Packet scheduling algorithms for interactive and streaming services under QoS guarantee in a CDMA system

One of the major issues for the deployment of future third-generation mobile communication systems with high-bandwidth and real-time multimedia applications is the specification of acceptable quality of service (QoS) requirements for mobile users. This paper presents scheduling algorithms focused on giving QoS guarantee in terms of bit rate in a packet switched CDMA scenario by taking into account the service classes that are defined in the UMTS system, with a special emphasis on the streaming and interactive services. The algorithm carries out three steps, namely prioritisation, resource allocation and availability check. Different alternatives are presented for these steps. Particularly, by extending the leaky bucket algorithm to the CDMA scenario for the prioritisation and the allocation process, we show that a non work conserving allocation strategy appears to be more efficient when aiming at guaranteeing a specific average bit rate with lower deviations around the mean value thus fitting better the allocated resources to the users' requirements. On the other hand, work conserving strategies achieve higher peak bit rates at the expense of exhibiting a much higher deviation around the mean value.