Robust cloud VoIP scheduling under VMs startup time delay uncertainty

In this paper, we address cloud VoIP service orchestration and scheduling to provide appropriate levels of quality of service to users, and performance to VoIP service providers. We consider voice quality affected by call processing, and cost contributed by billing hours for used VMs in a cloud. We believe that this bi-objective focus is reasonable and representative for real installations and applications. We conduct comprehensive simulation of our calls load balancing strategies on real data and show that not all approaches provide suitable quality of service. We analyze eight on-line dynamic non-clairvoyant scheduling strategies with variations in VM startup time delays to deal with realistic VoIP cloud environments. We show that the proposed strategies outperform currently in use strategies in terms of quality of service and provider cost. The robustness of these strategies is also discussed.