A threshold-based procedure to estimate sparse channels in an orthogonal frequency division multiplexing (OFDM) system is proposed. An optimal threshold is derived by maximising the probability of correct detection between significant and zero-valued taps estimated by the least squares (LS) estimator. Improved LS estimates are obtained by pruning the LS estimates with the statistically derived threshold. © 2008 The Institution of Engineering and Technology.

Rangarajan Aravind

Department of Electrical Engineering

J. Oliver

K. M.Muraleedhara Prabhu

Channel Estimation

Computer networks

Curve fitting

ENGINEERING TECHNOLOGY

Frequency allocation

Frequency division multiplexing

Frequency estimation

Least squares approximations

Orthogonal frequency division multiplexing

Technology

(OTDR) TECHNOLOGY

LEAST SQUARES (LS)

OFDM SYSTEMS

Optimal threshold

ORTHOGONAL FREQUENCY-DIVISION MULTIPLEXING (OFDM)

SPARSE CHANNELS

Estimation

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Electronics Letters

The authors consider the design of pilot sequences for channel estimation in the presence of carrier frequency offset (CFO) in systems that employ orthogonal frequency division multiplexing (OFDM). The CFO introduces intercarrier interference (ICI) which degrades the accuracy of the channel estimation. In order to minimise this effect, the authors design pilot sequence that minimises the mean square error (MSE) of the modified least squares (mLS) channel estimator. Since the identical pilot sequence, which minimises this MSE, has high peak-to-average power ratio of the OFDM signal, an alternative approach is proposed for channel estimation. The authors first introduce a new estimator as an alternative to the mLS estimator and design a low PAPR pilot sequences tailored to this new estimator. They show that the proposed procedure completely eliminates the effect of the ICI on the channel estimate. They then extend their design of pilot sequences for realistic sparse channels. Both analytical and computer simulation results presented in this study demonstrate the superiority of the proposed approach over conventional methods for channel estimation in the presence of ICI. © 2012 The Institution of Engineering and Technology.

IET Signal Processing

Improved least squares channel estimation for orthogonal frequency division multiplexing

We consider the design of pilot sequences for channel estimation in the presence of carrier frequency offset (CFO) in systems that employ orthogonal frequency division multiplexing (OFDM). The CFO introduces intercarrier interference (ICI) which degrades the accuracy of the channel estimation. To minimize this effect, we solve for the pilot sequence that minimizes the mean square error of the modified least squares (mLS) channel estimator. The transmission of this sequence results in high peak-to-average power ratio (PAPR) of the OFDM signal. To solve this problem, we first introduce a new estimator as an alternative to the mLS estimator. We then design a low PAPR pilot sequence tailored to this new estimator. We show that the proposed procedure completely eliminates the effect of the ICI on the channel estimate. Both analytical and computer simulation results demonstrate the superiority of the proposed scheme over the mLS estimator. © 2010 IEEE.

2010 International Conference on Signal Processing and Communications, SPCOM 2010

Pilot sequence design for improving OFDM channel estimation in the presence of CFO

We describe an algorithm for sparse channel estimation applicable to orthogonal frequency division multiplexing systems. The proposed algorithm uses a least squares (LS) technique for channel estimation and a generalized Akaike information criterion to estimate the channel length and tap positions. This effectively reduces the signal space of the LS estimator, and hence improves the estimation performance as demonstrated using computer simulations. For example, the proposed modified LS with sparse channel-estimation algorithm has a 5-dB lower mean square error in channel estimation when compared to the conventional approach [1], which translates to approximately 0.5 dB improvement in signal-to-noise ratio at the receiver. © 2005 IEEE.

IEEE Signal Processing Letters

Improving channel estimation in OFDM systems for sparse multipath channels

IET Communications

Efficient DFT-based channel estimation for OFDM systems on multipath channels

IEEE Transactions on Broadcasting

An investigation into time-domain approach for OFDM channel estimation

IEEE Standard for Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications

Sparse channel estimation in OFDM systems by threshold-based pruning

Journal	Electronics Letters
ISSN	00135194
Open Access	No