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Journal of communications and networks 20건

  1. [국내논문]   An OFDMA-Based Next-Generation Wireless Downlink System Design with Hybrid Multiple Access and Frequency Grouping Techniques   피인용횟수: 1

    Lee Won-Ick (School of Electrical, Seoul National University ) , Lee Byeong Gi (School of Electrical, Seoul National University ) , Lee Kwang Bok (School of Electrical, Seoul National University ) , Bahk Saewoong (School of Electrical, Seoul National University)
    Journal of communications and networks v.7 no.2 ,pp. 115 - 125 , 2005 , 1229-2370 ,

    초록

    This paper discusses how to effectively design a next-generation wireless communication system that can possibly provide very high data-rate transmissions and versatile quality services. In order to accommodate the sophisticated user requirements and diversified user environments of the next-generation systems, it should be designed to take an efficient and flexible structure for multiple access and resource allocation. In addition, the design should be optimized for cost-effective usage of resources and for efficient operation in a multi-cell environment. As orthogonal frequency division multiple access (OFDMA) has turned out in recent researches to be one of the most promising multiple access techniques that can possibly meet all those requirements through efficient radio spectrum utilization, we take OFDMA as the basic framework in the next-generation wireless communications system design. So, in this paper, we focus on introducing an OFDMA-based downlink system design that employs the techniques of hybrid multiple access (HMA) and frequency group (FG) in conjunction with intra-frequency group averaging (IFGA). The HMA technique combines various multiple access schemes on the basis of OFDMA system, adopting the multiple access scheme that best fits to the given user condition in terms of mobility, service, and environment. The FG concept and IFGA technique help to reduce the feedback overhead of OFDMA system and the other-cell interference (OCI) problem by grouping the sub-carriers based on coherence band-widths and by harmonizing the channel condition and OCI of the grouped sub-carriers.

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  2. [국내논문]   An Adaptive Power Saving Mechanism in IEEE 802.11 Wireless IP Networks  

    Pack Sangheon (School of Computer Science and Engineering, Seoul National University ) , Choi Yanghee (School of Computer Science and Engineering, Seoul National University)
    Journal of communications and networks v.7 no.2 ,pp. 126 - 134 , 2005 , 1229-2370 ,

    초록

    Reducing energy consumption in mobile hosts (MHs) is one of the most critical issues in wireles/mobile networks. IP paging protocol at network layer and power saving mechanism (PSM) at link layer are two core technologies to reduce the energy consumption of MHs. First, we investigate the energy efficiency of the current IEEE 802.11 power saving mechanism (PSM) when IP paging protocol is deployed over IEEE 802.11 networks. The result reveal that the current IEEE 802.11 PSM with a fixed wakeup interval (i.e., the static PSM) exhibits a degraded performance when it is integrated with IP paging protocol. Therefore, we propose an adaptive power saving mechanism in IEEE 802.11-based wireless IP networks. Unlike the static PSM, the adaptive PSM adjusts the wake-up interval adaptively depending on the session activity at IP layer. Specifically, the MH estimates the idle periods for incoming sessions based on the exponentially weighted moving average (EWMA) scheme and sets its wake-up interval dynamically by considering the estimated idle period and paging delay bound. For performance evaluation, we have conducted comprehensive simulations and compared the total cost and energy consumption, which are incurred in IP paging protocol in conjunction with various power saving mechanisms: The static PSM, the adaptive PSM, and the optimum PSM. Simulation results show that the adaptive PSM provides a closer performance to the optimum PSM than the static PSM.

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    회원님의 원문열람 권한에 따라 열람이 불가능 할 수 있으며 권한이 없는 경우 해당 사이트의 정책에 따라 회원가입 및 유료구매가 필요할 수 있습니다.이동하는 사이트에서의 모든 정보이용은 NDSL과 무관합니다.

    NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니담기를 통하여 원문복사서비스 이용이 가능합니다.

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  3. [국내논문]   An Investigation of Satellite Radio Access Technology for Beyond IMT-2000 Systems  

    Kang Kunseok (Digital Broadcasting Research Division of Electronics and Telecommunications Research Institute ) , Ryoo Sunheui (Digital Broadcasting Research Division of Electronics and Telecommunications Research Institute ) , Kim Byoung Gi (Digital Broadcasting Research Division of Electronics and Telecommunications Research Institute ) , Kim Sooyoung (Division of Electronics and Information Eng., Chonbuk National University ) , Ahn Do Seob (Digital Broadcasting Research Division of Electronics and Telecommunications Research Institute)
    Journal of communications and networks v.7 no.2 ,pp. 135 - 143 , 2005 , 1229-2370 ,

    초록

    This paper presents an investigation of satellite radio access technology for beyond IMT-2000 systems. Although we could not see any active role of a satellite system in the 3G networks, satellite system will provide strong advantages in future systems for certain applications. Because a satellite link has longer round trip delay than a terrestrial link, we need technologies that would make the satellite component especially efficient. After presenting the satellite radio interface of the 3G system, we suggest several points which need to be considered in the beyond 3G systems. We also suggest a few candidate technologies with various simulation results.

