• 제목/요약/키워드: frequency division duplex (FDD)

검색결과 31건 처리시간 0.021초

An Overlaid Hybrid-Division Duplex OFDMA System with Multihop Transmission

  • Sang, Young-Jin;Park, Jung-Min;Kim, Seong-Lyun;Kim, Kwang-Soon
    • ETRI Journal
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    • 제33권4호
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    • pp.633-636
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    • 2011
  • In this letter, we propose an overlaid hybrid division duplex (HDD) concept for cellular systems which divides a cell into inner and outer regions and utilizes the merits of both time division duplex (TDD) and frequency division duplex (FDD). The proposed system can take advantage of both TDD and FDD without handover between two duplex schemes. Moreover, it is shown that the proposed HDD system outperforms the conventional TDD or FDD system with mobile relay stations when the synchronization issue is considered in orthogonal frequency division multiple access systems. Thus, the proposed overlaid HDD can be considered as a new framework for future cellular systems.

Analysis of Capacity Decrease Through Calculating Statistically the Amount of Interference From IMT-2000 TDD System to FDD System (IMT-2000 TDD시스템에서 FDD시스템으로의 통계적인 간섭량 계산을 통한 FDD 시스템의 용량 감소 분석)

  • Kim, Sung-Jin;Choi, Sang-Sung;Lee, Hyung-Soo
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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    • pp.572-575
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    • 2003
  • There is two System for IMT-2000 Service. one is FDD(Frequency Division Duplex), the other is TDD(Time Division Duplex) system. At the 1920MHz, they have common boundary in IMT-2000 frequency allocation of Korea. In this paper, The amount of Interference From TDD MS(Mobile Station) and BS(Base Station) to FDD BS is Analyzed for Investigation on capacity variation of FDD service by frequency separation. the result and methodology in this paper will be used basically for calculating the guard-band between FDD and TDD service in the future

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Trends of TDD/FDD LTE Network Convergence (TDD/FDD LTE 네트워크 컨버전스 동향)

  • Seol, S.H.;Kim, S.C.
    • Electronics and Telecommunications Trends
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    • 제30권3호
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    • pp.123-130
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    • 2015
  • 본고는 TDD(Time Division Duplex)/FDD(Frequency-Division Duplex) 네트워크 컨버전스를 통해 LTE(Long Term Evolution) 서비스를 제공하고 있는 주요 사업자들의 동향에 대하여 분석 정리하였다. 본고의 분석 결과에 따르면, 상당수 사업자가 보유 주파수 여건을 고려하여 경쟁력을 높이기 위한 목적으로 네트워크 컨버전스를 추진한 것으로 나타났다. 향후 국내에서도 TDD/FDD 컨버전스를 촉진하고 주파수 이용 효율성을 개선하기 위한 정책방안에 대한 모색이 필요하다고 사료된다.

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On Mobility-Supporting Transmit Beamforming in MISO FDD Wireless Systems

  • Lee, Woo-Kwon;Sepko, Brian J.
    • Journal of Communications and Networks
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    • 제10권3호
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    • pp.308-315
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    • 2008
  • When operating in frequency-division duplex (FDD) mode, transmit beamforming in multiple-input single-output (MISO) wireless communication systems typically requires accurate knowledge of downlink channel state information (CSI) at the transmitter. In practical FDD systems, obtaining such downlink CSI at the transmitter is challenging, if not impractical. To circumvent such challenge and support user mobility, we present a new method for transmit beamforming based on simple beam-control commands (BCCs) in MISO FDD mobile systems. We then numerically evaluate the effects of BCC errors in terms of transmit power efficiency, system capacity, and outage probability.

A CP Detection Based SSS Detection Method for Initial Cell Search in 3GPP LTE FDD/TDD Dual Mode Downlink Receiver (3GPP LTE FDD/TDD 듀얼 모드 하향링크 수신기에서 초기 셀 탐색을 위한 CP 검출 기반의 SSS 검출 기법)

  • Kim, Jung-In;Jang, Jun-Hee;Choi, Hyung-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • 제35권1C호
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    • pp.113-122
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    • 2010
  • In this paper, we propose a CP (Cyclic Prefix) detection based SSS (Secondary Synchronization Signal) detection method for initial cell search in 3GPP LTE (3rd Generation Partnership Project Long Term Evolution) FDD/TDD (Frequency Division Duplex/Time Division Duplex) dual mode downlink receiver. In general, a blind coherent SSS detection method which can detect SSS without CP detection is applied. However, coherent detection method caused performance degradation by channel compensation error at high speed environment because it uses estimated CFR (Channel Frequency Response) at PSS (Primary Synchronization Signal), and it can be more serious problem in TDD mode due to increased distance between PSS and SSS. Also blind detectionhas the drawback of high computational complexity. Therefore, we proposed a CP type pre-decision structure with non-coherent SSS detection which has stable operation in high speed channel environments for 3GPP LTE TDD mode as well as FDD mode, and can reduce computational complexity by applying CP detection before SSS detection. Simulation results show that the proposed method has stable operation for 3GPP LTE TDD/FDD dual mode downlink receiver in various channel environments.

