# An Efficient Routing Scheme Based on Node Attributes for Opportunistic Networks in Oceans
## 1 Introduction  
The rapid development of the marine economy and ever-increasing human activities in oceans require reliable and cost-effectiveness networking services. Although terrestrial Internet can be easily accessed almost anytime and anywhere, the ocean faces challenges to support satisfied services due to huge differences with terrestrial environments in terms of geographical location, climatic conditions, and user distributions. The satellite can provide reliable Internet services in oceans; however, its expensive services make it difficult to become popular especially among ordinary users [1]. In such challenging environments, opportunistic networks (OppNets) are expected to play an important role, due to its easy and quick deployment without fixed infrastructure, forming dynamic networks by constant mobility of nodes.  
In OppNets, no prior knowledge is made with regard to the existence of a complete route between two nodes wishing to communicate. The communications of source and destination mainly rely on frequent mobility of nodes to create opportunistic contacts. Figure 1 is an illustration of routing in OppNets. In Figure 1, there is no direct route from source \(S\) to destination \(D\). At 14:00 p.m., node \(S\) forwards the packets to node 1; at 15:10 p.m., the carrier node 1 forwards the packets to node 4; the destination \(D\) receives the packets from node 4 at 16:00 p.m. Data packets from node \(S\) are eventually delivered to node \(D\) even if they might never be connected to the same network, at the same time [2]. This is due to the fact that the movement of intermediate nodes helps to forward the packets during delivery. However, the questions of how data forwarding of nodes is routed to the destination at low cost, and how to guarantee robust communication in the face of frequent changing networks still present major challenges in dynamic marine environments.  
Many studies have been carried out on routing schemes [3; 4; 5]. These routing schemes, based on dissemination and context technologies, can fulfill packet transmissions. However, most of them are based on an end-to-end connection and the fixed paths before packet transmissions, so they are not suitable for OppNets. Furthermore, the current node makes decisions on message delivery only dependent on local forwarders without consideration of further intermediate nodes. The question of whether the relay nodes with communication function have enough capability to participate in the message relay is ignored. In this case, the successful delivery ratio decreases and unnecessary network resources waste, especially in dynamic marine networking environments.  
In this paper, we propose an efficient routing scheme based on node attributes for opportunistic networks (RSNA) in oceans. The major contributions of the paper are as follows.  
(1) The delivery competency is constructed to predict the existence of the further intermediate nodes.  
(2) We design a forwarding willingness mechanism based on device capacity and movement behaviors to qualify whether the nodes can participate in the delivery process.  
(3) By using a utility metric combining delivery competency and forwarding willingness, we developed the RSNA, an efficient routing scheme based on node attributes in opportunistic networks to improve network performance.  
The rest of the paper is organized as follows. Section 2 introduces the related works. Section 3 gives a detailed description of the proposed scheme. The performance evaluation is given in Section 4. Finally, we conclude briefly the paper in Section 5.