• Title/Summary/Keyword: Wireless terminal

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A New Physical Layer Transmission Scheme for LPI and High Throughput in the Cooperative SC-FDMA System

  • Li, Yingshan;Wu, Chao;Sun, Dongyan;Xia, Junli;Ryu, Heung-Gyoon
    • Journal of Communications and Networks
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    • v.15 no.5
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    • pp.457-463
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    • 2013
  • In recent days, cooperative diversity and communication security become important research issues for wireless communications. In this paper, to achieve low probability of interception (LPI) and high throughput in the cooperative single-carrier frequency division multiple access (SC-FDMA) system, a new physical layer transmission scheme is proposed, where a new encryption algorithm is applied and adaptive modulation is further considered based on channel state information (CSI). By doing so, neither relay node nor eavesdropper can intercept the information signals transmitted from user terminal (UT). Simulation results show above new physical layer transmission scheme brings in high transmission safety and secrecy rate. Furthermore, by applying adaptive modulation and coding (AMC) technique according to CSI, transmission throughput can be increased significantly. Additionally, low peak-to-average power ratio (PAPR) characteristic can still be remained due to the uniform distribution of random coefficients used for encryption algorithm.

Software-based Quality Measurement of Mobile VoIP Services (소프트웨어 기반 모바일 VoIP 서비스 품질 측정)

  • Kim, Beom-Joon
    • The Journal of the Korea institute of electronic communication sciences
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    • v.6 no.1
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    • pp.55-60
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    • 2011
  • The mobile internet telephony service rapidly grows according to the extending deployment of smartphones. Unlike telephony service over a conventional public switched telephone network (PSTN) or mobile network, internet telephony service cannot guarantee its service quality, which can be severer in a wireless environment. Therefore, a more strict and systematic quality management is required for successful settlement and popularization of mobile internet telephony service. Existing quality management scheme using a specific measurement equipment cannot measure all the time so that it performs late management. In order to overcome the problem, this paper develops a software that can be equipped on a user terminal and measures the service quality all the time. By using the developed software, all-time and user-activating service quality monitoring can be supported.

Remote Measurement of ECU Sensor Signal based on the Embedded Linux and Web (임베디드 리눅스와 웹 기반의 ECU 센서신호 원격계측)

  • 이현호;최광훈;권대규;이성철
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1042-1045
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    • 2003
  • In this paper, we present a new method for the monitoring of Electric Control Unit's(ECU) self-diagnostic and the sensor signals of vehicle through Web. In order to measure the ECU's self-diagnostic and sensor signals, the interfaced circuit is designed to communicate ECU and terminal according to the ISO, SAE regulation of communication protocol standard. Microprocessor 80C196KC is used for communicating ECU's self-diagnostic signals and the results are sent to the Embedded Linux System(ELS) through RF module. ELS is developed by SA1110, RF module, Embedded Linux. All commands related in ECU communication are executed through Web. The CGI program composed in web server is executed by user and will return sensor signals from ECU Software on Embedded Linux system is developed to monitor the ECU's sensor signals using the arm compiler tool chain in which RS232 port is programmed by half duplex method. The possibility for remote measurement of ECU sensor signal through Web is verified through the developed systems and algorithms.

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Technological Assesment on Public R&D Activities (정보통신 공공 R&D 기술성 평가)

  • 여인갑
    • Proceedings of the Korea Society of Information Technology Applications Conference
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    • 2002.11a
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    • pp.433-439
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    • 2002
  • In this paper, we implemented technology assessment on the public R'||'&'||'amp;D activities in If field in order to select the promising technologies, so called 'star technology,' making for national industry development. Technology assessment frame in this study included qualitative factors. If technologies are classified five sector - network, wireless/broadcasting, SW/application, computer/terminal equipment,somiconductorjcomponent. Expert opinion interviews on each field are carried out. Assessment factors consist of technology usefulness and technology competitiveness. In the final analysis, 23 technology items selected as a promising technologies and the results can be used public R'||'&'||'amp;D planning and IT industry policy

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THE SYSTEM FOR UPDATING PARTIAL MAP

  • Jang, In-Sung;Lee, Moon-Soo;Kim, Ju-Wan
    • Proceedings of the KSRS Conference
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    • 2008.10a
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    • pp.270-273
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    • 2008
  • Telematics is a leading IT service where wireless internet service represented by information and mobility is extended to the area of transportations to provide Telematics service. One of the killer-application about Telematics is navigation system. Recently, due to the mass storage conversion, the performance of the terminal and mobile communications technology development, navigation system is also changed. It more and more develops into 3D in a pre-existence 2D map. In the future, it is expected to include the remote sensing map or video map. There is also the characteristic of all the information expressed in frequently a change partially happening. That is, POI(Point Of Interest) which is freshly registered or is deleted is many. In a pre-existence, Map Contents Providers offer the new version map by off-line monthly or quarterly. And a user wastes time and is inconvenient because of updating the total map by the off-line. Thus, in this paper, in order to resolve this, we describe MAUS(Map Air Update Server) for updating only the partial map that was changed

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Characteristics of Vertical Acceleration at Center of Mass of the Body in Normal Gait (정상보행시 체중심의 수직 가속도 특성)

