The eNodeB determines the downlink transmit energy per resource element (lte epre). Downlink cell-specific reference-signal (RS) lte epre is constant across the downlink system bandwidth and constant across all subframes until different cell-specific RS power information is received. The downlink RS lte epre is given by the parameter Reference-signal-power provided by higher layers.
In cases 16QAM, 64QAM, spatial multiplex TRI>1 or multi-user MIMO the DL power is given by ρA and ρB
A = + P power-offset ρ δ
10log (2) power-offset 10 = + + A A ρ δ P
thats simple idea behind lte epre downlink power control in lte