Abstract: Opportunistic networks is one of the newest hot research spots in wireless networks after mobile ad hoc net-works(MANET) and wireless sensor networks(WSN). As an exciting evolution of the legacy MANET paradigm,opportunistic networks have released the basic assumption of complete paths between data senders and receivers. With the support from devices movement and message forwarding, opportunistic networks enable users' communication in dis-connected environments, in which island of connected devices appears, disappears and reconfigures dynamically. In this paper, the concept, characteristics and typical applications of opportunistic networks were introduced. The hot spots ineluding routing strategy and mobility models were discussed and presented in detail. Other directions and foreground were also briefly presented.

Key words: Opportunistic networks,Routing,Mobility model