Adaptive Channel Estimation Techniques for FDD Massive MIMO Systems (FDD Massive MIMO 시스템에서의 적응 채널 추정 기법)

  • Chung, Jinjoo;Han, Yonghee;Lee, Jungwoo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • 제40권7호
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    • pp.1239-1247
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    • 2015
  • In frequency-division duplex (FDD) massive multiple-input multiple-output (MIMO) system, the computational complexity of downlink channel estimation is proportional to the number of antennas at a base station. Therefore, effective channel estimation techniques may have to be studied. In this paper, novel channel estimation algorithms using adaptive techniques such as Kalman and least mean square (LMS) filters are proposed in a channel model with temporal and spatial correlation.

Performance of CDMA/TDD in Multimode Scenario for Dual-band Operation (이중대역 동작을 위한 멀티모드 시나리오에서 CDMA/TDD의 성능)

  • Oh, Hyeong-Joo;Hwang, Seung-Hoon
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • 제45권11호
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    • pp.32-36
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    • 2008
  • In this paper, we investigate the capacity of CDMA/TDD in the inner zone of multimode scenario with dual-band operation where high frequency band is used for TDD in the inner zone and lower frequency band is utilized for FDD in the outer zone. The effects of various system parameters such as cell radius, date rate, and time slot allocation are analyzed.

An Enhanced AGC Structure and P-SCH Detection Method for Initial Cell Search in 3GPP LTE FDD/TDD Dual Mode Downlink Receiver (3GPP LTE FDD/TDD 듀얼 모드 하향 링크 수신기의 초기 셀 탐색을 위한 개선된 AGC 구조 및 P-SCH 검출 기법)

  • Chung, Myung-Jin;Jang, Jun-Hee;Choi, Hyung-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • 제35권3C호
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    • pp.302-313
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    • 2010
  • In this paper, we propose an enhanced AGC (Automatic Gain Control) structure and P-SCH detection method for initial cell search in 3GPP (3rdGenerationPartnershipProject) LTE (Long Term Evolution) FDD(Frequency Division Duplex) / TDD (Time Division Duplex) dual mode system. Since TDD frame structure consists of uplink subframe and downlink subframe, conventional AGC structure causes P-SCH detection performance degradation by increase of AGC variation due to signal power difference between uplink and downlink subframe. Also, P-SCH detection performance is degraded by distortion of P-SCH correlation characteristic in frequency offset and multipath fading channel environments. Therefore, we propose an AGC structure which can minimize P-SCH detection performance degradation with stable operation in 3GPP LTE TDD mode as well as FDD mode. Also we propose a P-SCH detection method which can reduce distortion of correlation chareteristics in frequency offset and multipath fading environments and obtain good P-SCH detection performance. Simulation results show that the proposed AGC structure and P-SCH detection method have stable AGC operation and excellent P-SCH detection performance for 3GPP LTE TDD / FDD dual mode downlink receiver in various channel environments.

GROUP SECRET KEY GENERATION FOR 5G Networks

  • Allam, Ali M.
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제13권8호
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    • pp.4041-4059
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    • 2019
  • Key establishment method based on channel reciprocity for time division duplex (TDD) system has earned a vital consideration in the majority of recent research. While most of the cellular systems rely on frequency division duplex (FDD) systems, especially the 5G network, which is not characterized by the channel reciprocity feature. This paper realizes the generation of a group secret key for multi-terminals communicated through a wireless network in FDD mode, by utilizing the nature of the physical layer for the wireless links between them. I consider a new group key generation approach, which using bitwise XOR with a modified pairwise secret key generation approach not based on the channel reciprocity feature. Precisely, this multi-node secret key agreement technique designed for three wireless network topologies: 1) the triangle topology, 2) the multi-terminal star topology, and 3) the multi-node chain topology. Three multi-node secret key agreement protocols suggest for these wireless communication topologies in FDD mode, respectively. I determine the upper bound for the generation rate of the secret key shared among multi-node, for the three multi-terminals topologies, and give numerical cases to expose the achievement of my offered technique.

Packet Scheduling Algorithm Considering a Minimum Bit Rate for Non-realtime Traffic in an OFDMA/FDD-Based Mobile Internet Access System

  • Kim, Dong-Hoi;Ryu, Byung-Han;Kang, Chung-Gu
    • ETRI Journal
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    • 제26권1호
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    • pp.48-52
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    • 2004
  • In this letter, we consider a new packet scheduling algorithm for an orthogonal frequency division multiplexing access/frequency division duplex (OFDMA/FDD)-based system, e.g., mobile broadband wireless access or high-speed portable internet systems, in which the radio resources of both time and frequency slots are dynamically shared by all users under a proper scheduling policy. Our design objective is to increase the number of non-realtime service (e.g., WWW) users that can be supported in the system, especially when the minimum bit rate requirement is imposed on them. The simulation results show that our proposed algorithm can provide a significant improvement in the average outage probability performance for the NRT service, i.e., significantly increasing the number of NRT users without much compromising of the cell throughput.

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