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Jose Rolim

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Università degli Studi di Bergamo (University of Bergamo)

London South Bank University

University of Cologne

Philipp Marquetand

University of Vienna

José L. Costa-Krämer

CSIC (Consejo Superior de Investigaciones Científicas-Spanish National Research Council)

Angelamaria Cardone

University of Salerno

Saulo Xavier de Souza

Centro Universitário do Distrito Federal – UDF Biblioteca Governador Eurico

Yildiz Technical University

Xianfeng David Gu

SUNY: Stony Brook University

Dominique Richon

Aalto University

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Papers by Jose Rolim

A Service Based Architecture for Multidisciplinary IoT Experiments with Crowdsourced Resources

by Jose Rolim, Marios Karagiannis, and Orestis Evangelatos

Lecture Notes in Computer Science, 2016

Work-in-progress: Efficient heuristics for low radiation paths in wireless sensor networks

2011 International Conference on Distributed Computing in Sensor Systems and Workshops (DCOSS), 2011

We call radiation at a point of a wireless network the total amount of electromagnetic quantity (... more We call radiation at a point of a wireless network the total amount of electromagnetic quantity (energy or power density) the point is exposed to. The impact of radiation can be high and we believe it is worth studying and control; towards radiation aware wireless networking we take (for the first time in the study of this aspect) a distributed computing, algorithmic approach.

Early Obstacle Detection and Avoidance for All to All Traffic Pattern in Wireless Sensor Networks

Lecture Notes in Computer Science, 2009

This paper deals with early obstacles recognition in wireless sensor networks under various traff... more This paper deals with early obstacles recognition in wireless sensor networks under various traffic patterns. In the presence of obstacles, the efficiency of routing algorithms is increased by voluntarily avoiding some regions in the vicinity of obstacles, areas which we call dead-ends. In this paper, we first propose a fast convergent routing algorithm with proactive dead-end detection together with a formal definition and description of dead-ends. Secondly, we present a generalization of this algorithm which improves performances in all to many and all to all traffic patterns. In a third part we prove that this algorithm produces paths that are optimal up to a constant factor of 2π + 1. In a fourth part we consider the reactive version of the algorithm which is an extension of a previously known early obstacle detection algorithm. Finally we give experimental results to illustrate the efficiency of our algorithms in different scenarios.

Near optimal geographic routing with obstacle avoidance in wireless sensor networks by fast-converging trust-based algorithms

by Pierre Leone and Jose Rolim

Proceedings of the 3rd ACM workshop on QoS and security for wireless and mobile networks - Q2SWinet '07, 2007

Geographic routing scales well in sensor networks, mainly due to its stateless nature. Still, mos... more Geographic routing scales well in sensor networks, mainly due to its stateless nature. Still, most of the algorithms are concerned with finding some path, while the optimality of the path is difficult to achieve. In this paper we are presenting a novel geographic routing algorithm with obstacle avoidance properties. It aims at finding the optimal path from a source to a destination when some areas of the network are unavailable for routing due to low local density or obstacle presence. It locally and gradually with time (but, as we show, quite fast) evaluates and updates the suitability of the previously used paths and ignores non optimal paths for further routing. By means of extensive simulations, we are comparing its performance to existing state of the art protocols, showing that it performs much better in terms of path length thus minimizing latency, space, overall traffic and energy consumption.

The Design of an Open and Integrated Sensor Network Management Platform

Lecture Notes in Computer Science, 2008

... Michalis Kalochristianakis1, Vasileios Gkamas1, Georgios Mylonas1, Sotiris Nikoletseas1, Jose... more

