Microwave path-loss modeling in urban line-of-sight environments

To model the path-loss characteristics in microwave urban line-of-sight (LOS) propagation, we performed measurements in metropolitan Tokyo at frequencies of 3.35, 8.45, and 15.75 GHz. The actual breakpoint distance was shorter than the theoretical one because of the influence of vehicles, pedestrians, and other objects on the road. This effect has been referred to as effective road height. We found that the breakpoint disappeared when the mobile-antenna height approached the effective road height. Based on these breakpoint characteristics, we propose new upper- and lower-bound formulas for LOS path loss in urban microcellular environments. They will be useful for the system and cell design of fourth-generation multimedia mobile communication systems using microwave bands.