In high-speed downlink packet access (HSDPA), the combination of adaptive modulation and coding, hybrid automatic repeat request, and an extended multicode operation has replaced two fundamental aspects of wideband code division multiple access systems, namely, variable spreading factor and fast power control. Despite its enhanced characteristics, the HSDPA operation can be problematic when the majority of incoming traffic load consists of low data rate delay-sensitive services such as mobile voice-over-Internet Protocol. To tackle this case, we propose an enhanced HSDPA operation that exploits multiple layers of the channelization code tree through a specifically designed packet scheduling and code allocation process. Enhanced HSDPA, when compared with the conventional HSDPA, provides a more flexible sharing of the available capacity and is able to increase the number of users that can be served with the required quality of service in terms of packet delay. The efficiency of the proposed scheme is confirmed by simulation results. Copyright © 2011 John Wiley & Sons, Ltd.