An Optimal Data Propagation Algorithm for Maximizing the Lifespan of Sensor Networks

by Pierre Leone and Jose Rolim

Lecture Notes in Computer Science, 2006

We consider the problem of data propagation in wireless sensor networks and revisit the family of... more We consider the problem of data propagation in wireless sensor networks and revisit the family of mixed strategy routing schemes. We show that maximizing the lifespan, balancing the energy among individual sensors and maximizing the message flow in the network are equivalent. We propose a distributed and adaptive data propagation algorithm for balancing the energy among sensors in the network. The mixed routing algorithm we propose allows each sensor node to either send a message to one of its immediate neighbors, or to send it directly to the base station, the decision being based on a potential function depending on its remaining energy. By considering a simple model of the network and using a linear programming description of the message flow, we prove the strong result that an energy-balanced mixed strategy beats every other possible routing strategy in terms of lifespan maximization. Moreover, we provide sufficient conditions for ensuring the dynamic stability of the algorithm. The algorithm is inspired by the gradient-based routing scheme but by allowing to send messages directly to the base station we improve considerably the lifespan of the network. As a matter of fact, we show experimentally that our algorithm is close to optimal and that it even beats the best centralized multi-hop routing strategy.

Numerical Estimation of the Impact of Interferences on the Localization Problem in Sensor Networks

Lecture Notes in Computer Science, 2006

ABSTRACT In this paper we numerically analyze the impact of interferences on the probability of s... more ABSTRACT In this paper we numerically analyze the impact of interferences on the probability of success of a localization algorithm. This problem is particularly relevant in the context of sensor networks. Actually, our numerical results are relevant even when we do not consider interferences. Moreover, our numerical computations show that the main harmful interferences are the ones occurring between sensors which get localized at the same time and send simultaneously their own location. This is demonstrated by varying the time span of the random waiting time before the emissions. We then observe that the longer the waiting time the closer the curves are to the ones obtained without interferences. Hence, this proves to be an efficient way of reducing the impact of interferences. Moreover, our numerical experiments demonstrate that among the sectors of disk with same area, the one with the smaller radius of emission and larger angle of emission is the more appropriate to the localization algorithm.

An Adaptive Blind Algorithm for Energy Balanced Data Propagation in Wireless Sensors Networks

by Pierre Leone and Jose Rolim

Lecture Notes in Computer Science, 2005

In this paper, we consider the problem of energy balanced data propagation in wireless sensor net... more In this paper, we consider the problem of energy balanced data propagation in wireless sensor networks and we generalise previous works by allowing realistic energy assignment. A new modelisation of the process of energy consumption as a random walk along with a new analysis are proposed. Two new algorithms are presented and analysed. The first one is easy to implement and fast to execute. However, it needs a priori assumptions on the process generating data to be propagated. The second algorithm overcomes this need by inferring information from the observation of the process. Furthermore, this algorithm is based on stochastic estimation methods and is adaptive to environmental changes. This represents an important contribution for propagating energy balanced data in wireless sensor netwoks due to their highly dynamic nature.

Localization Algorithm for Wireless Ad-Hoc Sensor Networks with Traffic Overhead Minimization by Emission Inhibition

Lecture Notes in Computer Science, 2006

Widely used positioning systems like GPS are not a valid solution in large networks with small si... more Widely used positioning systems like GPS are not a valid solution in large networks with small size, low cost sensors, due both to their size and their cost. Thus, new solutions for localization awareness are emerging, commonly based on the existence of a few references spread into the network. During a localization algorithms, each entity of the network can evaluate its geographical coordinates relative to these references. We propose a localization algorithm to reduce the number of transmitting nodes. The algorithm relies on self selecting nodes for location information disclosure. Each node makes a decision based on its proximity to the nodes in the area covered only by two of the references used for its own localization. We analyze different aspects of the location awareness propagation problem: communication overhead, redundant transmissions, network coverage.

Efficient Obstacle Avoidance for Sensory Data Propagation in Wireless Systems

Trends and Standards, 2010

... Wireless Network Traffic and Quality of Service Support: Trends and Standards, ed. Thomas Lag... more

Efficient Graph Planarization in Sensor Networks and Local Routing Algorithm

2012 IEEE 8th International Conference on Distributed Computing in Sensor Systems, 2012

Abstract-In this paper, we propose an efficient planarizationalgorithm and a routing algorithm de... more Abstract-In this paper, we propose an efficient planarizationalgorithm and a routing algorithm dedicatedto Unit Disk Graphs whose nodes are localized usingthe Virtual Raw Anchor Coordinate system (VRAC).Our first algorithm computes a planar 2-spanner underlight constraints on the edge lengths and induces a totalexchange of at most 6n node identifiers. Its total complexity is O(n?, with ? the maximum degreeof the

