Uplink Power Control Calculation in LTE
Transmit power of PUSCH
in subframe i is defined by
PPUSCH (i) = min{PMAX,10 log10 (MPUSCH (i)) + PO_PUSCH ( j) +α ( j) ⋅ PL + ΔTF (i) + f (i)} [dBm]
Pmax: max. allowed power,
MPUSCH: number of scheduled RBs,
PL: pathless [dB].
ΔTF (i) = 10 log 10 (2MPR Ks– 1) for Ks = 1.25 else 0,
MPR = TBS/NRE, NRE : number of Res,
UE specific, Ks defined by deltaMCS-Enabled,
PO_PUSCH(j) = PO_NOMINAL_PUSCH(j) + PO_UE_PUSCH(j).
semi-persistant / dynamic grant; j=0 / j=1:
PO_NOMINAL_PUSCH(j): cell specific
PO_UE_PUSCH(j): UE specific
α (0,1) = 0.0, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0
Random access grant; j=2:
PO_UE_PUSCH(2) = 0
PO_NOMINAL_PUSCH(2) = PO_PRE + ΔPreamble_Msg3
α (2) = 1
The closed loop part is given by:
f(i) = f(i-1) + δPUSCH (i – KPUSCH)
or
f(i) = δPUSCH (i – KPUSCH)
where δPUSCH is the signaled TPC.
wheter the recursive or absolute method is to be applied -> given by the parameter
Accumulation-enabled
Power headroom:
( ) {10log ( ( )) ( ) ( ) ( )} MAX 10 PUSCH O_PUSCH TF PH i = P − M i + P j +α ⋅ PL + Δ i + f i [dB]
Transmit power of PUCCH
is determined in a similar manner. However the open loop part is always fully applied.
Uplink Power Control Calculation in LTE
In LTE, uplink power control adjusts the UE’s transmission power to ensure optimal signal strength at the eNB while minimizing interference. The calculation is based on the path loss between the UE and eNB, which is estimated using the RSRP measurement. The eNB sends power control commands to the UE, adjusting its transmit power in steps to compensate for the channel conditions and maintain a target received signal quality at the eNB.