The radio applications in wireless sensor networks where the energy constraint is vital are considered. In this context, the impact of cooperative strategies is analyzed thanks to the realistic power model of a real radio transceiver. A system using a two-antenna source, two one-antenna relays and oneantenna destination is considered. Three types of association strategies of Space time coding and relaying technique, MIMO full cooperative relay (MFCR), MIMO simple cooperative relay (MSCR) and MIMO normal cooperative relay (MNCR) are presented. The power consumption model parameters are extracted from characteristics of CC2420, a wireless sensor transceiver widely used and commercially available. The Bit Error Rate (BER) performance of these models is simulated. It is shown that despite using more time slots, MFCR has the best BER performance and the longest transmission distance. Furthermore, the optimal energy efficient scheme selection is also derived to define which model should be used to minimize the total energy consumption.