Browsing by Author "Marathe, Madhav"
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Item Distributed Strategies for Channel Allocation and Scheduling in Software-defined Radio Networks(2008-01-14) Han, Bo; Kumar, V. S. Anil; Marathe, Madhav; Parthasarathy, Srinivasan; Srinivasan, AravindEquipping wireless nodes with multiple radios can significantly increase the capacity of wireless networks, by making these radios simultaneously transmit over multiple nonoverlapping channels. However, due to the limited number of radios and available orthogonal channels, designing efficient channel assignment and scheduling algorithms in such networks is a major challenge. In this paper, we present provably-good (centralized and distributed) algorithms for simultaneous channel allocation of individual links and packet-scheduling, in Software- Defined Radios (SDR) wireless networks. Our distributed algorithms are very simple to implement, and do not require any coordination even among neighboring nodes. A novel access hash function or random oracle methodology is one of the key drivers of our results. With this access hash function, each radio can know the transmitters’ decisions for links in its interference set for each time slot without introducing any extra communication overhead between them. Further, by utilizing the inductivescheduling technique, each radio can also backoff appropriately to avoid collisions. Extensive simulations demonstrate that our bounds are valid in practice.Item Modelling disease outbreaks in realistic urban social networks(2004) Eubank, Stephen; Guclu, Hasan; Kumar, V.S. Anil; Marathe, Madhav; Srinivasan, Aravind; Toroczkai, Zoltan; Want, NanHere we present a highly resolved agent-based simulation tool (EpiSims), which combines realistic estimates of population mobility,based on census and land-use data, with parameterized models for simulating the progress of a disease within a host and of transmission between hosts10. The simulation generates a largescale,dynamic contact graph that replaces the differential equations of the classic approach. EpiSims is based on the Transportation Analysis and Simulation System (TRANSIMS) developed at Los Alamos National Laboratory, which produces estimates of social networks based on the assumption that the transportation infrastructure constrains people’s choices about where and when to perform activities11. TRANSIMS creates a synthetic population endowed with demographics such as age and income, consistent with joint distributions in census data. It then estimates positions and activities of all travellers on a second-by-second basis. For more information on TRANSIMS and its availability, see Supplementary Information. The resulting social network is the best extant estimate of the physical contact patterns among large groups of people—alternative methodologies are limited to physical contacts among hundreds of people or non-physical contacts (such as e-mail or citations) among large groups.