Flexible and dynamic network coding for adaptive data transmission in DTNs

Existing network coding approaches for Delay-Tolerant Networks (DTNs) do not detect and adapt to congestion in the network. In this paper we describe CafNC (Congestion aware forwarding with Network Coding) that combines adaptive network coding and adaptive forwarding in DTNs. In CafNC each node learns the status of its neighbours, and their egonetworks in order to detect coding opportunities, and codes as long as the recipients can decode. Our flexible design allows CafNC to efficiently support multiple unicast flows, with dynamic traffic demands and dynamic senders and receivers. We evaluate CafNC with two real connectivity traces and a realistic P2P application, introducing congestion by increasing the number of unicast flows in the network. Our results show that CafNC improves the success ratio, delay and packet loss, as the number of flows grows in comparison to no coding and hub-based static coding, while at the same time achieving efficient utilisation of network resources. We also show that static coding misses a number of coding opportunities and increases packet loss rates at times of increased congestion

Performance comparison of baseline routing protocols in pocket switched network

Pocket Switched Network (PSN) is a branch of Delay Tolerant Network (DTN) which is intended to work in a challenged network. Challenged network is network with lack of infrastructure such as disaster area. As such, the network has intermittent connectivity. PSN provides a new paradigm to distribute messages in the network by taking advantage of roaming nodes from one place to another. In this paper, network performances of eight PSN routing protocols are investigated namely, First Contact, Direct Delivery, Epidemic, PRotocol using History of Encounter and Transitivity (PRoPHET), Spray and Wait, Binary Spray and Wait, Fuzzy Spray, Adaptive Fuzzy Spray and Wait. The performance metrics are packet delivery ratio, overhead ratio and average latency. Opportunistic Network Environment (ONE) simulator is used to evaluate the network performance. Experiments show that Epidemic has the best performance in term of message delivery ratio, but it has the highest overhead ratio. Direct Delivery has the lowest overhead ratio (zero overhead ratio) and PRoPHET has the lowest latency average