Adding multicast capabilities to wireless multi-hop token-passing protocols: Extending the RT-WMP

Support for real-time traffic and multi-hop is a basic requirement in certain applications as, for example, cooperative robot team missions. Normally, point-to-point communication is sufficient to allow such a collaboration. However, there exist situations in which multicast and/or broadcast capabilities, even with real-time requirements, allow a better usage of the available bandwidth leaving more time for unicast communications. This is the case, for example, in which a server generates real-time traffic that has to be delivered to a subset (that can be the whole set) of the nodes of the network. In this paper we present a solution to incorporate the capability of sending multicast messages in token-passing real-time wireless protocols. The solution has been implemented and tested as an extension of RT-WMP (a real-time wireless multi-hop protocol with priority management support). In addition, using these new characteristics, another type of unicast/multicast protocol is proposed, analyzed, evaluated and compared with the plain RT-WMP.