• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10B
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• pp.981-987
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• 2009

Recently, the study on wireless body area network for providing ubiquitous healthcare services has been actively done, including the standardization of the IEEE and others. Wireless body area network is usually configured in tree format using multi-hop communication mode due to the power limitation and the characteristics of human body. In this case, differently from existing sensor network, the wireless body area network tends to be disconnected due to the frequent movement of human body. The number of connections which can be supported at each node has some limitations due to the constraint imposed on power consumption. In this paper, we have proposed a heuristic algorithm for optimal selection of parent node with guaranteed QoS for a disconnected node, which considers the priority on packet transmission. Simulation has been performed to evaluate the performance of the proposed algorithm.

• Journal of Advanced Navigation Technology
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• v.22 no.1
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• pp.37-42
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• 2018

Recently, there have been many studies on the IoT environment in which the sensors attached to the equipment automatically transmit and process the site information in real time through the network to control the equipment. The core of such a system is a network for data transmission and reception, and a wired network with wide transmission distance is a priority. However, in the case of a wired network, there is a problem that the time and cost consumed to configure the communication is higher than that of the wireless. In this paper, we propose LPWA - based wireless data transmission system using LPWA and BLE communication to solve this problem. The proposed system collects data from equipment through BLE and transmits data to the server using LPWA. Experimental results show that the spreading factor of maximum length of LPWA is 8, and the minimum length is 9.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.225-231
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• 2013

A bird's-eye view is an elevated view of an object from above, with a perspective as though the observer were a bird, often used in the making of blueprints, floor plans and maps. It can be used under severe weather conditions when visibility is poor. Under low visibility environments, drivers can communicate each other using V2V communication to get each vehicle's status to prevent collision and other accidents. Ubiquitous transportation sensor networks(u-TSN) and its application are emerging rapidly as an exciting new paradigm to provide reliable and comfortable transportatione services. The ever-growing u-TSN and its application will provide an intelligent and ubiquitous communication and network technology for traffic safety area.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.6
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• pp.827-832
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• 2002

The development of dedicated network management system is essential to meet the following conditions: the system must run the configuring and repair processing for the dedicated communication network, and can manage new next generation data dedicated communication network of various types. In general it is effective that the system is consisted of decentralized module to be accessible for business logic and datum to remote area. To solve these problems, a method is to use object-oriented design techniques. That is, it is to abstract reusability objects and make component module using the abstracted objects. In this paper, we propose a management system of dedicated communication network service using object-oriented design techniques which are UML(Unified Modeling Language).

• Journal of Information Technology Applications and Management
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• v.13 no.2
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• pp.87-97
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• 2006

Due to limited radio resource, an effective paging strategy is essential for improving the utility of radio channels. In current mobile communication networks, when a mobile-terminated call occurs, the network locates the mobile by paging all cells within the location area simultaneously. In this study, we introduces paging strategies that can page some cells or only one cell within the location area to reduce paging cost on radio channels using paging agents. We propose another new paging strategy that can page only one cell within the location area and may have better performance. We also compare the performance of our proposed paging strategy with the performance of the current simultaneous paging strategy and some new paging strategies using paging agents. This paper suggests the most effective paging strategy using mathematical models. The result of this research will be used to select a proper paging strategy in the mobile communication networks.

• Journal of Korean Institute of Industrial Engineers
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• v.22 no.4
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• pp.551-565
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• 1996

We present the required handover capacity of personal communication service exchange(PCX). We use the flow-based mobility model. The dimension of PCX area and the number of radio port controller(RPC) in a PCX are determined according to the traffic carrying capacity of switching system and RPC. For the rectangular or square-shaped PCX/RPC area and the personal communication service environment with pedestrian traffic, we perform numerical computations to investigate the sensitivity to cell size, portable station(PS) terminating traffic, its density, and its average speed. The results how that the size of PCX/RPC area decreases as the PS terminating traffic and the PS density increase, and the PCX handover capacity required is more than 73,000 in the number of transactions per hour.

• Journal of Communications and Networks
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• v.13 no.2
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• pp.160-166
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• 2011

In u-healthcare services based on wireless body sensor networks, reliable connection is very important as many types of information, including vital signals, are transmitted through the networks. The transmit power requirements are very stringent in the case of in-body networks for implant communication. Furthermore, the wireless link in an in-body environment has a high degree of path loss (e.g., the path loss exponent is around 6.2 for deep tissue). Because of such inherently bad settings of the communication nodes, a multi-hop network topology is preferred in order to meet the transmit power requirements and to increase the battery lifetime of sensor nodes. This will ensure that the live body of a patient receiving the healthcare service has a reduced level of specific absorption ratio (SAR) when exposed to long-lasting radiation. We propose an efficientmethod for delivering delay-intolerant data packets over multiple hops. We consider forward error correction (FEC) in an erasure correction mode and develop a mathematical formulation for packet-level scheduling of delay-intolerant FEC packets over multiple hops. The proposed method can be used as a simple guideline for applications to setting up a topology for a medical body sensor network of each individual patient, which is connected to a remote server for u-healthcare service applications.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.1
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• pp.25-36
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• 2021

This paper presents a topology based on packet tracer and a five-step scenario model to make it easier for students to understand the network on which VLANs are applied. Virtual LAN (VLAN), developed as an alternative solution to the Routers that distribute broadcast traffic, is a virtual local area network that logically configured regardless of the physical network. The VLAN prevents the network performance degradation resulting from the broadcast traffic by dividing the broadcast domain so that the bandwidth can be used more efficiently. In addition, it enhances the security because on communication between the devices belonging to different VLANs is impossible. The five-step scenarios in this paper presented an efficient implementation case for students to understand and validate the various functions of VLANs through ping/telnet/tracert test and simulation, after setting up each step of programming switches and routers in the virtual network.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.2
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• pp.199-210
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• 1998

It is very important to analyze and predict the propagation characteristics of LEO communication satellite at the service area using computer simulation. In this paper, the propagation characteristics of a satellite communication system are analyzed using ray tracing technique. We predicted the receiving environment and obtain the delay profile and total received power at each position using ray tracing method by changing both the azimuth and elevation angles after establishing the imaginary receiving space. The final goal of this paper is to analyze and understand the wave propagation characteristics of the satellite communication network about 2 GHz frequency band. The prediction method presented in this paper may help us to design satellite transceiver system and to construct a satellite communication network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.202-208
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• 2015

A wireless ship area network is required to configure and control various sensors and electrical instruments embedded or boarded in a ship. In such environment, wireless communication protocol adopting relaying function is needed because direct link or communication between two nodes is hardly guaranteed due to spatial constraints in a ship. In this study, we introduce and analyze a WiMedia Distributed MAC (D-MAC) based approach considering throughput and energy constraint of wireless communication module. Performance evaluation results demonstrate that the relay-based wireless communication protocol improves reliability of wireless communication network in a ship.