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3 pages, 152 KiB

Open AccessEditorial

Wireless Systems and Networks in the IoT

by Damianos Gavalas, Modestos Stavrakis, Periklis Chatzimisios, Zhichao Cao and Xiaolong Zheng

Sensors 2020, 20(8), 2279; https://doi.org/10.3390/s20082279 - 17 Apr 2020

Cited by 2 | Viewed by 2214

Abstract

This Special Issue is focused on breakthrough developments in the field of Wireless Systems and Networks in the IoT. The selected contributions report current scientific progress in a wide range of topics covering clock error compensation in sensor networks, backscatter communication networks, Radio-Frequency [...] Read more.

This Special Issue is focused on breakthrough developments in the field of Wireless Systems and Networks in the IoT. The selected contributions report current scientific progress in a wide range of topics covering clock error compensation in sensor networks, backscatter communication networks, Radio-Frequency Identification (RFID)-based inventory management, resource allocation in Long-Term Evolution (LTE)/LTE-A, (Long Range Wide-Area Network (LoRaWAN) modeling and key generation for the IoT. Full article

(This article belongs to the Special Issue Wireless Systems and Networks in the IoT)

Research

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15 pages, 3212 KiB

Open AccessArticle

Compensation Method for Sensor Network Clock Error Based on Cyclic Symmetry Algorithm

by Hailiang Feng, Zhanxin Yang, Yuhai Shi and Narjes Nabipour

Sensors 2020, 20(6), 1738; https://doi.org/10.3390/s20061738 - 20 Mar 2020

Cited by 3 | Viewed by 2079

Abstract

Since the existing methods cannot evaluate the time delay of different layers of sensor networks, there are some problems such as the low precision of clock error compensation, high time delay, and low efficiency of communication in sensor networks. To solve this problem, [...] Read more.

Since the existing methods cannot evaluate the time delay of different layers of sensor networks, there are some problems such as the low precision of clock error compensation, high time delay, and low efficiency of communication in sensor networks. To solve this problem, a method of clock error compensation in sensor networks based on a cyclic symmetry algorithm is proposed. Based on the basic theory of cyclic symmetry, the cyclic symmetry matrix of the sensor network is constructed; in the communication process, all nodes are extended to get the cumulative delay rate of the sensor network in the specified time domain. Using the cumulative delay rate of the cyclic network and the sensor network, the autoregressive integral sliding mode control model is established to compensate for the cumulative error of clock synchronization. The simulation results show that the compensation accuracy of this method is more than 98%, which can effectively reduce the delay of sensor network. It improves the communication efficiency of the sensor network, meets the communication requirements of the sensor network, and has a very broad application prospect. Full article

(This article belongs to the Special Issue Wireless Systems and Networks in the IoT)

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16 pages, 5008 KiB

Open AccessArticle

Channel Prediction Based on BP Neural Network for Backscatter Communication Networks

by Jumin Zhao, Hao Tian and Deng-ao Li

Sensors 2020, 20(1), 300; https://doi.org/10.3390/s20010300 - 05 Jan 2020

Cited by 15 | Viewed by 2969

Abstract

Backscatter communication networks are receiving a lot of attention thanks to the application of ultra-low power sensors. Because of the large amount of sensor data, increasing network throughput becomes a key issue, so rate adaption based on channel quality is a novel direction. [...] Read more.

Backscatter communication networks are receiving a lot of attention thanks to the application of ultra-low power sensors. Because of the large amount of sensor data, increasing network throughput becomes a key issue, so rate adaption based on channel quality is a novel direction. Most existing methods share common drawbacks; that is, spatial and frequency diversity cannot be considered at the same time or channel probe is expensive. In this paper, we propose a channel prediction scheme for backscatter networks. The scheme consists of two parts: the monitoring module, which uses the data of the acceleration sensor to monitor the movement of the node itself, and uses the link burstiness metric β to monitor the burstiness caused by the environmental change, thereby determining that new data of channel quality are needed. The prediction module predicts the channel quality at the next moment using a prediction algorithm based on BP (back propagation) neural network. We implemented the scheme on readers. The experimental results show that the accuracy of channel prediction is high and the network goodput is improved. Full article

(This article belongs to the Special Issue Wireless Systems and Networks in the IoT)

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16 pages, 1407 KiB

Open AccessArticle

Intelligent Management of Chemical Warehouses with RFID Systems

by Jumin Zhao, Fangfang Xue and Deng-ao Li

Sensors 2020, 20(1), 123; https://doi.org/10.3390/s20010123 - 24 Dec 2019

Cited by 8 | Viewed by 3142

Abstract

At present, most chemical warehouses rely on human management, which is a time-consuming and laborious process. Therefore, it is very meaningful to use radio frequency identification (RFID) systems for the intelligent management of chemicals. Detecting the remaining amount of chemicals is an important [...] Read more.

