Path loss model for TETRA networks in metropolitan areas

This paper reports on measurements of the attenuation in the transmitted RF-power of a TETRA system, operating in the UIIF band. The measurements data are consistent with a log-distance path loss model for arbitrary T-R separation, with a path loss exponent n = 4.0 ± 0.5. Small scale fading is characterized by a Gaussian signal level distribution (log-normal) with standard deviation s = 8.6 ± 0.2. Furthermore, the reference distance in the far field of the transmitting antenna from the measurements is d₀ = 1 km. Interestingly, the average value of the received RF-power approaches a level close to the dynamic sensitivity of the TETRA receivers at approximately the same distance (around 5 km) from a base station, for various low-altitude base station locations with similar transmission characteristics. This distance provides a simple characterization reference indicative of the attenuation of the RF-power in the particular urban environment; it also provides a rule of thumb for cell planning in metropolitan locations similar to that of the Greek capital.