i. In cdma2000 and WCDMA, power control is essential in both forward link and reverse link.
ii. The reverse link power control is present right from 2G CDMA standards to curb the near-far effect.
iii. Since, in CDMA, all users transmit and receive at same frequency and at same time, interference is always present. In such a situation, if a mobile is close to base station its power at the base station will be more than the mobile which is far. The mobile which is far will lose its power in the journey to base station due to shadowing effects.
iv. Thus, there is power control on the reverse link. The power at the base station received from all the mobile stations should be same and satisfy minimum SNR level.
v. In the forward link, the slow power control of 2G CDMA standards fail if the mobile is surrounded by high interfering noise.
vi. Hence, forward link power control is employed at high level in both 3G CDMA standards of cdma2000 and WCDMA.
vii. The power control in cdma2000 and WCDMA is to minimize interference due to presence of other mobile users, fading, lognormal shadowing as well as from fast Rayleigh fading.
viii. In cdma2000, power control is at the rate of 800Hz in both the links and it is at a rate of 1500Hz in both the links in WCDMA.