  Cooperative diversity is a technique in which various radio terminals relay
signals for each other. Cooperative diversity results when cooperative
communications is used primarily to leverage the spatial diversity available
among distributed radios. In this paper different cooperative diversity schemes
and their applications in various wireless networks are discussed. In this
paper the impact of cooperative diversity on the energy consumption and
lifetime of sensor network and the impact of cooperation in cognitive radio are
discussed. Here, user scheduling and radio resource allocation techniques are
also discussed which are developed in order to efficiently integrate various
cooperative diversity schemes for the emerging IEEE 802.16j based systems.
