Normalized Rate Guarantee Scheduler for High Speed Downlink Packet Access

High speed downlink packet access (HSDPA) is a packet-based data service in UMTS networks that supports data rates of several Mbit/s, making it suitable for applications ranging from file transfer to multimedia streaming. One of the salient points of HSDPA is the use of MAC-layer scheduling to perform resource management (i.e., bandwidth allocation between terminals), taking into account the radio channel conditions of all users. Usually, additional factors like fairness between users, cell throughput or quality-of-service (QoS) parameters are also considered in the scheduling mechanism. In this paper we consider different QoS classes or user groups and study resource allocation among those user groups using HSDPA MAC-layer scheduling. We propose a normalized rate guarantee (NRG) scheduler, which is an extension of a previous QoS scheduler by Hosein (2002). When allocating the available bandwidth, the NRG scheduler takes into account the fact that QoS requirements (in terms of minimum bandwidth) may vary from one flow to the other. It tries to apportion loss rates in a fairer way during congestion. Another goal of NRG is to avoid the deterioration of QoS when best-effort load is increased.