At present, most chemical warehouses rely on human management, which is a time-consuming and laborious process. Therefore, it is very meaningful to use radio frequency identification (RFID) systems for the intelligent management of chemicals. Detecting the remaining amount of chemicals is an important process in the management of a chemical warehouse. It helps managers find the chemicals that are going to run out and replenish them in time. However, in a traditional chemical warehouse, managers usually inspect each chemical on the shelf in turn manually, which is a waste of time and labor. Although some solutions using RFID technology have been proposed, they are expensive and difficult to deploy in a real environment. In order to solve this problem, we propose an intelligent system called the RF-Detector in this paper, which combines robotics and RFID technology. An RFID reader and an antenna are installed on the robot, which achieves automatic scanning of the chemicals. The RF-Detector can achieve two functions: One function is to detect the remaining amount of chemicals using the changes in received signal strength indication (RSSI) and read rate, and the other is to locate chemicals using the phase curve, so that managers can quickly find the chemicals with an insufficient amount remaining. In this paper we implement the RF-Detector and evaluate its performance. The experimental results show that the RF-Detector achieves about 93% detection accuracy and 92% positioning accuracy for chemicals. Full article

(This article belongs to the Special Issue Wireless Systems and Networks in the IoT)

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16 pages, 2759 KiB

Open AccessArticle

Fast and Reliable Burst Data Transmission for Backscatter Communications

by Jumin Zhao, Xiaojuan Liu and Dengao Li

Sensors 2019, 19(24), 5418; https://doi.org/10.3390/s19245418 - 09 Dec 2019

Cited by 4 | Viewed by 2532

Abstract

Computational radio frequency identification (CRFID) sensors are able to transfer potentially large amounts of data to the reader in the radio frequency range. However, the existing EPC C1G2 protocol is inefficient when there are abundant critical and emergency data to be transmitted and [...] Read more.

Computational radio frequency identification (CRFID) sensors are able to transfer potentially large amounts of data to the reader in the radio frequency range. However, the existing EPC C1G2 protocol is inefficient when there are abundant critical and emergency data to be transmitted and cannot adapt to changing energy-harvesting and channel conditions. In this paper, we propose a fast and reliable method for burst data transmission by fragmenting large data packets into blocks and we introduce a burst transmission mechanism to optimize the EPC C1G2 communication procedure for burst transmission when there are critical and emergency data to be transmitted. In addition, we utilize erasure codes to reduce Acknowledgement (ACK) delay and to improve system reliability. Our results show that our proposed scheme significantly outperforms the current fixed frame length approach and the dynamic frame length and charging time adaptation scheme (DFCA) and that the goodput is close to the theoretically optimal value under different energy-harvesting and channel conditions. Full article

(This article belongs to the Special Issue Wireless Systems and Networks in the IoT)

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16 pages, 452 KiB

Open AccessArticle

Energy Efficient Resource Allocation for M2M Devices in LTE/LTE-A

by Hajer Ben Rekhissa, Cecile Belleudy and Philippe Bessaguet

Sensors 2019, 19(24), 5337; https://doi.org/10.3390/s19245337 - 04 Dec 2019

Cited by 6 | Viewed by 3244

Abstract

Machine-to-machine (M2M) communication consists of the communication between intelligent devices without human intervention. Long term evolution (LTE) and Long-term evolution-advanced (LTE-A) cellular networks technologies are excellent candidates to support M2M communication as they offer high data rates, low latencies, high capacities and more [...] Read more.

