Is it possible to calculate the path loss in an UMTS system if the current HNB CPICH power and RSCP values are known?

Please let me further elaborate on my question:

Let's say we have an HNB with 2 Watts of power allocated for the common pilot channel. This would mean that the radiated signal power at the HNB site (with 1dBi antenna attached) should be around 33-34dBm.

Now, by using a mobile phone to test the reception, we can see that that the RSCP power will be -25dBm on the site and will gradually reduce when increasing the distance between the HNB and UE.

What I don't understand, is how exactly the radiated CPICH power and measured RSCP values are correlated. My goal is to calculate the exact path loss value in dBm by using these 2 parameters.

I know the RSCP range is [-25;-120] by specification, but how does it correspond to standard power measurements performed with an RF power meter?

Experimentally I can see that when the power meter measures ~28 dBm a couple of meters away from the HNB, this will correspond to -36 dBm RSCP on the test phone (the values are not exact, I'm just using them to illustrate my point).

I apologize for the noob question and I will be immensely grateful if anyone could explain this relation to me in an understandable way (for someone without an engineering degree).

Kind Regards