International Journal of Modern Engineering Research (IJMER) www.ijmer.com Vol.3, Issue.2, March-April. 2013 pp-845-848 ISSN: 2249-6645 www.ijmer.com 845 | Page Gaurav Sachan, 1 D. K. Sharma, 2 Karishma Tyagi, 3 Abhimanyu Prasad 4 1234 Department of Computer Science & Engineering, Vishveshwarya Group of Institutions, Dadri, G.B.Nagar-273010, U. P., INDIA Abstract: Mobile ad hoc networks (MANET) are characterized by multi-hop wireless links and resource constrained nodes. One of the major challenges in mobile ad hoc networks (MANETs) is link failures due to mobility. Because nodes in a MANET act as routers for any ongoing packet communication and have limited transmission ranges, the communication links are broken, and packet losses occur. To improve network lifetime, energy balance is an important concern in such networks. Geographic routing has been widely regarded as efficient and scalable. However, it cannot guarantee packet delivery in some cases, such as faulty location services. The matter gets even worse when the nodes on the boundaries of routing holes suffer from excessive energy consumption, since geographic routing tends to deliver data packets along the boundaries by perimeter routing. This paper will be a basis for study in the domain of geographic routing for the new researcher point of view. Keywords: MANET, geographic routing, energy efficient, location information. I. Introduction An ad-hoc network, as the name suggests, is a network formed by nodes connected arbitrarily for some temporary time. They provide a powerful paradigm for modeling open self configuring wireless networks and seem so appropriate to use in the fourth generation of mobile networks. Obviously, a convergence of all these technologies with 3G/4G [18] mobile networks will probably lead to various integrated solutions. A Mobile Ad-hoc network (MANET) is consists of mobile routers connected wirelessly to each other where each node is free to move. This results in a continuously changing topology. Some examples of the possible uses of ad hoc networking include business associates sharing information during a meeting, soldiers relaying information for situational awareness on the battlefield and emergency disaster relief personnel coordinating efforts after a hurricane or earthquake. In recent years, geographic routing algorithms have been extensively studied due to the popularity and availability of positioning services such as the global positioning system (GPS). Geographic routing is a promising candidate for large- scale wireless ad hoc networks due to its simplicity and scalability and takes advantage of the location information of the nodes are the very valuable for wireless networks. Since geographic routing does not require a route management process, it carries a low overhead compared to other routing schemes, such as proactive, reactive, and hybrid topology based routing protocols. Geographic routing protocols work on the assumption that every node is aware of its own position in the network; via mechanisms like GPS or distributed localization schemes and that the physical topology of the network is a good approximation of the network connectivity. In other words, these routing protocols assume that if two nodes are physically close to each other, they would have radio connectivity between them, which is true in most cases. Hence the protocols use node location information to route packets from source to destination. One big advantage of geographic routing schemes is the fact that there is no need to send out route requests or periodic connectivity updates. This can save a lot of protocol overhead and consequently, energy of the nodes. The most significant difference between MANETs and traditional networks is the energy constraint. Some applications such as environment monitoring need MANETs to run for a long time. Therefore, extending the lifetime of MANETs is important for every MANET routing protocol. However, most geographic routing algorithms take the shortest local path, depleting the energy of nodes on that path easily. The nodes located on the boundaries of holes may suffer from excessive energy consumption since the geographic routing tends to deliver data packets along the whole boundaries by perimeter routing if it needs to bypass the hole. There should be a mechanism at node for robust communication of high priority messages. This can be achieved by keeping nodes all the time powered up which makes nodes out of energy and degrades network life time. Also, there can be a link or node failure that leads to reconfiguration of the network and re-computation of the routing paths, route selection in each communication pattern results in either message delay by choosing long routes or degrades network lifetime by choosing short routes resulting in depleted batteries. Therefore the solutions for such environments should have a mechanism to provide low latency, reliable and fault tolerant communication, quick reconfiguration and minimum consumption of energy. Routing protocols have a critical role in most of these activities. To measure the suitability and performance of any given protocol, some metrics are required. On the basis of these metrics any protocol can be assessed against its performance [3]. The remaining part of this survey paper is organized as follows:-In section II, we will discuss the taxonomy related to Geographic routing. In section III literature review in the field of geographic routing mechanism and in section IV we describe research challenges for geographic routing in MANET, the comparative study of previous protocols given in section V and in section VI; we will conclude the paper and give the future scope of this paper. Enhanced Energy Aware Geographic Routing Protocol in MANET: A Review