• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.9
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• pp.2573-2589
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• 2023

As 5G mobile systems carry multiple services and applications, numerous user, and application types with varying quality of service requirements inside a single physical network infrastructure are the primary problem in constructing 5G networks. Radio Access Network (RAN) slicing is introduced as a way to solve these challenges. This research focuses on optimizing RAN slices within a singular physical cell for vehicle-to-everything (V2X) and enhanced mobile broadband (eMBB) UEs, highlighting the importance of adept resource management and allocation for the evolving landscape of 5G services. We put forth two unique strategies: one being offline network slicing, also referred to as standard network slicing, and the other being Online reinforcement learning (RL) network slicing. Both strategies aim to maximize network efficiency by gathering network model characteristics and augmenting radio resources for eMBB and V2X UEs. When compared to traditional network slicing, RL network slicing shows greater performance in the allocation and utilization of UE resources. These steps are taken to adapt to fluctuating traffic loads using RL strategies, with the ultimate objective of bolstering the efficiency of generic 5G services.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.912-916
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• 2004

The home network is the technique to guarantee a safe, economical, socially integrated, and healthy life to the family and it provides domestic safety, instrument control, controllable energy and health monitoring by the connection of the home appliances using wired and wireless networks. A home control system has been developed for managing and controlling home appliances. This paper designs the broadband PLC home controller using broadband PLC technology which can save much cost at a network infrastructure using the existing power line at a home and design the USB home controller using USB technology which is low cost and has many goods with it. And the embedded home server manages those. The CDMA module provides mobile functions to the home control system in this paper. And we choose the OSGi specification which is compatible with other home middleware and can accept various communication techniques of home network

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.9
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• pp.560-562
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• 2014

Broadband power divider operating over the frequency band assigned for all domestic mobile communications is designed and implemented. The implemented power divider with 20Watts power rating has the maximum insertion loss of 3.49dB, input reflection coefficient of below -18.48dB and output reflection coefficient of below -20.2dB, above 24.7dB isolation and -141.2dBc of 3rd PIMD over the operating frequency of 810 ~ 2620MHz.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.4
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• pp.1832-1853
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• 2018

The personal health record (PHR) system is a promising application that provides precise information and customized services for health care. To flexibly protect sensitive data, attribute-based encryption has been widely applied for PHR access control. However, escrow, exposure and abuse of private keys still hinder its practical application in the PHR system. In this paper, we propose a coordinated ciphertext policy attribute-based access control with user accountability (CCP-ABAC-UA) for the PHR system. Its coordinated mechanism not only effectively prevents the escrow and exposure of private keys but also accurately detects whether key abuse is taking place and identifies the traitor. We claim that CCP-ABAC-UA is a user-side lightweight scheme. Especially for PHR receivers, no bilinear pairing computation is needed to access health records, so the practical mobile PHR system can be realized. By introducing a novel provably secure construction, we prove that it is secure against selectively chosen plaintext attacks. The analysis indicates that CCP-ABAC-UA achieves better performance in terms of security and user-side computational efficiency for a PHR system.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.5 no.1
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• pp.43-59
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• 2006

A compact and broadband $4\times1$ array antenna was developed for 3G smart antenna system testbed. The $4\times1$ uniform linear away antenna was designed to operate at 1.885 to 2.2GHz with a total bandwidth of 315MHz. The array elements were based on the novel broadband L-probe fed inverted hybrid E-H (LIEH) shaped microstrip patch, which offers 22% size reduction to the conventional rectangular microstrip patch antenna. For steering the antenna beam, a commercial variable attenuator (KAT1D04SA002), a variable phase shifter (KPH350SC00) with four units each, and the corporate 4-ways Wilkinson power divider which was fabricated in-house were integrated to form the beamforming feed network. The developed antenna has an impedance bandwidth of 17.32% $(VSWR\leq1.5)$, 21.78% $(VSWR\leq2)$ with respect to center frequency 2.02GHz and with an achievable gain of 11.9dBi. The design antenna offer a broadband, compact and mobile solution for a 3G smart antenna testbed to fully characterized the IMT-2000 radio specifications and system performances.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.7 no.1
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• pp.41-58
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• 2007

