A power-aware admission control scheme for supporting the assured forwarding model in CDMA cellular networks

The differentiated services (DiffServ) architecture for provisioning quality of service (QoS) in the Internet provides a flexible framework for supporting a variety of services in heterogeneous environments. The assured forwarding (AF) per hop behaviour is a means of providing differential treatment of various DiffServ classes through achieving higher forwarding probabilities for higher priority classes. Extending the AF model to support fine grain QoS specification in W-CDMA environments allows mobile users in third-generation systems to benefit from the economical savings made possible by resource sharing among different classes of aggregated traffic. We consider extending the AF model to support the delivery of quasi constant bit-rate (QCBR) traffic streams on the downlink. In our study, each QCBR stream is assumed to have a prescribed average bit-rate and time duration, and is expected to be transmitted to completion without interruption at the requested bit-rate. The availability of such a service is beneficial for transmitting real-time traffic to mobile devices with limited power and buffering resources. The proposed mechanisms are based on integrating a suitable power-sharing structure for achieving differential treatment between classes with a crude power prediction algorithm for estimating the probability that no forced termination will occur at certain instants in the future. We compare the performance of a non-predictive scheme with a predictive scheme for different AF classes and source information bit-rates. Our results show that significant improvement in the forwarding probability, throughput, and power utilization for the DiffServ classes can be attained using the predictive scheme.