SeadaZunigaKrishnamachariHelmy_Sensys04

SeadaZunigaKrishnamachariHelmy_Sensys04 - Energy-Efficient...

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Unformatted text preview: Energy-Efficient Forwarding Strategies for Geographic Routing in Lossy Wireless Sensor Networks * Karim Seada, Marco Zuniga, Ahmed Helmy, Bhaskar Krishnamachari Department of Electrical Engineering University of Southern California { seada, marcozun, helmy, bkrishna } @usc.edu ABSTRACT Recent experimental studies have shown that wireless links in real sensor networks can be extremely unreliable, devi- ating to a large extent from the idealized perfect-reception- within-range models used in common network simulation tools. Previously proposed geographic routing protocols com- monly employ a maximum-distance greedy forwarding tech- nique that works well in ideal conditions. However, such a forwarding technique performs poorly in realistic conditions as it tends to forward packets on lossy links. We identify and illustrate this weak-link problem and the related distance- hop trade-off, whereby energy efficient geographic forward- ing must strike a balance between shorter, high-quality links, and longer lossy links. The study is done for scenarios with and without automatic repeat request (ARQ). Based on an analytical link loss model, we study the distance-hop trade-off via mathematical analysis and exten- sive simulations of a wide array of blacklisting/link-selection strategies; we also validate some strategies using a set of real experiments on motes. Our analysis, simulations and ex- periments all show that the product of the packet reception rate (PRR) and the distance traversed towards destination is the optimal forwarding metric for the ARQ case, and is a good metric even without ARQ. Nodes using this metric often take advantage of neighbors in the transitional region (high-variance links). Our results also show that reception- based forwarding strategies are more efficient than purely distance-based strategies; relative blacklisting schemes re- duce disconnections and achieve higher delivery rates than absolute blacklisting schemes; and that ARQ schemes be- come more important in larger networks. Categories and Subject Descriptors C.2.1 [ Network Architecture and Design ]: Wireless communications; C.4 [ Performance of Systems ]: Perfor- * This work has been supported in part by NSF under grants number 0347621 and 0134650, Intel, Pratt&Whitney, and a gift grant from Ember Corporation. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee....
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SeadaZunigaKrishnamachariHelmy_Sensys04 - Energy-Efficient...

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