Architectures for wireless sensor networks

The vision of ubiquitous computing requires the development of devices and technologies that can be pervasive without being intrusive. The basic component of such a smart environment will be a small node with sensing and wireless communications capabilities, able to organize itself flexibly into a network for data collection and delivery. Building such a sensor network presents many significant challenges, especially at the architectural, protocol, and operating system level. Although sensor nodes might be equipped with a power supply or energy scavenging means and an embedded processor that makes them autonomous and self-aware, their functionality and capabilities will be very limited. Therefore, collaboration between nodes is essential to deliver smart services in a ubiquitous setting. New algorithms for networking and distributed collaboration need to be developed. These algorithms will be the key for building self-organizing and collaborative sensor networks that show emergent behavior and can operate in a challenging environment where nodes move, fail, and energy is a scarce resource. The question that rises is how to organize the internal software and hardware components in a manner thatwill allowthem towork properly and be able to adapt dynamically to new environments, requirements, and applications. At the same time the solution should be general enough to be suited for as many applications as possible. Architecture definition also includes, at the higher level, a global view of the whole network. The topology, placement of base stations, beacons, etc. is also of interest. In this chapter, we will present and analyze some of the characteristics of the architectures for wireless sensor networks. Then, we will propose a new dataflow-based architecture that allows, as a new feature, the dynamic reconfiguration of the sensor nodes software at runtime

A Crosslayer Routing Protocol (XLRP) for Wireless Sensor Networks

The advent of wireless sensor networks with emphasis on the information being routed, rather than routing information has redefined networking from that of conventional wireless networked systems. Demanding that need for contnt based routing techniques and development of low cost network modules, built to operate in large numbers in a networked fashion with limited resources and capabilities. The unique characteristics of wireless sensor networks have the applicability and effectiveness of conventional algorithms defined for wireless ad-hoc networks, leading to the design and development of protocols specific to wireless sensor network. Many network layer protocols have been proposed for wireless sensor networks, identifying and addressing factors influencing network layer design, this thesis defines a cross layer routing protocol (XLRP) for sensor networks. The submitted work is suggestive of a network layer design with knowledge of application layer information and efficient utilization of physical layer capabilities onboard the sensor modules. Network layer decisions are made based on the quantity of information (size of the data) that needs to be routed and accordingly transmitter power leels are switched as an energy efficient routing strategy. The proposed routing protocol switches radio states based on the received signal strength (RSSI) acquiring only relevant information and piggybacks information in data packets for reduced controlled information exchange. The proposed algorithm has been implemented in Network Simulator (NS2) and the effectiveness of the protocol has been proved in comparison with diffusion paradigm

Enhancing Network Lifetime in Wireless Sensor Networks Adopting Elephant Swarm Optimization

Enhancing the lifetime of wireless sensor networks had baffled researchers for quite some time now. The authors of this research manuscript draw inspiration from the behavior of large elephant swarms and incorporate their behavior into wireless sensor networks. The complex elephant swarm behavior is incorporated using a cross layer approach. The elephant optimization discussed in this paper enables optimized routing techniques, adaptive radio link optimization and balanced scheduling to achieve a cumulative enhanced network performance. The proposed elephant swarm optimization is compared with the popular protocol. The experimental study presented proves that the Elephant Swarm Optimization technique enhances the network life time by about 73%

Underwater Wireless Sensor Networks: How Do Acoustic Propagation Models Impact the Performance of Higher-Level Protocols?

Several Medium Access Control (MAC) and routing protocols have been developed in the last years for Underwater Wireless Sensor Networks (UWSNs). One of the main difficulties to compare and validate the performance of different proposals is the lack of a common standard to model the acoustic propagation in the underwater environment. In this paper we analyze the evolution of underwater acoustic prediction models from a simple approach to more detailed and accurate models. Then, different high layer network protocols are tested with different acoustic propagation models in order to determine the influence of environmental parameters on the obtained results. After several experiments, we can conclude that higher-level protocols are sensitive to both: (a) physical layer parameters related to the network scenario and (b) the acoustic propagation model. Conditions like ocean surface activity, scenario location, bathymetry or floor sediment composition, may change the signal propagation behavior. So, when designing network architectures for UWSNs, the role of the physical layer should be seriously taken into account in order to assert that the obtained simulation results will be close to the ones obtained in real network scenarios

