• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.393-398
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• 2014

A highly efficient dual-mode linear CMOS stacked-FET power amplifier (PA) is implemented for 3G UMTS and 4G LTE handset applications. High efficiency is achieved at a backed-off output power ($P_{out}$) below 12 dBm by employing an active-bypass amplifier, which consumes very low quiescent current and has high load-impedance. The output paths between high- and low-power modes of the PA are effectively isolated by using a bypass switch, thus no RF performance degradation occurs at high-power mode operation. The fabricated 900 MHz CMOS PA using a silicon-on-insulator (SOI) CMOS process operates with an idle current of 5.5 mA and shows power-added efficiency (PAE) of 20.5%/43.5% at $P_{out}$ = 12.4 / 28.2 dBm while maintaining an adjacent channel leakage ratio (ACLR) better than -39 dBc, using the 3GPP uplink W-CDMA signal. The PA also exhibits PAE of 35.1% and $ACLR_{E-UTRA}$ of -33 dBc at $P_{out}$ = 26.5 dBm, using the 20 MHz bandwidth 16-QAM LTE signal.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.291-294
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• 2011

4G WiBro service in Korea, the world's fourth-generation communication is standardized. VoIP service has been activated one of the application in WiBro communications infrastructure. When using VoIP in the WiBro service, complementing the existing VoIP vulnerabilities in the encryption and authentication technology is a need for research. In this paper, fourth-generation WiBro, LTE, and the definition, 1G, 2G, 3G and 4G compares. And, WiBro service in the VoIP edaehan technical, administrative, physical, and hacker attacks and vulnerability analysis is the study of security measures. Enhanced security measures for the WiBro service to VoIP security through encryption and authentication technologies are studied.

• Electronics and Telecommunications Trends
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• v.30 no.1
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• pp.102-113
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• 2015

급증하는 모바일 트래픽 용량에 대처하고 사용자의 QoS(Quality of Service)를 만족시킬 수 있는 기술 중 하나로 단위면적당 용량 증대에 기여할 수 있는 소형셀 기술이 부각되고 있다. 소형셀 기지국 기술은 3G, 4G 이동통신시스템에서는 셀의 소형화를 통한 용량 증대, 음영지역 해소를 위하여 사용되고 있으며, 5G 이동통신에서는 보다 밀집한 셀의 구성 및 셀 소형화를 통한 용량증대 기술로 UDN(Ultra Dense Network) 분야와 연계되어 연구 중이다. 본고에서는 소형셀 기지국 주요 기술분석을 통하여 상용 소형셀 기지국의 개발 접근방법을 제시하고, 소형셀 표준화 동향을 통한 소형셀 기지국 진화방향을 알아본다. 또한, 소형셀 기지국 기술 시장 동향분석으로 국내 및 글로벌 시장의 규모를 파악하여 향후 5G 이동통신에서의 소형셀 기술의 나아가야 하는 방향을 제시하고자 한다.

• TTA Journal
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• s.153
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• pp.67-72
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• 2014

• Journal of Information Technology Services
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• v.11 no.2
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• pp.339-353
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• 2012

Mobile communication technology is advancing forward to deliver more connected devices and richer content and applications. The number of subscriptions continues to grow along with an explosive increase in the mobile data traffic demand. Thereby, it creates a significant network capacity shortage concerns for mobile network operators. In order to address this problem, it is essential to increase the network capacity at a low additional cost. The device-to-device (D2D) communication based proximity service is believed to have a promising future mobile communication technology that is capable to create new mobile service opportunities and offload traffic to the eNB. In addition, it is also required to develop new mobile communication services and its business models not only to accommodate the increasing mobile traffic demand but also to foster profitability of mobile business service providers such as the network providers, contents providers and platform providers. In this article, we first analyze current mobile business eco-system in the context of CPNT based value chain. Then, propose service development framework and business model creation methodologies for the device-to-device communication based services in the beyond LTE/LTE-Advanced systems.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.4
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• pp.39-44
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• 2014

