  The basic idea behind an active queue management (AQM) is to sense the
congestion level within the network and inform the packet sources about, so
that they reduce their sending rate. In literature a lot off mechanisms of AQM
are studied. But there are not used in the context of the DiffServ architecture
where different types of packet with different requirements of QoS share the
same link. In this paper, we study an access control mechanism for RT and NRT
packets arriving in a buffer implemented at an end user in HSDPA. The mechanism
uses thresholds to mange access in the buffer and gives access priority to RT
packets. In order to control the arrival rate of the NRT packets in the buffer
an active queue management is used. We study the effect of the feedback
function on the QoS parameters for both kinds of packets .Mathematical
description and analytical results are given, and numerical results show that
the proposed function achieves higher QoS for the NRT packets in the system.
