to the nodes and we present experimental results.

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Section: Related Researchmentioning

confidence: 99%

Optimal Data Collection Time in LoRa Networks—A Time-Slotted Approach

Zorbas

Caillouet

Abdelfadeel

et al. 2021

Sensors

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“…Based on LoRa, Sigfox, or NB-IoT, these protocols allow for communications over a few kilometers in urban areas. In [23] LoRa and NB-Iot are used for node communications in the context of machine vibrations monitoring. Nodes are synchronized every 10 s using LoRa with an accuracy of 5 µs.…”

Section: Related Workmentioning

confidence: 99%

Energy-Efficient GPS Synchronization for Wireless Nodes

2021

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Synchronization is a challenging problem for wireless nodes, especially for applications demanding good synchronization accuracy over wide areas. In that case, the GPS is a valuable solution as the nodes can independently synchronize to UTC. However, the energy consumption of a GPS receiver (over 100 mW when switched on) is not sustainable on a wireless node. Therefore, in this work, we developed a synchronization scheme based on periodic extinctions of the GPS receiver. The goal is to study the GPS power switching effect on the synchronization accuracy. To do so, a node with dedicated timestamping hardware was designed. Two clock models were compared to predict the node time when the GPS is off and the impact of a Kalman filter, to remove the GPS noise, was evaluated. From experimental data, we show that the choice of the clock model depends on the accuracy needed and that the Kalman filter improves the estimation of the clock frequency for both models. In our design, the GPS can be off from 60% up to 95% of the time for mean synchronization errors of 20 ns to 420 ns, respectively. This work demonstrates that GPS power switching is an efficient solution to reduce energy costs while maintaining a high synchronization accuracy.

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“…Some adopt an on-demand approach, where each ED transmits its synchronization request to the GW. To reduce the energy consumption, simple algorithms synchronizing all the EDs in one-shot are preferred such as [ 28 , 29 ].…”

Section: Framework For Performance Evaluationmentioning

confidence: 99%

Collision-Free Transmissions in an IoT Monitoring Application Based on LoRaWAN

Haiahem¹,

Minet

Boumerdassi

et al. 2020

Sensors

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With the Internet of Things (IoT), the number of monitoring applications deployed is considerably increasing, whatever the field considered: smart city, smart agriculture, environment monitoring, air pollution monitoring, to name a few. The LoRaWAN (Long Range Wide Area Network)architecture with its long range communication, its robustness to interference and its reduced energy consumption is an excellent candidate to support such applications. However, if the number of end devices is high, the reliability of LoRaWAN, measured by the Packet Delivery Ratio (PDR), becomes unacceptable due to an excessive number of collisions. In this paper, we propose two different families of solutions ensuring collision-free transmissions. The first family is TDMA (Time-Division Multiple Access)-based. All clusters transmit in sequence and up to six end devices with different spreading factors belonging to the same cluster are allowed to transmit in parallel. The second family is FDMA (Frequency Divsion Multiple Access)-based. All clusters transmit in parallel, each cluster on its own frequency. Within each cluster, all end devices transmit in sequence. Their performance are compared in terms of PDR, energy consumption by end device and maximum number of end devices supported. Simulation results corroborate the theoretical results and show the high efficiency of the solutions proposed.

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A Multichannel Low-Power Wide-Area Network With High-Accuracy Synchronization Ability for Machine Vibration Monitoring

Cited by 46 publications

References 25 publications

Optimal Data Collection Time in LoRa Networks—A Time-Slotted Approach

Optimal Data Collection Time in LoRa Networks—A Time-Slotted Approach

Energy-Efficient GPS Synchronization for Wireless Nodes

Collision-Free Transmissions in an IoT Monitoring Application Based on LoRaWAN

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