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    회원님의 원문열람 권한에 따라 열람이 불가능 할 수 있으며 권한이 없는 경우 해당 사이트의 정책에 따라 회원가입 및 유료구매가 필요할 수 있습니다.이동하는 사이트에서의 모든 정보이용은 NDSL과 무관합니다.

    NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니담기를 통하여 원문복사서비스 이용이 가능합니다.

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  4. [국내논문]   MUVIS: Multi-Source Video Streaming Service over WLANs  

    Li Danjue (Department of Electrical and Computer Engineering, University of California-Davis ) , Chuah Chen-Nee (Department of Electrical and Computer Engineering, University of California-Davis ) , Cheung Gene (Hewlett-Packard Laboratories Japan ) , Yoo S. J. Ben (Department of Electrical and Computer Engineering, University of California-Davis)
    Journal of communications and networks v.7 no.2 ,pp. 144 - 156 , 2005 , 1229-2370 ,

    초록

    Video streaming over wireless networks is challenging due to node mobility and high channel error rate. In this paper, we propose a multi-source video streaming (MUVIS) system to support high quality video streaming service over IEEE 802.1l-based wireless networks. We begin by collocating a streaming proxy with the wireless access point to help leverage both the media server and peers in the WLAN. By tracking the peer mobility patterns and performing content discovery among peers, we construct a multi-source sender group and stream video using a rate-distortion optimized scheme. We formulate such a multi-source streaming scenario as a combinatorial packet scheduling problem and introduce the concept of asynchronous clocks to decouple the problem into three steps. First, we decide the membership of the multisource sender group based on the mobility pattern tracking, available video content in each peer and the bandwidth each peer allocates to the multi-source streaming service. Then, we select one sender from the sender group in each optimization instance using asynchronous clocks. Finally, we apply the point-to-point rate-distortion optimization framework between the selected sender-receiver pair. In addition, we implement two different caching strategies, simple caching simple fetching (SCSF) and distortion minimized smart caching (DMSC), in the proxy to investigate the effect of caching on the streaming performance. To design more realistic simulation models, we use the empirical results from corporate wireless networks to generate node mobility. Simulation results show that our proposed multi-source streaming scheme has better performance than the traditional server-only streaming scheme and that proxy-based caching can potentially improve video streaming performance.

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    회원님의 원문열람 권한에 따라 열람이 불가능 할 수 있으며 권한이 없는 경우 해당 사이트의 정책에 따라 회원가입 및 유료구매가 필요할 수 있습니다.이동하는 사이트에서의 모든 정보이용은 NDSL과 무관합니다.

    NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니담기를 통하여 원문복사서비스 이용이 가능합니다.

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  5. [국내논문]   Transmission Techniques for Downlink Multi-Antenna MC-CDMA Systems in a Beyond-3G Context  

    Portier Fabrice (Institute of Electronics and Telecommunications in Rennes, France ) , Raos Ivana (E.T.S.I. Telecommunication, Universidad Politecnica de Madrid, Spain ) , Silva Adao (Dept. Elect & Telec., Inst. Telec, Univ. Aveiro, Portugal ) , Baudais Jean-Yves (Institute of Electronics and Telecommunications in Rennes, France ) , Helard Jean-Francois (Institute of Electronics and Telecommunications in Rennes, France ) , Gameiro Atilio (Dept. Elect & Telec., Inst. Telec, Univ. Aveiro, Portugal ) , Zazo Santiago (E.T.S.I. Telecommunication, Universidad Politecnica de Madrid, Spain)
    Journal of communications and networks v.7 no.2 ,pp. 157 - 170 , 2005 , 1229-2370 ,

