Measurements of downlink power level distributions in LTE networks

Human exposure to the radio frequency electromagnetic fields (EMF) emitted by radio base stations (RBS) is proportional to the transmitted power. Thus, knowledge of actual power levels is key for a correct estimate of the actual EMF exposure. In this study, downlink output power distributions for RBSs in a 4G LTE mobile communication network have been determined. By extracting data using the operations support system (OSS) of the network, statistics were obtained based on 24 hours measurements for more than 5000 RBSs. The network measurement approach was verified with in-situ power density measurements. It was found that the actual output power levels are significantly below the theoretical maximum. For high-traffic periods, the 90^th percentile transmitted power was found to be about 12% of the theoretical maximum.