Transmit diversity generally requires more
than one antenna at the transmitter. However,
many wireless devices are limited by size or
hardware complexity to one antenna. Recently, a
new class of methods called cooperative commu-
nication has been proposed that enables single-
antenna mobiles in a multi-user environment to
share their antennas and generate a virtual mul-
tiple-antenna transmitter that allows them to
achieve transmit diversity. This article presents
an overview of the developments in this bur
-
geoning field.