A.3 Example implementation of downlink power control in UE for 1.28Mcps TDD when TSTD is used
25.2243GPPPhysical layer procedures (TDD)TS
Downlink power control is based on a quality target, set by higher layers. An example implementation for a UE TPC calculation algorithm is SIR based. In this algorithm, an outer loop sets a target SIR value, SIRtarget, which may be adjusted from time to time in order to ensure that the quality target is met. In the meantime, as part of an inner loop a calculation of SIR in associated downlink transmissions may be carried out. When the measured value is higher than the target SIR value, TPC command = "down". When the measurement is lower than or equal to the target SIR, TPC command = "up".
When TSTD is applied, the UE can use the consecutive measurements of SIR to calculate SIRAVG:
SIRAVG(i) = w1SIR(i-1) + w2SIR(i),
where, w1 + w2 = 1, w1 >= 0, w2 >= 0, and SIR(i) is the measurement of SIR in sub-frame i and SIRAVG(i) is the measurement of SIRAVG in sub-frame i. If SIRAVG is greater than the target SIR value, TPC command = "down". If the SIRAVG is smaller than the target SIR value, TPC command = "up".
In case of a downlink transmission pause on the DPCH, the example in Annex A.1 can be used for DL power control with RSCPvirt(i) and ISCP(i) replaced by RSCPAVG(i) and ISCPAVG(i), where
RSCPAVG(i) = w1RSCPvirt(i-1) + w2RSCPvirt(i),
ISCPAVG(i) = w1ISCP(i-1) + w2ISCP(i).