A Performance Comparison ofMulti-Hop Wireless Ad Hoc Network Routing ProtocolsJosh Broch David A. Maltz David B. Johnson Yih-Chun Hu Jorjeta JetchevaComputer Science DepartmentCarnegie Mellon UniversityPittsburgh, PA 15213http://www.monarch.cs.cmu.edu/AbstractAn ad hoc network is a collection of wireless mobile nodes dynamicallyforming a temporary network without the use of any existing network infras-tructure or centralized administration. Due to the limited transmission rangeof wireless network interfaces, multiple network "hops" may be needed forone node to exchange data with another across the network. In recent years,a variety of new routing protocols targeted specifically at this environmenthave been developed, but little performance information on each protocoland no realistic performance comparison between them is available. Thispaper presents the results of a detailed packet-level simulation comparingfour multi-hop wireless ad hoc network routing protocols that cover a rangeof design choices: DSDV, TORA, DSR, and AODV. We have extendedthe ns-2 network simulator to accurately model the MAC and physical-layerbehavior of the IEEE 802.11 wireless LAN standard, including a realisticwireless transmission channel model, and present the results of simulationsof networks of 50 mobile nodes.1 IntroductionIn areas in which there is little or no communication infrastructureor the existing infrastructure is expensive or inconvenient to use,wireless mobile users may still be able to communicate through theformation of an ad hoc network. In such a network, each mobile nodeoperates not only as a host but also as a router, forwarding packetsfor other mobile nodes in the network that may not be within directwireless transmission range of each other. Each node participates inan ad hoc routing protocol that allows it to discover “multi-hop” pathsthrough the network to any other node. The idea of ad hoc networkingis sometimes also called infrastructureless networking [13], since themobile nodes in the network dynamically establish routing amongthemselves to form their own network “on the fly.” Some examples ofthe possible uses of ad hoc networking include students using laptopcomputers to participate in an interactive lecture, business associatessharing information during a meeting, soldiers relaying informationfor situational awareness on the battlefield [12, 21], and emergencydisaster relief personnel coordinating efforts after a hurricane orearthquake.This work was supported in part by the National Science Foundation (NSF) underCAREER Award NCR-9502725, by the Air Force Materiel Command (AFMC) underDARPA contract number F19628-96-C-0061, and by the AT&T Foundation under aSpecial Purpose Grant in Science and Engineering. David Maltz was also supportedunder an IBM Cooperative Fellowship, and Yih-Chun Hu was also supported by anNSF Graduate Fellowship. The views and conclusions contained here are those of theauthors and should not be interpreted as necessarily representing the official policies orendorsements, either express or implied, of NSF, AFMC, DARPA, the AT&T Foundation,IBM, Carnegie Mellon University, or the U.S. Government.To appear in Proceedings of the Fourth Annual ACM/IEEE InternationalConference on Mobile Computing and Networking (MobiCom’98),October 25–30, 1998, Dallas, Texas, USA. Copyright ! 1998 ACM.Many different protocols have been proposed to solve the multi-hop routing problem in ad hoc networks, each based on differentassumptions and intuitions. However, little is known about the actualperformance of these protocols, and no attempt has previously beenmade to directly compare them in a realistic manner.This paper is the first to provide a realistic, quantitative analysiscomparing the performance of a variety of multi-hop wireless ad hocnetwork routing protocols. We present results of detailed simulationsshowing the relative performance of four recently proposed ad hocrouting protocols: DSDV [18], TORA [14, 15], DSR [9, 10, 2], andAODV [17]. To enable these simulations, we extended the ns-2network simulator [6] to include:Node mobility.A realistic physical layer including a radio propagation modelsupporting propagation delay, capture effects, and carriersense [20].Radio network interfaces with properties such as transmissionpower, antenna gain, and receiver sensitivity.The IEEE 802.11 Medium Access Control (MAC) protocol usingthe Distributed Coordination Function (DCF) [8].Our results in this paper are based on simulations of an ad hoc networkof 50 wireless mobile nodes moving about and communicating witheach other. We analyze the performance of each protocol and explainthe design choices that account for their performance.2 Simulation Environmentns is a discrete event simulator developed by the University ofCalifornia at Berkeley and the VINT project [6]. While it providessubstantial support for simulating TCP and other protocols over con-ventional networks, it provides no support for accurately simulatingthe physical aspects of multi-hop wireless networks or the MAC pro-tocols needed in such environments. Berkeley has recently releasedns code that provides some support for modeling wireless LANs, butthis code cannot be used for studying multi-hop ad hoc networks asit does not support the notion of node position; there is no spatialdiversity (all nodes are in the same collision domain), and it can onlymodel directly connected nodes.In this section, we describe some of the modifications we made tons to allow accurate simulation of mobile wireless networks.2.1 Physical and Data Link Layer ModelTo accurately model the attenuation of radio waves between anten-nas close to the ground, radio engineers typically use a model thatattenuates the power of a signal as 12at short distances ( is thedistance between the antennas), and as 14at longer distances.The crossover point is called the reference distance, and is typicallyaround 100 meters for outdoor low-gain antennas 1.5m above theground plane operating in the 1–2GHz band [20]. Following thispractice, our signal propagation model combines both a free spacepropagation model and a two-ray ground reflection model. When atransmitter is within the reference distance of the receiver, we usethe free space model where the signal attenuates as 12. Outside ofthis distance, we use the ground reflection model where the signalfalls off as 14.Each mobile node has a position and a velocity and moves aroundon a topography that
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