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    Comparative study of task allocation strategies in multirobot systems
    (IEEE-INST Electrical Electronics Engineers Inc, 2013-01) Hatime, Hicham; Pendse, Ravi; Watkins, John Michael
    In this paper, we present a comparative study of three distributed strategies for task allocation in a multirobot system. The objective is to determine the course of action for each robot and the targets it needs to service. A theoretical section is provided to support the dynamics of these techniques and some of the results. The first technique is a neural network-based approach, known as self-organizing map (SOM), that assigns targets to the robot on the basis of competition. The second technique is a combinatorial technique, known as the Hungarian method for solving assignment problems. The third technique is an integer linear programming-based optimization approach that tries to minimize the cost of task allocation. By implementing these three techniques, we observed that SOM tends to yield better results in terms of cost of assignment and execution time, but suffers from lack of fairness and workload balancing. In contrast, the other two methods fulfill the two criteria, but at the expense of a relatively higher cost.
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    Adaptive algorithms for sensor activation in renewable energy based sensor systems
    (ELSEVIER SCIENCE BV, 2013-06) Jaggi, Neeraj; Madakasira, Sreenivas; Mereddy, Sandeep Reddy; Pendse, Ravi
    Upcoming sensor networks would be deployed with sensing devices with energy harvesting capabilities from renewable energy sources such as solar power. A key research question in such sensor systems is to maximize the asymptotic event detection probability achieved in the system, in the presence of energy constraints and uncertainties. This paper focuses on the design of adaptive algorithms for sensor activation in the presence of uncertainty in the event phenomena. Based upon the ideas from increase/decrease algorithms used in TCP congestion avoidance, we design an online and adaptive activation algorithm that varies the subsequent sleep interval according to additive increase and multiplicative decrease depending upon the sensor's current energy level. In addition, the proposed algorithm does not depend on global system parameters, or on the degree of event correlations, and hence can easily be deployed in practical scenarios. We analyze the performance of proposed algorithm for a single sensor scenario using Markov chains, and show that the proposed algorithm achieves near-optimal performance. Through extensive simulations, we demonstrate that the proposed algorithm not only achieves near-optimal performance, but also exhibits more stability with respect to sensor's energy level and sleep interval variations. We validate the applicability of our proposed algorithm in the presence of multiple sensors and multiple event processes through simulations.
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    Analytical estimation of path duration in mobile Ad Hoc networks
    (IEEE, 2012-06) Namuduri, Kameswara; Pendse, Ravi
    Path duration is an important design parameter that determines the performance of a mobile ad hoc network (MANET). For example, it can be used to estimate the route expiry time parameter for routes in "on demand" routing protocols. This paper proposes an analytical model to estimate path duration in a MANET using the random way point mobility model as a reference. The salient feature of the proposed model is that it establishes a relationship between path duration and MANET design parameters including node density, transmission range, number of hops, and velocity of nodes. Although this relationship has been previously demonstrated through simulations, a detailed analytical model is not available in the literature to present. In particular, the relationship between path duration and node density has not been derived in previous models. The accuracy of the proposed model is validated by comparing the results obtained from the analytical model with the experimental results ava! ilable in literature and with the results of simulations carried out in ns-2.
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    Bridging the generation gap
    (IEEE, 2005-12) Bahety, V.; Pendse, Ravi
    The demand for mobile service increase many service providers which they start finding solutions for integrating third and fourth generation networks and to develop mobility protocols. This article introduces the macromobility, micromobility, and ad hoc routing protocols the Internet Engineering Task Force (IETF) has discussed. The aim is to familiarize readers with various mobility protocols, point out differences, and generate interest to pursue research. Cellular IP can perform handoffs in a number of ways, and it uses an efficient paging technique. To achieve this, it uses two mappings: paging cache (PC) and routing cache (RC). PCs are used only to search for (mobile node) MNs while RCs are used to route data to the MNs. Micromobility protocols complement MIP by reducing signaling overheads and enabling faster handoffs for seamless connectivity. These protocols handle local movements of MN without any interaction with MIP. It reduces the bandwidth consumption and another advantage of reducing signaling overheads is that it helps to conserve the power reserves of MNs.
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    Mobility and layer 2 tunnels
    (2006) Bhagavathula, Ravi; Best, Patricia K.; Pendse, Ravi
    An increase in the size and requirements of a mobile workforce is driving the development of better mobility oriented services in terms of both content and connectivity. Even though traditional Mobile IP has been the primary means of providing mobility to nodes roaming between foreign networks, its extension to support the mobility of entire networks leads to an increase in the encapsulation overheads. In addition, the increasing perception within the mobile workforce as to the inadequacies of Layer 3 connectivity provided by traditional Mobile IP opens up the possibility of considering the mobility problem from a Layer 2 perspective. This paper presents a Layer 2 extension to the traditional implementation of Mobile IP by replacing the IP-IP tunnels of Mobile IP with L2TPv3 based Layer 2 tunnels. Simulations results obtained from performance evaluation indicate comparable performance of the proposed Layer 2 mobility solution with respect to traditional Mobile IP in terms of real-time and best-effort traffic streams. The proposed Layer 2 mobility solution increases the possible services available to mobile nodes with minimal performance degradation.