• Title/Summary/Keyword: Interference Cancellation

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Current-Integrating DFE with Sub-UI ISI Cancellation for Multi-Drop Channels

  • Park, Hwan-Wook;Lim, Hyun-Wook;Kong, Bai-Sun
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.16 no.1
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    • pp.112-117
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    • 2016
  • This paper presents a half-rate current-integrating DFE receiver with sub-unit interval (sub-UI) inter-symbol interference (ISI) cancellation. By having a single additional DFE tap in each data path, the proposed DFE receiver can minimize BER degradation due to input pattern dependency and feedback tap latency problems in conventional current-integrating DFE receivers. The proposed DFE receiver was designed and fabricated in a 45 nm CMOS process, whose measurement results indicated that the BER bathtub width is increased from 0.235 UI to 0.315 UI (34% improvement) at $10^{-12}$ BER level.

Interference Signal Cancellation Algorithm using Parallel sub-filters for W-CDMA repeater (병렬 부 필터를 이용한 W-CDMA 중계기용 간섭 신호 제거 알고리즘)

  • Moon, Sung-Bae;Oh, Seung-Rohk
    • Journal of IKEEE
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    • v.14 no.3
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    • pp.205-209
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    • 2010
  • We propose a new interference cancellation algorithm for W-CDMA repeater. The proposed algorithm uses the parallel multiple sub-filters instead of one long filter. We justify that convergence rate can be improved by using the proposed algorithm. The improvement of convergence rate is verified in a practical benchmark test condition.

Novel Beamforming and User Scheduling Algorithm for Inter-cell Interference Cancellation

  • Kim, Kyunghoon;Piao, Jinhua;Choi, Seungwon
    • IEIE Transactions on Smart Processing and Computing
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    • v.5 no.5
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    • pp.346-348
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    • 2016
  • Coordinated multi-point transmission is a candidate technique for next-generation cellular communications systems. We consider a system with multiple cells in which base stations coordinate with each other by sharing user channel state information, which mitigates inter-cell interference (ICI), especially for users located at the cell edge. We introduce a new user scheduling method that considers both ICI and intra-cell orthogonality. Due to the influence of ICI cancellation and the loss reduction of effective channel gain during the beamforming process, the proposed method improves the system sum rate, when compared to the conventional method, by an average of 0.55bps/Hz for different numbers of total users per cell.

Performance Enhancement by Interference Cancellation Scheme in Transmit Diversity using STBC over Time Selective Fading Channel (Time Selective Fading 채널 환경에서 STBC를 이용하는 송신 다이버시티에서 간섭제거기법에 의한 성능 개선)

  • Kim, Jang-Wook;Jin, Yang-Hee;Oh, Chang-Heon;Cho, Sung-Joon
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 2003.11a
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    • pp.239-242
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    • 2003
  • Transmit diversity using STBC(Space Time Block Code) provides the same diversity gain as MRRC(Maximal Ratio Receiver Combining), when the fading channel is constant across two consecutive symbols. But, when the channel condition is changed for the two consecutive symbols, the transmit diversity using STBC does not offer good performance due to the large doppler shift. In this paper, we have proposed a interference cancellation scheme for performance enhancement in transmit diversity using STBC over time selective fading channel. Simulation results for various doppler shift rates are presented for the transmit diversity using the proposed scheme.

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A Study on Feedforward System for IMT-2000

  • Jeon, Joong-Sung;Choi, Dong-Muk;Kim, Min-Jung
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2005.06a
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    • pp.1176-1185
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    • 2005
  • A linear power amplifier is particularly emphasized on the system using a linear modulations, such as 16QAM and QPSK with pulse shaping, because intermodulation distortion which causes adjacent channel interference and co-channel interference is mostly generated in a nonlinear power amplifier. In this paper, parameters of a linearization loop, such as an amplitude imbalance, a phase imbalance and a delay mismatch, are briefly analyzed to get a specific cancellation performance and linearization bandwidth. Experimental results are presented for IMT-2000 frequency band. The center frequency of the feedforward amplifier is 2140 MHz with 60 MHz bandwidth. When the average output power of feedforward amplifier is 20 Watt, the intermodulation cancellation performance is more than 21 dB. In this case, the output power of feedforward amplifier reduced 3.5 dB because of extra delay line loss and coupling loss. The feedforward amplifier efficiency is more than 7.2 % for multicarrier signals, 59 dBc for ACPR.

