Impact of HSDPA transmit power allocation schemes on the performance of UMTS networks

In UMTS networks, the transmit power for the HSDPA can be a large fraction of the total transmit power of a NodeB. We investigate the impact of three HSDPA transmit power allocation schemes on the performance of a UMTS system with dedicated channel users and HSDPA users. The continuous HSDPA power allocation scheme avoids large steps of the transmit power in order to prevent irregularities in the downlink power control of dedicated channels. In contrast, the traffic-aware scheme switches the HSDPA power on only if data has to be transmitted. The power-ramping scheme combines the continuous and the traffic-aware scheme. The simulation model considers the complete interference situation in the network and uses a novel model to calculate HSDPA bandwidths. The results quantify the performance loss with the continuous scheme caused by additional interference, and show that the power-ramping scheme leads to results close to the traffic-aware scheme.