Energy efficient routing in ad hoc disaster recovery networks Gil Zussman * , Adrian Segall Department of Electrical Engineering, Technion––Israel Institute of Technology, Haifa 32000, Israel Abstract The terrorist attacks on September 11, 2001 have drawn attention to the use of wireless technology in order to locate survivors of structural collapse. We propose to construct an ad hoc network of wireless smart badges in order to acquire information from trapped survivors. We investigate the energy efficient routing problem that arises in such a network and show that since smart badges have very limited power sources and very low data rates, which may be inadequate in an emergency situation, the solution of the routing problem requires new protocols. The problem is formulated as an anycast routing problem in which the objective is to maximize the time until the first battery drains-out. We present iterative algorithms for obtaining the optimal solution of the problem. Then, we derive an upper bound on the network lifetime for specific topologies and describe a polynomial algorithm for obtaining the optimal solution in such topo- logies. Finally, numerical results regarding the upper bound and the algorithms are presented. Ó 2003 Elsevier B.V. All rights reserved. Keywords: Routing; Energy efficient; Energy conserving; Power aware; Disaster recovery networks; Ad hoc networks; Smart badges; IEEE 802.15 1. Introduction The terrorist attacks on the World Trade Cen- ter and the Pentagon on September 11, 2001 have drawn ever-increasing attention to improving res- cue efforts following a disaster. One of the tech- nologies that can be effectively deployed during disaster recovery is wireless ad hoc networking [25]. For example, rescue forces can use a Mobile Ad Hoc Network (MANET) in the lack of fixed communication systems. Furthermore, a wireless sensor network can be quickly deployed following a chemical or biological attack in order to identify areas affected by the chemical/biological agents [2]. We propose another application of an ad hoc network, which can be used in order to gather information from trapped survivors of structural collapse. There are various possible reasons for structural collapse. The most frequent reasons are earth- quakes, terror attacks, structural problems, and missile attacks. Regardless of the reason, the consequences of a collapse are usually very tragic. For example, in 1995 alone, the Kobe earthquake resulted in the death of nearly 5500 people, 168 people were killed in the Oklahoma City bombing, and more than 500 people were killed in the col- lapse of the Sampoong department store in Seoul. Thus, the importance of improving rescue tech- niques requires no explanation. * Corresponding author. E-mail addresses: gilz@tx.technion.ac.il (G. Zussman), segall@ee.technion.ac.il (A. Segall). URLs: http://www.comnet.technion.ac.il/~gilz, http://www. comnet.technion.ac.il/segall. 1570-8705/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved. doi:10.1016/S1570-8705(03)00041-6 Ad Hoc Networks 1 (2003) 405–421 www.elsevier.com/locate/adhoc