Spectrum efficiency gains resulting from the implementation of adaptive transmit power control in fixed terrestrial links at 38 GHz

Adaptive transmit power control can be used to improve the spectrum efficiency of terrestrial point to point fixed links by limiting the transmit power to that required to maintain a constant bit error rate (BER) regardless of the propagation conditions. This results in a reduced transmit power being used during clear sky conditions, lowering the interference resulting from the ATPC link. This improves the frequency reuse factor associated with a given band and geographic area, providing a spectrum efficiency gain. The project described in this paper found that implementing ATPC in the 38 GHz band gives significant improvements in spectrum efficiency as measured by the increase in the number of links assigned to channel 1 (from ~50% to ~70%) and the decrease in the maximum bandwidth used (from ~300 MHz to ~180 MHz).