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IP anycast is a powerful network layer mechanism that can be used for transparent communications between clients and a distributed service infrastructure. Unfortunately, large-scale deployment of IP anycast would cause a number of severe problems, including excessive routing table growth and potential routing instability. In order to solve these problems, a number of overlay network architectures have been proposed over the last years. In this paper we show that the robustness of anycast services provided via such anycast architectures can be significantly improved by using SCTP transport layer facilities. More specifically, the proposed approach adds the following important features to existing anycast overlays: Robustness to anycast overlay node failure or network reconfiguration, seamless anycast service delivery to mobile clients, and true stateful anycast communications over an entirely stateless infrastructure. Furthermore, we argue that the number of overlay nodes can be drastically reduced in comparison with the earlier architectures, without degrading service quality or increasing the end-to-end path stretch.

Mobile WiMAX is today one of the potential technology choices for delivering mobile broadband access. Despite its potential, existing radio coverage calculations only relate to a low level physical data rate, rather than to the actual MAC (Medium Access Control) throughput, which is more meaningful from a user's perspective. We therefore elaborated on linking high level MAC throughput to low level radio coverage. We simulated the complete system, thereby ultimately combining two metrics most sought for: MAC throughput by radio coverage range. With respect to those metrics, the impact of time dispersion models, MIMO (Multiple Input Multiple Output), the packet size and the number of users is studied. In a 5 MHz band at 2.5 GHz, maximum ranges are found to vary between 1.2 km and 1.9 km, while the highest MAC throughput was found here to vary between 4.64 Mbps and 10.32 Mbps, for the considered parameters values and use case.