@conference {
	title = {Loss Network Models and Multiple Metric Performance Sensitivity Analysis for Mobile Wireless Multi-Hop Networks},
	author = {Baras, John S., Perumal, Senni., Tabatabaee, Vahid., Somasundaram, Kiran K., Purkayastha, Punyaslok.},
	year = {2008},
	month = {11/2008},
	abstract = {We develop and evaluate a new method for estimating and optimizing various performance metrics of mobile wireless multi-hop networks, including MANETs. The method utilizes 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 considers effects of the hidden nodes, node scheduling algorithms, MAC and PHY layer failures and unsuccessful packet transmission attempts at the MAC layer in~arbitrary time-varying network topologies where multiple paths share nodes. The method then applies Automatic Di{\textregistered}erentiation (AD) to these implicit performance models, to compute sensitivities of various performance metrics with respect to net- work parameters. We demonstrate the method by applying it to time-varying mobile network topologies, including reduced connectivity instances, with both random access MAC (contention mode of the 802.11) as well as reservation-based MAC (USAP TDMA based protocol). We analyze throughput, delay and packet loss as metrics and investigate metric optimization and tradeoff analysis. Finally, we provide numerical results for realistic mobile networks with time-varying topologies.},
	address = {Maui, Hawaii},
	booktitle = {Fourth International Wireless Internet Conference (WICON 2008)}
}
@conference {
	title = {A Policy-Based Routing Scheme for Multi-Robot Systems},
	author = {Purkayastha, Punyaslok., Hovareshti, Pedram., Baras, John S.},
	year = {2008},
	month = {06/2008},
	abstract = {In this paper, we consider a policy-based routing scheme for a wireless communication network consisting of a set of robots as nodes. Our scheme provides a communication infrastructure that enables the multi-robot system to accomplish its assigned tasks. Our scheme is adaptive and can be implemented in a distributed manner by the nodes of the network. The scheme makes estimates of link and path costs in the network and uses these estimates to construct probabilistic routing tables in the nodes. We use ideas from the literature on simulation methods for approximate dynamic programming to compute, in a distributed manner, the cost estimates.We propose two schemes that update the probabilistic routing tables at the nodes of the network. One of the schemes is an adaptation of the Linear Reward Inaction rule found in studies of stochastic learning automata. Our other scheme is a modification of an Ant-Based Routing algorithm. We assume a simple model of the link behavior in the wireless network - a message transmission on a wireless link is assumed to be successful with a certain probability and is lost otherwise. We also analyze our algorithms and show that our probabilistic update schemes direct packets along paths with low costs.},
	address = {Ajaccio, France},
	booktitle = {16th Mediterranean Conference on Control and Automation},
	pages = {pp. 970-975}
}
@conference {
	title = {Constrained Coalitional Games and Networks of Autonomous Agents},
	author = {Baras, John S., Jiang, Tao., Purkayastha, Punyaslok.},
	year = {2008},
	month = {03/2008},
	abstract = {We develop a unifying analytical and optimization based framework for the design, operation and performance evaluation of networks of dynamic autonomous agents. The fundamental view is that agents in such a network are dynamic entities that collaborate because via collaboration they can accomplish objectives and goals much better than working alone, or even accomplish objectives that they cannot achieve alone at all. Yet the benefits derived from such collaboration require some costs (e.g. communications), or equivalently, the collaboration is subject to constraints. Understanding and quantifying this tradeoff between the benefits vs the costs of collaboration, leads to new methods that can be used to analyze, design and control/operate networks of agents. Although the inspiration for the framework comes from social and economic networks, the fundamental ideas and in particular the methodology of dynamic constrained coalitional games (DCCG) can unify many concepts and algorithms for networks in various areas: social networks, communication networks, sensor networks, economic networks, biological networks, physics networks. We then analyze a specific instance of such tradeoffs arising in the design of security-aware network protocols. We extend network utility maximization (NUM) so as to encompass security metrics such as {\textquotedblleft}trust{\textquotedblright}. The trust values assigned to nodes are based on interaction history and community-based monitoring. The effect of these trust values on the resulting protocols is that in routing and media access scheduling node trustworthiness is automatically considered and used. We develop a distributed algorithm for the joint physical-MAC-routing protocol design. Our extension to NUM with security concerns leads to resilient networks.},
	address = {St. Julians, Malta},
	booktitle = {Third International Symposium on Communications, Control and Signal Processing},
	pages = {pp. 972-979}
}
