ABSTRACT
CONTENTS 7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 7.2 Multicast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196 7.3 Single-Node Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 7.4 Multiple-Copy Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 7.5 Single-Copy Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 7.6 Discussion and Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 7.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
7.1 Introduction In recent years, there has been much research activity regarding opportunistic networks, or delay-tolerant networks (DTNs) [9, 12], which are a type of wireless network for challenged environments. In opportunistic networks, end-to-end paths be-
Single Node Model Multiple Copies Model Single Copy Model [46], [41], [14] [1], [44], [6], [40], [29], [32], [10], [39], [15], [21]
[27], [24], [37], [18]
tween some or all of the nodes in the network do not exist most of the time. DTNs are characterized by intermittent connectivity, unknown mobility patterns, and limited network capacity. These networks have a variety of applications, including crisis environments, such as emergency response and military battlefields [20, 26], vehicular DTN road communication [19, 4], deep-space communication [25, 3], connectivity of developing countries [28, 22], and social contact networks [23, 11].
