An IP cross-layer scheduler for QoS provisioning in NGNs

Next-Generation Networks (NGNs) will support Quality of Service (QoS) over a mixed wired and wireless IP-based infrastructure. A relative model of service differentiation in Differentiated Services architecture is a scalable solution for delivering multimedia traffic. However, the dynamic nature of radio channels makes it difficult to achieve the target quality provisioning working at the IP and lower layers separately as in the classical approach. In this work, an IP cross-layer scheduler able to support a Proportional Differentiation Model (PDM) for delay guarantees also over wireless is described. The key idea is to leverage feedbacks from the lower layers about the actual delays experienced by packets in order to tune at run-time the priority of the IP queues with the objective of supporting a PDM at the network node on the whole across multiple layers. A simulation analysis demonstrates the reliability and robustness of the proposal in achieving consistent results even with highly time-variant performance of the MAC and PHY layers, differently from the classical approach. Furthermore, considerations on the required additional functionality and likely deployment scenarios highlight the scalability and backward compatibility of the designed solution.