Quality of service and power consumption in WCDMA cellular systems with SIR-based closed loop power control

In this work we investigate and discuss the behavior of a wideband CDMA cellular system from the point of view of the power efficiency and the quality level at the physical layer. More precisely, special attention is given to the role played by the SIR-based closed loop power control when it tries to compensate for channel loss variations in different conditions of fading velocity. It is shown that, for a heavily loaded system in a slow fading environment, the largest amount of power is required by those users experiencing the worst quality level. This aspect should be taken into account in the management of the system resources. The results have been obtained from a suitable simulation tool which joins the system level analysis with the link level analysis and includes many features of the WCDMA air interface of UMTS.