Path diversity gain with network coding and multipath transmission in wireless mesh networks

Abstract

In this paper we investigate the performance that can be achieved by exploiting path diversity through multipath forwarding together with redundancy through linear network coding, in wireless mesh networks with directional links. A key contribution of the paper is to capture the tradeoff between packet delay and throughput achieved by combining multipath forwarding and network coding, and compare this tradeoff with that of simple multipath routing where different flows follow different paths, the transmission of multiple copies of packets over multiple paths, and single path routing. The analytical framework considers the case of end-to-end retransmission for achieving reliability, and is generalized for an arbitrary number of paths and hops. We also derive the minimum and maximum number of coded packets that are needed at the receiver to retrieve all packets sent by the sender; this can be used to obtain a lower and upper bound for the delay in the case of linear network coding with multipath forwarding.

Delay and throughput of network coding with path redundancy for wireless mesh networks

“…In this paper, we extend our work in [1]. In that paper we investigated the performance that can be achieved by exploiting path diversity through multipath forwarding for end to end retransmissions.…”

“…The derivation of the equations in this section is based on [1] section II. There is a small change for the case of network coding.…”

On the performance of network coding and forwarding schemes with different degrees of redundancy for wireless mesh networks

“…The derivation of the equations in this section is based on Appendix B of [37]. There is a small change for the case of network coding.…”

“…There is a small change for the case of network coding. For the case of n paths consisting of m hops, with paths being either node disjoint or not, the corresponding analysis can be found in [37]. The corresponding throughput and delay expressions are rather complicated and are not useful for giving further insights.…”

“…The second reason for which multicopy achieves lower delay than NC is the higher redundancy employed. Recall that, G-NC-L denotes a greedy variant of network coding based forwarding, that is able to decode a packet after receiving 3 coded packets, when a packet gen of size 3 is used, while G-NC-U requires at least 4 (see Appendix A in [37]). It is also interesting to note that, although MC experiences a larger number of failed frames than all other schemes employing multiple paths, their effect on delay is balanced by the gain due to higher redundancy.…”