Symmetric Coherent Link Degree, Adaptive Throughput-Transmission Power for Wireless Sensor Networks

2014 IEEE International Conference on Distributed Computing in Sensor Systems, 2014

Topology Control Protocols configure transmission power of nodes in order to achieve specific pro... more Topology Control Protocols configure transmission power of nodes in order to achieve specific properties to a given topology. These properties include the creation and maintenance of neighborhoods or other topological entities (like trees or clusters), load balancing in terms of connectivity degrees and provision of link symmetry. We see topology control as a two-fold problem where topological properties can also be affected by local network throughput. We propose SCLD-A2TP, a protocol that operates in a two phase adaptive scheme. First transmission power is adaptively adjusted with low throughput settings and nodes achieve a sufficient degree of symmetric and coherent links. Secondly throughput is maximized insofar as the degree is maintained. We assess various distributed heuristics for SCLD-A2TP via testbed experiments and show that up to an extend, link quality and symmetry as well as degree conformity of links can be regulated successfully by transmission power and adaptive throughput control.

Design and evaluation of a real-time locating system for wireless sensor networks

Journal of Location Based Services, 2014

Evaluating target tracking protocols for wireless sensor networks that can localize multiple mobi... more Evaluating target tracking protocols for wireless sensor networks that can localize multiple mobile assets, can be a very challenging task. Such protocols usually aim at the minimization of communication overhead, data processing for the participating nodes, as well as delivering adequate tracking information of the mobile assets in a timely manner. Simulations on such protocols are performed using theoretical models that are based on unrealistic assumptions like the unit disk graph communication model, ideal network localization and perfect distance estimations. With these assumptions taken for granted, theoretical models claim various performance milestones that cannot be achieved in realistic conditions. In this paper we design a new localization protocol, where mobile assets can be tracked passively via software agents. Moreover, we address and mitigate issues that hinder performance over the wireless medium and provide a fully deployable protocol. The design, implementation and experimentation of this new protocol along with further optimizations, were performed using the WISEBED framework. We apply our protocol in a real indoors wireless sensor testbed with multiple experimental scenarios to showcase scalability and trade-offs between network properties and configurable protocol parameters. By analysis of the real world experimental output, we present results that depict a more realistic view of the target tracking problem, regarding power consumption and the quality of tracking information. Finally we also conduct some very focused simulations to assess the scalability of our protocol in very large networks and multiple mobile assets.

A Comparative Study of Performance of AES Final Candidates Using FPGAs

Lecture Notes in Computer Science, 2000

In this paper we study and compare the performance of FPGA-based implementations of the five fina... more In this paper we study and compare the performance of FPGA-based implementations of the five final AES candidates (MARS, RC6, Rijndael, Serpent, and Twofish). Our goal is to evaluate the suitability of the aforementioned algorithms for FPGA-based implementations. Among the various time-space implementation tradeoffs, we focused primarily on time performance. The time performance metrics are throughput and key-setup latency. Throughput corresponds to the amount of data processed per time unit while the key-setup latency time is the minimum time required to commence encryption after providing the input key. Time performance and area requirement results are provided for all the final AES candidates. To the best of our knowledge, we are not aware of any published results that include key-setup latency results. Our results suggest that Rijndael and Serpent favor FPGA implementations the most since their algorithmic characteristics match extremely well with the hardware characteristics of FPGAs.

