Re: Range calculation
flatulent said:
Your calculations are free space. In the real world there are reflections that produce multipath interference and Fresnel zone attenuation. There are also obstructions.
For the shorter paths these are less troublesome.
There is also co-channel and adjacent-channel interference that will reduce your range.
For calculate covering wide urban area (outside house or low attenuate walls in house), most common using model is 'Okamura-Hata' and coarse descriptions calculate a 12 dB attenuation per double distance (for example UMTS) and from my experience for 900 and 1800 MHz is very close to real world measure.
House is very tricky to predict depend of build materials, and special if wall build on materia with much bound water (gips, CaSO4 + 2 * H2O, i not know name in english, guess gypsum) and board of this is very common to build walls for rooms inside house in sweden, and seem very hard for frequency above 2 GHz to passed...
For example UMTS drops very fast inside house (in sweden) and more or less useless few meter behind wall in house if not have a UMTS base station very, very close.... or big windows without metallic heat reflection layer...
you can have -55 dBm UMTS outside windows, but <3 m inside, signal goes under -90 dBm and I sense surrounding gypsym walls suck down (absorbed) all > 2 GHz in rooms like cold black body chamber, even if not passed walls - i'm unbelive this first time i see this situation...
same situation for bluetoth and Wlan, and have hard to cover more than closest rooms , but unwanted, same signal can going very wide distanse outside house passed trougth windows...
GSM 900 and 1800 have not trouble in same house and I cannot understud how few 100 MHz higher frequency above GSM 1800 can give so much more covering trouble...
gheeees.... not easy to predict...