Measurement experiment of LTE terminal transmit power for interference estimation in Satellite/Terrestrial Integrated mobile Communications System

Satellite/Terrestrial Integrated mobile Communications System (STICS) employs the frequency sharing between the satellite and terrestrial components for efficient spectrum utilization. It is required to estimate the interference level between the satellite and terrestrial link to realize the frequency sharing because co-channel interference occurs between the satellite and terrestrial link outside the satellite beam. Measurement campaign of the cellular phone transmit power in 3G network operated in Japan has been carried out to obtain the reference data of estimating the interference level. On the other hand, recently, Long Term Evolution (LTE) is rapidly penetrated into terrestrial mobile network in Japan. Therefore, in future application of LTE to terrestrial component in STICS, we have conducted the measurement experiment of transmit power for LTE terminal to estimate the interference level in STICS satellite receiver. Measurement setup to measure LTE signal is studied and a realtime spectrum analyzer is applied to measure the time-and-frequency-based LTE signal. Measurement has been carried out at six to eight measurement sites per mobile communication carrier with population density of from 60 to 27,000 /km
²
in Kansai district in Japan for the operational band of 1920-1980 MHz. The initial analysis of the measured data indicates that the correlation between transmit power and population density is not observed in LTE signal. This trend is different from the fact that the correlation between the measured EIRP of 3G voice transmission in LTE terminal and the population density is observed. From these observations we confirmed the trend of LTE terminal transmit power.