Network Lifetime and Coverage Fraction Analysis for Wireless Sensor Networks

285-291In Wireless Sensor Networks, two crucial parameters are lifetime of the network and optimal coverage for sensed region. This paper addresses the issues and challenges pertaining to these parameters for further investigation, and provides a method to approximate the energy utilization and optimal coverage inside the bottleneck zone for wireless sensor networks. The proposed analytical framework calculates correctly the network lifetime upper bound of wireless sensor networks. The derivation of the network lifetime upper bound is carried out using (i) network coding and (ii) network coding with duty cycle. Based on that, an approximate derivation is made and the corresponding results are obtained from the simulation study. The comparison of the results of the previous study and those obtained in this paper reveals that the actual network lifetime upper bound is lower in the present case. This is due to the assumption made by authors of previous work, on coder nodes’ presence throughout the bottleneck zone instead of only one hop distance away from the sink. In addition, the effect of coverage fraction in case of node failure, on network lifetime upper bound is derived for the previously reported and present model. The simulated results obtained from new derivation show that the coverage fraction is lesser than that obtained by previous model

Network Lifetime and Coverage Fraction Analysis for Wireless Sensor Networks

In Wireless Sensor Networks, two crucial parameters are lifetime of the network and optimal coverage for sensed region. This paper addresses the issues and challenges pertaining to these parameters for further investigation, and provides a method to approximate the energy utilization and optimal coverage inside the bottleneck zone for wireless sensor networks. The proposed analytical framework calculates correctly the network lifetime upper bound of wireless sensor networks. The derivation of the network lifetime upper bound is carried out using (i) network coding and (ii) network coding with duty cycle. Based on that, an approximate derivation is made and the corresponding results are obtained from the simulation study.  The comparison of the results of the previous study and those obtained in this paper reveals that the actual network lifetime upper bound is lower in the present case. This is due to the assumption made by authors of previous work, on coder nodes’ presence throughout the bottleneck zone instead of only one hop distance away from the sink. In addition, the effect of coverage fraction in case of node failure, on network lifetime upper bound is derived for the previously reported and present model. The simulated results obtained from new derivation show that the coverage fraction is lesser than that obtained by previous model

LR3: Link Reliable Reactive Routing Protocol for Wireless Sensor Networks

Existing reliable-oriented routing protocols computes link reliability based on the packet reception ratio and neglects impact of various parameters such as noise, shadowing, battery-lifespan, uncertainty and geographic locations. In this paper, we propose a Link Reliable Reactive Routing (LR3) protocol for WSNs to accomplish reliable and resilience to out-of-order transmission and path diversity at each hop. The log-normal shadowing model is used to estimate link reliability and a back-off scheme is used to determine delay. A new cost estimated to? nd forwarding nodes on mentor path that includes link reliability, delay, status of queue at forwarding node and packet advancement at the forwarding node. LR3 is simulated using NS-2 and results show that it outperforms other reactive routing protocols in terms of packet delivery ratio, latency, link reliability and data transmission cost [1][2]

Energy saving and reliability for Wireless Body Sensor Networks (WBSN)

In healthcare and medical applications, the energy consumption of biosensor nodes affects the collection of biomedical data packets, which are sensed and measured from the human body and then transmitted toward the sink node. Nodes that are near to the sink node consume more energy as all biomedical packets are aggregated through these nodes when communicated to sink node. Each biosensor node in a wireless body sensor networks (WBSNs) such as ECG (Electrocardiogram), should provide accurate biomedical data due to the paramount importance of patient information. We propose a technique to minimise energy consumed by biosensor nodes in the bottleneck zone for WBSNs, which applies the Coordinated Duty Cycle Algorithm (CDCA) to all nodes in the bottleneck zone. Superframe order (SO) selection in CDCA is based on real traffic and the priority of the nodes in the WBSN. Furthermore, we use a special case of network coding, called Random Linear Network coding (RLNC), to encode the biomedical packets to improve reliability through calculating the probability of successful reception (PSR) at the sink node. It can be concluded that CDCA outperforms other algorithms in terms of energy saving as it achieves energy savings for most biosensor nodes in WBSNs. RLNC employs relay nodes to achieve the required level of reliability in WBSNs and to guarantee that the biomedical data is delivered correctly to the sink nod

Mobile Target Detection in Wireless Sensor Networks With Adjustable Sensing Frequency

How to sense and monitor the environment with high quality is an important research subject in the Internet of Things (IOT). This paper deals with the important issue of the balance between the quality of target detection and lifetime in wireless sensor networks. Two target-monitoring schemes are proposed. One scheme is Target Detection with Sensing Frequency K (TDSFK), which distributes the sensing time that currently is only on a portion of the sensing period into the entire sensing period. That is, the sensing frequency increases from 1 to K. The other scheme is Target Detection with Adjustable Sensing Frequency (TDASF), which adjusts the sensing frequency on those nodes that have residual energy. The simulation results show that the TDASF scheme can improve the network lifetime by more than 17.4% and can reduce the weighted detection delay by more than 101.6%