A survey on energy efficient techniques in wireless sensor networks

International audienceThe myriad of potential applications supported by wireless sensor networks (WSNs) has generated much interest from the research community. Various applications range from small size low industrial monitoring to large scale energy constrained environmental monitoring. In all cases, an operational network is required to fulfill the application missions. In addition, energy consumption of nodes is a great challenge in order to maximize network lifetime. Unlike other networks, it can be hazardous, very expensive or even impossible to charge or replace exhausted batteries due to the hostile nature of environment. Researchers are invited to design energy efficient protocols while achieving the desired network operations. This paper focuses on different techniques to reduce the consumption of the limited energy budget of sensor nodes. After having identified the reasons of energy waste in WSNs, we classify energy efficient techniques into five classes, namely data reduction, control reduction, energy efficient routing, duty cycling and topology control. We then detail each of them, presenting subdivisions and giving many examples. We conclude by a recapitulative table

Soluções para redes de sensores sem fio com mobilidade: protocolo de roteamento com priorização de mensagens e mecanismo de predição de conectividade local

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Automação e Sistemas, Florianópolis, 2013.As redes de sensores sem fio (RSSF) proporcionam uma ampla gama de aplicações em diversos setores da sociedade. A comunicação entre os nodos sensores é o elemento básico do funcionamento das redes de sensores. Por isso, o trabalho desta tese se concentra em duas questões essenciais para aperfeiçoamento de protocolos de rede. Primeiramente, uma arquitetura para protocolos de roteamento com garantia de qualidade de serviço foi proposta no escopo de cenárioscom mobilidade. O protocolo proposto utiliza métricas para tomada de decisão para realizar retransmissão de mensagens que refletem as condições da rede, sejam redes densas ou esparsas, com grande ou pouca carga de mensagem. A proposta do protocolo de comunicação foi avaliada sob a ótica de um cenário de aplicação envolvendo mobilidade e diferentes cargas de mensagens. Além disso, as métricas foram desagregadas e analisadas para verificar a sua influência para diferentes condições de rede. Em conjunto à análise das métricas, diversos trabalhos da literatura foram analisados sob os mesmos aspectos e condições de rede para melhor avaliar o ganho do protocolo proposto, o qual se mostrou hábil para o atendimento de requisitos de qualidade de serviço demandado pela aplicação. O segundo aspecto igualmente importante para o desempenho das redes de sensores trata-se do aspecto fundamental para realização da comunicação em ambientes com mobilidade, que é a conectividade. A conectividade foi estudada na sua característica essencial que se refere ao enlace entre dois nodos móveis. Dois modelos foram projetados para proporcionar a estimativa de conectividade por meio da qualidade de enlace para protocolos e aplicações. O primeiro modelo proposto se baseia no comportamento estatístico dos padrões de mobilidade para realizar a estimativa da qualidade de enlace. O segundo modelo proposto se baseia no método de aprendizado sistema classificador para aprender o comportamento do padrão de mobilidade. Ambos os modelos foram implementados e testados com diferentes padrões de mobilidade. Ademais, alguns trabalhos da literatura também foram implementados, avaliados e comparados com os modelos propostos. O método de aprendizado com sistema classificador se mostrou eficiente na estimação de conectividade, bem como capaz de se adaptar a mudanças no padrão de mobilidade.Abstract : Wireless sensor networks (WSN) provide a wide range of applications in various sectors of society. The communication among the sensor nodes is the basic element of sensor networks function. Given this premisse, this thesis focuses on two key issues for the improvement of network protocols. Firstly, an protocol for routing protocols with guaranteed quality of service was proposed to deal with mobility scenarios. The proposed protocol uses several metrics that reflect the network conditions in dense or sparse networks with small or large load of messages for routing decisions. The proposed communication protocol was evaluated from the perspective of an application scenario involving mobility and different loads of messages. Furthermore, the metrics were disaggregated and analyzed to check their influence with different network conditions. Moreover, several algorithms from the iii literature were analyzed under the same aspects and network conditions to better assess the gain of the proposed protocol. The proposed protocol proved to be able to fulfill the quality of service requirements demanded by the application. The second equally important aspect for the performance of WSN it is the fundamental aspect for achieving communication in environments with mobility: the connectivity. Two models were designed to provide connectivity estimation by means of link quality to improve protocols and applications. The first proposed model is based on statistical behavior mobility patterns to perform the estimation of link quality. The second proposed model is based on a learning method classifier system to learn the behavior of the mobility pattern. Both models were implemented and tested with different mobility patterns. Furthermore, other existing approaches have also been implemented, evaluated, and contrasted against the proposed models. The learning method with classifier system is efficient for estimation of connectivity, as well as able to adapt to changes in mobility pattern