MISO Amplify Forward scheme and its viability

In this paper, we consider a MISO equivalent of a three node cooperative communication system as described in [1] and compare its energy efficiency with a pure relaying scheme. Specifically, we first quantify the transmit energy required to maintain a target error probability at the destination in an Amplify Forward (AF) based MISO scheme. Based on theoretical analysis, we reason that AF based MISO scheme is not a viable option from an energy efficiency standpoint - pure relaying strategy is shown to be more energy efficient in this framework.