    초록

    The combination of multiple antennas and multi-carrier code division multiple-access (MC-CDMA) is a strong candidate for the downlink of the next generation mobile communications. The study of such systems in scenarios that model real-life trans-missions is an additional step towards an optimized achievement. We consider a realistic MIMO channel with two or four transmit antennas and up to two receive antennas, and channel state information (CSI) mismatches. Depending on the mobile terminal (MT) class, its number of antennas or complexity allowed, different data-rates are proposed with turbo-coding and asymptotic spectral efficiencies from 1 to 4.5 bit/s/Hz, using three algorithms developed within the European IST-MATRICE project. These algorithms can be classified according to the degree of CSI at base-station (BS): i) Transmit space-frequency prefiltering based on constrained zero-forcing algorithm with complete CSI at BS; ii) transmit beamforming based on spatial correlation matrix estimation from partial CSI at BS; iii) orthogonal space-time block coding based on Alamouti scheme without CSI at BS. All presented schemes require a reasonable complexity at MT, and are compatible with a single-antenna receiver. A choice between these algorithms is proposed in order to significantly improve the performance of MC-CDMA and to cover the different environments considered for the next generation cellular systems. For beyond-3G, we propose prefiltering for indoor and pedestrian microcell environments, beamforming for suburban macrocells including high-speed train, and space-time coding for urban conditions with moderate to high speeds.

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    회원님의 원문열람 권한에 따라 열람이 불가능 할 수 있으며 권한이 없는 경우 해당 사이트의 정책에 따라 회원가입 및 유료구매가 필요할 수 있습니다.이동하는 사이트에서의 모든 정보이용은 NDSL과 무관합니다.

    NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니담기를 통하여 원문복사서비스 이용이 가능합니다.

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  6. [국내논문]   Mobility Management Requirements and Framework for Systems Beyond IMT-2000  

    Jung Hee Young (Protocol Engineering Center, Electronics Telecommunications Research Institute ) , Koh Seok Joo (School of Electronics Engineering and Computer Science, Kyungpook National University)
    Journal of communications and networks v.7 no.2 ,pp. 171 - 177 , 2005 , 1229-2370 ,

    초록

    This paper addresses mobility management (MM) requirements and framework for systems beyond IMT-2000 (SBI2K), based on the standardization works that has so far been done in ITU-T study group 19. We first identify the requirements for MM in SBI2K. Based on the identified MM requirements, we describe the MM framework for location management and handover management for SBI2K. We then review and analyze some of the existing IP-based MM protocols. From the analysis and comparison, we see that the existing MM schemes cannot meet all of the MM requirements for SBI2K. It is naturally concluded that further work is needed to enhance the available MM schemes SBI2K.

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    회원님의 원문열람 권한에 따라 열람이 불가능 할 수 있으며 권한이 없는 경우 해당 사이트의 정책에 따라 회원가입 및 유료구매가 필요할 수 있습니다.이동하는 사이트에서의 모든 정보이용은 NDSL과 무관합니다.

    NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니담기를 통하여 원문복사서비스 이용이 가능합니다.

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  7. [국내논문]   Mobility and QoS Support in 4G Wireless Networks  

    Kim Taehyoun (Department of Electrical and Electronic Engineering, Yonsei University ) , Lee Jaiyong (Department of Electrical and Electronic Engineering, Yonsei University)
    Journal of communications and networks v.7 no.2 ,pp. 178 - 191 , 2005 , 1229-2370 ,

    초록

    Fourth-generation (4G) wireless networks will be the IP-based cellular networks integrating Internet with the existing cellular networks. Two important issues should be concerned in the IP-based cellular networks, IP mobility, and quality-of-service (QoS) guarantees. In this paper, we proposed two mechanisms to solve the problems with IP mobility and RSVP-based QoS provisioning. First, virtual-IP (VIP) allocation scheme in areas with a large rate of handoff can minimize the wireless signaling overhead due to IP mobility. The access routers (ARs) create dynamically the VIP zone by using the measured handoff rate derived from the history of the handoff into neighboring ARs. We show that VIP allocation scheme reduces the binding update messages in the wireless link than hierarchical mobile IPv6. Second, the new advance resource reservation protocol called proportional aggregate RSVP (PA-RSVP) can minimize waste of bandwidth and soft state refresh overhead due to IP mobility. It allocates the bandwidth in advance between the mobility anchor point and neighboring ARs using proportional aggregate reservation. We also show that PA-RSVP provides an improved performance over existing protocols.

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    NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니담기를 통하여 원문복사서비스 이용이 가능합니다.

