| In this paper we derive exact closed form bit error
rate (BER) or symbol error rate (SER) expressions for OFDM
systems with carrier frequency offset (CFO).We consider the performance
of an OFDM system subject to CFO error in frequency
flat Rayleigh fading channel with BPSK and 4PSK modulation
schemes. Our results can easily be reduced to the respective
analytical error rate expressions for the OFDM systems without
CFO error. Furthermore, the simulation results are provided to
verify the accuracy of the new error rate expressions.
I. INTRODUCTION
Orthogonal frequency division multiplexing (OFDM) is a
promising technology for eliminating the frequency selectivity
of the wireless communication channels. By definition, OFDM
expects the subcarries to be orthogonal. But, the factors such as
carrier frequency mismatching, time variations due to Doppler
shift or phase noise usually eliminate the orthogonality of
the subcarries. This gives rise to intercarrier interference
(ICI) which degrades the performance of OFDM systems
significantly [1].
A careful literature survey reveals two most widely used
methods of error performance analysis of OFDM systems.
One method is to approximate the ICI as a Gaussian processe
based on the central limit theorm [2]-[4]. However, in [5],
Keller and Hanzo showed that such approximation leads to
wrong results (in their own words “pessimistic”) for high
signal to noise ratios. On the other hand, Pollet et al [6] derive
analytically the signal to noise ratio degradation due to the ICI.
Zao and Haggman [7] use the moments of ICI distribution to
come up with more accurate BER result. The approach due to
Sathananthan and Tellambura [8] is unique in comparison with
all the above approaches since they use characteristic functions
and Beaulieu series [9] to derive exact BER expressions in the
presence of ICI. However, their exact results are given only for
the AWGN channel in the form of infinite series expansions.
We follow the procedure presented in Sathananthan and
Telambura with diferent mathematical insight to come up
with exact closed form BER/SER expressions in the presence
of ICI. The standard error rate expressions without ICI are
shown to be some special cases of our more general results.
Furthermore, selected numerical results are provided to verify
the accuracy of the formulation.
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