Power control technique for high speed downlink packet access system

In this paper a Power Control technique for the High Speed Downlink Packet Access (HSDPA) system is proposed and compared to the UMTS-standard technique. In addition to compensating the propagation losses (distance-loss, shadowing and fast fading), the proposed technique adapts the signal-to-cochannel interference ratio (C/I) to be in the required range. The power control algorithm uses a predefined C/I threshold (C/I_th) specific for each service and data rate. When the measured C/I of the user equipment is above (lower) than the C/I_th, the decrease (increase) of power is ordered adaptively depending on the difference between the two values. The two techniques were evaluated by simulation in the framework of the project IST-FITNESS (IST-2000-30116, Fourth-generation Intelligent Transparent Networks Enhanced through Space-time Systems), where an effective software platform simulating the HSDPA network was developed. The numerical results quantitatively outline the benefits on system performance, for each technique, achieved in terms of average transmitted power and outage probability of C/I versus velocity.