08-02-2012, 12:56 PM
Preamble-based SNR Estimation in Frequency Selective Channels for Wireless OFDM System
06-14-02.PDF (Size: 153.83 KB / Downloads: 77)
I. INTRODUCTION
OFDM is a multicarrier modulation scheme that provides
strong robustness against intersymbol interference (ISI) by
dividing the broadband channel into many narrowband subchannels
in such a way that attenuation across each subchannel
stays flat. Orthogonalization of subchannels is performed with
low complexity by using the fast Fourier transform (FFT). The
serial high-rate data stream is converted into multiple parallel
low-rate streams, each modulated on a different subcarrier.
V. SIMULATION RESULTS
The performance of PS estimator is evaluated and compared
with the performance of MMSE, Boumard’s and Ren’s estimator
using Monte-Carlo simulation. OFDM system parameters
used in the simulation are taken from WiMAX specifications
giving N = 256 subcarriers and cyclic prefix length of
32 samples [8].
CONCLUSION
In this paper, a novel preamble-based SNR estimator for
wireless OFDM systems has been proposed. Reuse of the
synchronization preamble for the SNR estimation purposes by
exploiting its time domain periodic structure puts no additional
overhead on transmitted OFDM frame. Increasing the number
of repeated parts by nulling the subcarriers on specified
positions improves the performance of considered estimator,
but also increases its sensitivity to frequency selectivity. Low
complexity and robustness to frequency selectivity combined
with the bandwidth efficiency favors the proposed estimator
compared to the considered preamble-based estimators given
in the literature.
06-14-02.PDF (Size: 153.83 KB / Downloads: 77)
I. INTRODUCTION
OFDM is a multicarrier modulation scheme that provides
strong robustness against intersymbol interference (ISI) by
dividing the broadband channel into many narrowband subchannels
in such a way that attenuation across each subchannel
stays flat. Orthogonalization of subchannels is performed with
low complexity by using the fast Fourier transform (FFT). The
serial high-rate data stream is converted into multiple parallel
low-rate streams, each modulated on a different subcarrier.
V. SIMULATION RESULTS
The performance of PS estimator is evaluated and compared
with the performance of MMSE, Boumard’s and Ren’s estimator
using Monte-Carlo simulation. OFDM system parameters
used in the simulation are taken from WiMAX specifications
giving N = 256 subcarriers and cyclic prefix length of
32 samples [8].
CONCLUSION
In this paper, a novel preamble-based SNR estimator for
wireless OFDM systems has been proposed. Reuse of the
synchronization preamble for the SNR estimation purposes by
exploiting its time domain periodic structure puts no additional
overhead on transmitted OFDM frame. Increasing the number
of repeated parts by nulling the subcarriers on specified
positions improves the performance of considered estimator,
but also increases its sensitivity to frequency selectivity. Low
complexity and robustness to frequency selectivity combined
with the bandwidth efficiency favors the proposed estimator
compared to the considered preamble-based estimators given
in the literature.