ABSTRACT
The opportunistic network (OppNet) has been introduced as an emerging networking approach where energy-restricted mobile nodes are experienced with intermittent connectivity within a sporadic network topology. As end-to-end transmissions of messages are absent here, mobile nodes collaborate among themselves for routing data from source to destination. Each node possesses the ability to store the received message, to carry it for a temporary time, and finally to deliver it to the destination whenever the connectivity is available. Accordingly, routing is quite challenging because it is difficult to select the most-suited relay node and to minimize message latency in OppNet. Moreover, the amount of energy that is spent by the nodes during scanning, transmitting, receiving, and carrying a message is another compelling issue to address in OppNet. Energy can be consumed in a controlled manner during message transmission so that each node has sufficient remaining energy. Otherwise, the success ratio of message delivery and network lifetime might be limited due to the expenditure of excessive energy. So, routing protocols should consider the challenging issues of OppNet, including the energy efficiency aspect for message routing. Various routing strategies have been proposed for OppNet scenarios, considering several networking aspects. In this chapter, we consider several OppNet routing protocols from various genres that are designed to deliver data effectively. Epidemic, Spray and Wait, and Spray and Focus are included from replication-based; PRoPHET from probabilistic-based; and finally, SCORP, dLife, dLifeComm, and Bubble Rap from social-aware routing strategy. A detailed investigation is performed on these protocols for evaluating their energy efficiency considering the performance metric – average remaining energy. In addition, a comparative analysis of their performance in terms of delivery ratio, average latency, and overhead ratio is also provided. The Opportunistic Network Environment (ONE) simulator is used as the simulation tool to evaluate the performance of the selected OppNet routing protocols.
