A Comparative Study of On-Demand Routing Protocols for Mobile Ad-hoc Networks Mandeep Kaur Research Scholar Lovely Professional University Phagwara, Punjab Manmohan Sharma Associate Professor Lovely Professional University Phagwara, Punjab Abstract- With a boost of mobile devices in today’s era, Mobile Ad Hoc Network has become an essential part and has gained an interest of researchers. It is a collection of self- organizing and adaptive mobile nodes or devices that works without fixed infrastructure where every single mobile node work as an end device and as well as router to move forward the data packets. As MANET is of highly dynamic in nature, the mobile nodes moves openly and freely and change their positions very often. This paper emphasis on various on-demand routing protocols. A critical overview of each protocol is also provided on the basis of the related work done in this area. We also tabulate the comparative analysis of these protocols on the basis of various parameters. Keywords-MANET, AODV, DSR, TORA I. INTRODUCTION Wireless networks are having huge attention mainly developed in two types: Infrastructure mode and Infrastructure less or Ad-hoc mode. In first one, Access Points [AP] are used for communication between nodes. They help in forwarding data from node to node. While in Ad-hoc or Infrastructure less mode it works without Access point or centralized device. So each and every node is capable of doing both the jobs i.e. to forward data and also to transmit their own data [1]. MANET comprises of mobile components in a wireless network. These mobile nodes are having short range of transmission so nodes seek the support of their neighboring nodes to forward the data packets [2, 13]. The topology of MANET is much more dynamic as compared to the internet i.e. a wired network. So the protocols that are used in wired network will not be suitable for this network [3]. Due to this kind of nature the protocol must not require too much effort to establish a connection. Despite of having a single path the protocol should have multiple paths between the source and the destination. Due to the dynamic nature congestion is likely to occur on some routes in the network scenario so the protocol may acquire other route for communication. If one link has blocked or failed due to leaving of a node or any other cause communication should be continued with other links (if available). The path acquired for communication should be free from loop otherwise the data sent through that path may get stuck in that loop and will never reach to its destination. So the protocol should be designed in a way that hides all the complexity of the communication mechanism and provides an easy interface to the user. MANET works best in the situation of emergency like natural disasters, military, etc. due to its minimal configuration, easily development and without centralized governing structure. [4]. Each and every node in the network discovers the path by RREQ and RREP packets [5]. The resource (bandwidth, battery power and memory space) availability is the major issue in this kind of network. Because the nodes or mobile devices are mainly battery worked so battery power is the primary issue. Instead of searching a new path and to retransmit a data packet, nodes also consume battery power in data transmission. So power management should be main concern. International Journal of Latest Trends in Engineering and Technology (IJLTET) Special Issue RICSIT-2016 79 ISSN: 2278-621X