• Title/Summary/Keyword: blind estimation

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Performance Evaluation of Joint Blind Equalizer and Carrier Recovery for QAM Signal (QAM 신호를 위한 Blind 등화기 Carrier Recovery 결합에 관한 성능평가)

  • 송재철;최형진
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.19 no.11
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    • pp.2067-2080
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    • 1994
  • Recently, joint blind equalization and carrier recovery for digital mobile transmission system is of growing interest. In this paper, we describe new receiver structure of joint godard blind equalizer and various recovery loop for QAM modulated signal. After a brief review of Godard blind equalizer and MAP estimation Costas loop, Generalized Costas loop, Leclert loop, Angular form loop, we present two kinds of receiver structures for joint blind equalization and carrier recovery. Using a Monto Carlo simulation technique, we can confirm that two kinds of receiver structures operate very well in the steady state.

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A Joint Channel Estimation and Data Detection for a MIMO Wireless Communication System via Sphere Decoding

  • Patil, Gajanan R.;Kokate, Vishwanath K.
    • Journal of Information Processing Systems
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    • v.13 no.4
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    • pp.1029-1042
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    • 2017
  • A joint channel estimation and data detection technique for a multiple input multiple output (MIMO) wireless communication system is proposed. It combines the least square (LS) training based channel estimation (TBCE) scheme with sphere decoding. In this new approach, channel estimation is enhanced with the help of blind symbols, which are selected based on their correctness. The correctness is determined via sphere decoding. The performance of the new scheme is studied through simulation in terms of the bit error rate (BER). The results show that the proposed channel estimation has comparable performance and better computational complexity over the existing semi-blind channel estimation (SBCE) method.

Improved Blind Multipath Estimation for Long Code DS-CDMA

  • Yu Qian;Bi Guoan;Zhang Gaonan
    • Journal of Communications and Networks
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    • v.7 no.3
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    • pp.278-283
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    • 2005
  • This paper proposes a blind channel estimation scheme for long code direct sequence code division multiple access (DS­CDMA) systems with multipath fading channels. This scheme combines the advantages of Toeplitz displacement and correlation matching methods to achieve improved performance. The basic idea is to remove the effects of noise and interferences with Toeplitz displacement operation and then estimate the multi path channel parameters with the correlation matching method. Simulation results are presented to show that the proposed scheme provides better MSE performance and robustness against the near-far problem.

Integer Frequency Offset Estimation of OFDM Systems

  • Yoon, Dae-Gung;Han, Dong-Seog
    • Proceedings of the Korea Society of Information Technology Applications Conference
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    • 2005.11a
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    • pp.255-258
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    • 2005
  • A blind-mode integer frequency offset estimation algorithm is proposed for an OFDM system. Imperfect integer frequency offset estimation causes ambiguity in the data sub-carrier position. Morelli's blind integer frequency offiet estimation algorithm exploits the likelihood function by comparing the power in sub-carriers. It, however, shows performance degradation when there is the fractional frequency offset. The proposed algorithm solves this by using interpolation in the frequency domain. In this algorithm, it is exploited that the effect of the frequency offset is shown as a shift of power spectrum. By calculating the covariance of over-sampled samples, most approximate samples to integer point are obtained. It enables integer frequency offset estimation less affected by fractional frequency offset.

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Blind Channel Estimation based on Hadamard Matrix Interstream Transmission for Multi-Cell MIMO Networks (다중 셀 MIMO 네트워크를 위한 Hadamard 행렬 Interstream 전송 기반 Blind 채널 추정)

  • Yang, Jae-Seung;Hanif, Mohammad Abu;Park, Ju-Yong;Lee, Moon-Ho
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.15 no.4
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    • pp.119-125
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    • 2015
  • In this paper, we introduce a Hadamard matrix interstream transmission based blind channel estimation for multi-cells multiple-input and multiple-output (MIMO) networks. The proposed scheme is based on a network with mobile stations (MS) which are deployed with multi cells. We assume that the MS have the signals from both cells. The signal from near cell are considered as desired signal and the signals from the other cells are interference signal. Since the channel is blind, so that we transmit Hadamard matrix pattern pilot stream to estimate the channel; that gives easier and fast channel estimation for large scale MIMO channel. The computation of Hadamard based system takes only complex additions, and thus the complexity of which is much lower than the scheme with Fourier transform since complex multiplications are not needed. The numerical analysis will give perfection of proposed channel estimation.

