• Title/Summary/Keyword: LTE-R

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Standardization of 3GPP LTE and LTE-Advanced (3GPP LTE 및 LTE-Advanced 표준화 동향)

  • No, Tae-Gyun;Go, Yeong-Jo;Lee, Gyeong-Seok;An, Jae-Yeong;Kim, Yeong-Jin
    • Electronics and Telecommunications Trends
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    • v.23 no.3
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    • pp.1-9
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    • 2008
  • 3GPP는 WCDMA의 3세대 이동통신 표준화 이후 HSDPA, MBMS, HSUPA 등의 기술을 지속적으로 추가하여 3세대 이동통신 시스템을 개량해 왔다. 또한 2005년부터는 OFDMA/SC-FDMA 전송방식을 기반으로 하는 LTE 표준화를 진행해 왔다. 현재는 ITU-R의 IMT-Advanced 표준을 위해 LTE를 개선한 LTE-Advanced를 준비하고 있다. LTE-Advanced는 IMT-Advanced 표준의 유력한 후보 중 하나로 사업자들의 폭넓은 지지를 받고 있다. 이에 본 고에서는 3GPP에서 추진하고 있는 LTE 표준 기술과 LTE-Advanced 표준화 동향을 살펴보고자 한다.

Currnet Status of LTE Pricing Plan (해외의 LTE 서비스 요금제 동향)

  • Kim, S.C.;Lee, B.R.
    • Electronics and Telecommunications Trends
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    • v.26 no.5
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    • pp.146-153
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    • 2011
  • 2011년 7월 초 기준 전 세계적으로 218개의 이동통신사업자들이 LTE(Long Term Evolution) 투자를 진행하고 있으며 24개 사업자들이 상용 LTE 서비스를 제공 중에 있다. 상용 LTE 서비스를 제공하고 있는 통신사업자에 있어 수익원천은 통신요금에 국한되고 있다. 해외의 LTE 요금제는 데이터 전송의 처리량 및 이용제한에 따른 QoS(Quality of Service) 요금 모델이라고 할 수 있다. LTE 서비스를 제공하고 있는 이동통신사들은 서비스 기능이나 품질별로 다양한 계층화된 요금제를 제공하여 사용자들이 선택할 수 있도록 하고 있다. 결국 이러한 요금체계에서는 이동통신사업자들이 LTE의 특성을 가장 잘 반영하고 있는 서비스를 개발해 이용자들이 상위 요금수준을 선택할 수 있도록 하는가가 LTE 활성화의 핵심과제가 되고 있다. 본 고에서는 해외 주요 이동통신사업자의 LTE 서비스 요금제 동향을 분석하고 시사점을 제시하고자 한다.

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Overview of SAE/LTE security

  • Prasad, Anand R.;Zhang, Xiaowei
    • IEIE Transactions on Smart Processing and Computing
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    • v.2 no.1
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    • pp.36-43
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    • 2013
  • This paper provides an overview of the security in the System Architecture Evolution (SAE) / Long-Term Evolution (LTE) system. Security is an integral part of SAE/LTE with improvements over the Third Generation (3G) system. This paper reviews the SAE/LTE system architecture, and discusses the security requirements, algorithms, Authentication and Key Agreement (AKA), Security Mode Command (SMC), key hierarchy and security for mobility.

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Performance Evaluation of Semi-Persistent Scheduling in a Narrowband LTE System for Internet of Things (사물인터넷을 위한 협대역 LTE 시스템에서의 준지속적 스케줄링의 성능 평가)

  • Kim, Sunkyung;Cha, Wonjung;So, Jaewoo;Na, Minsoo;Choi, Changsoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.9
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    • pp.1001-1009
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    • 2016
  • In LTE networks, the base station transmits control information over the physical downlink control channel (PDCCH) including scheduling grants, which are used to indicate the resources that the user equipment uses to send data to the base station. Because the size of the PDCCH message and the number of the PDCCH transmissions increase in proportion to the number of user equipments, the overhead of the PDCCH may cause serious network congestion problems in the narrowband LTE (NB-LTE) system. This paper proposes the compact PDCCH information bit allocation to reduce the size of the PDCCH message and evaluates the performance of the semi-persistent scheduling (SPS) in the NB-LTE system. The simulation results show that the SPS can significantly reduce the signaling overhead of the PDCCH and therefore increase the system utilization.

Evaluation for the Introduction Impact of an Integrated Railway Wireless Network : A Case Study of the Wonju-Gangneung Rail Line (철도통합무선통신망 도입효과의 평가 -원주-강릉구간에 대한 사례를 중심으로-)

  • Cho, Hanbyeog;Jang, Jeong Ah;Jo, Chang-hee;Yun, Hak-Sun
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.15 no.4
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    • pp.129-142
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    • 2016
  • This study performs an evaluation, using the economic feasibility analysis method, of the LTE based railway wireless networks (LTE-R) service that is planned to be used for the future railway networks in Korea. Its objectives are using the evaluation results and working to reflect the factors that lead to a maximization of benefits in designing an integrated railway wireless network. This study analyzes the impact of implementing an LTE-R on the railway networks, in contrast to the existing wireless network methods, e.g. VHR and TRS to new rail lines on an economic view. This results found that the benefit cost ratio is greater than 1.0 with a 10% contribution to benefits of the wireless network service in the case study on the Wonju-Gangneung rail line that will start operations in 2018; as a result, an ICT design is desired. For the introduction of an LTE-R service for the Wonju-Gangneung rail line, design specifications need to increase to benefits for each service, which will verify actual contributions and therefore result in an overall economic effect.