A compact and broadband $4{\times}1$ array antenna was developed for 3G smart antenna system testbed. The $4{\times}1$ uniform linear array antenna was designed to operate at 1.885 to 2.2GHz with a total bandwidth of 315MHz. The array elements were based on the novel broadband L-probe fed inverted hybrid E-H (LIEH) shaped microstrip patch, which offers 22% size reduction to the conventional rectangular microstrip patch antenna. For steering the antenna beam, a commercial variable attenuator (KAT1D04SA002), a variable phase shifter (KPH350SC00) with four units each, and the corporate 4-ways Wilkinson power divider which was fabricated in-house were integrated to form the beamforming feed network. The developed antenna has an impedance bandwidth of 17.32% ($VSWR{\leq}1.5$), 21.78% ($VSWR{\leq}2$) with respect to center frequency 2.02GHz and with an achievable gain of 11.9dBi. The design antenna offer a broadband, compact and mobile solution for a 3G smart antenna testbed to fully characterized the IMT-2000 radio specifications and system performances.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.5
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• pp.1984-2002
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• 2020

With the appearance of wireless spectrum crisis in traditional cellular network, device-to-device (D2D) communication has been regarded as a promising solution to ease heavy traffic burden by enabling precise content delivery among mobile users. However, due to the channel sharing, the interference between D2D and cellular users can affect the transmission rate and narrow the throughput in the network. In this paper, we firstly present a weighted interference minimization cluster formation model involving both social attribute and physical closeness. The weighted-interference, which is evaluated under the susceptible-infected(SI) model, is utilized to gather user in social and physical proximity. Then, we address the cluster formation problem via spectrum clustering with iterative operation. Finally, we propose the stable matching theory algorithm in order to maximize rate oriented to accomplish the one-to-one resource allocation. Numerical results show that our proposed scheme acquires quite well clustering effect and increases the accumulative transmission rate compared with the other two advanced schemes.

• The Journal of the Korea Contents Association
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• v.5 no.6
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• pp.65-73
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• 2005

Request about fast diffusion of internet and high-capacity multimedia service is increasing day after day. Because existent wireless LAN is short range, if subscriber is far away in base station transceiver system(Base Station), subscriber's quality of service becomes low, and wileless internet is expensive. Lately, WiBro(Wireless Broadband Internet) system that is developed in domestic by world first, is high-speed portable internet service that is situated in middle area of mobile phone and wireless LAN. In this paper, service traffic model and characteristics are analyzed to provide multimedia service based on IEEE 802.16 BWA accomplishes base of WiBro and simulation is conducted according to various traffic mixing ratio. Finally, on the basis of these simulation results, maximum allowable number of subscriber per cell is calculated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.8
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• pp.853-860
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• 2012

In this paper, We shed light on radio spectrum policy and strategic planning of the United States of America and draw some conclusions. First of all, as the radio technology evolves with time, paradigm shift from command & control to market-based approach and spectrum commons is reviewed. Strategic spectrum planning of USA is also analyzed and some suggestions are drawn. In particular, USA plan for developing dynamic spectrum access(DSA) technologies and implementation of the test-bed for the DSA spectrum sharing is discussed, which improves the spectral utilization. Finally We deal with spectrum re-farming issue for mobile broadband and implicative points based on the National Broadband Plan.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.5
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• pp.408-417
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• 1996

In this paper, we quantiatively analyze the broadband CDMA systems with high chip rate, which virually eliminates the multipath fading effects by distinguishing each reflected paths in the process of despreading. We model the broadband multipath propagation channel with random time-variant impulse response as a linear filter of tapped delay line to evaluate the performance of broadband CDMA systems in multipath fading environment. This statistical model, based on extensive experimental data, was established to characterize the urban radio propagation medium in various environments. We perform computer simulation of the transmission and reception of broadband CDMA systems by applying it to abve channel model. From the simulation results, we confirm that the broadband CDMA systems inherenly reduce the effects of multipath fading phenomena which causes to degrade the performance of mobile communication systems, based on the results of eye-diagram and BER curve.