Benefits of Network Coding for Unicast Application in Disruption-Tolerant Networks

Abstract

In this paper, we investigate the benefits of applying a form of network coding known as Random Linear Coding (RLC) to unicast application in Disruption Tolerant Networks (DTNs). Under RLC, nodes store and forward random linear combinations of packets as they encounter each other. For the case of a single group of packets originating from the same source and destined for the same destination, we prove a lower bound on the probability that the RLC scheme achieves the minimum time to deliver the group of packets. Although RLC achieves a significant reduction in group delivery delay, it fares worse in terms of average packet delivery delay and network transmissions. When replication control is employed, RLC schemes reduce the group delivery delay without increasing the number of transmissions. In general, the benefit achieved by RLC is more significant under stringent resource (bandwidth and buffer) constraints, limited signaling, highly dynamic networks, and when it is applied to packets from same flow. For more practical settings with multiple continuous flows in the network, we show the importance of deploying RLC schemes with a carefully tuned replication control in order to achieve reduction in average delay.

Towards Practical Store-Carry-Forward Networking: Examples and Issues

“…Limited replication can be realized deterministically (e.g., [27]) or probabilistically (e.g., [22]). Packet-level coding techniques such as Network Coding (NC) are helpful to mitigate the inefficiency of duplication in storage constrained situations (e.g., [12], [20], [32]). …”

“…For both of SC case and NC case, we use Random Linear Network Coding (RLNC) [32] with systematic coding on a certain small Galois Fields, although SC can use a more strict erasure correcting coding such as Reed-Solomon Coding. In SC, the source node generates an additional coded messages and the relay nodes only replicate and forward the messages to the next nodes.…”

Performance modeling of data transmission by using random linear network coding in DTNs

“…Recently, some researchers consider to employ RLNC to improve data transmission performance in DTNs [18,19], where a linear combination of some existing (buffered) packets at the node rather than the copy of a single packet is exchanged when two nodes meet. In this way, a coded packet contains the information about all the packets which are combined together and contributes to the recovery of these packets at the destination.…”

“…We call this category of packet transmissions 'Encode and Forward' mode. In [18], Zhang et al exploit RLNC for unicast data transmissions in DTNs, where epidemic routing is assumed. They demonstrate the transmission performance improvement by encoding the packets with the same source and destination.…”

On Optimal Packet Routing in Deterministic DTNs

“…The algorithm presented in this paper was originally developed in the framework of our research on network coding to calculate the minimum delivery time for a set of packets. For this reason a sketch of the algorithm appears in our work [18]. In comparison to [18], this paper investigates the complexity of a general class of problems, presents a more complete description of the algorithm, showing how it can be used to determine the actual scheduling that minimizes not only the maximum delivery time, but also the average delivery time and the average delivery delay.…”