The first step is to translate the 0.2 millijoules in Watts. But to do that, you need to re-read the requirements… it is 0.2 millijoules per second ?
Then once you know the watts, you can translate that as dBm.
Then, you can apply the free space propagation loss to 1 MS emitting at maximum power (33dBm)
You’ll get, as an output from this formula, a distance. That is is the minimal distance between the MS and the petrol.
If you have several MS at this distance, the power is doubled (= +3dB)
Now for a base station, I would use the sum of each frequency emitted. Typically, one frequency is transmitted at 60dBm (that’s a very high value, but I guess you’re okay to take some margins 🙂 )
A typical BTS emits 4 frequencies in each direction. So that’s 66dBm per direction.
But I doubt a base station could be a problem. Just being 30m above ground, I’m sure it’ll be below 0.2millijouls (per sec. ?).
The MS is the real terror here…