ABSTRACT
This chapter describes one of the most interesting cases of opportunistic networks, i.e., the mobile-relay forwarding (MRF) approach. MRF assumes that a small subset of nodes have fewer restrictions in terms of resource constraints and follow completely different mobility patterns with respect to the vast majority of nodes in the network. The chapter also describes different types of architecture that have been proposed to exploit the MRF concept. Mobile relays (MRs) are specialized nodes that move throughout the network to collect data from source nodes and deliver it to the destination node or access point. MRs may be classified in two broad categories: they can be part of the environment or specifically designed as part of the network infrastructure. MRs are opportunistically exploited by the other users to bring messages to the destination, thus connecting nodes that would never be connected together, or anyway significantly improving the network performance.
