Power measurements of OFDM signals

There are many ways to measure the output power from wireless devices $average power, peak envelope power, instantaneous peak power and average peak power being examples. In addition, there are multiple instruments and methods available to make these measurements - spectrum analyzers, power meters with peak power sensors, average power sensors and diode detectors. The dynamic nature of signals that use orthogonal frequency division multiplexing (OFDM) is such that these various methods can give widely different results depending on the type of measuring instrument used and the power measurement required. The requirements for output power in the regulatory standards can be confusing, leading to incorrect or inaccurate measurements. Problems can also be created when alternative methods of power measurements are used in the production line to set the output power of individual devices to ensure they comply with national restrictions on output power. The paper reviews the various methods used to make power measurements of OFDM signals for regulatory purposes and recommends suitable methods for production line measurements of 802.11a and 802.11g devices.