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  8. [국내논문]   AAA System for PLMN-WLAN Internetworking  

    Janevski Toni (Faculty of Electrical Engineering, University Sv. Kiril i Metodji)
    Journal of communications and networks v.7 no.2 ,pp. 192 - 206 , 2005 , 1229-2370 ,

    초록

    Integration of mobile networks and Internet has started with 2.5 generation of mobile cellular networks. Internet traffic is today dominant traffic type worldwide. The hanger for higher data rates needed for data traffic and new IP based services is essential in the development of future wireless networks. In such situation, even 3G with up to 2 Mbit/s has not provided data rates that are used by Internet users with fixed broadband dial-up or through wired local area networks. The solution to provide higher bit rates in wireless access network has been found in wireless LAN although initially it has been developed to extend wired LAN into wireless domain. In this paper, we propose and describe a solution created for interoperability between mobile cellular network and WLAN. The integration between two networks, cellular and WLAN, is performed on the authentication, authorization, and accounting, i.e., AAA side. For that purpose we developed WLAN access controller and WLAN AAA gateway, which provide gateway-type access control as well as charging and billing functionalities for the WLAN service. In the development process of these elements, we have considered current development stadium of all needed network entities and protocols. The provided solution provides cost-effective and easy-to-deploy PLMN-WLAN Internetworking scenario.

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    NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니담기를 통하여 원문복사서비스 이용이 가능합니다.

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  9. [국내논문]   Seamless and Secure Mobility Management with Location-Aware Service (LAS) Broker for Future Mobile Interworking Networks   피인용횟수: 1

    Lee Minsoo (School of Electrical and Electronics Engineering, Chung-Ang University ) , Kim Gwanyeon (School of Electrical and Electronics Engineering, Chung-Ang University ) , Park Sehyun (School of Electrical and Electronics Engineering, Chung-Ang University)
    Journal of communications and networks v.7 no.2 ,pp. 207 - 221 , 2005 , 1229-2370 ,

    초록

    The proliferation of wireless local area networks (WLANs) offering high data rate in hot spot area have spurred the demand for possible WLANs and third-generation (3G) cellular network integration solutions as the initiative step towards 4G systems. This paper provides a novel architecture for seamless location-aware integration of WLANs into 3G cellular networks and also an analysis for the efficient handover techniques. We introduce location as a key context in secure roaming mechanism for context-aware interworking in 4G systems. The fast secure roaming with location-aware authentication is implemented at an entity called location-aware service (LAS) broker that utilizes the concepts of direction of user and pre-warming zone. The location-ware interworking architecture supports seamless roaming services among heterogeneous wireless networks including WLANs, wireless metropolitan area networks (WMANs), and 3G cellular networks. This paper also includes a description of procedures needed to implement efficient mobility and location management. We show how the LAS broker with pre-warming and context transfer can obtain significant lower latency in the vertical handover.

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    NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니담기를 통하여 원문복사서비스 이용이 가능합니다.

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  10. [국내논문]   Usability and Evaluation of a Deployed 4G Network Prototype  

    Cuevas Antonio (Departmento de Ingenieria Telematica, Universidad Carlos III de Madrid, Spain ) , Serrano Pablo (Departmento de Ingenieria Telematica, Universidad Carlos III de Madrid, Spain ) , Moreno Jose I. (Departmento de Ingenieria Telematica, Universidad Carlos III de Madrid, Spain ) , Bernardos Carlos J. (Departmento de Ingenieria Telematica, Universidad Carlos III de Madrid, Spain ) , Jahnert Jurgen (Rechenzentrum Universitat Stuttgart, Germany ) , Aguiar Rui L. (Instituto de Telecommunicacoes/Universidade de Aveiro, Aveiro, Portugal ) , Marques Victor (Portugal Telecom Inovacao, Aveiro, Portugal)
    Journal of communications and networks v.7 no.2 ,pp. 222 - 230 , 2005 , 1229-2370 ,

    초록

    This article presents a field evaluation of an IP-based architecture for heterogeneous environments that has been developed under the aegis of the Moby Dick project, covering UMTS-like (universal mobile telecommunications system) TD-CDMA (time division-code division multiple access) wireless access technology, wireless and wired LANs. The architecture treats all transmission capabilities as basic physical and data-link layers, and replaces all higher-level tasks by IP-based strategies. The Moby Dick architecture incorporates mobile IPv6, fast handovers, AAA-control (authentication, authorisation, accounting), charging and quality of service (QoS) in an integrated framework. The architecture further allows for optimised control on the radio link layer resources. It has been implemented and tested by expert users, and evaluated by real users on field trials with multiple services available.

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    회원님의 원문열람 권한에 따라 열람이 불가능 할 수 있으며 권한이 없는 경우 해당 사이트의 정책에 따라 회원가입 및 유료구매가 필요할 수 있습니다.이동하는 사이트에서의 모든 정보이용은 NDSL과 무관합니다.

    NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니담기를 통하여 원문복사서비스 이용이 가능합니다.

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