• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.5
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• pp.676-683
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• 2002

In this paper, LAN Access Point is realized by making out bluetooth protocol stack in Linux Kernel, porting Linux in an embeded system employed bluetooth module. Hardware for a general-purpose embeded system is designed and Linux Kernel is ported after deploying Bluetooth Module. Also, Boot loader for system booting and management is composed, and Kernel is modified to meet with the system. Finally, Ethernet devise driver is made out, and bluetooth protocol Stack and Lan Access Point are realized. The possibility of TCP/IP communication through LAN Access Point to PC employed Bluetooth module, which is considered as client, is evaluated. From the evaluation results, we can see that the performance in Telnet FTP, Web browsing through Bluetooth LAN Access Point is satisfactory.

• Journal of IKEEE
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• v.27 no.1
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• pp.109-115
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• 2023

In this paper, we design and implement an Ultra-Wide Band (UWB, 3.1~10.6 GHz) antenna with 5G mobile communication (3.42~3.70 GHz) and Wireless Local Area Network (WLAN, 5.15~5.825 GHz) bands rejection characteristics. The proposed antenna consists of a planar radiation patch with two slots. The upper slot contributes to reject 5G mobile communication band and the lower slot contributes to reject WLAN band. The Voltage Standing Wave Ratio (VSWR) values of the proposed antenna show good performances in whole UWB band except for rejection bands based on VSWR 2.0. The proposed UWB antenna was simulated using High Frequency Struture Simulator (HFSS) by Ansoft. The simulated antenna showed dual rejection bands of 3.31~3.92 GHz and 5.04~5.90 GHz in UWB band, and measured antenna showed dual rejection bands of 3.35~3.97 GHz and 5.06~5.97 GHz. The largest VSWR values measured at each rejection band are 13.60 at 3.64 GHz and 10.25 at 5.52 GHz. The measured maximum gain is 5.31 dBi at 10.00 GHz. The lowest gains for the measured antenna at rejection bands are -8.73 dBi at 3.70 GHz and -4.36 dBi at 5.56 GHz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.11
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• pp.2442-2450
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• 2010

Using sensor devices applied to various objects will be needed wireless network that it is easy to install in them. Tiny devices configured to processor that bas comparatively low computing ability are inappropriate to use devices that are wireless LAN, etc. In result, network devices needed to not only have simple communication protocol, but have Plug and Play function that it works as soon as it connects without installing any device driver. it also will industrially have both low power and low cost because of mobility of it. From IEEE 802.11 standard, WPAN(Wireless Personal Area Network) included in LAN is being developed by WPAN WG(Working Group) on area with low power consumption and low complexity. In addition to, it is standardizing MAC and PRY of the standard that is expected to wirelessly communicate within 10m. WPAN will be used generally in the more near future because of both low power and low cost of Zigbee. In this paper we designed zigbee based user authentication module for a automotive smart-key system.

• The KIPS Transactions:PartC
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• v.11C no.3
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• pp.395-400
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• 2004

Being aware of growing needs for wireless communication led to the development of UWB systems, this study proposed an impulse for single band UWB systems which does not count a carrier; analyzed the characteristics and the problems of pulses suggested by the existing poise of the Un system; finally, proposed TDMG(Time Delay Multiple Gaussian) pulse that generates signals of UWB without attenuation of pulse width. The hardware structure of the TDMC pulse for the single band UWB system was modelled after describing the pulse in a mathematical method in an attempt to compare with performances of the existing pulses through computer simulation. The outcome of the test unveiled the fact that each center frequency of the TDMG pulse rose approximately 1GHz, and also each l0dB fractional bandwidth of the TDMG pulse was widened over 1GHz. In the case of derivative, center frequencies of the TDMG pulse rose over 1GHz each. As a consequence, the TDMG pulse appeared to have better quality frequency, satisfying the characteristics of spectrum and the band of frequency recommended by the FCC and decreasing interference with other wireless communication systems.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.1
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• pp.1-9
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• 2008

