• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.5
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• pp.91-98
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• 2012

Since the major cellular data service providers in U.S, Japan as well as in Korea started the LTE (Long Term Evolution) service, there has been more strong need for the methods that can accurately measure the MIMO (Multi Input-Multi Output) OTA (Over The Air) performance of LTE handsets because the performance of the MIMO antenna determines the data throughput in the downlink. In this paper, the hand effect on the MIMO antenna performance is analyzed by numerically and experimentally. The hand effect on the LTE mobile handset is analyzed by measuring the link level performance in the MIMO OTA system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• pp.456-458
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• 2019

In this paper, transmission performance of streaming audio as a railway communication service based on LTE-R is analyzed. Performance analysis is perfomed with computer simulation based on NS(Network Simulation)-3, audio frame of MPEG(Moving Picture Experts Group)-4 is used as target application service for straming audio traffic. Results of this paper can be used to implement LTE-R networks and develope application services over LTE-R network.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• pp.641-644
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• 2017

Usage of LTE(Long Term Evolution) technology is expanded to industrial an emergency service field beyond commercial communications of mobile internet focused on smartphone. In this paper, transmission performance of LTE technology be supplied to various service area is analyzed on the level of application traffics. Performance is evaluated with compter simulation based NS(Network Simulator)-2, CBR(Constant Bit Rate), VBR(Variable Bit Rate File) traffic is used as simulation target. Results and methods of this paper can be used for research and developmemt of LTE based networks.

• Electronics and Telecommunications Trends
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• v.25 no.6
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• pp.20-28
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• 2010

본 고에서는 20MHz 대역에서 다운링크 100Mbps, 업링크 50Mbps의 데이터 전송속도를 지원하는 IP 기반의 셀룰러 기술인 LTE 및 IMT - Advanced 요구사항을 만족하는 최초의 규격이 될 것으로 보이는 LTE-Advanced에 대해서 살펴보았다. LTE 기술의 이론적인 하향링크 최대 성능은 20MHz 대역폭에서 약 326Mbps 정도이다. 최근까지 전 세계 대규모 이동통신사들이 LTE를 차세대 네트워크 표준으로 채택하고 구체적인 상용화 일정 발표 및 시범테스트에 돌입하고 2010년 현재 5개 이동통신 사업자는 상용서비스를 실시하고 있다. 실질적인 4세대인 LTE-Advanced 기술은 2011년 3월 중에 마무리되고, 빠르면 2012년에 설치되기 시작할 것이다. 차세대 이동통신 표준화 동향 중에서 특히 3GPP LTE 표준화 동향 시장 및 서비스 동향을 살펴본다. 또한 ETRI가 개발한 3GPP LTE 단말 모뎀 개발 현황을 살펴보았다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6A
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• pp.458-467
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• 2009

Long Tenn Evolution (LTE) is the next generation mobile phone technology which has being standardized by the Third Generation Partnership Project (3GPP). In the existing mobile communication networks, voice traffic is delivered through circuit switched networks. In LTE, however, all kinds of traffic are transferred through IP based packet switched networks which has best-effort characteristic. Therefore, providing QoS in LTE system is difficult. In order to provide QoS in LTE, RRM is very important. Especially, in part of RRM, call admission control (CAC) performs an important function to reduce network congestion and guarantee a certain level of QoS for on-going calls. In this paper, we propose a CAC algorithm in order to provide QoS for various kinds of services in LTE system. The performance of the proposed algorithm is evaluated with various simulation environments. The results show that the proposed algorithm provides QoS through rejections of requested calls. Especially, the proposed CAC algorithm can be satisfied with packet delay requirement defined in LTE specification.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.77-87
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• 2017

