A New Transmission Protocol for Cooperative Communications

Cooperative wireless communication is a hot research area for attaining diversity through virtual antenna array that is formed by sharing resources among different users.Different strategies of resource utilization such as amplify-and-forward (AF) and decode-and-forward (DF) already exist in cooperative networks.Although the implementation of these strategies is simple, their utilization of the channel state information (CSI) is generally poor.In this paper a new strategy, based on the previously existing ones, called CSI directed estimate and forward (CDEF) with estimate domain reduction is proposed.A closed form solution for the optimal signal estimation at the relay using minimum mean square error (MMSE) as well as a possible set reduction of the estimation domain is given. We will show that this new strategy attains better symbol error rate (SER) and outage performance than AF and DF.