We consider the problem of pilot-aided accurate least squares (LS) channel estimation in the presence of carrier frequency offset (CFO). We first formulate the mean square error (MSE) of the LS channel estimator in the presence of CFO and then show how to select the pilot sequence (with element values constrained to plus or minus one) that minimizes the MSE. Our main conclusion is that, in the presence of CFO accurate channel estimates can be obtained by transmitting identical pilot symbol on all subcarriers. We demonstrate our results via computer simulations. ©2009 IEEE.

Rangarajan Aravind

Department of Electrical Engineering

J. Oliver

K. M.Muraleedhara Prabhu

ACCURATE CHANNELS

CARRIER FREQUENCY OFFSET (CFO)

CARRIER FREQUENCY OFFSETS

CHANNEL ESTIMATOR

INTERCARRIER INTERFERENCE

Least squares

LEAST SQUARES CHANNEL ESTIMATION

OFDM SYSTEMS

PILOT AIDED

PILOT SEQUENCES

PILOT SYMBOLS

SUB-CARRIERS

Block codes

Channel Estimation

Computer simulation

Estimation

Frequency allocation

Mean Square Error

Orthogonal frequency division multiplexing

Signal encoding

Strain energy

Frequency 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

Improved channel estimation in OFDM systems in the presence of CFO

2009 15th Asia-Pacific Conference on Communications, APCC 2009

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

IEEE Transactions on Broadcasting

A New ICI Matrices Estimation Scheme Using Hadamard Sequence for OFDM Systems

IEEE Transactions on Communications

Training sequence design for frequency offset and frequency-selective channel estimation

Digital Signal Processing

Training sequence selection for frequency offset estimation in frequency selective channels

Channel estimation for OFDM transmission in multipath fading channels based on parametric channel modeling

An investigation into time-domain approach for OFDM channel estimation

Journal	2009 15th Asia-Pacific Conference on Communications, APCC 2009
Open Access	No