the cell will not get the its re- quired SIN either, and may even cause MS2 to drop its SIN even lower. Power control will thus aim to overcome near-far effects and thereby increase capacity with acceptable link quality. The UMTS Network and Radio Access Technology Figure 8.1 Power control to prevent near-far effect. 8.2.1.1 Fast Power Control (FPC) The FDD mode uses fast power control with 1.5 kHz frequency (i.e. 1500 times/s) in both UL and DL. It operates at a faster rate than any path loss change. The FPC uses the closed-loop option as noted in Chapter 4. We see higher gains of FPC in low mobile speeds than for high mobile speeds, and in received powers than in transmitted powers. At speeds above 50 km/h, e.g. FPC does not contribute much due to the higher multi- path gains. We can find more information about fast power control in [1]. Other gains of FPC depend on diversity, e.g. multi-path diversity, receive, transmit antenna diversity, and macro-diversity. Less diversity implies more variations in the transmitted power. Thus, we get smaller power rise 1 in the presence of more multi-path diversity. In DL macrocell coverage with WCDMA, power rise gets critical because it directly intervenes in the required transmission power, which determines the transmitted inter- ference. Hence, to maximize the DL capacity, we should select the quantity of diversity, such that it minimizes the transmission power required by a link, since the received power level does not affect the capacity in the DL. In the UL, the level of transmission power from the different MSs does have direct impact on the interference to the adjacent cells, and the received power determines the level of interference to other users in the same cell. Diversity in this case does not have much im- pact, which means that UL capacity of a cell would be maximized by minimizing the re- quired received powers, and the amount of diversity would not affect the UL capacity. When MSs move at high velocities, the FPC does not follow fast fading; we would re- qui