05.083GPPRadio subsystem link controlTS
The same algorithm as above can be used for downlink power control. The formula for quality based control in the MS
Pn+1 = Pref + (Ln + IBTS,n)
can be written for the BTS as:
Pdn+1 = Pref + (Ln + CH,n)
where Pd is the BTS output power (equal to PBTS – Pb). CH is the received interference level at the MS.
Substituting the path loss and dropping the iteration index gives: Pd = Pref + (PBTS – C + CH)
The received signal C and interference CH is measured in the MS and transferred to the BTS, which can calculate the output power.