Development of an Energy and Geographic Aware Opportunistic Network Coding Scheme Mario J. Engelbrecht and Magdalena J. Grobler TeleNet Research Group North-West University Potchefstroom, South Africa Email: {20704313, leenta.grobler}@nwu.ac.za Abstract—Mobile Ad-Hoc Networks and Wireless Sensor Net- works are communication networks that consist of nodes with limited energy resources. Therefore, routing protocols imple- mented in such networks need to be energy efficient. Network Coding (NC) is a technique that optimises the throughput of a network. In this paper we investigate the effect of power failure of energy-constraint nodes on network throughput, and propose a NC scheme that not only increases the throughput of a network as opposed to traditional routing mechanisms, but also does so in an energy efficient manner. The proposed scheme incorporates geo- routing into one of the leading NC schemes, CORE, and while it delivers more throughput than CORE, it also focusses on energy efficiency by extending the life span of nodes in a network. The NC scheme is implemented and simulated in OMNET++ and the results show significant improvement in prolonging the life span of a node as well as throughput increase. Index Terms—Mobile Ad-Hoc Network, Wireless Sensor Net- work, Network Coding, Opportunistic Routing, Geo-Routing, Energy efficiency. I. I NTRODUCTION The evolution of communication networks has led us to an era where you cannot only perform surgery halfway across the world, but do so while being in the comfort of your own home. By eliminating the need for wires, wireless networks revolutionized communication networks by enabling nodes to communicate while being in a mobile state . The concept opened many doors to new applications and possibilities. Wireless Ad-Hoc Networks are networks formed by wireless nodes. They are self-established and do not depend on any infrastructure. Mobile Ad-Hoc Networks (MANETs) and Wireless Sensor Networks (WSNs) are wireless communication networks that consist of nodes with limited energy resources [1], [2]. Nodes need energy to transmit, receive and process data. When a node is drained from all its energy resources, it cannot perform any functions and is of no use to the network, or in the case of user operated nodes, the operating client. It is imperative that nodes in such networks remain alive for as long as possible, especially in WSNs where each node is responsible for moni- toring a specific area or item [3]. Therefore, routing protocols implemented in such networks need to be energy efficient. Energy efficiency in networks refers to the monitoring of the energy levels of nodes, or the calculation of the amount of energy required per transmission, and using the acquired data as deciding factors when performing routing. Network Coding (NC) is a technique that optimises the throughput of a network by coding packets [4]. NC can be divided into two categories namely deterministic NC and op- portunistic NC [5]. In deterministic NC, coding opportunities are determined from the network topology and used to assign encoding and decoding roles to specific nodes. In opportunistic NC, nodes calculate the local coding opportunities using the available information acquired from neighbour nodes. In this case, encoding and decoding are performed without prior knowledge of the topology. Opportunistic routing is the pre- ferred option when routing in MANETs, since the topologies in such networks are dynamic. Opportunistic routing (OR) is a technique that allows rout- ing without prior knowledge of the exact next-hop node; hence OR routes opportunistically as opposed to fixed-path routing protocols [6]. In OR, there is a small pause before each transmission. The pause can be exploited to include routing conditions to be considered before performing further routing. Geo-Routing (GR) refers to routing based on the geograph- ical coordinates of nodes [7]. In this paper we investigate the effect of energy-constrained nodes on a network, and propose a NC scheme that not only increases the throughput of a network as opposed to traditional routing mechanisms, but also does so in an energy efficient manner. The proposed scheme incorporates GR into one of the leading NC schemes, CORE, and while it delivers more throughput as CORE, it also focusses on energy efficiency by extending the life span of nodes in a network. The NC scheme is implemented and simulated in OMNET++ and the results show significant improvement in prolonging the lifetime of a node. The remainder of this paper is arranged as follows: In section II, we give background on MANETs, WSNs, OR, GR and NC. In section III, we discuss related work, specifically COPE and CORE. Section IV presents the NC scheme after which the implementation is explained in section V. The simulation parameters are discussed in section VI, followed by the results and discussion thereof. A conclusion is drawn in section VII and we take a look at future work in section VIII.