Developing 3D applications for mobile devices

2005 2nd Asia Pacific Conference on Mobile Technology, Applications and Systems, 2005

... Motorola, United States CB Vieira, CLF Saad, EGO Silva, MGS Oliveira, M. Araújo, PVCG Filho, ... more

Irida: A Real-Time Wireless Sensor Network Visualization Feedback Protocol

by Jose Rolim and Marios Karagiannis

2012 IEEE 8th International Conference on Distributed Computing in Sensor Systems, 2012

In this paper, we describe the implementation of a real time visualization and feedback system fo... more In this paper, we describe the implementation of a real time visualization and feedback system for Wireless Sensor Network algorithms. The system is based on a fixed hardware testbed, which is deployed on a vertical flat surface and a feedback loop system that takes information about the current state of the network and projects this state, in a visual way, on the surface itself using a video projector. The protocol used is open and simple to use, and can be easily adapted for different hardware configurations. We call our system Irida.

Las Vegas versus determinism for one-way communication complexity, finite automata, and polynomial-time computations

Lecture Notes in Computer Science, 1997

... As a consequence we have found another substantial difference between one-way and two-waycomm... more

Randomized Energy Balance Algorithms in Sensor Networks

Lighweight target tracking using passive traces in sensor networks

We study the important problem of tracking moving targets in wireless sensor networks. We try to ... more We study the important problem of tracking moving targets in wireless sensor networks. We try to overcome the limitations of standard state of the art tracking methods based on continuous location tracking, i.e. the high energy dissipation and communication overhead imposed by the active participation of sensors in the tracking process and the low scalability, especially in sparse networks. Instead, our approach uses sensors in a passive way: they just record and judiciously spread information about observed target presence in their vicinity; this information is then used by the (powerful) tracking agent to locate the target by just following the traces left at sensors. Our protocol is greedy, local, distributed, energy efficient and very successful, in the sense that (as shown by extensive simulations) the tracking agent manages to quickly locate and follow the target; also, we achieve good trade-offs between the energy dissipation and latency.

Algorithmic aspects of wireless sensor networks-Preface

... Jie Gao Magnus Halldorsson Riko Jacob Alexander Kroller Fabian Kuhn Miroslaw Kutylowski Alber... more

A Service Based Architecture for Multidisciplinary IoT Experiments with Crowdsourced Resources

by Jose Rolim, Marios Karagiannis, and Orestis Evangelatos

Lecture Notes in Computer Science, 2016

Work-in-progress: Efficient heuristics for low radiation paths in wireless sensor networks

2011 International Conference on Distributed Computing in Sensor Systems and Workshops (DCOSS), 2011

We call radiation at a point of a wireless network the total amount of electromagnetic quantity (... more We call radiation at a point of a wireless network the total amount of electromagnetic quantity (energy or power density) the point is exposed to. The impact of radiation can be high and we believe it is worth studying and control; towards radiation aware wireless networking we take (for the first time in the study of this aspect) a distributed computing, algorithmic approach.

Early Obstacle Detection and Avoidance for All to All Traffic Pattern in Wireless Sensor Networks

Lecture Notes in Computer Science, 2009

This paper deals with early obstacles recognition in wireless sensor networks under various traff... more This paper deals with early obstacles recognition in wireless sensor networks under various traffic patterns. In the presence of obstacles, the efficiency of routing algorithms is increased by voluntarily avoiding some regions in the vicinity of obstacles, areas which we call dead-ends. In this paper, we first propose a fast convergent routing algorithm with proactive dead-end detection together with a formal definition and description of dead-ends. Secondly, we present a generalization of this algorithm which improves performances in all to many and all to all traffic patterns. In a third part we prove that this algorithm produces paths that are optimal up to a constant factor of 2π + 1. In a fourth part we consider the reactive version of the algorithm which is an extension of a previously known early obstacle detection algorithm. Finally we give experimental results to illustrate the efficiency of our algorithms in different scenarios.

Near optimal geographic routing with obstacle avoidance in wireless sensor networks by fast-converging trust-based algorithms

by Pierre Leone and Jose Rolim

Proceedings of the 3rd ACM workshop on QoS and security for wireless and mobile networks - Q2SWinet '07, 2007

Geographic routing scales well in sensor networks, mainly due to its stateless nature. Still, mos... more Geographic routing scales well in sensor networks, mainly due to its stateless nature. Still, most of the algorithms are concerned with finding some path, while the optimality of the path is difficult to achieve. In this paper we are presenting a novel geographic routing algorithm with obstacle avoidance properties. It aims at finding the optimal path from a source to a destination when some areas of the network are unavailable for routing due to low local density or obstacle presence. It locally and gradually with time (but, as we show, quite fast) evaluates and updates the suitability of the previously used paths and ignores non optimal paths for further routing. By means of extensive simulations, we are comparing its performance to existing state of the art protocols, showing that it performs much better in terms of path length thus minimizing latency, space, overall traffic and energy consumption.

