  Wireless communication technology has seen a remarkably fast evolution due to
its capability to provide a quality, reliable and high-speed data transmission
amongst the users. However, transmission of information in wireless channels is
primarily impaired by deleterious multipath fading, which affects the quality
and reliability of the system. In order to overcome the detrimental effects of
fading, Multiple-Input Multiple-Output (MIMO) technology is an attractive
scheme that employs multiple transceiver antennas to carry the data over the
same frequency band over a variety of signal paths. This technology has shown
great solutions due to its ability to provide better spectral efficiency,
capacity, throughput and robustness of the data transmission. But in practice,
it is impractical to install multiple antennas on small-sized devices. Hence,
to overcome the limitations of MIMO gain in the future wireless networks,
cooperative diversity has recently draw in attention due to its ability to
circumvent the difficulties of implementing actual antenna arrays in
Multiple-Input and Multiple-Output (MIMO). By exploiting the broadcast feature
of the wireless medium, cooperation among multiple nearby nodes is formed for
data transmission. At the receiver, the signals are either coherently or
differentially detected. Coherent detection requires exact channel estimation,
which is difficult to apply in a time-varying channel. Hence, when the nodes
are mobile, or when the channel is inaccurately estimated, the differential
detection techniques that omit channel estimation become an alternative as
compared to coherent detection. This article presents a review of the
differential transmission techniques for cooperative diversity networks.
