Sagar Padiya et al./ Elixir Network Engg. 75 (2014) 27887-27891 27887 Introduction Mobile ad hoc network is a network consisting of mobile nodes (Laptop, Personal Digital Assistants (PDAs) and wireless phones) with the characteristics of self-organization and self- configuration which enable it to form a new network quickly [01]. A Mobile Ad hoc Network or in short, MANET, is a relatively new communication paradigm. A MANET network consists of a group of mobile devices (nodes) communicating through a wireless medium. Unlike a traditional infrastructure network, the network is established solely by the MANET devices themselves without the need of any fixed infrastructure such as an access point or base station. A node may be able to communicate with other nodes far away with the cooperation of intermediate nodes, forwarding the packets to the destination. In this multi hop communication, each node operates as both host and router. Routing protocol such as Dynamic Source Routing [DSR] and AODV have been designed to handle such environment [02]. Minimal configuration, quick deployment and the absence of central governing authority make MANET suitable for emergency situations such as natural disasters, military conflicts and emergency medical situations. However, since there is no centralized administration, the performance of a MANET greatly depends on the cooperation of all nodes in the network. A MANET (Mobile Ad-hoc Network) is a self configuring system of mobile nodes connected by wireless links. In a MANET, the nodes are free to move randomly, changing the networks topology rapidly and unpredictably. MANETs are decentralized, and therefore all network activities are carried out by nodes themselves. Each node is both an end-system as well as a relay node (router) to forward packets for other nodes. Most of the routing algorithms designed for MANET such as DSR and AODV are based on the assumption that every node forwards every packet. But some of the nodes may act as the selfish nodes. These nodes use the network and its services but they do not cooperate with other nodes. Such selfish nodes do not consume any energy such as CPU power, battery and also bandwidth for retransmitting the data of other nodes and they reserve them only for themselves. This paper discusses three techniques namely 1) Reputation based technique, 2) Credit based technique and 3) Acknowledgement based technique to detect selfish nodes in MANET [03]. In reputation based technique, network nodes collectively detect and declare the misbehaviour of a suspicious node. Such a declaration is then propagated throughout the network. Credit based technique provide incentives for nodes to faithfully perform networking functions. In order to achieve this goal, virtual (electronic) currency (credit) or similar payment system may be set up. Nodes get paid for providing services to other nodes. Acknowledgement based technique provide rely on the reception of an acknowledgment to verify that a packet has been forwarded. Classification of Techniques Several techniques have been proposed to detect misbehaving nodes in mobile ad hoc network. These techniques can be classified into three categories: A Reputation-Based Technique: Reputation based technique on the other hand rely on building a reputation metric for each node according to its behavioral pattern. A monitoring method used by most systems in this category is called a watchdog. Watchdog was proposed by Marti et al. [04] to detect data packet non forwarding by overhearing the transmission of the next node. [05], [06], [07] use similar monitoring technique but then propagate collected information to nearby nodes and are susceptible to false praise and false accusation attacks. Mr. Bansal and Mr. Baker proposed a system called OCEAN [08] where the reputation of a neighbor is evaluated using only locally available information and thus avoid sophisticated and potentially vulnerable techniques of reputation Survey of innovated techniques to Detect selfish nodes Sagar Padiya, Rakesh Pandit and Sachin Patel ABSTRACT An Ad-hoc network is a collection of mobile nodes dynamically forming a temporary network without the use of any existing network infrastructure or centralized administer. Because of limited communication range among mobile nodes in ad-hoc network, several network hopes may be needed to deliver a packet from one node to another node in the wireless network. In such a network each node acts as an end system as well as a relay node (or router). Most of the routing algorithms designed for MANET such as AODV and DSR are based on the assumption that every node forwards every packet. But in practice some of the nodes may act as the selfish nodes. These nodes use the network and its services but they do not cooperate with other nodes. Such selfish nodes do not consume any energy such as CPU power, battery and also bandwidth for retransmitting the data of other nodes and they reserve them only for themselves. The original AODV and DSR routing algorithms can be modified to detect such selfish nodes. In this paper, we survey innovated techniques as well as proposed techniques to detect Selfish Nodes for MANET. Finally we provide some directions for further research. © 2014 Elixir All rights reserved. ARTICLE INFO Article history: Received: 28 December 2012; Received in revised form: 15 October 2014; Accepted: 28 October 2014; Keywords ACK2, BMF, Cooperative System in MANET, Misbehaving Nodes, Mobile Ad-hoc Network (MANET) Area, Nodes, Selfish Nodes. Elixir Network Engg. 75 (2014) 27887-27891 Network Engineering Available online at www.elixirpublishers.com (Elixir International Journal) Tele: E-mail addresses: padiyasagar@gmail.com © 2014 Elixir All rights reserved