• Journal of Information Processing Systems
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• v.19 no.3
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• pp.377-384
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• 2023

The existence of abnormal breakpoint data leads to poor channel balance in wireless sensor networks (WSN). To enhance the communication quality of WSNs, a method for positioning abnormal breakpoint data in WSNs on the basis of signal reconstruction is studied. The WSN signal is collected using compressed sensing theory; the common part of the associated data set is mined by exchanging common information among the cluster head nodes, and the independent parts are updated within each cluster head node. To solve the non-convergence problem in the distributed computing, the approximate term is introduced into the optimization objective function to make the sub-optimization problem strictly convex. And the decompressed sensing signal reconstruction problem is addressed by the alternating direction multiplier method to realize the distributed signal reconstruction of WSNs. Based on the reconstructed WSN signal, the abnormal breakpoint data is located according to the characteristic information of the cross-power spectrum. The proposed method can accurately acquire and reconstruct the signal, reduce the bit error rate during signal transmission, and enhance the communication quality of the experimental object.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.1
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• pp.80-84
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• 2010

Data multicasting from a source to multiple sinks in wireless sensor networks is used to achieve both reducing communication costs and energy efficiency. Almost all existing schemes for the multicasting might be effectively performed by optimal construction of a multicasting tree between a source and multiple stationary sinks. However, in practical sensor applications, sinks could move around on the wireless sensor networks for own missions, such as scouting of soldiers and saving lives of victims by firefighters. Unfortunately, the sink mobility causes frequent entire reconstruction of the multicasting tree and thus it leads to exhaustion of battery power of sensors. Hence, we propose an energy-efficient multicast protocol to support multiple mobile sinks by the local multicast tree reconstruction, called Local Update-based geographic Multicasting for Mobile sinks (LUMM) for wireless sensor networks. Our simulation results show that our scheme for mobile sinks is more efficient in terms of energy resource management than other exist works.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1849-1854
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• 2017

Recently, RF energy harvesting, in which energy is collected from the external RF signals, is considered as a promising technology to resolve the energy shortage problem of wireless sensors. In addition, it is important to guarantee secure communication between sensors for implementing Internet-of-Things. In this paper, we propose a power splitting-based network analog coding for maximizing a physical layer security in 2-hop networks where the wireless-powered relay can harvest energy from the signals transmitted by two sources. We formulate systems where two sources, relay, and eavesdropper exist, and find an optimal power splitting ratio for maximizing the minimum required secrecy capacity using an exhaustive search. Through simulations under various environments, it is demonstrated that the proposed scheme improves the minimum required secrecy capacity by preventing the eavesdropper from overhearing source signals, compared to the conventional scheme.

• Nuclear Engineering and Technology
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• v.54 no.7
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• pp.2444-2452
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• 2022

The field-programmable gate array (FPGA) is gaining popularity in industrial automation such as nuclear power plant instrumentation and control (I&C) systems due to the benefits of having non-existence of operating system, minimum software errors, and minimum common reason failures. Separate functions can be processed individually and in parallel on the same integrated circuit using FPGAs in comparison to the conventional microprocessor-based systems used in any plant operations. The use of FPGAs offers the potential to minimize complexity and the accompanying difficulty of securing regulatory approval, as well as provide superior protection against obsolescence. Wireless sensor networks (WSNs) are a new technology for acquiring and processing plant data wirelessly in which sensor nodes are configured for real-time signal processing, data acquisition, and monitoring. ZigBee (IEEE 802.15.4) is an open worldwide standard for minimum power, low-cost machine-to-machine (M2M), and internet of things (IoT) enabled wireless network communication. It is always a challenge to follow the specific topology when different Zigbee nodes are placed in a large network such as a plant. The research article focuses on the hardware chip design of different topological structures supported by ZigBee that can be used for monitoring and controlling the different operations of the plant and evaluates the performance in Vitex-5 FPGA hardware. The research work presents a strategy for configuring FPGA with ZigBee sensor nodes when communicating in a large area such as an industrial plant for real-time monitoring.

• Journal of Digital Contents Society
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• v.8 no.3
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• pp.323-328
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• 2007

Communication systems beyond 3G should provide more than 100 Mbps for wireless access. In addition to smart antennas, wireless multi-hop networks are proposed to increase the cell size and throughput. For example, Zigbee technology is expected to provide low cost and low power connectivity and can be implemented in wireless mesh networks larger than is possible with Bluetooth. Also, home embedded system using wireless mesh network is one of the key market areas for Zigbee applications. If the line-of-sight path is shadowed by home obstacles, a direct connection between the access point (AP) and the node is not possible at high frequencies. Therefore, by using multi-hop relay scheme the end node can be reached to AP. In this paper, the relaying of data between the AP and the end node is investigated and the throughput and PER(Packet Error Rate) are evaluated in multi-hop wireless mesh networks by using DSSS/BPSK system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7B
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• pp.628-640
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• 2004

The demand for next generation networks can be condensed into always-best-connected, ubiquitous, mobile, all-lP, and converged networks. IPv6 has been introduced for all-IP ubiquitous communications, and vehicles are coming to represent an important communication platform. In this paper. we propose various resource management schemes for in-vehicle mobile networks, which are adaptive to different hardware configurations. We focus on power and wireless bandwidth since they are critical resources for mobile communications. Based on the mobility characteristics of in-vehicle networks, we propose vehicle-aware power saving schemes. The main idea behind these power saving schemes is to adjust mobile router (MR) advertisement interval and binding lifetime. In addition, according to different wireless environments, we propose adaptive bandwidth management schemes using multihoming: best-connected MR selection based on location, and high-data-rate MR selection based on priority By mathematical analysis, it is shown that our schemes save power prominently for both the dormant nodes and active nodes. In addition, simulation results show that proposed multiple mobile router architecture outperforms previous simple redundant router architecture in preserving session and providing sufficient bandwidth.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9B
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• pp.1390-1398
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• 2010

We present the concept of applying Wireless Mesh Networking (WMN) technology into Smart Grid, which is recently rising as a potential technology in various areas thanks to its advantages such as low installation costs, high scalability, and high flexibility. Smart Grid is an intelligent, next-generation electrical power network that can maximize energy efficiency by monitoring utility information in real-time and controlling the flow of electricity with IT communications technology converged to the existing power grid. WMNs must be designed for Smart Grid communication systems considering not only the high level of reliability, QoS support and mass-data treatment but also the properties of the traditional power grid. In addition, it is essential to design techniques based on international standards to support interoperability and scalability. In this paper, we evaluate the performance of IEEE 802.11s based Smart Grid Mesh Networks by conducting preliminary simulation studies with the ns-3 simulator. We also outline some challenging issues that should be reviewed when considering WMNs as the candidate for Smart Grid communication infrastructure.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06d
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• pp.267-268
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• 2011

Recent research activities in cooperative communication focus on achieving energy efficiency and reliability. Relay selection strategy for cooperative communication improves the performance significantly. However, due to imbalance consumption of power, network might die earlier and more than 90% energy remains unused. In this paper, we provide a framework of an energy-efficient medium access control protocol that minimizes these problems and improves energy efficiency.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.101-104
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• 2002

In this parer, a novel architecture for Home gateway is Proposed. In home network system, there exist many different kinds of data types, like audio, video, and control information. And the communication is over multiple networks, like bluetooth, wireless LAN, USB, IEEE1394, and Power Line Communication (PLC). The hardware architecture of the Home gateway presented in this paper is based on ISO/1EC JTC 1/sc 2S/WG 1(1,2). The architecture proposed in this paper takes into account the characteristics of home network environment, so the Packets in the home network system can be processed very efficiently.