Time variant channel estimation using a modified complex exponential basis expansion model in LTE-OFDM systems

Idrees, Nazar Muhammad; Haselmayr, Werner; Schellander, David; Springer, Andreas

doi:10.1109/pimrc.2010.5671762

Cited by 15 publications

(9 citation statements)

References 12 publications

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“…According to the FFT property, we can see that the formula (1) is a cycle of length N. and then through the addition of NG cyclic prefix, with NG is greater than the channel impulse response, the impulse response and transmission time domain data sequence linear convolution into a round Product, tTo a certain extent, it can counteract the effect of intersymbol interference, and finally generate the transmitted symbols by the Serial parallel conversion and filtering [4].…”

Section: The Theory Of Apofdm Systemmentioning

confidence: 99%

APOFDM system design based on all phase FFT technology

Wu¹

2017

JEIS

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Abstract:The traditional OFDM system as an important part of current wireless communication technology, its advantages are obvious, but one of shortcoming is easily affected by the frequency deviation. An effective solution is to improve data signal processing technology in the front of the system, thus can reduce the effects of system faults and improve the performance of the system. All phase data processing under the research idea of it is in this, after 20 years of research and development, now all phase FFT technology has been applied to image processing, signal processing, signal spectrum analysis, wireless communication transmission, etc. In this paper, using all phase FFT processing technology and detailed the APOFDM, Finally, using MATLAB simulation tools to analyze its advantages.

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Section: The Theory Of Apofdm Systemmentioning

confidence: 99%

APOFDM system design based on all phase FFT technology

Wu¹

2017

JEIS

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“…The Complex Exponential Basis Expansion Model (CE-BEM) as proposed in [12] and presented in [20] and [15] for the lth tap of the CIR is defined as…”

Section: A Complex Exponential Basis Expansion Modelmentioning

confidence: 99%

“…In [20], Modified CE-BEM was presented to scale the highest frequency in CE-BEM exactly to the Doppler spread f d l of the lth tap. Motivation behind the modification was the tracking inefficiency of the conventional CE-BEM due to the use of higher frequencies than the highest Doppler frequency of the channel tap.…”

Section: B Modified Ce-bemmentioning

confidence: 99%

Improving time variant channel estimation for 3GPP LTE-downlink

Idrees

Haselmayr

Petit

et al. 2012

2012 IEEE 23rd International Symposium on Personal, Indoor and Mobile Radio Communications - (PIMRC)

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Accurate estimation of the doubly selective mobile radio channels is essential to achieve satisfactory performance in wideband wireless communication systems like 3GPP LTE. Pilot Assisted Channel Estimation (PACE) techniques like Linear Minimum Mean Squared Error (LMMSE), Least Square (LS) etc. are used to estimate the channel states at a certain time-frequency grid specified by the pilot symbols. A model like Basis Expansion Model (BEM) is used to track the doubly selective channel in time between the pilot symbols. BEM performance is sensitive to the PACE results. Imperfections in the PACE results are inevitable due to Inter Carrier Interference (ICI) at high speeds, changing signal to noise ratio (SNR) of the system and mismatch in the parameter values used in PACE calculations. We are able to reduce the effect of such imperfections by shaping the noise at the high frequencies in extended Fixed CE-BEM. Simulations show a decrease in MSE by a factor of ≈ 2 when the LMMSE results, obtained at 0dB SNR, are used to track the doubly selective channel at 350 km/h.

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“…According to this characteristic, in the conventional CE-BEM method [6] b q (n) = e j2p(q−Q/2)/N , and the relationship between g q,l and h ideal l (n) is deduced as:…”

mentioning

confidence: 99%

“…It should be noted that the FFT length of z sym (k) is 2N because of symmetric extension. Similar to the conventional CE-BEM method [6], the corresponding basis coefficient g sym q,l for h sym ideal l (n) can be calculated from z sym (k):…”

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confidence: 99%

Symmetric extension method for basis expansion models under fast‐varying channels

Wang

Chen

Hou³

et al. 2013

Electron. lett.

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A symmetric extension method for basis expansion modelling (BEM) under a fast-varying channel is proposed. The conventional DFT BEM approach suffers from power leakage and results in a modelling error floor, especially at the channel boundaries. Proposed is a novel symmetric extension method to reduce the leakage power efficiently. Numerical results show that the performance of the proposed channel modelling method is robust under different normalised Doppler frequencies and the modelling errors at the channel boundaries can be eliminated substantially. Introduction: Basis expansion modelling (BEM) is one of the possible ways to approximate the time-variation of the channel within a certain time window and has recently attracted a lot of attention for fast-varying channel estimation [1]. Using BEM, the varying channel can be efficiently modelled by representing the time varying taps as a superposition of bases or base waveforms with time invariant coefficients. Based on this idea, different BEM methods have been proposed in previous works. The polynomial BEM in [2] approaches the real channel when the polynomial order approaches infinity. The Karhunen-Loève decomposition BEM in [3] requires channel statistics. Though the discrete Fourier transform (DFT) BEM in [4] avoids these disadvantages, it suffers from high frequency leakage. Reference [5] proposed a simple windowing and dewindowing technique at the receiver to improve the precision of the DFT BEM.Among the existing BEM methods, the major drawback of BEM is that the rectangular window associated with the truncated DFT introduces spectral leakage, which results in modelling error floors. We propose a novel symmetric extension method to solve this problem. The channel response continuity at the boundaries is improved by symmetric extension. Its corresponding power spectrum is more concentrated on a few coefficients and the spectrum leakage power is reduced.

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Time variant channel estimation using a modified complex exponential basis expansion model in LTE-OFDM systems

Cited by 15 publications

References 12 publications

APOFDM system design based on all phase FFT technology

APOFDM system design based on all phase FFT technology

Improving time variant channel estimation for 3GPP LTE-downlink

Symmetric extension method for basis expansion models under fast‐varying channels

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