Analog Signal Buffering and Reconstruction

Wireless sensor networks (WSNs) are capable of a myriad of tasks, from monitoring critical infrastructure such as bridges to monitoring a person\u27s vital signs in biomedical applications. However, their deployment is impractical for many applications due to their limited power budget. Sleep states are one method used to conserve power in resource-constrained systems, but they necessitate a wake-up circuit for detecting unpredictable events. In conventional wake-up-based systems, all information preceding a wake-up event will be forfeited. To avoid this data loss, it is necessary to include a buffer that can record prelude information without sacrificing the power savings garnered by the active use of sleep states.;Unfortunately, traditional memory buffer systems utilize digital electronics which are costly in terms of power. Instead of operating in the target signal\u27s native analog environment, a digital buffer must first expend a great deal of energy to convert the signal into a digital signal. This issue is further compounded by the use of traditional Nyquist sampling which does not adapt to the characteristics of a dynamically changing signal. These characteristics reveal why a digital buffer is not an appropriate choice for a WSN or other resource-constrained system.;This thesis documents the development of an analog pre-processing block that buffers an incoming signal using a new method of sampling. This method requires sampling only local maxima and minima (both amplitude and time), effectively approximating the instantaneous Nyquist rate throughout a time-varying signal. The use of this sampling method along with ultra-low-power analog electronics enables the entire system to operate in the muW power levels. In addition to these power saving techniques, a reconfigurable architecture will be explored as infrastructure for this system. This reconfigurable architecture will also be leveraged to explore wake-up circuits that can be used in parallel with the buffer system

Lifetime and Energy Hole Evolution Analysis in Data-Gathering Wireless Sensor Networks

Abstract-Network lifetime is a crucial performance metric to evaluate data-gathering wireless sensor networks (WSNs) where battery-powered sensor nodes periodically sense the environment and forward collected samples to a sink node. In this paper, we propose an analytic model to estimate the entire network lifetime from network initialization until it is completely disabled, and determine the boundary of energy hole in a data-gathering WSN. Specifically, we theoretically estimate the traffic load, energy consumption, and lifetime of sensor nodes during the entire network lifetime. Furthermore, we investigate the temporal and spatial evolution of energy hole, and apply our analytical results to WSN routing in order to balance the energy consumption and improve the network lifetime. Extensive simulation results are provided to demonstrate the validity of the proposed analytic model in estimating the network lifetime and energy hole evolution process. Index Terms-wireless sensor network, network lifetime, energy hole, energy efficiency, routing

Codificação de rede na retransmissão oportunista de mensagens em redes de sensores sem fio IEEE 802.15.4

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Automação e Sistemas, Florianópolis, 2014As Redes de Sensores sem Fio (RSSF) vêm apresentando uma penetração cada vez maior nas mais distintas áreas, dados a sua versatilidade e o seu baixo custo. Mais recentemente foi proposto seu emprego no chão de fábrica, com o surgimento de diversos padrões específicos, com especial destaque ao padrão IEEE 802.15.4. O ambiente industrial possui duas características que o diferenciam dos demais ambientes de aplicação das RSSF: requisitos de tempo real na troca de mensagens e alto índice de ruído eletromagnético que provocam altas taxas de perdas de mensagens. Sendo assim, é determinante para a aplicação das RSSF no ambiente industrial que se maximize a confiabilidade na troca de mensagens com garantias temporais. Neste sentido, esta tese propõe um novo algoritmo de codificação de rede para retransmissão oportunista de mensagens, aplicado a redes de sensores sem fio no padrão IEEE 802.15.4. Essa proposta emprega técnicas de codificação de rede, cooperação e diversidade temporal objetivando aumentar a confiabilidade na troca de mensagens. A codificação de rede é utilizada em nodos retransmissores para, sempre que necessário, agrupar um conjunto de mensagens e retransmiti-las. O coordenador da rede, ao receber o conjunto de mensagens originais e mensagens codificadas, consegue aumentar significativamente a taxa de sucesso das mensagens recebidas e, consequentemente, minimizar o consumo energético e do uso do meio na rede. Para comprovar a eficácia dessa proposta foi realizado um conjunto de ensaios experimentais com várias plataformas de nodos, principalmente o MicaZ, e simulações no OMNeT++, em variadas topologias de rede. Com o comparativo da nova técnica com técnicas tradicionais de retransmissão de mensagens se comprovou o melhor desempenho da nova proposta. Também foram realizados ensaios experimentais que comprovaram a factibilidade da codificação de rede em nodos das RSSF.Abstract: Wireless Sensor Networks (WSN) based applications have been increased in different applications areas, due to their versatility and low cost. Recently, its adoption has been proposed on factory floor, with the emergence of several specific standards, with special emphasis on the IEEE 802.15.4 standard. The industrial environment has two particular features that differs from traditional WSN application environments:(i) real-time constraints in messaging streams and (ii) high level of electromagnetic noise, which causes high rates of loss messages.Therefore, it is mandatory for industrial WSN application to maximize the reliability in messages exchanging with temporal guarantees. In this sense, this thesis proposes a new network coding algorithm for opportunistic relaying messages, applied to IEEE 802.15.4 WSN. This proposal employs network coding techniques, time diversity and cooperation in order to increase the message reliability. Network coding is adopted at relays nodes to group a set of messages and retransmit them. The network coordinator, upon receiving the set of original messages and coded messages can signicantly increase the success rate of incoming messages and, consequently, minimize the energy consumption through the network. To assess the effectiveness of this proposal several studies have been conducred in diferent sensor nodes platforms, especially the MicaZ and simulations in OMNeT++ considering various network topologies. Simulation results show that the proposed approach outperforms traditional ralaying techniques. Experimental assessment indicates the feasibility of network coding in the WSN nodes