# Quantitative Study on the Impact of Energy Consumption Based Dynamic Selfishness in MANETs +
## 1 Introduction  
With the pervasiveness of Internet of Things (IoT) and the rapid development of communication technologies, mobile ad hoc networks (MANETs) have become more and more important in IoT-related areas, especially in smart IoT. MANET is a wireless network that consists of a number of autonomous, self-organized, limited energy capacity, and mobile nodes, which communicate with each other over wireless communication links in an ad hoc manner without the assistance of any centralized authority [1]. MANET has a wide usage in industrial applications and other scenarios that requires the immediate establishment communication with dynamic survival networks. Every node in a MANET functions as both host, which acts as a normal terminal device, and router, which forwards packets to assist routing operations. These nodes can be any personal device such as laptops, mobile phones, or tablets that are battery-driven in general [2]. Due to lack of centralized authorities and limited transmission range of wireless communication links, most communications among the nodes in MANETs highly depend on multi-hop routing mechanisms. As a result, forwarding tasks become critically importantduring the communication process [3]. However, the resource-constrained mobile nodes in MANETs are unwilling to forward data packets for others' interests in order to conserve their own resources. In general, the nodes in the network are divided into three categories: normal, malicious, and selfish nodes. Normal nodes always operate network functionalities in a cooperative way. Malicious nodes intentionally damage others by causing network outages, while saving resources is not a priority. Selfish nodes take advantage of the network to send/receive packets with their own interests, but they refuse to forward packets for others because of the limited computation and communication resources. They do not have direct intentions to damage other nodes or the network. However, the selfish nodes in MANETs have great impacts on the overall network performance. This paper mainly focuses on the evaluation of the impact of node selfishness on the network performance in MANETs. Selfishness is a most common passive denial of service (DoS) attack that lowers the network performance [4]. As clearly depicted in Figure 1, the presence of selfish nodes causes negative implications on the network (e.g., network partitioning problems). In most literature, the impacts of selfish nodes on routing protocols, detection, or incentive mechanisms are the main topics [5; 6; 7]. However, we are interested in investigating the selfish node impacts on the overall network performance because the quantification of the investigation could provide reliable information to detection and incentive mechanisms. In this study, we hypothesize that mobility, density, proportion, and combination of selfish nodes are related to the overall network performance, and we utilize computer simulation based experiments to test this hypothesis. All the related issues are discussed in detail in the following sections from various aspects. This paper is partially based on our previous conference paper [3] where the impacts of selfish nodes in MANETs were studied. However, the selfish nodes discussed in the previous work were all static selfish nodes, which means the selfishness is unchanged during the whole process. In fact, static selfishness is not practical in the real world. In order to more realistically investigate node selfishness in MANETs, energy consumption based dynamic selfishness is discussed in this paper. The major contributions of our work are summarized as follows. * To the best of our knowledge, this is the first work in which the dynamic selfishness is quantitatively studied by considering mobility, density, proportion, and combination of selfish nodes in MANETs and evaluated from various aspects including average packet loss rate, average round-trip delay, and throughput.