Institute for Systems Research Technical Reports
Permanent URI for this collectionhttp://hdl.handle.net/1903/4376
This archive contains a collection of reports generated by the faculty and students of the Institute for Systems Research (ISR), a permanent, interdisciplinary research unit in the A. James Clark School of Engineering at the University of Maryland. ISR-based projects are conducted through partnerships with industry and government, bringing together faculty and students from multiple academic departments and colleges across the university.
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Item Distributed Topology Control for Stable Path Routing in Multi-hop Wireless Networks(2010-03) Somasundaram, Kiran; Baras, John; Jain, Kaustubh; Tabatabaee, VahidIn this paper, we introduce the stable path topology control problem for routing in mobile multi-hop networks. We formulate the topology control problem of selective link-state broadcast as a graph pruning problem with restricted local neighborhood information. We develop a multi-agent optimiza- tion framework where the decision policies of each agent are restricted to local policies on incident edges and independent of the policies of the other agents. We show that under a condition called the positivity condition, these independent local policies preserve the stable routing paths globally. We then provide an efficient algorithm to compute an optimal local policy that yields a minimal pruned graph, which we call the Stable Path Topology Control (SPTC) algorithm. Using simulations, we demonstrate that this algorithm, when used with the popular ETX metric, outperforms topology control mechanisms commonly used for Mobile Ad Hoc Networks.Item Distributed Topology Control for Stable Path Routing in Mobile Ad Hoc Networks(2009-11-25) Somasundaram, Kiran; Jain, Kaustubh; Tabatabaee, Vahid; Baras, JohnItem Distributed Topology Control for Stable Path Routing in Mobile Ad Hoc Networks(2009-12-09) Somasundaram, Kiran K.; Jain, Kaustubh; Tabatabaee, Vahid; Baras, John S.In this paper, we introduce the stable path topology control problem for routing in Mobile Ad Hoc Networks (MANETs). We formulate the problem as a constrained multiagent optimization problem with only local neighborhood information. We develop and prove local pruning strategies that solve this problem. We also introduce the notion of distorted pruning, which offers a systematic method to trade path stability off against the hop count metric. Finally, we quantify the performance of our pruning algorithms using several simulation scenarios.Item Component Based Performance Modelling of the Wireless Routing Protocols(2008) Tabatabaee, Vahid; Baras, John S.; Purkayastha, Punyaslok; Somasundaram, KiranIn this paper, we propose a component based methodology for modelling and design of wireless routing protocols. Componentization is a standard methodology for analysis and synthesis of complex systems. Throughout the paper, we use Optimized Link State Routing (OLSR) protocol as a case study to demonstrate effectiveness of our methodology. We focus on modelling of three main components: neighborhood discovery, selector of topology information to disseminate, and the path selection components. For each component, we identify the inputs, outputs, and a generic methodology for modelling. Using the neighborhood discovery component, we will present our design methodology and design a modified enhanced version of the OLSR NDC, and compare its performance to the neighborhood discovery component of the OLSR protocol.Item Performance Metric Sensitivity Computation for Optimization and Trade-off Analysis in Wireless Networks(2008-02-26) Baras, John S.; Tabatabaee, Vahid; Papageorgiou, George; Rentz, NicolasWe develop and evaluate a new method for estimating and optimizing various performance metrics for multi-hop wireless networks, including MANETs. We introduce an approximate (throughput) loss model that couples the physical, MAC and routing layers effects. The model provides quantitative statistical relations between the loss parameters that are used to characterize multiuser interference and physical path conditions on the one hand and the traffic rates between origin-destination pairs on the other. The model takes into account effects of the hidden nodes, scheduling algorithms, IEEE 802.11 MAC and PHY layer transmission failures and finite packet transmission retries at the MAC layer in arbitrary network topologies where multiple paths share nodes. We apply Automatic Differentiation (AD) to these implicit performance models, and develop a methodology for sensitivity analysis, parameter optimization and trade-off analysis for key wireless protocols. Finally, we provide simulation experiments to evaluate the effectiveness and performance estimation accuracy of the proposed models and methodologies.Item Robust Routing with Unknown Traffic Matrices(2006) Tabatabaee, Vahid; Kashyap, Abhishek; Bhattacharjee, Bobby; La, Richard J.; Shayman, Mark; Shayman, Mark; ISR