IMS(IP Multi-Media Subsystem) base on the IP service platform which can offer multimedia as the voice, audio, video, and data is service platform. In 3G mobile communication in the early day, IMS had a suggestion for supporting to multimedia service in the 3GPP. But now It is broadly substituting in the IPTV, wire phone company and it is substituted in internet platform base on the soft-switch in currently. Especially nowadays, 4G LTE in a mobile communication company is rapidly growing in market. Therefore, in this study, we had designed to the main prosser that can admit to 1,000 user over and SIP gateway which can link the IMS 코어 that can link SIP Device which adopt the standard protocol on the SIP.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06d
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• pp.137-140
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• 2011

최근 활발하게 연구되고 있는 4G 이동 통신 시스템의 하나인 LTE-Advanced 시스템에서 릴레이 기법은 주요 기술로써 고려되고 있다. 릴레이 기법을 도입함으로써 LTE-Advanced 시스템은 셀 가장자리 유저들에게 좋은 성능의 서비스를 제공할 수 있을 뿐 아니라 셀 커버리지를 늘릴 수 있을 것으로 기대된다. 하지만 LTE-Advanced 시스템에 릴레이 기술을 도입하는 구체적인 기법은 아직 연구되지 못하고 있다. 이러한 상황에서 우리는 기존의 직교 할당 방식과 중첩 할당 방식을 이용하여 릴레이 기법을 도입시 새로운 자원 할당 방법을 제안할 것이다. 제안 기법의 기본 아이디어는 서비스 지역에 진입한 단말이 채널 정보를 이용하여 eNB(eNodeB)로 접속할지 RS(Relay Station)로 접속할지를 결정한다. 기존의 직교 할당 방식과 중첩 할당 방식을 그대로 적용하는 경우와 비교하여 우리가 새로 제안하는 자원 할당 기법은 전송률 뿐만 아니라 공정성 측면에서도 우수한 성능을 나타낸다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1672-1678
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• 2022

In this paper, the relay antenna was designed in consideration of the performance of the 28GHz band 5G mobile communication relay horn antenna, such as radiation pattern and return loss. A horn array for 5G mobile communication repeater was designed by arranging the antenna elements in phase, and the performance was analyzed. Unlike conventional WCDMA (3G) and LTE (4G), in millimeter wave band communication, high path loss occurs between transmission and reception. In the design of a 5G millimeter wave horn antenna, antenna performance such as isolation and gain between antenna elements as well as gain and bandwidth of the antenna must be additionally considered. The antenna gain of the single horn antenna (1×1) and the array horn antenna (2×4) in the 28GHz band is about 10.44d Bi and 19.58dBi, respectively, and the return loss is designed to be less than -18dB. It has proven its validity and has been shown to be suitable for application to 5G mobile communication relay system.

• ETRI Journal
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• v.38 no.2
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• pp.302-313
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• 2016

Use of a passive bistatic radar (PBR) system in the surveillance or monitoring of an area has its advantages. For example, a PBR system is able to utilize any available signal of opportunity (for example, broadcasting, communication, or radio navigation signals) for the purposes of surveillance. With this in mind, there are potentially many research areas to be explored; in particular, the capability of signals from existing and future communication systems, such as 4G and 5G. Long-Term Evolution (LTE) is the world's most current communication system. Given this fact, this paper presents the latest feasibility studies and experimental results from using LTE signals in PBR applications. Details are provided about aspects such as signal characteristics, experimental configurations, and SNR studies. Six experimental scenarios are carried out to investigate the detection performance of our proposed system on ground-moving targets. The ability to detect is demonstrated through use of the cross-ambiguity function. The detection results suggest that LTE signals are suitable as a source signal for PBR.

• Journal of Convergence Society for SMB
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• v.6 no.3
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• pp.21-27
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• 2016

In this paper, we introduce the PB/MC-CDMA (Partial Block/Multi-Carrier-Code Division Multiple Access) system to mitigate inter-cell interference (ICI) and enhance user capacity in the small cell environment. In 5G mobile communications, the number of devices connected to the network is expected to increase exponentially with the expansion of the IoT (Internet of Things) services. In addition, each device is expected to be required by the various data rates by their content types. In LTE/LTE-A, there are some limitations that large scale connectivity and supporting various data rates. Therefore, we introduce a PB/MC-CDMA physical layer system which is suitable for the small cell environment, and evaluate the performance in the multi cell environment which is affected by ICI. Through computer simulation results, we demonstrate the effectiveness of PB/MC-CDMA for the small cell environment.