The Design of an Open and Integrated Sensor Network Management Platform

Lecture Notes in Computer Science, 2008

... Michalis Kalochristianakis1, Vasileios Gkamas1, Georgios Mylonas1, Sotiris Nikoletseas1, Jose... more

An Optimal Data Propagation Algorithm for Maximizing the Lifespan of Sensor Networks

by Pierre Leone and Jose Rolim

Lecture Notes in Computer Science, 2006

We consider the problem of data propagation in wireless sensor networks and revisit the family of... more We consider the problem of data propagation in wireless sensor networks and revisit the family of mixed strategy routing schemes. We show that maximizing the lifespan, balancing the energy among individual sensors and maximizing the message flow in the network are equivalent. We propose a distributed and adaptive data propagation algorithm for balancing the energy among sensors in the network. The mixed routing algorithm we propose allows each sensor node to either send a message to one of its immediate neighbors, or to send it directly to the base station, the decision being based on a potential function depending on its remaining energy. By considering a simple model of the network and using a linear programming description of the message flow, we prove the strong result that an energy-balanced mixed strategy beats every other possible routing strategy in terms of lifespan maximization. Moreover, we provide sufficient conditions for ensuring the dynamic stability of the algorithm. The algorithm is inspired by the gradient-based routing scheme but by allowing to send messages directly to the base station we improve considerably the lifespan of the network. As a matter of fact, we show experimentally that our algorithm is close to optimal and that it even beats the best centralized multi-hop routing strategy.

Numerical Estimation of the Impact of Interferences on the Localization Problem in Sensor Networks

Lecture Notes in Computer Science, 2006

ABSTRACT In this paper we numerically analyze the impact of interferences on the probability of s... more ABSTRACT In this paper we numerically analyze the impact of interferences on the probability of success of a localization algorithm. This problem is particularly relevant in the context of sensor networks. Actually, our numerical results are relevant even when we do not consider interferences. Moreover, our numerical computations show that the main harmful interferences are the ones occurring between sensors which get localized at the same time and send simultaneously their own location. This is demonstrated by varying the time span of the random waiting time before the emissions. We then observe that the longer the waiting time the closer the curves are to the ones obtained without interferences. Hence, this proves to be an efficient way of reducing the impact of interferences. Moreover, our numerical experiments demonstrate that among the sectors of disk with same area, the one with the smaller radius of emission and larger angle of emission is the more appropriate to the localization algorithm.

An Adaptive Blind Algorithm for Energy Balanced Data Propagation in Wireless Sensors Networks

by Pierre Leone and Jose Rolim

Lecture Notes in Computer Science, 2005

In this paper, we consider the problem of energy balanced data propagation in wireless sensor net... more In this paper, we consider the problem of energy balanced data propagation in wireless sensor networks and we generalise previous works by allowing realistic energy assignment. A new modelisation of the process of energy consumption as a random walk along with a new analysis are proposed. Two new algorithms are presented and analysed. The first one is easy to implement and fast to execute. However, it needs a priori assumptions on the process generating data to be propagated. The second algorithm overcomes this need by inferring information from the observation of the process. Furthermore, this algorithm is based on stochastic estimation methods and is adaptive to environmental changes. This represents an important contribution for propagating energy balanced data in wireless sensor netwoks due to their highly dynamic nature.