  • Yi, Jin-Bock;Kang, Sung-Jae;Kim, Young-Ho
    • Physical Therapy Korea
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    • v.9 no.3
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    • pp.39-46
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    • 2002
  • In this study, vertical acceleration of center of mass was observed along normal gait phases in 9 healthy male volunteers (aged $25.7{\pm}2.18$). The developed wireless accelerometric device was attached on the intervertebral space between L3 and L4 using a semi-elastic waist belt. A three-dimensional motion analysis system, synchronized with the accelerometry, was used for detecting gait phases. There was no significant correlation between the body weight and the acceleration. The first peak curve covered loading response phase. The second downward peak point was matched accurately with the opposite toe-off. In mid-stance and terminal stance, the acceleration curve highly resembled the vertical ground reaction force curve. There was no significant difference in timing between the final upward peak point and the initial contact. Therefore, the developed accelerometry system would be helpful in determining determine temporal gait pattems in patients with gait disorders.

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Design and Implementation of a Mobile Terminal Device for Video Transmission in Multiple Networks (다중 네트워크에서의 동영상 전송을 위한 이동 단말 장치의 설계 및 구현)

  • Kim, Jong-Heon;Lee, Dong-Soo
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.12 no.2
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    • pp.38-44
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    • 2013
  • In this paper, we designed and implemented a mobile video transmission device with 1080i resolution and 30fps frame rate using wireless multi-access technologies. The video acquisition delay time of 16us and jitter of 21ms for this equipment were obtained, respectively. The device is designed to access various communication networks. In order to evaluate the performance of its video transmission capability, a server and monitoring viewer are implemented. In the performance test using LTE network, 211ms delay time was obtained at 3Mbps transmission. Rendering of 1fps frame rate at the 265kbps transmission was confirmed for the transmission test using Inmarsat network.

A Novel Hearability Enhancement Method for Forward-Link Multilateration Using OFDM Signal

  • Park, Ji-Won;Lim, Jeong-Min;Lee, Kyu-Jin;Sung, Tae-Kyung
    • Journal of Electrical Engineering and Technology
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    • v.8 no.3
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    • pp.638-648
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    • 2013
  • Together with the GPS-based approach, geo-location through mobile communication networks is a key technology for location-based service. To save the cost, most geo-location system is implemented on the existed network service, which has a cellular structure. Still, multilateration is limited in cellular structure because it is difficult for the mobile terminal to acquire distance measurements from multiple base stations. This low hearability in the receiver is caused by co-channel interference and multipath environment. Therefore, hearability enhancement is necessary for multilateration under multipath and interference environment. Former time domain based hearability methods were designed for real signals. However, orthogonal frequency division multiplexing (OFDM) signal, which its usage has been increased in digital wireless communication, is a complex signal. Thus, different hearability enhancement method is needed for OFDM signals. This paper proposes a hearability enhancement method for forward-link multilateration using OFDM signals, which employ interference cancellation and multipath mitigation. A novel interference cancellation and multipath mitigation strategy for complex-valued OFDM signals is presented that has an iterative structure. Simulation results show that the proposed multilateration method provides the user's position with an accuracy of less than 80m through the mobile WiMAX cellular network in multipath environment.

Bandwidth Requirement and Priority-based Synchronization Methods in Hybrid Client-Server Architecture for Mobile Multiplayer Games (모바일 멀티플레이어 게임을 위한 하이브리드 클라이언트-서버 구조의 대역폭 요건과 우선순위 기반 동기화 기법)

  • Kim, Jinhwan
    • Journal of Korea Multimedia Society
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    • v.17 no.4
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    • pp.526-534
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    • 2014
  • Most of the multiplayer games available online are based on a client-server architecture because this architecture gives better administration control to the game providers than peer-to-peer architecture. In this architecture, the server is responsible for all the communication between the connected clients. The weakness of this architecture is its bandwidth requirement and scalability. Peer-to-peer architectures have then been proposed to solve these issues. In this paper, we propose a hybrid client-server architecture in which the game state is partially shared by the mobile terminal to achieve consistency among different players. Like a peer-to-peer architecture, this architecture uses client-side capacities to reduce bandwidth requirements for the server and improves consistency in wireless networks. Client events have different timeliness and consistency requirements according to their nature in the game world. These requirements lead to tasks with different priorities on CPU processing. In the proposed architecture, either the server or the client applies consistency mechanism according to the priority level. Simulation experiments show that the bandwidth of the server in this architecture is smaller than that of the client-server architecture. As a result, the server in the proposed architecture can accommodate more clients with enhancing the scalability.

An Efficient PFMIPv6 and WLAN Interworking Scheme for Fast Handover (고속 핸드오버를 위한 PFMIPv6와 무선랜의 효율적인 연동 방안)

  • Park, Min-Ji;Min, Sang-Won;Kim, Bok-Ki
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37 no.3B
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    • pp.174-180
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    • 2012
  • As the number of a smart phone user over the world surprisingly grows and a wireless Internet market expands, service requirement of a mobile terminal is increasing. However, because there is no consideration of mobility in the early standard step, it is difficult to expect to improve the service performance in handover procedure. This paper proposes a PFMIPv6 handover scheme by using probe request message and authentication message and by using buffering scheme in IEEE 802.11. In addition, we simulated this proposal scheme and verified that the proposed handover scheme is improved in terms of handover delay, and average FTP throughput during the handover period.