A.1 Example implementation of downlink power control in the UE
25.2243GPPPhysical layer procedures (TDD)TS
The power control may be realized by two cascaded control loops. The outer loop controls the transmission quality, whose reference value is set by higher layers [15], by providing the reference value for the inner loop. This reference value should be the SIR at the UE [15]. The inner loop controls the physical quantity for which the outer loop produces the reference value (e. g. the SIR) by generating TPC commands. This may be done by comparing the measured SIR to its reference value. When the measured value is higher than the target SIR value, TPC command = "down". When this is lower than or equal to the target SIR value, TPC command = "up".
In case of a downlink transmission pause on the DPCH or PDSCH, the receive power (RSCP) of the data can no longer be used for inner loop SIR calculations in the UE. In this case the UE should trace the fluctuations of the pathloss based on the P-CCPCH and use these values instead for generating the TPC commands. This pathloss together with the timeslot ISCP measurement in the data timeslot, which is ongoing, should be used to calculate a virtual SIR value:
SIRvirt(i) = RSCPvirt(i) ISCP(i) + 10 lg SF,
RSCPvirt(i) = RSCP0 + L0 – L(i) + 
,
RSCP: Received signal code power in dBm
ISCP: Interference signal code power in the DPCH / PDSCH timeslot in dBm
SF： Used spreading factor
L: pathloss in dB measured on the P-CCPCH. The same weighting of the long- and short-term pathloss should be used as for uplink open loop power control, see Annex A.1
i: index for the frames during a transmission pause, 1 i number of frames in the pause
L0: weighted pathloss in the last frame before the transmission pause in dB
RSCP0: RSCP of the data that was used in the SIR calculation of the last frame before the pause in dBm
TPC (k): power control stepsize in dB according to the TPC bit generated and transmitted in frame k, TPC bit "up" = +stepsize, TPC bit "down" = stepsize