Machine-to-machine (M2M) communication consists of the communication between intelligent devices without human intervention. Long term evolution (LTE) and Long-term evolution-advanced (LTE-A) cellular networks technologies are excellent candidates to support M2M communication as they offer high data rates, low latencies, high capacities and more flexibility. However, M2M communication over LTE/LTE-A networks faces some challenges. One of these challenges is the management of resource radios especially on the uplink. LTE schedulers should be able to meet the needs of M2M devices, such as power management and the support of large number of devices, in addition to handling both human-to-human (H2H) and M2M communications. Motivated by the fundamental requirement of extending the battery lives of M2M devices and managing an LTE network system, including both M2M devices and H2H users, in this paper, two channel-aware scheduling algorithms on the uplink are proposed. Both of them consider the coexistence of H2H and M2M communications and aim to reduce energy consumption in M2M devices. The first algorithm, called FDPS-carrier-by-carrier modified (CBC-M), takes into account channel quality and power consumption while allocating radio resources. Our second algorithm, recursive maximum expansion modified (RME-M), offers a balance between delay requirement and energy consumption. Depending on the system requirements, RME-M considers both channel quality and system deadlines in an adjustable manner according to M2M devices needs. Simulation results show that the proposed schedulers outperform the round-robin scheduler in terms of energy efficiency and have better cell spectral efficiency. Full article

(This article belongs to the Special Issue Wireless Systems and Networks in the IoT)

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23 pages, 586 KiB

Open AccessArticle

LoRaWAN Modeling and MCS Allocation to Satisfy Heterogeneous QoS Requirements

by Dmitry Bankov, Evgeny Khorov and Andrey Lyakhov

Sensors 2019, 19(19), 4204; https://doi.org/10.3390/s19194204 - 27 Sep 2019

Cited by 21 | Viewed by 3547

Abstract

LoRaWAN infrastructure has become widely deployed to provide wireless communications for various sensor applications. These applications generate different traffic volumes and require different quality of service (QoS). The paper presents an accurate mathematical model of low-power data transmission in a LoRaWAN sensor network, [...] Read more.

LoRaWAN infrastructure has become widely deployed to provide wireless communications for various sensor applications. These applications generate different traffic volumes and require different quality of service (QoS). The paper presents an accurate mathematical model of low-power data transmission in a LoRaWAN sensor network, which allows accurate validation of key QoS indices, such as network capacity and packet loss ratio. Since LoRaWAN networks operate in the unlicensed spectrum, the model takes into account transmission attempt failures caused by random noise in the channel. Given QoS requirements, we can use the model to study how the performance of a LoRaWAN network depends on the traffic load and other scenario parameters. Since in LoRaWAN networks the transmissions at different modulation and coding schemes (MCSs) typically do not collide, we use the model to assign MCSs to the devices to satisfy their QoS requirements. Full article

(This article belongs to the Special Issue Wireless Systems and Networks in the IoT)

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25 pages, 4096 KiB

Open AccessArticle

An Efficient Key Generation for the Internet of Things Based Synchronized Quantization

by Mike Yuliana, Wirawan and Suwadi

Sensors 2019, 19(12), 2674; https://doi.org/10.3390/s19122674 - 13 Jun 2019

Cited by 18 | Viewed by 2925

Abstract

One solution to ensure secrecy in the Internet of Things (IoT) is cryptography. However, classical cryptographic systems require high computational complexity that is not appropriate for IoT devices with restricted computing resources, energy, and memory. Physical layer security that utilizes channel characteristics is [...] Read more.

One solution to ensure secrecy in the Internet of Things (IoT) is cryptography. However, classical cryptographic systems require high computational complexity that is not appropriate for IoT devices with restricted computing resources, energy, and memory. Physical layer security that utilizes channel characteristics is an often used solution because it is simpler and more efficient than classical cryptographic systems. In this paper, we propose a signal strength exchange (SSE) system as an efficient key generation system and a synchronized quantization (SQ) method as a part of the SSE system that synchronizes data blocks in the quantization phase. The SQ method eliminates the signal pre-processing phase by performing a multi-bit conversion directly from the channel characteristics of the measurement results. Synchronization is carried out between the two authorized nodes to ensure sameness of the produced keys so it can eliminate the error-correcting phase. The test results at the IoT devices equipped with IEEE 802.11 radio show that SSE system is more efficient in terms of computing time and communication overhead than existing systems. Full article

(This article belongs to the Special Issue Wireless Systems and Networks in the IoT)

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