Fundamental limitations of power control in W-CDMA

Power control is considered as an important means to combat near-far fading effects and maintain acceptable connections in wireless communications systems. When applying power control in practice, the performance is restricted by a number of fundamental limitations. Here, these are addressed from a control theory perspective. Limited update rate, limited feedback bandwidth, time delays, measurement errors, feedback errors and filtering effects among other aspects all affect the resulting performance, and are related to radio channel characteristics. Simulations further illustrate the hampering effects.