Human Hand Effect on The MIMO OTA Performance of LTE Mobile Handset (LTE 이동 단말의 MIMO 무선 성능과 Hand effect)

  • Cho, Y.S.;Kim, Y.R.;Noh, S.P.;Shim, H.J.;Kim, I.K.
    • 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.

Access Delay Characteristics of Wi-Fi Network According to User Increase in Subway Section (지하철 구간에서 이용객 증가에 따른 Wi-Fi 접속 지연 특성)

  • Koh, Seoung-chon;Choi, Kyu-Hyoung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.5
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    • pp.3455-3461
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    • 2015
  • LTE and Wi-Fi networks provide wireless communication services to passengers in subway where the number of network access fluctuates according to passenger movement. While the number of network access increase, LTE can provide stable communication service but Wi-Fi suffers temporal access delay to network. This paper analyzes the increase in access delay of Wi-Fi network according to increasing user in subway section by making mathematical modeling of Wi-Fi network and simulation study. The access delay characteristics of Wi-Fi network is measured along an subway line and the results are compared to the theoretical study. These results can be applied to the connection method to build an efficient network structure between LTE and Wi-Fi interworking network and the future introduction of LTE-R.

A study on the reliability and availability improvement of wireless communication in the LTE-R (철도통합무선망(LTE-R) 환경에서 무선통신 안정성과 가용성 향상을 위한 방안 연구)

  • Choi, Min-Suk;Oh, Sang-Chul;Lee, Sook-Jin;Yoon, Byung-Sik;Kim, Dong-Joon;Sung, Dong-Il
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.24 no.9
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    • pp.1172-1179
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    • 2020
  • With the establishment of the railway integrated radio network (LTE-R) environment, radio-based train control transmission and reception and various forms of service are provided. The smooth delivery of these services requires improved performance in a highly reliable and available wireless environment. This paper measured the LTE-R radio communication environment to improve radio communication performance of railway integrated wireless network reliability and availability, analyzed the results, and established the wireless environment model. Based on the built-up model, we also proposed an improved radio-access algorithm to control trains for improved reliability, suggesting a way to improve stability for handover that occur during open-air operation, and proposed an algorithm for frequency auto-heating to improve availability. For simulation, data were collected from the Korea Rail Network Authority (Daejeon), Manjong-Gangneung KTX route, which can measure the actual data of LTE-R wireless environment, and the results of the simulation show performance improvement through algorithm.

Handover based on Maximum Cell Residence Time and Adaptive TTT for LTE-R High-Speed Railways

  • Cho, Hanbyeog;Han, Donghyuk;Shin, Sungjin;Cho, Hyoungjun;Lee, Changsung;Lim, Goeun;Kang, Mingoo;Chung, Jong-Moon
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.11 no.8
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    • pp.4061-4076
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    • 2017
  • With the development of high-speed railway technologies, train velocities can now reach speeds up to 350 km/h, and higher in the future. In high-speed railway systems (HSRs), loss of communication can result in serious accidents, especially when the train is controlled through wireless communications. For to this reason, operators of Long Term Evolution for Railway (LTE-R) communication systems install eNodeBs (eNBs) with high density to achieve highly reliable communications. However, densely located eNBs can result in unnecessary frequent handovers (HOs) resulting in instability because, during every HO process, there is a period of time in which the communication link is disconnected. To solve this problem, in this paper, an HO scheme based on the maximum cell residence time (CRT) and adaptive time to trigger (aTTT), which are collectively called CaT, is proposed to reduce unnecessary HOs (using CRT estimations) and decrease HO failures by improving the handover command transmission point (HCTP) in LTE-R HSR communications.

The Present Status and Future of Disaster Safety Communication Network (재난안전통신망의 현황과 미래)

  • Hong, Sung-Hwa;Lee, Seong-Real
    • Journal of Advanced Navigation Technology
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    • v.24 no.2
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    • pp.115-120
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    • 2020
  • PS-LTE, which is mentioned as a next-generation disaster network technology, is a communication technology that supports communication between terminals and group communication necessary for public safety communication based on LTE technology. Currently, Korea is establishing a PS-LTE network construction plan and installing a PS-LTE system. The world is currently making a lot of efforts to build a disaster network system using PS-LTE. However, due to the characteristics of the closed network that only the related persons can access, it can not be operated like the existing commercial network, so it is necessary to build a new network. And it is expected that many periods and costs will be required. In order to establish a disaster safety communication network efficiently, it is necessary to consider the linkage of PS-LTE network, which is newly constructed by complementing the problems such as security and access priority to existing LTE network rather than unconditional new construction.