• Title/Summary/Keyword: Channel Estimation

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Power Control for D2D Communication in the Cellular System: The Impact of Channel Estimation Error

  • Oh, Changyoon
    • Journal of the Korea Society of Computer and Information
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    • v.23 no.8
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    • pp.51-57
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    • 2018
  • In this paper, we investigate the impact of channel estimation error on the D2D power control algorithm. In the previous work, D2D power control algorithm has been proposed under the assumption that the channel between the transmitter and the corresponding receiver is perfectly estimated. In reality, the channel estimation error is more often the case. The first question is that the power control algorithm designed for perfect channel estimation is still valid under the channel estimation error environment ? The second question is, if it is not valid, what could be the possible remedy for the channel estimation error ? In this paper, to answer the first question, we investigate the impact of the channel estimation error on the power control algorithm. We first review the D2D power control algorithm designed for perfect channel estimation. Then, we model the channel estimation error. Finally, we summarize the main results observed from the analysis of the simulation.

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.

Least Square Channel Estimation Scheme of OFDM System using Fuzzy Inference Method (퍼지 추론법을 적용한 OFDM 시스템의 LS(Least Square) 채널추정 기법)

  • Kim, Nam;Choi, Jung-Hun
    • The Journal of the Korea Contents Association
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    • v.9 no.5
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    • pp.84-90
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    • 2009
  • In this paper, the new channel estimation was proposed that have the low complexity and high performance using Fuzzy inference method uses recently from various field for estimation about uncertainty in channel estimation of OFDM. Proposed method is channel estimation performance improve, calculation and interpolation for statistics character of channel using the pilot before LS channel estimation by Fuzzy inference method. Simulation result in QPSK proposed channel estimation method shows the enhancement of 5.5dB compared to the LS channel estimation and the deterioration of 1.3dB compared to the MMSE channel estimation in mean square error point $10^{-3}$. symbol error rate shows similarity performance the MMSE $10^{-1.96}$, proposed channel estimation $10^{-1.93}$ and enhancement of $10^{-0.35}$ compared to the LS channel estimation in signal to noise ratio point 20dB.

Least Square Channel Estimation for Two-Way Relay MIMO OFDM Systems

  • Fang, Zhaoxi;Shi, Jiong
    • ETRI Journal
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    • v.33 no.5
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    • pp.806-809
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    • 2011
  • This letter considers the channel estimation for two-way relay MIMO OFDM systems. A least square (LS) channel estimation algorithm under block-based training is proposed. The mean square error (MSE) of the LS channel estimate is computed, and the optimal training sequences with respect to this MSE are derived. Some numerical examples are presented to evaluate the performance of the proposed channel estimation method.

A Novel Channel Estimation using 2-Dimensional Linear Iinterpolation for OFDM MIMO systems (2차원 선형보간법을 이용한 OFDM MIMO 시스템에서의 채널 추정)

  • Oh, Tae Youl;Ahn, Sung Soo;Choi, Seung Won
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.7 no.3
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    • pp.107-113
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    • 2011
  • An OFDMA(Orthogonal Frequency Division Multiple Access) includes a MIMO(Multi-Input Multi-Output) scheme for improving spectral efficiency and data throughput. Recognizing that the performance of MIMO system is heavily dependent upon the accuracy of channel estimation, we propose a novel channel estimation for the MIMO scheme based on OFDMA. Conventional interpolation-based channel estimation suffers from poor estimation error at specific subcarriers. Proposed scheme makes use of a planar interpolation instead of linear interpolation for those subcarriers of bad accuracy. Simulation results show that the proposed scheme improves the performance of MIMO system by improving the accuracy in channel estimation especially for the adverse subcarrier positions. It is observed that the proposed scheme outperforms the conventional method by about 2dB in terms of both mean squared error and overall bit error rate with a reasonable computational complexity.

A robust detection scheme of OSTBCs with channel estimation errors over time-selective fading channels (실제적인 Time-Selective Fading Channels에서의 Orthogonal Space-Time Block Codes의 Detection Scheme)

  • Yu, Dong-Hun;Lee, Jae-Hong
    • Proceedings of the IEEK Conference
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    • pp.17-18
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    • 2006
  • In this paper, we propose a robust detection scheme of OSTBCs with channel estimation errors over time-selective fading channels. Channel estimation errors are inevitable over time-selective fading channels and even small channel estimation errors dramatically degrade the performance of space-time block coding schemes. Therefore, it is desired to investigate the effect of channel estimation errors on the performance of the proposed detection scheme compared with the existing detection scheme. The proposed detection scheme minimizes noise enhancement and impact of channel estimation errors which occur in an existing detection scheme. It is shown by simulations that the proposed detection scheme performs better than the existing detection scheme over time-selective fading channels.

