• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.256-259
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• 2003

This paper presents mutual authentication scheme between user and network on mobile communications using public key scheme based on counter, and simultaneously shows key agreement between user and user using random number for secure communications. This is also a range of possible solutions to authentication and key agreement problem-authentication and key agreement protocol based on nonce and count, and secure end-to-end protocol based on the function Y=f(.)$\^$1/, C$\^$i/ is count of user I, and f(.) is one way function.

• Asia-Pacific Journal of Business
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• v.3 no.2
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• pp.16-22
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• 2012

Korean mobile telecommunications market is shifting from 2G to 3G service. Considering the revenue of voice-based communication has reached its maximum, 3G services can provide telecommunication companies with the opportunity to increase their revenues. As the competition in the market is becoming fierce, mobile carriers are trying to increase their profits by preventing their customers from switching to rivals. In this regard, managing customer can be a key success factor of the mobile telecommunications business by retaining existing customer. In this research, we tried to develop and test a model that aids further understanding of the determinants of continuance intention to use the current 3G service. We conducted empirical study through the analysis of 3G service users' data in Korea. The results indicated that continuance intention to use the current 3G is dependent on the customer's satisfaction with the service quality, handset, and brand image. We hope that analysis results will have significant implications in terms of both practical and theoretical aspects.

• Journal of Electrical Engineering and information Science
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• v.2 no.5
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• pp.33-39
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• 1997

In this paper we proposed a new traffic load shedding scheme which maximizes the throughput of traffic control by decreasing the load of the hot-spot cell using minimum load cell selection (MLCS) algorithm and deployed control flow of calls to define characteristic for hadoff region. we compared the performance of the random shedding approach with that of the proposed algorithm. The results of simulation show that MLCS algorithm minimizes the cal blocking rate under a high-density traffic compared to the random shedding scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.11
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• pp.5449-5464
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• 2018

Recent works have validated the possibility of reducing the energy consumption in wireless heterogeneous networks, achieved by switching on/off some base stations (BSs) dynamically. In this paper, to realize energy conservation, the discrete time Markov Decision Process (DTMDP) is developed to match up the BS switching operations with the traffic load variations. Then, an asynchronous decision-making algorithm, which is based on the Bellman equation and the on/off priorities of the BSs, is firstly put forward and proved to be optimal in this paper. Through reducing the state and action space during one decision, the proposed asynchronous algorithm can avoid the "curse of dimensionality" occurred in DTMDP frequently. Finally, numerical simulations are conducted to validate the effectiveness and advantages of the proposed asynchronous on/off strategies.

• ETRI Journal
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• v.37 no.2
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• pp.348-358
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• 2015

Mobile devices have been widespread and become very popular with connectivity to the Internet, and a lot of desktop PC applications are now aggressively ported to them. Unfortunately, mobile devices are often vulnerable to malicious attacks due to their common usage and connectivity to the Internet. Therefore, the demands on the development of mobile security systems increase in accordance with advances in mobile computing. However, it is very hard to run a security program on a mobile device all of the time due the device's limited computational power and battery life. To overcome these problems, we propose a novel mobile security scheme that migrates heavy computations on mobile devices to cloud servers. An efficient data transmission scheme for reducing data traffic between devices and servers over networks is introduced. We have evaluated the proposed scheme with a mobile device in a cloud environment, whereby it achieved a maximum speedup of 13.4 compared to a traditional algorithm.

• ETRI Journal
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• v.43 no.3
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• pp.400-413
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• 2021

This paper theoretically and empirically explores the reliability gain that can be obtained by installing multiple antennas in on-vehicle broadcasting receivers. Analytical derivations reveal that maximal-ratio-combining-based diversity allows a multi-antenna receiver (MR) to achieve significantly better coverage probability than a single-antenna receiver (SR). In particular, the notable MR gains for low-power reception and high-throughput services are highlighted. We also discuss various aspects of mobile MRs, including geometric coverage, volume of the users served, and impact of receiver velocity. To examine the feasibility of MRs in the real world, extensive field experiments were conducted, particularly with on-air ATSC 3.0 broadcast transmissions. Relying on the celebrated erroneous second ratio criterion, MRs with two and four antennas were verified to achieve notable reliability gains over SRs in practice. Furthermore, our results also prove that layered-division multiplexing can cope better with receiver mobility than traditional time-division multiplexing when multiple services are intended in the same radio frequency channel.

• Electronics and Telecommunications Trends
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• v.35 no.6
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• pp.129-136
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• 2020

Korea launched the world's first commercial 5G services in April 2019. Mobile traffic is expected to increase further with the acceleration of mobile-centric data utilization. It is one of the most important indexes of the growth of the mobile communications market, and it has a close relationship with frequency demand and supply, network management, and information communication policy. To overcome the limitations of an analytical solution due to the high complexity of the real world, this paper estimates the diffusion of 5G users using systemic thinking and the behavior of individual agents. Based on these demand forecasts, contributions to the establishment of strategic policies are suggested. For better understanding, global 5G predictions of subscribers and mobile traffic are also compared.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.1 no.1
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• pp.77-83
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• 1997

In this paper, we present a comparison between QCELP(Qualcomm Code Excited Linear Predictor) speech coder that is operating in digital mobile communication system and CS-ACELP(Conjugate Structure Algebraic Code Excited Linear Prediction) speech coder that is scheduled to use for IMT-2000 (International Mobile Telecommunications 2000) system. The performance comparison might give help to design of the speech coding algorithms so that the robustness of the algorithms to channel errors engaged by mobile communication system be optimized.

• ETRI Journal
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• v.19 no.3
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• pp.83-97
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• 1997

The CDMA Mobile System (CMS) has been developed by Electronics and Telecommunications Research Institute (ETRI) and field-tested for commercial service deployment in Korea. The project was started in 1989 and completed in 1995 with the CMS commercial test. During the course of development, there had been active technical cooperation with Qualcomm, Inc. and Korean manufacturers. The CMS adopted the basic CDMA concepts conforming to Korean CDMA system which was derived form IS-95. The CMS functions are allocated to subsystems by considering efficiency and expandability. The CMS consists of mobile stations and the infrastructure which is composed of base stations, mobile exchanges and home location register/authentication center. The commercial field tests performed both in Taejon and Seoul have indicated that the CMS capacity is 10 to 15 times larger than that of AMPS. This paper overviews the development history, system characteristics, architecture and test results.

• Electronics and Telecommunications Trends
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• v.36 no.5
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• pp.51-61
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• 2021

To reduce mobile network deployment costs and expand service coverage, mobile infrastructure sharing is becoming increasingly important. This paper introduces the concept and potential benefits of mobile infrastructure sharing as documented in the existing literature. Then, the current status of significant cases of mobile infrastructure sharing in major overseas countries is examined. Finally, sharing 5G infrastructure in rural areas in Korea is introduced. The Korean case is expected to complete national 5G coverage successfully without involving negative competition.