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Performance Analysis of GHICW(Group-wise Hybrid Interference Cancellation scheme based on Wiener filtering) in Multi Rate DS/CDMA System (그룹형 하이브리드 위너 필터링 간섭제거 기법을 이용한 다중 데이터 율 DS/CDMA 시스템의 성능분석)

  • 최원태;박상규
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.26 no.8B
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    • pp.1176-1182
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    • 2001
  • 본 논문에서는 서로 다른 데이터 율 신호들의 다중 접속 간섭을 제거하기 위해 그룹형 하이브리드 위너 필터링 간섭 제거 기법(Group-wise Hybrid Interference Cancellation scheme based on Wiener filtering : GHICW)을 제안하고 AWGN 채널과 레일리 페이딩 채널환경에서 그 성능을 상용검파기와 비교 분석하였다. 본 논문에서 제시한 수신 기법은 동일 데이터 율을 가진 사용자를 그룹으로 묶어 처리함으로써 기존의 간섭제거 시스템보다 시스템 처리 지연이 적고, 하드웨어 구현이 간단하며, 큰 전력으로 전송되는 높은 데이터 율 사용자의 신호들을 위너 필터를 이용해 재생하여 낮은 데이터 율 사용자와 높은 데이터 율 사용자의 수신 성능을 향상시킨다.

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Performance Improvement of Wireless Positioning System Using IC-IPDL Method (IC-IPDL 기법을 이용한 무선 측위 시스템의 성능 개선)

  • 김상헌;정양석;윤대희;이충용
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.2A
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    • pp.124-129
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    • 2002
  • We propose a wireless positioning system using IC-IPDL method that exploits the modified-IPDL method and the interference cancellation techniques to improve hearability. In the proposed system, IPDL method is modified to maintain the transmission of CPICH for stability of CDMA network Simultaneously in mobile CPICH is cancelled out using the interference cancellation techniques for improving hearability. The simulation results showed that the proposed location system has a compatible performance to the standard IPDL method though CPICH exists during idle period.

Adaptive Techniques for Joint Optimization of XTC and DFE Loop Gain in High-Speed I/O

  • Oh, Taehyoun;Harjani, Ramesh
    • ETRI Journal
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    • v.37 no.5
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    • pp.906-916
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    • 2015
  • High-speed I/O channels require adaptive techniques to optimize the settings for filter tap weights at decision feedback equalization (DFE) read channels to compensate for channel inter-symbol interference (ISI) and crosstalk from multiple adjacent channels. Both ISI and crosstalk tend to vary with channel length, process, and temperature variations. Individually optimizing parameters such as those just mentioned leads to suboptimal solutions. We propose a joint optimization technique for crosstalk cancellation (XTC) at DFE to compensate for both ISI and XTC in high-speed I/O channels. The technique is used to compensate for between 15.7 dB and 19.7 dB of channel loss combined with a variety of crosstalk strengths from $60mV_{p-p}$ to $180mV_{p-p}$ adaptively, where the transmit non-return-to-zero signal amplitude is a constant $500mV_{p-p}$.

Wireless Repeating Interference Canceller Using Delay Estimation Least Mean Square Adaptive Algorithm (지연 추정 LMS 적응 알고리즘을 이용한 무선 중계 간섭 제거기)

  • Kang, Yong-Jin;Song, Joo-Tae;Jeon, Ig-Tae;Kim, Joo-Wan;Ha, Sung-Hee;Van, Ji-Hun;Lee, Jong-Hyun
    • Proceedings of the IEEK Conference
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    • 2007.07a
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    • pp.119-120
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    • 2007
  • The operation of Interference cancellation algorithm for wireless repeater cancellation depends on either existing correlation properties between desired signal and reference signal or not At the time, due to the correlation properties at the ICS system, adaptive algorithms without considering system delay do not function properly. Thus, this system should be oscillated. In this paper, to solve these problems, we use the delayed least mean square algorithm. For the best performance of ICS, the system delays must be estimated. To efficiently estimate the delay of ICS, we use relations between bandwidth and correlation properties of the received signal.

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Block-Ordered Layered Detector for MIMO-STBC Using Joint Eigen-Beamformers and Ad-Hoc Power Discrimination Scheme

  • Lee Won-Cheol
    • Journal of Communications and Networks
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    • v.8 no.3
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    • pp.275-285
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    • 2006
  • Suitable for multi-input multi-output (MIMO) communications, the joint beamforming space-time block coding (JBSTBC) scheme is proposed for high-speed downlink transmission. The major functionality of the scheme entails space-time block encoder and joint transmit and receive eigen-beamformer (EBF) incorporating with block-ordered layered decoder (BOLD), and its operating principle is described in this paper. Within these functionalities, the joint EBFs will be utilized for decorrelating fading channels to cause an enhancement in the spatial diversity gain. Furthermore, to fortify the capability of layered successive interference cancellation (LSIC) in block-ordered layered decoding process, this paper will develop a simple ad-hoc transmit power discrimination scheme (TPDS) based on a particular power discrimination function (PDF). To confirm the superior behavior of the proposed JBSTBC scheme employing ad-hoc TPDS, computer simulations will be conducted under various channel conditions with the provision of detailed mathematical derivations for clarifying its functionality.