  In this paper, a new low-complexity demodulation scheme is proposed for
interleaved orthogonal frequency division multiple access (OFDMA) downlink
system with N subcarriers and M users using circular convolution. In the
proposed scheme, each user's signal is extracted from the received interleaved
OFDMA signal of M users by using circular convolution in the time domain and
then fast Fourier transformed in the reduced size N over M. It is shown that
the computational complexity of the proposed scheme for the interleaved OFDMA
downlink system is much less than that of the conventional one.