Localization Algorithm for Wireless Ad-Hoc Sensor Networks with Traffic Overhead Minimization by Emission Inhibition

Lecture Notes in Computer Science, 2006

Widely used positioning systems like GPS are not a valid solution in large networks with small si... more Widely used positioning systems like GPS are not a valid solution in large networks with small size, low cost sensors, due both to their size and their cost. Thus, new solutions for localization awareness are emerging, commonly based on the existence of a few references spread into the network. During a localization algorithms, each entity of the network can evaluate its geographical coordinates relative to these references. We propose a localization algorithm to reduce the number of transmitting nodes. The algorithm relies on self selecting nodes for location information disclosure. Each node makes a decision based on its proximity to the nodes in the area covered only by two of the references used for its own localization. We analyze different aspects of the location awareness propagation problem: communication overhead, redundant transmissions, network coverage.

Efficient Obstacle Avoidance for Sensory Data Propagation in Wireless Systems

Trends and Standards, 2010

... Wireless Network Traffic and Quality of Service Support: Trends and Standards, ed. Thomas Lag... more

Efficient Graph Planarization in Sensor Networks and Local Routing Algorithm

2012 IEEE 8th International Conference on Distributed Computing in Sensor Systems, 2012

Abstract-In this paper, we propose an efficient planarizationalgorithm and a routing algorithm de... more Abstract-In this paper, we propose an efficient planarizationalgorithm and a routing algorithm dedicatedto Unit Disk Graphs whose nodes are localized usingthe Virtual Raw Anchor Coordinate system (VRAC).Our first algorithm computes a planar 2-spanner underlight constraints on the edge lengths and induces a totalexchange of at most 6n node identifiers. Its total complexity is O(n?, with ? the maximum degreeof the

Symmetric Coherent Link Degree, Adaptive Throughput-Transmission Power for Wireless Sensor Networks

2014 IEEE International Conference on Distributed Computing in Sensor Systems, 2014

Topology Control Protocols configure transmission power of nodes in order to achieve specific pro... more Topology Control Protocols configure transmission power of nodes in order to achieve specific properties to a given topology. These properties include the creation and maintenance of neighborhoods or other topological entities (like trees or clusters), load balancing in terms of connectivity degrees and provision of link symmetry. We see topology control as a two-fold problem where topological properties can also be affected by local network throughput. We propose SCLD-A2TP, a protocol that operates in a two phase adaptive scheme. First transmission power is adaptively adjusted with low throughput settings and nodes achieve a sufficient degree of symmetric and coherent links. Secondly throughput is maximized insofar as the degree is maintained. We assess various distributed heuristics for SCLD-A2TP via testbed experiments and show that up to an extend, link quality and symmetry as well as degree conformity of links can be regulated successfully by transmission power and adaptive throughput control.

Design and evaluation of a real-time locating system for wireless sensor networks

Journal of Location Based Services, 2014

Evaluating target tracking protocols for wireless sensor networks that can localize multiple mobi... more Evaluating target tracking protocols for wireless sensor networks that can localize multiple mobile assets, can be a very challenging task. Such protocols usually aim at the minimization of communication overhead, data processing for the participating nodes, as well as delivering adequate tracking information of the mobile assets in a timely manner. Simulations on such protocols are performed using theoretical models that are based on unrealistic assumptions like the unit disk graph communication model, ideal network localization and perfect distance estimations. With these assumptions taken for granted, theoretical models claim various performance milestones that cannot be achieved in realistic conditions. In this paper we design a new localization protocol, where mobile assets can be tracked passively via software agents. Moreover, we address and mitigate issues that hinder performance over the wireless medium and provide a fully deployable protocol. The design, implementation and experimentation of this new protocol along with further optimizations, were performed using the WISEBED framework. We apply our protocol in a real indoors wireless sensor testbed with multiple experimental scenarios to showcase scalability and trade-offs between network properties and configurable protocol parameters. By analysis of the real world experimental output, we present results that depict a more realistic view of the target tracking problem, regarding power consumption and the quality of tracking information. Finally we also conduct some very focused simulations to assess the scalability of our protocol in very large networks and multiple mobile assets.

