Effects of Solar Radio Emissions on Outdoor Radio Propagation at 38 GHz Bands for D2D Communications

Abstract

This letter presents empirical data documenting the effects of solar radio emissions on outdoor radio propagation at 38 GHz millimeter-wave (mmWave) band for both line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios. Comparing the measurement data collected during a sunny day with the counterpart data collected at night, higher path loss exponent (PLE) values were observed during the day compared to nighttime. This is attributable to the decrease in the carrier-to-noise ratio for day-time signal propagation in sunny sky compared to nighttime. About 4% and 25% increase in PLE values was observed during the day for LOS and NLOS scenarios, respectively. This translates into corresponding decrease in the radio coverage of the wireless transmitter during the day compared to nighttime. Time-domain waveforms were also examined, and it was found that the average received signal envelope was 103 times below a given threshold during the day, and 19 times below the same threshold at night. This, thus, shows that the received signal envelope fades out many more times during the day compared to nighttime.