the parameter LTE_config.map_resolution defines the resolution for the large scale path loss values (distance dependent path loss, shadow fading, antenna gain). These values are combined to an effective path loss value, but only for a finite number of points on an equidistand grid with the spacing as defined in LTE_config.map_resolution. For a given user position, the path loss value of the next closest grid point is used. Since the number of grid points scales with smaller resolution and with a larger region of interest, more path loss values have to be calculated. Therefore, you shouldn’t make this value too small to avoid unnecessary overhead.