Algorithmic Aspects of Capacity in Wireless Networks V.S. Anil Kumar * Basic and Applied Simulation Science (CCS-5) and National Infrastructure and Analysis Center (NISAC) Los Alamos National Laboratory MS M997, P.O. Box 1663 Los Alamos, NM 87545 anil@lanl.gov Madhav V. Marathe Department of Computer Science and Virginia BioInformatics Institute Virginia Tech Blacksburg, VA 24061 mmarathe@vbi.vt.edu Srinivasan Parthasarathy † Department of Computer Science University of Maryland College Park, MD 20742 sri@cs.umd.edu Aravind Srinivasan ‡ Department of Computer Science and Institute for Advanced Computer Studies University of Maryland College Park, MD 20742 srin@cs.umd.edu ABSTRACT This paper considers two inter-related questions: (i) Given a wireless ad-hoc network and a collection of source-destination pairs {(si ,ti )}, what is the maximum throughput capacity of the network, i.e. the rate at which data from the sources to their corresponding destinations can be transferred in the network? (ii) Can network protocols be designed that jointly route the packets and schedule transmissions at rates close to the maximum throughput capacity? Much of the ear- lier work focused on random instances and proved analyt- ical lower and upper bounds on the maximum throughput capacity. Here, in contrast, we consider arbitrary wireless networks. Further, we study the algorithmic aspects of the above questions: the goal is to design provably good algo- rithms for arbitrary instances. We develop analytical per- formance evaluation models and distributed algorithms for * The work is supported by the Department of Energy under Contract W-7405-ENG-36. † Most of the work was done while visiting Los Alamos National laboratory. Research supported in part by NSF Award CCR-0208005 and NSF ITR Award CNS-0426683. ‡ Research supported in part by NSF Award CCR-0208005 and NSF ITR Award CNS-0426683. 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. SIGMETRICS’05, June 6–10, 2005, Banff, Alberta, Canada. Copyright 2005 ACM 1-59593-022-1/05/0006 ...$5.00. routing and scheduling which incorporate fairness, energy and dilation (path-length) requirements and provide a uni- fied framework for utilizing the network close to its maxi- mum throughput capacity. Motivated by certain popular wireless protocols used in practice, we also explore “shortest-path like” path selection strategies which maximize the network throughput. The theoretical results naturally suggest an interesting class of congestion aware link metrics which can be directly plugged into several existing routing protocols such as AODV, DSR, etc. We complement the theoretical analysis with extensive simulations. The results indicate that routes obtained using our congestion aware link metrics consistently yield higher throughput than hop-count based shortest path metrics. Categories and Subject Descriptors C.4 [Computer Systems Organization]: PERFORMANCE OF SYSTEMS—Modeling techniques ; F.2.3 [Theory of Com- putation]: ANALYSIS OF ALGORITHMS AND PROB- LEM COMPLEXITY—Tradeoffs among Complexity Mea- sures General Terms Algorithms, Performance Keywords capacity modeling, end-to-end scheduling, linear program- ming, wireless networks 1. INTRODUCTION Two central questions in communication networks are: what is the throughput capacity of the network, and how can