Routing and Forwarding Protocols in Wireless Multi-hop Ad-hoc Networks in Context of Opportunistic Networks: An Analysis

In recent years opportunistic networks have gain popularity in research and industry. In these networks, nodes come into contact with each other opportunistically and communicate wirelessly. An opportunistic network consists of nodes. These nodes are typically handheld devices carried by people which are equipped with large memory, good sensing capability, high computational power with short-range radio transmission functionality and wirelessly connected to each other [1]. An opportunistic network node can be either mobile or fixed. A mobile node is a mobile device carried by humans with integrated technology such as a Wi-Fi, cameras, Bluetooth etc. A fixed node, working as an access point, is a device set in certain locations to disseminate information to mobile nodes. The transmission range between two connected nodes is usually short. When nodes get into each other’s transmission range, contacts will appear opportunistically. That is why the performance of these networks depends on the mobility of nodes. The widespread use of all these computing and communication devices creates a huge number of contact opportunities that are key to opportunistic communication. Routing is the most compelling challenge in opportunistic networking. There has been a lot of research in the past on routing in multi-hop ad-hoc networks [2, 3] i.e. in opportunistic networks. Routing algorithms have to cope with the typical limitations of wireless networks: high power consumption, low wireless bandwidth, high error rates. Routing performance improves when more knowledge about the topology of the network can be exploited. But this kind of knowledge is not easily available in opportunistic networks due to unpredictable topology. The network is formed opportunistically based on proximity and network availability, by randomly connecting and disconnecting the networks and devices. In opportunistic network intermittent connectivity is frequent and mobile nodes can communicate with each other even if route connecting them didn’t previously exists. The design of efficient routing strategies for opportunistic networks is generally a complicated task due to the absence of knowledge about the topological evolution of the network. In the second section, we provide a brief description of the primary routing approaches in opportunistic networks available in the literature and analyze them on the basis of different parameters.