Even though current LTE/LTE-A mobile networks provide enough high data rate and low latency to support conventional wireless services, to support ultra-low delay services, such as virtual reality and remote control, in the next generation mobile communication network, it is required to provide very low delay about several ms. However, in the uplink transmission of the LTE/LTE-A system, the process of scheduling grant is required to obtain uplink resources for uplink transmission from the eNB. The process of granting uplink resources from eNB brings additional fixed latency, which is one of the critical obstacles to achieve low delay in uplink transmissions. Thus, in this paper, we propose a novel uplink transmission scheme called Cut-in uplink transmission, to reduce uplink latency. We provide the performance of the proposed uplink transmission scheme through simulations and show the proposed uplink transmission scheme provides lower uplink transmission delay than conventional uplink transmission scheme in LTE/LTE-A mobile networks.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.442-448
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• 2018

In this paper, a microstrip antenna for LTE / LTE-A is designed and fabricated for a broadband mobile communication system. The proposed antenna is designed to have the characteristics of using FR-4 (er = 4.3), size of $40mm{\times}50mm$, and LTE / LTE-A frequency bands of 2.3 GHz and 2.5 GHz. 2014, and the simulation result shows that the gain is 2.391 dBi at 2.3 GHz and 2.566 dBi at 2.5 GHz. The S-parameter also showed a result of less than -10 dB (WSWR 2: 1) in the desired frequency band. The broadband mobile communication antenna has been miniaturized, high performance, and light weight, and an excellent and low cost system is continuously being developed, and a broadband mobile communication system is used by many people. Since LTE / LTE-A technology has been proposed according to the development of system and demand, it is expected that many users will design and manufacture antennas satisfying the above conditions and apply the applied technology.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.6
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• pp.903-909
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• 2018

In December 2017, the world's first LTE-R for 250km/h high-speed railway was commercialized with the opening of Wonju-Gangneung high-speed railway. LTE-R has many advantages such as voice and video call, high-speed data transmission, coverage redundancy and DU redundancy. But it requires efficient use of radio resources because of a limited bandwidth of 10MHz for UL and DL, respectively. The existing unicast scheme has limited high frequency efficiency so when the number of users increases, service is limited due to the network load, which could be a problem for LTE-R in terms of stability and reliability. On the other hand, the multicast scheme via eMBMS can provide stable service even if the number of video users is high. This paper derives the number of unicast scheme users considering the LTE-R network with LAB test and calculation result, and proposes implementation plans and considerations for eMBMS commercialization on LTE-R.

• Journal of Satellite, Information and Communications
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• v.9 no.2
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• pp.28-32
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• 2014

In this paper, we analyzed the performance of cyclostationary signal detection scheme for LTE system. We applied the cyclostationary signal detection scheme to the cognitive radio(CR) technology, which improves the usage efficiency of spectrums and shares frequencies, and we detected the signal in the long term evolution(LTE) band. LTE system has been designated as the standard to improve the maximum data rate and provide the low latency in the 3rd generation partnership project(3GPP). In this paper, we generated the LTE signals based on the orthogonal frequency division multiple access(OFDMA) and analyzed the performance of signal detection in accordance with the segment and threshold of the generated signals. Gaussian channel was used in the simulation and we discussed the future studies to apply the CR to the LTE system.

• Journal of Venture Innovation
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• v.2 no.1
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• pp.13-21
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• 2019

In LTE environment, which is 4th generation mobile communication systems, there is concern about private information exposure by transmitting initial identifier in plain text. This paper suggest mutual authentication protocol, which uses one-time password utilizing challenge-response and AES-based Milenage key generation algorithm, as solution for safe initial identification communication, preventing unique identification information leaking. Milenage key generation algorithm has been used in LTE Security protocol for generating Cipher key, Integrity key, Message Authentication Code. Performance analysis evaluates the suitability of LTE Security protocol and LTE network by comparing LTE Security protocol with proposed protocol about algorithm operation count and Latency.Thus, this paper figures out initial identification communication's weak points of currently used LTE security protocol and complements in accordance with traditional protocol. So, it can be applied for traditional LTE communication on account of providing additional confidentiality to initial identifier.