In this letter, we investigate rural large-scale path loss models based on the measurements in a central area of South Korea (rural area) in spring. In particular, we develop new close-in (CI) path loss models incorporating a diffraction component. The transmitter used in the measurement system is located on a hill and utilizes omnidirectional antennas operating at 1400 and 2250 MHz frequencies. The receiver is also equipped with omnidirectional antennas and measures at positions totaling 3,858 (1,262 positions for LOS and 2,596 positions for NLOS) and 4,957 (1,427 positions for LOS and 3,530 positions for NLOS) for 1400 and 2250 MHz, respectively. This research demonstrates that the newly developed CI path loss models incorporating a diffraction component significantly reduce standard deviations (STD) and are independent of frequency, especially for LOS beyond the first meter of propagation, making them suitable for use with frequencies up to a millimeter-wave.

翻译：在这篇文章中，我们研究了基于韩国中部（农村地区）春季测量的模型。特别地，我们开发出了新的绕射分量的近距路径损耗模型。测量系统中的发射器位于山丘上，并且使用在1400和2250 MHz频率下操作的全向天线。接收器也配备全向天线，并且在LOS（1,262个位置）和NLOS（2,596个位置）方位上分别进行了4,957次（1400 MHz）和3,530次（2250 MHz）测量。本研究表明，新开发的CI路径损耗模型并入绕射分量，显著减少了标准偏差（STD），并且不依赖于频率，特别是对于超过传播的第一米的LOS，使其适用于高达毫米波的频率。