Maximizing Wireless Communications Energy Efficiency
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 is 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. 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 be used in the channel, and so on. Signal PAPR is therefore economically expensive, and must be accepted only when a value to the communication system justifies its cost.