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Summary: IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 7, NO. 10, OCTOBER 2008 1
A Robust Asynchronous Multiuser
STBC-OFDM Transmission Scheme for Frequency-Selective Channels
Dandan Wang, Student Member, IEEE, Hlaing Minn, Senior Member, IEEE, and Naofal Al-Dhahir, Fellow, IEEE
Abstract--In this paper, we propose a robust STBC trans-
mission scheme to combat timing synchronization errors over
frequency-selective multiple-access channels. We start by deriv-
ing the equivalent channel model in the presence of timing syn-
chronization errors. Based on this correlated equivalent channel
model, the statistical channel power gain profile is analyzed and
shown to exhibit unequal channel power gains on different sub-
carriers. Furthermore, a robust statistical bit loading algorithm
is proposed to optimize the BER performance in scenarios where
link adaptation based on instantaneous channel information
is infeasible or undesirable. Simulation results show that our
proposed scheme is robust to timing synchronization errors,
providing around 7.5dB SNR advantage at the BER of 10-4
over the conventional scheme in various channel environments.
Index Terms--STBC, OFDM, bit loading, asynchronous,
multiple-access, ISI.
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