Energy Efficiency Maxima for Wireless Communications: 5G, IoT, and Massive MIMO
Any power amplifier (PA) is a peak-power limited circuit. It must be designed to provide whatever the signal maximum peak envelope power (PEP) may ever be. In contrast, communication coverage and range are based on signal root-mean-square (rms) power, usually called the average signal power. To the extent that the PEP exceeds this average power there exists a peak-power to average power ratio (PAPR) that is greater than 1. The average output power reduction from signal PAPR therefore reduces available communication range from a particular sized PA. Large PAPR values cause several important economic and realization problems, including: a) the communication range available from a particular PA is proportionally reduced, b) the PA needed to provide a required communication range must be proportionally larger, c) the maximum output power from the PA is not available to the channel for communication range and coverage, and so on. Signal PAPR is therefore economically expensive, and high values must be accepted only when a value to the communication system justifies its cost.