Routing in Opportunistic Networks: Implementation and Research Challenges
Opportunistic Networks can be defined as Delay Tolerant Networks, which are formed dynamically with participating nodes' help. Opportunistic Networks follow the Store-Carry-Forward principle to deliver/route the data in the network. Routing in Opportunistic Network starts with the Seed Node (Source Node) which delivers the data with the help of Intermediate nodes. Intermediate nodes store the data while roaming in the network until it comes in contact with the appropriate forwarding node (relay node) or the destination node itself. An extensive literature survey is performed to analyze various routing protocols defined for Opportunistic Network. With mobility-induced routing, establishing and maintaining the routing path is a major challenge. Further, the Store-Carry-Forward routing paradigm imposes various challenges while implementing and executing the network. Due to the unavailability of a suitable relay node, data needs to be stored within the Node's Memory, which imposes buffer storage issues at the node level. Also, uncontrolled flooding may impose link-level Congestion and be treated as overhead to maintain the network. Another major challenge can be maintaining the energy level of the nodes in the network. Recently developed ONE (Opportunistic Network Environment) Simulator is used to simulate and emulate the environment required by Opportunistic Network. Along with the extensive literature survey of the protocols, a few of the existing protocols viz. Direct Delivery, ProPHET, Epidemic, and Spray & Wait Routing are implemented using ONE Simulator to analyze their performance while in execution. Results are being compared, and the researchers' future direction is identified to address the open problems and challenges in the Opportunistic Network.