• International journal of advanced smart convergence
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• v.7 no.3
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• pp.23-36
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• 2018

In wireless communication, efficient spectrum usage is an issue that has been an attractive research area for many technologies. Recently new technologies innovations allow compact radios to transmit with power efficient communication over very long distances. For example, Low-Power Wide Area Networks (LPWANs) are an attractive emerging platform to connect the Internet-of-Things (IoT). Especially, LoRa is one of LPWAN technologies and considered as an infrastructure solution for IoT. End-devices use LoRa protocol across a single wireless hop to communicate to gateway(s) connected to the internet which acts as a bridge and relays message between these LoRa end-devices to a central network server. The use of the (ISM) spectrum sharing for such long-range networking motivates us to implement spectrum sensing testbed for cognitive radio network based on LoRa and GNU radio. In cognitive radio (CR), secondary users (SUs) are able to sense and use this information to opportunistically access the licensed spectrum band in absence of the primary users (PUs). In general, PUs have not been very receptive of the idea of opportunistic spectrum sharing. That is, CR will harmfully interfere with operations of PUs. Subsequently, there is a need for experimenting with different techniques in a real system. In this paper, we implemented spectrum sensing for cognitive radio networks based on LoRa and GNU Radio, and further analyzed corresponding performances of the implemented systems. The implementation is done using Microchip LoRa evolution kits, USRPs, and GNU radio.

• International Journal of Advanced Culture Technology
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• v.4 no.4
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• pp.1-5
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• 2016

In this paper, we present the study on the proposed design of a real-time transmission of a video from the drone to broadcasting station (OBVan) by using F8L10D-N LoRa Module. Nowadays, LoRa technology is proved to be the mass of low cost, long range machine-to-machine connectivity. Particularly in the field of broadcasting and communication system, F8L10D-N LoRa RF Module spread spectrum technology with long transmission distance and strong penetrative ability that is double stronger than traditional FSK as well as PSK modulation scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.4
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• pp.569-574
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• 2018

This paper proposes and implements a LoRa-based emergency exit guide system which can direct the optimal refuge path accounting for the real state of the fires. Each 4-way emergency exit guide sign presents a right direction through one of four LED signs toward the possible exit dynamically calculated by the shortest path algorithm. We constructed a simulation environment with 8 spots of the emergency exit guide signs and 2 exits, which can simulate variant cases of fire accidents, and showed that the proposed algorithm can presents the right guidance for each emergency exit guide sign. We also evaluated the performances of LoRa-based wireless communications using a self developed communication module in the various indoor and outdoor environments. The proposed system can be applied to small and medium sized buildings as well as larger ones in terms of cost efficiency, in which there's no needs to invest for the complex equipments except only sensors and emergency exit guide signs.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.6
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• pp.897-906
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• 2022

In this paper, we propose a novel MAC protocol based on the harmonic transmission of ACK, called HAT-LoRa, for improving the reliability and the utilization in multiple gateway LoRa Networks. LoRa is basically vulnerable to collision due to the primitive pure ALOHA-like MAC. Whereas data frame delivery can be guaranteed by the transparent bridge of multiple receiving gateways, ACK is still transmitted by a single gateway in LoRa Network. HAT-LoRa provides the augmented reception opportunity of ACK via the simultaneous transmissions of identical ACK in multiple spreading factors. The proposed method reduces the expected transmission times of ACK double gateway environment as well as single gateway environment, by 55 and 60% in maximum, by 35% and 40% in average, in a single- and double-gateway environment, respectively. Especially, it outperforms under the environment where the distance between end device and gateways are similar to each other.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.5
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• pp.275-281
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• 2018

Along with the growing market for pets and the increasing interest in pet management, the need for pet management systems is increasing. Development of IoT-related technologies has made it possible to develop the related systems. This paper implements a variety of functions through Bluetooth 4.0 and LoRa communication between devices using Arduino and Android applications depending on distances. In the paper, users can receive real-time location information through the communication between Android applications and devices attached to pets, store pet information, manage pet information, and store stroll courses more conveniently with the developed system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.3
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• pp.677-685
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• 2017

Supply rate is very low because conventional smart system of streetlight management requires a lot of time and cost until now. In this paper, we demonstrated maintaining system for streetlight which uses LoRaWAN to solve following those reasons. Using LoRaWAN is subject to build long range and low power communication. Furthermore, it helps to make low initial and cost for maintenance. Detecting problem of streetlight in real time and controling streetlight based on situation and environment are additional benefits. This system on control part is carried by administrator in GUI environment. Finally, we verified the proposed system of performance for LoRaWAN communication and sensor accuracy.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.3
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• pp.440-448
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• 2021

This paper presents problems of network technology in smart grid and implements a blockchain-based LoRa multi-hop network to solve them. Since some smart grid applications are operated in harsh environments, it is difficult to establish communication infrastructure. We propose a LoRa network with multi-hop using the Flooding routing protocol. Smart grid environment composes an independent network using various power grid protocols depending on the application. Since this has a problem that an independent infrastructure must be established for each network, a single gateway device supports multiple power grid protocols to implement a method for network integration. Lastly, the author applied Hyperledger-based blockchain to the LoRa network to ensure the integrity of data in a smart grid environment, and strengthened security by physically distributing it. After constructing the three suggestions on the actual test bed, we confirmed that the network operates normally through experiments.

• KNOM Review
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• v.22 no.2
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• pp.29-38
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• 2019

The rapid growth of IoT (Internet of Things) owing to the advancement and spread of technologies such as wireless networks, communication modules, sensors, smart terminals, etc. enables the development of new services in diverse public and private sectors. In particular, research on IoT technology and its applications has increased in the field of science. To establish an IoT infrastructure in this field, KREONET launched the wireless IoT network, called ScienceLoRa, based on low power wide area network (LPWAN). ScienceLoRa aims to collect a variety of data from sensors and utilize and analyze the collected data for research in a variety of scientific fields. In this article, the authors present the concept, current status, applications and future plans of ScienceLoRa.

• Journal of Digital Contents Society
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• v.18 no.4
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• pp.761-768
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• 2017

As the loss prevention system using bluetooth has a short communication range, it has a problem which its location is not known if it is strayed out of a certain distance. To overcome shortcoming of such an existing loss prevention system, this paper proposes a GPS-based wireless loss prevention system without communication fee using the LoRa Communication with a long distance. The proposed system performs a remote control application on the smart-phone and then is able to get a long-distance GPS coordinates about the location of the loss prevention system on the google map. For performance evaluation of the implemented proposed system, the experiments for transmitting and receiving data are done in open terrain, indoor and outdoor areas and the experiment results identified the superiority of the proposed system in the long-distance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.138-146
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• 2019

LoRa LPWAN network system uses a license-exempt wireless communication system and implements data measurement through the integrated sensor based on Mems and wireless communication of existing measurement sensors. This system has superior technological / economic superiority using existing network and long distance communication compared to existing wireless measurement system, and secured economical efficiency by minimizing system construction equipment compared to wired measurement system. It is confirmed that the economical efficiency can be reduced by 41% compared to the conventional wired metering system. Since the LoRa LPWAN network system is excellent in terms of maintenance and operation, if installed in many bridges in Korea in the future, it will be developed as an excellent system in the maintenance of bridges. Etc.), and plant field (fire safety, etc.).