Aloysio Pedroza

CTCP: Reliable Transport Control Protocol for sensor networks

This work presents collaborative transport control protocol (CTCP), a new transport protocol for sensor networks. It aims at providing end-to-end reliability and adapts itself to different applications through a two level mechanism of reliability variation. CTCP achieves these properties using hop-by-hop acknowledgments and a storage control algorithm that operates at each node along a flow. It was observed that distributed fault recovery increases 98% the average delivery rate and that duplication of storage responsibility minimizes the message loss. Its congestion control differentiates communication losses from buffer overflow. CTCP is called collaborative because all nodes detect and act on congestion control and also because it includes distributed storage responsibility. It is scalable and independent of the underlying network layer. The protocol energy consumption overhead was calculated and discussed for two reliability levels.

Underwater monitoring system for oil exploration using acoustic sensor networks

This paper proposes an underwater monitoring system built with sensors distributed over a subsea infrastructure, which is responsible for operation and transportation of oil production. We consider the use of currently available equipment. Data is transmitted by underwater acoustic modems installed on the sensors, platforms and vessels used for logistic support of the oil exploration. These vessels are used to collect data and provide references for positioning the sensors. However, the vessels may not be within the sensor range at all times, requiring the use of Delay/Disruption Tolerant Network. This work performs an analysis of the behavior of the monitoring system, investigating the features that influence the underwater sensor network, using the Opportunistic Network Environment simulator. In this case, the displacement of logistic-support vessels on the maritime routes is very important, therefore we consider real-world scenarios based on the Brazilian offshore oil exploration area.

Optimized datapath design by evolutionary computation

High-level design entry tools offer a nice framework to deal with todays complex systems while shortening the design cycle. Nevertheless, such tools provide poor quality results both in area usage and timing performance issues. This paper presents a methodology to design optimized datapaths based on evolutionary techniques and HLS tools. VHDL descriptions of the system are automatically generated by Genetic Programming. To improve the design of the structural quality of such descriptions, a two-stage multi-objective optimization algorithm is used to ensure both desired functionality and area constraints.

Using genetic programming and high level synthesis to design optimized datapath

This paper presents a methodology to design optimized electronic digital systems from high abstraction level descriptions. The methodology uses Genetic Programming in addition to high-level synthesis tools to automatically improve design structural quality (area measure). A two-stage, multiobjective optimization algorithm is used to search for circuits with the desired functionality subjected additionally to chip area constraints. Experiment with a square-root approximation datapath design targeted to FPGA exemplifies the proposed methodology.

Quality of service in a DiffServ domain using policy-based management

The Differentiated Services architecture has been proposed to offer quality of service in the Internet. Most works on Diffserv (DS) handles QoS guarantees in a per node basis, which assumes that assuring QoS in a single node also leads to the desired QoS in the entire DS domain. Nevertheless, this is not always true. This paper proposes a framework that offers QoS in a DS domain using Policy-based Management and fuzzy logic techniques. The QoS controller reconfigures all DS nodes according to ingress traffic and domain policies. Policy Based Management is used in this framework to provide QoS in DS domain, controlling heterogeneous equipments of different manufacturers. The performance and functionalities of a prototype are shown by simulation of a voice over IP application.

Mobility Support for Wireless Sensor Networks

This work proposes a two-tier approach for mobility support in wireless sensor networks. It is based on local interactions among sensors, on global tasks of mobile agents and on location prediction. We demonstrate the correctness of a simple location prediction model. We also propose, evaluate and compare two algorithms for mobile agents decision. The proposed scheme is stateless and does not need a routing protocol. All computing (location prediction and mobile agents decision) are of linear complexity. We observed a better performance as mobility degree and node density grow.

Collaborative Transport Control Protocol for Sensor Networks

This work presents collaborative transport control protocol (CTCP), a new transport protocol for sensor networks. It aims at providing end-to-end reliability and adapts itself to different applications through a mechanism of reliability variation. Its congestion control and detection differentiates communication losses from buffer overflow. CTCP is called collaborative because all nodes detect and act on congestion control and also because it includes distributed storage responsibility. It is scalable and independent of the underlying network layer. It was observed that distributed fault recovery increases reliability and that duplication of storage responsibility minimizes the message loss.

HW/SW codesign of protocols based on performance optimization using genetic algorithms

A design-to-hardware methodology applied to the synthesis of communication protocols based on performance analysis techniques and genetic algorithms is presented. The process requires a choice between the tasks to be implemented in hardware and those to be implemented in software, i.e., the selection of the best HW/SW partition. The proposed methodology uses a genetic algorithm to optimize an error function defined by the required performance and the implementation cost of the protocol. The protocol performance is analyzed by a modelling environment called Tangram-II. The cost of the hardware corresponding to a given implementation is calculated by the Synopsys and ALTERA tools. The methodology is intended as a tool to help protocol designers to select the best performance/cost compromise.

Proposing, specifying, and validating a controller-based routing protocol for a clean-slate Named-Data Networking

Named-Data Networking (NDN) is the most prominent proposal for a clean-slate proposal of Future Internet. Nevertheless, NDN routing schemes present scalability concerns due to the required number of stored routes and of control messages. In this work, we present a controller-based routing protocol using a formal method to unambiguously specify, and validate to prove its correctness. Our proposal codes signaling information on content names, avoiding control message overhead, and reduces router memory requirements, storing only the routes for simultaneously consumed prefixes. Additionally, the protocol installs a new route on all routers in a path with a single route request to the controller, avoiding replication of routing information and automating router provisioning. As a result, we provide a protocol proposal description using the Specification and Description Language and we validate the protocol, proving that CRoS behavior is free of dead or live locks. Furthermore, the protocol validation guarantees that the scheme ensures a valid working path from consumer to producer, even if it does not assure the shortest path.

Anytime route planning with constrained devices

Urban mobility became a major challenge around the world, with frequent congestion and ever growing travel time. Albeit recent advances in the area of Intelligent Transportation Systems (ITS), it is still difficult to predict and manage the road infrastructure due to dynamics and instability of the traffic. One key issue is how, given some traffic monitoring information, a vehicle decides to dynamically change its route. In this paper, we analyze algorithms of the anytime class to make the route planning considering GPS traces of buses in Rio de Janeiro, as a measurement of traffic flows. Anytime algorithms inform, in a timely fashion, a sub-optimal response and progressively improves it as time goes by. We evaluate time and memory consumption, route length, arrival time, average velocity, distance traveled, and pathways on an experimental platform composed of Raspberry Pi nodes. For different time windows, the results show that ARA* allows finding alternative routes that, if used, help reduce traffic congestion.