Comparison of QoS Routing Approaches for Intermittently Connected Mobile Ad Hoc Networks

A Mobile Ad Hoc Networks (MANET) is a group of mobile nodes that can communicate with each other using multihop wireless links without utilizing any fixed based-station infrastructure and centralized management controller. Due to intervening bodies, communication links are susceptible to frequent failures, which can cause intermittent connectivity. This can cause partitions in the Network. Existing ad hoc routing protocols unable to deliver packets in the presence of a network partition between source and destination since they are designed for network where end to end connectivity exists between nodes. In highly mobile or sparse networks, where partitions are not exceptional events, these routing algorithms will fail to deliver packets since no route is found to reach their destinations. To deal with such networks researchers have suggested to use flooding-based routing schemes and Message Ferrying Schemes. Even though flooding based schemes are robust and have a high probability of message delivery, they suffer from an enormous overhead in terms of bandwidth, buffer space and energy consumption due to large number of transmissions per packet. Flooding based scheme is not suitable if partitions last for a long duration of time. Message Ferry distributes messages between nodes which are located in different partitions which may be disconnected or partitions lasts for long duration of time. In this paper we compare different Message Ferrying Schemes which are specifically designed for disconnected networks. The performance of the routing approaches is compared in terms of their control overhead, amount of data delivered, and average latency in packet delivery.