  This paper puts forth a class of new transceiver designs for interleaved
frequency division multiple access (IFDMA) systems. These transceivers are
significantly less complex than conventional IFDMA transceiver. The simple new
designs are founded on a key observation that multiplexing and demultiplexing
of IFDMA data streams of different sizes are coincident with the IFFTs and FFTs
of different sizes embedded within the Cooley-Tukey recursive FFT decomposition
scheme. For flexible resource allocation, this paper puts forth a new IFDMA
resource allocation framework called Multi-IFDMA, in which a user can be
allocated multiple IFDMA streams. Our new transceivers are unified designs in
that they can be used in conventional IFDMA as well as multi-IFDMA systems. Two
other well-known multiple-access schemes are localized FDMA (LFDMA) and
orthogonal FDMA (OFDMA). In terms of flexibility in resource allocation,
Multi-IFDMA, LFDMA, and OFDMA are on an equal footing. With our new transceiver
designs, however, IFDMA has the following advantages (besides other known
advantages not due to our new transceiver designs): 1) IFDMA/Multi-IFDMA
transceivers are significantly less complex than LFDMA transceivers; in
addition, IFDMA/Multi-IFDMA has better Peak-to-Average Power Ratio (PAPR) than
LFDMA; 2) IFDMA/Multi-IFDMA transceivers and OFDMA transceivers are comparable
in complexity; but IFDMA/Multi-IFDMA has significantly better PAPR than OFDMA.