A Comparative Study of Performance of AES Final Candidates Using FPGAs

Lecture Notes in Computer Science, 2000

In this paper we study and compare the performance of FPGA-based implementations of the five fina... more In this paper we study and compare the performance of FPGA-based implementations of the five final AES candidates (MARS, RC6, Rijndael, Serpent, and Twofish). Our goal is to evaluate the suitability of the aforementioned algorithms for FPGA-based implementations. Among the various time-space implementation tradeoffs, we focused primarily on time performance. The time performance metrics are throughput and key-setup latency. Throughput corresponds to the amount of data processed per time unit while the key-setup latency time is the minimum time required to commence encryption after providing the input key. Time performance and area requirement results are provided for all the final AES candidates. To the best of our knowledge, we are not aware of any published results that include key-setup latency results. Our results suggest that Rijndael and Serpent favor FPGA implementations the most since their algorithmic characteristics match extremely well with the hardware characteristics of FPGAs.

Developing 3D applications for mobile devices

2005 2nd Asia Pacific Conference on Mobile Technology, Applications and Systems, 2005

... Motorola, United States CB Vieira, CLF Saad, EGO Silva, MGS Oliveira, M. Araújo, PVCG Filho, ... more

Irida: A Real-Time Wireless Sensor Network Visualization Feedback Protocol

by Jose Rolim and Marios Karagiannis

2012 IEEE 8th International Conference on Distributed Computing in Sensor Systems, 2012

In this paper, we describe the implementation of a real time visualization and feedback system fo... more In this paper, we describe the implementation of a real time visualization and feedback system for Wireless Sensor Network algorithms. The system is based on a fixed hardware testbed, which is deployed on a vertical flat surface and a feedback loop system that takes information about the current state of the network and projects this state, in a visual way, on the surface itself using a video projector. The protocol used is open and simple to use, and can be easily adapted for different hardware configurations. We call our system Irida.

Las Vegas versus determinism for one-way communication complexity, finite automata, and polynomial-time computations

Lecture Notes in Computer Science, 1997

... As a consequence we have found another substantial difference between one-way and two-waycomm... more

Randomized Energy Balance Algorithms in Sensor Networks

Lighweight target tracking using passive traces in sensor networks

We study the important problem of tracking moving targets in wireless sensor networks. We try to ... more We study the important problem of tracking moving targets in wireless sensor networks. We try to overcome the limitations of standard state of the art tracking methods based on continuous location tracking, i.e. the high energy dissipation and communication overhead imposed by the active participation of sensors in the tracking process and the low scalability, especially in sparse networks. Instead, our approach uses sensors in a passive way: they just record and judiciously spread information about observed target presence in their vicinity; this information is then used by the (powerful) tracking agent to locate the target by just following the traces left at sensors. Our protocol is greedy, local, distributed, energy efficient and very successful, in the sense that (as shown by extensive simulations) the tracking agent manages to quickly locate and follow the target; also, we achieve good trade-offs between the energy dissipation and latency.

Algorithmic aspects of wireless sensor networks-Preface

... Jie Gao Magnus Halldorsson Riko Jacob Alexander Kroller Fabian Kuhn Miroslaw Kutylowski Alber... more

Design and evaluation of a lightweight tracking algorithm using WSN

by Ioannis Chatzigiannakis and Jose Rolim

Proceedings - 8th IEEE International Conference on Mobile Ad-hoc and Sensor Systems, MASS 2011, 2011

Evaluating target tracking protocols for wireless sensor networks that can localize multiple mobi... more Evaluating target tracking protocols for wireless sensor networks that can localize multiple mobile devices, can be a very challenging task. Such protocols usually aim at minimizing communication overhead, data processing for the participating nodes, as well as delivering adequate tracking information of the mobile targets in a timely manner. In this paper we design a new localization protocol, where mobile assets can be tracked passively via software agents. We address the issues that hinder its performance due to the real environment conditions and provide a deployable protocol. The implementation, integration and experimentation of this new protocol and it's optimizations, were performed using the WISEBED framework. We apply our protocol in an indoors wireless sensor testbeds with multiple experimental scenarios to showcase scalability and trade-offs between network properties and configurable protocol parameters. The analysis of experimental results, depict a real view of the target tracking problem, regarding power consumption and the quality of tracking information.