Rayleigh-Quotient and Iterative-Threshold-Test-Based Blind TOA Estimation for IR-UWB Systems

  • Shen, Bin;Zhao, Chengshi;Cui, Taiping;Kwak, Kyung-Sup
    • ETRI Journal
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    • v.32 no.2
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    • pp.333-335
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    • 2010
  • This letter proposes a non-coherent blind time-of-arrival (TOA) estimation scheme for impulse radio ultra-wideband systems. The TOA estimation is performed in two consecutive phases: the Rayleigh-quotient theorem-based coarse-signal acquisition (CSA) and the iterative-threshold-test-based fine time estimation (FTE). The proposed scheme serves in a blind manner without demanding any a priori knowledge of the channel and the noise. Analysis and simulations demonstrate that the proposed scheme significantly increases the signal detection probability in CSA and ameliorates the TOA estimation accuracy in FTE.

Joint Blind Parameter Estimation of Non-cooperative High-Order Modulated PCMA Signals

  • Guo, Yiming;Peng, Hua;Fu, Jun
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.12 no.10
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    • pp.4873-4888
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    • 2018
  • A joint blind parameter estimation algorithm based on minimum channel stability function aimed at the non-cooperative high-order modulated paired carrier multiple access (PCMA) signals is proposed. The method, which uses hierarchical search to estimate time delay, amplitude and frequency offset and the estimation of phase offset, including finite ambiguity, is presented simultaneously based on the derivation of the channel stability function. In this work, the structure of hierarchical iterative processing is used to enhance the performance of the algorithm, and the improved algorithm is used to reduce complexity. Compared with existing data-aided algorithms, this algorithm does not require a priori information. Therefore, it has significant advantage in solving the problem of blind parameter estimation of non-cooperative high-order modulated PCMA signals. Simulation results show the performance of the proposed algorithm is similar to the modified Cramer-Rao bound (MCRB) when the signal-to-noise ratio is larger than 16 dB. The simulation results also verify the practicality of the proposed algorithm.

Simple Blind Channel Estimation Scheme for Downlink MC-CDMA Systems (하향링크 MC-CMDMA 시스템을 위한 간단한 미상 채널 추정 방법)

  • Seo, Bang-Won
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37 no.6A
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    • pp.480-487
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    • 2012
  • In multicarrier code-division multiple access (MC-CDMA) systems, conventional blind channel estimation schemes require the inverse matrix calculation or eigenvalue decomposition of the received signal covariance matrix. Therefore, computational complexity of the conventional schemes is too high and they cannot be employed in downlink systems. In this paper, we propose a simple blind channel estimation scheme with very low computational complexity. Simulation results show that the proposed scheme has better channel estimation and bit error rate (BER) performance than the conventional schemes.

A Consideration on ML Blind Signal Estimation based on Finite-Alphabet Characteristic in QPSK Modulation (QPSK 신호 입력시스템에서의 유한 알파벹 기반 ML 블라인드 신호 추정 비교)

  • Kwon, S.M.;Kim, S.J.;Lee, J.M.;Kim, C.K.;Cheon, J.M.
    • Proceedings of the KIEE Conference
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    • 2003.11c
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    • pp.685-688
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    • 2003
  • In this paper, a performance comparison between two blind signal estimation algorithms in a LTI channel is considered. The two algorithms, Iterative Least-Squares with Projection (ILSP) and a modified ILSP, are based on the finite-alphabet property of input symbols. This case typically arises in a multiple access system with a sensor array antenna at the receiving end. We start with the formulation of a maximum-likelihood (ML) estimation problem under an additive white Gaussian noise assumption. A blind ML estimator is derived with its iterative algorithm for calculation. Then we narrow down the consideration of this problem to QPSK case so that a modified algorithm is proposed for $\pi$/4-QPSK case. The modified version is compared with the original ILSP algorithm in terms of the rate of the convergence to global minima. A computer simulation shows that the modified algorithm gives a better performance. This result implies that the performance of the blind separation algorithms may be greatly improved by adopting a smart coding scheme with rich structure.

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Joint Blind Data/Channel Estimation Based on Linear Prediction

  • Ahn, Kyung-Seung;Byun, Eul-Chool;Baik, Heung-Ki
    • Proceedings of the IEEK Conference
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    • 2001.09a
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    • pp.869-872
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    • 2001
  • Blind identification and equalization of communication channel is important because it does not need training sequence, nor does it require a priori channel information. So, we can increase the bandwidth efficiency. The linear prediction error method is perhaps the most attractive in practice due to the insensitive to blind channel estimator and equalizer length mismatch as well as for its simple adaptive algorithms. In this paper, we propose method for fractionally spaced blind equalizer with arbitrary delay using one-step forward prediction error filter from second-order statistics of the received signals for SIMO channel. Our algorithm utilizes the forward prediction error as training sequences for data estimation and desired signal for channel estimation.

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