he first slot of a downlink transmission gap, then Slast = computed in the first slot of the downlink transmission gap. Otherwise Slast = Sj com- puted in the last slot before the downlink transmission gap. Sj will be updated according to the following recursive relation: S = 0.93758--1 -0.96875TPC_cmd,Apro (4.37) Si-1 = St. Si-1 is the value of Sj computed for the previous slot. Si-1 = 0 when we activate the up- link DPCCH, and also at the end of the first slot after each downlink transmission gap. This relation gets executed in all slots with simultaneous uplink and downlink DPCCH The UMTS Network and Radio Access Technology transmission, and in the first slot of a downlink transmission gap if a downlink TPC command is transmitted in that slot. TPC_cmd is the most recent power control com- mand derived by the UE [11]. After a transmission gap in either the uplink or the downlink, there exists a recovery period following resumption of simultaneous uplink and downlink DPCCH transmis- sion. This period has a Recovery Period Length (RPL) and is expressed as a number slots. The RPL is equal to the minimum value out of the transmission gap length and 7 slots. Table 4.15 illustrates the two recovery period modes for the power control algo- rithm, where the Recovery Period Power (RPP) control mode is signalled with the other compressed mode parameters [13]. For RPP mode 0, the step size does not change dur- ing the recovery period and ordinary transmit power control applies, i.e. the algorithm for processing TPC commands determined by the value of PCA. For RPP mode 1, dur- ing RPL slots after each transmission gap, power control algorithm 1 applies with a step size ARP-TPC instead of ATPC, regardless of the value of PCA. We define the uplink DPCCH transmit power change, which does not apply to the first slot after the transmis- sion gap, as: (4.38) where ARP-TPC denotes the recovery power control step size and is expressed in dB. When the PCA has the value 1, ARP-TPC, it is equal to the minimum value of 3 dB and 2ATPC,