To‐send‐or‐not‐to‐send: An optimal stopping approach to network coding in multi‐hop wireless networks

Abstract

Network coding is all about combining a variety of packets and forwarding as much packets as possible in each transmission operation. The network coding technique improves the throughput efficiency of multi-hop wireless networks by taking advantage of the broadcast nature of wireless channels. However, there are some scenarios where the coding cannot be exploited due to the stochastic nature of the packet arrival process in the network. In these cases, the coding node faces two critical choices: forwarding the packet towards the destination without coding, thereby sacrificing the advantage of network coding, or, waiting for a while until a coding opportunity arises for the packets. Current research works have addressed this challenge for the case of a simple and restricted scheme called reverse carpooling where it is assumed that two flows with opposite directions arrive at the coding node. In this paper the issue is explored in a general sense based on the COPE architecture requiring no assumption about flows in multi-hop wireless networks. In particular, we address this sequential decision making problem by using the solid framework of optimal stopping theory, and derive the optimal stopping rule for the coding node to choose the optimal action to take, i.e. to wait for more coding opportunity or to stop immediately (and send packet). Our simulation results validate the effectiveness of the derived optimal stopping rule and show that the proposed scheme outperforms existing methods in terms of network throughput and energy consumption.

To Code or Not to Code: When and How to Use Network Coding in Energy Harvesting Wireless Multi-Hop Networks

“…In our prior two studies, we also concentrated on two primary trade-offs. In [9], addressing the to-send-or-not-to-send problem, we examined a trade-off between enhancing coding gain on one hand and reducing end-to-end delay on the other. Similarly, in [12], tackling the to-overhear-or-not-to-overhear problem, we investigated a trade-off between increasing coding gain and diminishing energy consumption in multi-hop wireless networks.…”

“…We have addressed this decision-making in coding nodes under the title of the to-send-or-not-to-send in our previous study [9], which we briefly review in this section. Considering the nature of the decision-making conditions of this problem, we have modeled it using optimal stopping theory.…”

“…In the first decision-making approach, which we distinctively named To-Send-or-Not-to-Send in one of our previous research studies [9], nodes during the encoding process strive to make the best decisions for selecting the coding degree of the packets intended for transmission. Here, the term coding degree refers to the number of original packets that are combined together in a coded packet [10].…”

To overhear or not to overhear: a dilemma between network coding gain and energy consumption in multi-hop wireless networks

“…We defined the coding gain as the ratio of the number of transmissions required by the non-coding approach to the minimum number of transmissions used by COPE or the proposed scheme to deliver the same set of packets to the nexthops successfully [52]. Fig.…”

September 2020

“…This revolution in the industries has resulted in the building of automatic working mode using learning and mining. To provide a form of connectivity with other devices, internet is being used as a passage and this aspect is known as industrial IoT (IIoT) [3]. A crucial component of this IIoT is WSNs which is used to exchange knowledge between the various intelligent objects.…”