Virtual gateways: enabling connectivity between MAC heterogeneous sensor networks

Over the years many different MAC protocols have been developed for sensor networks, each optimised for a different set of application requirements. Since these MAC protocols are not compatible with each other, there is generally no interoperability between sensor networks. This is a severe problem when connectivity between sensor networks is required. In this paper, we demonstrate the feasibility of using Virtual Gateways, sensor nodes running multiple MAC protocols simultaneously on top of a single radio interface, to enable connectivity between sensor networks. To this end we have developed MultiMAC, a network stack for TinyOS capable of running multiple MAC protocols simultaneously. We show that the architecture of the MultiMAC stack is flexible and extensible enough to support a wide variety of MAC protocols and that the overhead of this network stack is minimal. We also discuss the results of our initial experiments with a testbed on the impact of using virtual gateways.