Power control#Transmit Power Control

Transmitter power control, shorter or abbreviated TX Power Control TPC, is a RF power control in wireless systems with mobile subscribers. Purpose is to reduce radio interference and a longer battery life in mobile devices.

Principle of operation

The example of a GSM mobile phone base station ( BS) and a mobile station (MS ), the principle of operation are explained:

The receiver in the MS measures the received field strength of the signal coming from the transmitter the BS. The measured value is transmitted in a signaling message ( measurement report ) to the BS. The BS (or a higher-level network element ) decides on the basis of predetermined threshold values ​​and hysteresis if it is intended to reduce, increase or maintain its transmit power.

This control circuit is also for applying the opposite direction: The transmission power of the MS measured by the BS. Here, however, no measurement report is sent to the MS, but the BS as hierarchically higher network element determines whether the transmit power of the MS is to be changed. To this end, a Power Control Command is sent to the MS.

In practice usually more complex algorithms for the power control can be used. In particular, not only the received field strength but also the quality (e.g. bit error rate ) taken into account, to avoid that the transmit power of a disturbed signal is still further reduced. Furthermore, several measurement reports averaged ( partially weighted) in order to avoid unnecessary up and down controlling the transmission power by short level changes.

• Wireless technology
• Mobile