The 25dB attenuation value may be true for certain types of walls or materials, but should not be attached to distance (which could be free space).
I recall one site I tested where the plate glass doors in some underground mall entrances were worth 25 dB of attenuation. When the doors were open,
900 MHz signals would pass and cellular service worked on the other side. As the doors closed, the calls would drop.The white paper does outline the difficulties with RF in a chaotic, uncontrolled (unlicensed) environment. Their symptoms described are important to many unlicensed bands. Do you really want to have Bluetooth and WiFi in the same house at the same time? Buyer beware.
I wonder if their optimism for Echelon would hold true for other PL technologies... like Insteon... etc.
RF Dude