According to the ubiquitous trend, the needs for the context based application service have been increased. These services take on Location Based Service which is based on the current location of users. It is widely used that localization techniques use GPS or ground wave and more efficient and accurate methods have been studied. Recently, not only services which targeted outdoor but also services which targeted indoor, for example home services and facility guidance of the building come into the spotlight. In case of the outdoor positioning area, COTH (Commercial Off-The-Shelf) has been released and used but relatively it doesn't produce an outcome in the indoor positioning area. Therefore, this paper Proposes the indoor positioning technique using wireless LAN (Local Area Network) which is one of the widely used wireless communication technique. It analyzes the typical WLAN location positioning methodology has been studied and their advantage and disadvantage also suggests how to design and implement the specific WLAN positioning system. In addition, it suggests new methods that progress the accuracy of the existing systems and improve the efficient computation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1105-1110
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• 2011

It is possible to synchronize the spatio-temporal data with a server using a wireless network. These data has the benefit to be up-to-date and able to service to the user efficiently. However, the mobile devices or the wireless network are very vulnerable to various hard or soft failures. If an failure occurs during a synchronization process, the spatio-temporal data which is synchronizing could be inconsistent state. In this paper, we propose the recovery scheme to solve the problem caused by the errors which occur during the synchronization on mobile environments. The proposed scheme writes the log records for the synchronization process into the both local storages of the server and the mobile client. When the errors arise, the data which are synchronizing are recovered using the written log records. Also, we design and implement the proposed recovery scheme on the synchronization system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.10
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• pp.2218-2226
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• 2009

TDMA based MAC protocol supporting wireless mesh network has many advantage rather than 802.11 DCF/EDCA protocol based on packet. But TDMA based MAC protocol require new synchronization method because of mobile point oscillator's difference, and distributed environments. This thesis propose synchronization method for TDMA based MAC protocol. It divides MP(Mobile Points) states into 4 types. If MP is in sync mode, it schedules TDMA local start time in time skew interval using beacon. It proposes compensation algorithms to compensate time skew caused by clock drift. This proposal show that general time error and clock drift rate value reduced and get synchronized result.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.8
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• pp.1196-1204
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• 2022

In this paper, we propose an optimization algorithm that maximizes the network lifetime in wireless ad-hoc networks using the broadcast transmission method. The optimization algorithm proposed in this paper applies tabu search algorithm, a metaheuristic method that improves the local search method using the memory structure. The proposed tabu search algorithm proposes efficient encoding and neighborhood search method to the network lifetime maximization problem. By applying the proposed method to design efficient broadcast routing, we maximize the lifetime of the entire network. The proposed tabu search algorithm was evaluated in terms of the energy consumption of all nodes in the broadcast transmission occurring in the network, the time of the first lost node, and the algorithm execution time. From the performance evaluation results under various conditions, it was confirmed that the proposed tabu search algorithm was superior to the previously proposed metaheuristic algorithm.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.4
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• pp.81-87
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• 2016

With the rapid growth of the up-to-date smartphone and wireless network technologies, huge and various types of smart applications using these technologies are actively developed recently. Especially, multiplex types of smart applications using smartphone are developed and diffused with the rapid development of the ubiquitous sensor network technology using various sensors and the mobile computing technology that enables us to get network services at any time in any places. In this paper, we design a smart application that can accurately diagnose and process the current state of the local environment, objects, and persons remotely based on the context information such as local ecology, circumstances, medical or healthcare records and realtime sound or motion pictures using up-to-date samrtphone technology on the USN based mobile computing environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.5
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• pp.1120-1128
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• 2004

In this paper, we has designed and implemented Up-converter for K-band with high IMD3 performance using balanced power amplifier. It is consisted of PA module and, Local Oscillator module with reject Filter, mixer module and If block, and Up-converter has a local loop path to decide whether it operate or not and has the sensing port to inspect output power level. According to the power budget of designed Up-converter, K-band balanced power amplifier was fabricated by commercial MMIC. Measurement results of up-converter show about 40dB Gain, PldB of 29dBm and OIP3 was 38.25dBm, that is good performance compared to power budgets. We has adjusted gate voltage of MMIC to control more than 30 dB gain. This up-converter was used in transceiver for PTP and PTMP, and applied to digital communication system that use QAM and QPSK modulation.