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Sparse Channel Estimation of Single Carrier Frequency Division Multiple Access Based on Compressive Sensing

  • Zhong, Yuan-Hong;Huang, Zhi-Yong;Zhu, Bin;Wu, Hua
    • Journal of Information Processing Systems
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    • v.11 no.3
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    • pp.342-353
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    • 2015
  • It is widely accepted that single carrier frequency division multiple access (SC-FDMA) is an excellent candidate for broadband wireless systems. Channel estimation is one of the key challenges in SC-FDMA, since accurate channel estimation can significantly improve equalization at the receiver and, consequently, enhance the communication performances. In this paper, we study the application of compressive sensing for sparse channel estimation in a SC-FDMA system. By skillfully designing pilots, their patterns, and taking advantages of the sparsity of the channel impulse response, the proposed system realizes channel estimation at a low cost. Simulation results show that it can achieve significantly improved performance in a frequency selective fading sparse channel with fewer pilots.

An Efficient Channel Estimation for Amplify and Forward Cooperative Diversity with Relay Selection

  • Jeong, Hyun-Doo;Lee, Jae-Hong
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • pp.94-98
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    • 2009
  • In this paper, we propose a new channel estimation scheme for amplify and forward cooperative diversity with relay selection. In order to select best relay, it is necessary to know channel state information (CSI) at the destination. Most of the previous works, however, assume that perfect CSI is available at the destination. In addition, when the number of relay is increased it is difficult to estimate CSI through all relays within coherence time of a channel because of the large amount of frame overhead for channel estimation. In a proposed channel estimation scheme, each terminal has distinct pilot signal which is orthogonal each other. By using orthogonal property of pilot signals, CSI is estimated over two pilot signal transmission phases so that frame overhead is reduced significantly. Due to the orthogonal property among pilot signals, estimation error does not depend on the number of relays. Simulation result shows that the proposed channel estimation scheme provides accurate CSI at the destination.

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Doubly-Selective Channel Estimation for OFDM Systems Using a Pilot-Embedded Training Scheme

  • Wang, Li-Dong;Lim, Dong-Min
    • Journal of electromagnetic engineering and science
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    • v.6 no.4
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    • pp.203-208
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    • 2006
  • Channel estimation and data detection for OFDM systems over time- and frequency-selective channels are investigated. Relying on the complex exponential basis expansion channel model, a pilot-embedded channel estimation scheme with low computational complexity and spectral efficiency is proposed. A periodic pilot sequence is superimposed at a low power on information bearing sequence at the transmitter before modulation and transmission. The channel state information(CSI) can be estimated using the first-order statistics of the received data. In order to enhance the performance of channel estimation, we recover the transmitted data which can be exploited to estimate CSI iteratively. Simulation results show that the proposed method is suitable for doubly-selective channel estimation for the OFDM systems and the performance of the proposed method can be better than that of the Wiener filter method under some conditions. Through simulations, we also analyze the factors which can affect the system performances.

A Low-Complexity 2-D MMSE Channel Estimation for OFDM Systems (OFDM 시스템을 위한 낮은 복잡도를 갖는 2-D MMSE 채널 추정 기법)

  • Kim, Jung-In;Jang, Jun-Hee;Choi, Hyung-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.5C
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    • pp.317-325
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    • 2011
  • For OFDM (Orthogonal Frequency Division Multiplexing) systems, 2-D MMSE (2-Dimensional Minimum Mean Square Error) channel estimation provides optimal performance in frequency/time selective fading channel environment. However, the 2-D MMSE channel estimation has high computational complexity due to the large matrix size, because the 2-D MMSE channel estimation considers time as well as frequency axis for channel estimation. To reduce the computational complexity, we propose a modified 2-D MMSE channel estimator which is based on 1-D MMSE channel estimation with weighted sum. Furthermore, we consider RMS delay spread and Doppler frequency estimation for 2-D MMSE channel estimation. We show that the proposed method can significantly reduce computational complexity as well as that it can perform close to 2-D MMSE channel estimation.