While the technological capabilities regarding digital data transmission, storage, and computation have exponentially increased during the last decades, the advances associated with analog wireless equipment were only moderate. Therefore, today hardware cost and power consumption of radio interfaces form the main obstacles for constructing future wireless systems featuring either ultra-low complexity or ultra-high performance. However, in the advent of the Internet of things (IoT), where cheap and small devices are supposed to perform wireless sensing, and with the increasing demands for performance in critical infrastructure applications, it is inevitable further pushing radio technology towards these extremes.