  The growing popularity of Internet of Things (IoT) applications brings new
challenges to the wireless communication community. Numerous smart devices and
sensors within IoT will generate a massive amount of short data packets. Future
wireless transmission systems need to support the reliable transmission of such
small data with extremely high energy efficiency. In this article, we introduce
a novel data-oriented approach for characterizing the energy efficiency of
wireless transmission strategies for IoT applications. Specifically, we present
new energy efficiency performance limits targeting at individual data
transmission sessions. Through preliminary analysis on two channel-adaptive
transmission strategies, we develop several important design guidelines on
green transmission of small data. We also present several promising future
applications of the proposed data-oriented energy efficiency characterization.
