Performance analysis of an experimental wireless relay sensor network

Communication through relay channels in wireless sensor networks can create diversity and consequently improve the robustness of data transmission for ubiquitous computing and networking applications. In this paper, we investigate the performances of relay channels in terms of diversity gain and throughput via both experimental research and theoretical analysis. Two relaying algorithms, dynamic relaying and fixed relaying, are utilised and tested to find out what the relay channels can contribute to system performances. The tests are based on a wireless relay sensor network comprising a source node, a destination node and a couple of relay nodes, and carried out in an indoor environment with rare movement of objects nearby. The tests confirm, in line with the analytical results, that more relay nodes lead to higher diversity gain in the network. The test results also show that the data throughput between the source node and the destination node is enhanced by the presence of the relay nodes. Energy consumption in association with the relaying strategy is also analysed. Copyright �� 2009 John Wiley & Sons, Ltd.

Secure routing and trust computation in multihop infrastructureless networks

Today's wireless networks rely mostly on infrastructural support for their operation. With the concept of ubiquitous computing growing more popular, research on infrastructureless networks have been rapidly growing. However, such types of networks face serious security challenges when deployed. This dissertation focuses on designing a secure routing solution and trust modeling for these infrastructureless networks. ^ The dissertation presents a trusted routing protocol that is capable of finding a secure end-to-end route in the presence of malicious nodes acting either independently or in collusion, The solution protects the network from active internal attacks, known to be the most severe types of attacks in an ad hoc application. Route discovery is based on trust levels of the nodes, which need to be dynamically computed to reflect the malicious behavior in the network. As such, we have developed a trust computational model in conjunction with the secure routing protocol that analyzes the different malicious behavior and quantifies them in the model itself. Our work is the first step towards protecting an ad hoc network from colluding internal attack. To demonstrate the feasibility of the approach, extensive simulation has been carried out to evaluate the protocol efficiency and scalability with both network size and mobility. ^ This research has laid the foundation for developing a variety of techniques that will permit people to justifiably trust the use of ad hoc networks to perform critical functions, as well as to process sensitive information without depending on any infrastructural support and hence will enhance the use of ad hoc applications in both military and civilian domains. ^

Location management and routing in urban vehicular ad hoc networks

In recent years, urban vehicular ad hoc networks (VANETs) are gaining importance for inter-vehicle communication, because they allow for the local communication between vehicles without any infrastructure, configuration effort, and without expensive cellular networks. But such architecture may increase the complexity of routing since there is no central control system in urban VANETs. Therefore, a challenging research task is to improve urban VANETs' routing efficiency. ^ Hence, in this dissertation we propose two location-based routing protocols and a location management protocol to facilitate location-based routing in urban VANETs. The Multi-hop Routing Protocol (MURU) is proposed to make use of predicted mobility and geometry map in urban VANETs to estimate a path's life time and set up robust end-to-end routing paths. The Light-weight Routing Protocol (LIRU) is proposed to take advantage of the node diversity under dynamic channel condition to exploit opportunistic forwarding to achieve efficient data delivery. A scalable location management protocol (MALM) is also proposed to support location-based routing protocols in urban VANETs. MALM uses high mobility in VANETs to help disseminate vehicles' historical location information, and a vehicle is able to implement Kalman-filter based predicted to predict another vehicle's current location based on its historical location information. ^

Writer and activist Susan Brownmiller speaking at the last AD-Hoc meeting before the 5th Avenue March

General note: Title and date provided by Bettye Lane.

Recomendr-entity recommendation based on ad-hoc dimensions

The growing availability and popularity of opinion rich resources on the online web resources, such as review sites and personal blogs, has made it convenient to find out about the opinions and experiences of layman people. But, simultaneously, this huge eruption of data has made it difficult to reach to a conclusion. In this thesis, I develop a novel recommendation system, Recomendr that can help users digest all the reviews about an entity and compare candidate entities based on ad-hoc dimensions specified by keywords. It expects keyword specified ad-hoc dimensions/features as input from the user and based on those features; it compares the selected range of entities using reviews provided on the related User Generated Contents (UGC) e.g. online reviews. It then rates the textual stream of data using a scoring function and returns the decision based on an aggregate opinion to the user. Evaluation of Recomendr using a data set in the laptop domain shows that it can effectively recommend the best laptop as per user-specified dimensions such as price. Recomendr is a general system that can potentially work for any entities on which online reviews or opinionated text is available.

Ad hoc procedure for optimising agreement between observational records

Observational studies in the field of sport are complicated by the added difficulty of having to analyse multiple, complex events or behaviours that may last just a fraction of a second. In this study, we analyse three aspects related to the reliability of data collected in such a study. The first aim was to analyse and compare the reliability of data sets assessed quantitatively (calculation of kappa statistic) and qualitatively (consensus agreement method). The second aim was to describe how, by ensuring the alignment of events, we calculated the kappa statistic for the order parameter using SDIS-GSEQ software (version 5.1) for data sets containing different numbers of sequences. The third objective was to describe a new consultative procedure designed to remove the confusion generated by discordant data sets and improve the reliability of the data. The procedure is called "consultative" because it involves the participation of a new observer who is responsible for consulting the existing observations and deciding on the definitive result.

AD-HOC principles of minimum energy expenditure as corollaries of the constructal law the cases of river basins and human vascular systems

In a recent paper [1] Reis showed that both the principles of extremum of entropy production rate, which are often used in the study of complex systems, are corollaries of the Constructal Law. In fact, both follow from the maximization of overall system conductivities, under appropriate constraints. In this way, the maximum rate of entropy production (MEP) occurs when all the forces in the system are kept constant. On the other hand, the minimum rate of entropy production (mEP) occurs when all the currents that cross the system are kept constant. In this paper it is shown how the so-called principle of "minimum energy expenditure" which is often used as the basis for explaining many morphologic features in biologic systems, and also in inanimate systems, is also a corollary of Bejan's Constructal Law [2]. Following the general proof some cases namely, the scaling laws of human vascular systems and river basins are discussed as illustrations from the side of life, and inanimate systems, respectively.

Sensor Integration for Smart Cities Using Multi-Hop Networks

Smart Cities are designed to be living systems and turn urban dwellers life more comfortable and interactive by keeping them aware of what surrounds them, while leaving a greener footprint. The Future Cities Project [1] aims to create infrastructures for research in smart cities including a vehicular network, the BusNet, and an environmental sensor platform, the Urban Sense. Vehicles within the BusNet are equipped with On Board Units (OBUs) that offer free Wi-Fi to passengers and devices near the street. The Urban Sense platform is composed by a set of Data Collection Units (DCUs) that include a set of sensors measuring environmental parameters such as air pollution, meteorology and noise. The Urban Sense platform is expanding and receptive to add new sensors to the platform. The parnership with companies like TNL were made and the need to monitor garbage street containers emerged as air pollution prevention. If refuse collection companies know prior to the refuse collection which route is the best to collect the maximum amount of garbage with the shortest path, they can reduce costs and pollution levels are lower, leaving behind a greener footprint. This dissertation work arises in the need to monitor the garbage street containers and integrate these sensors into an Urban Sense DCU. Due to the remote locations of the garbage street containers, a network extension to the vehicular network had to be created. This dissertation work also focus on the Multi-hop network designed to extend the vehicular network coverage area to the remote garbage street containers. In locations where garbage street containers have access to the vehicular network, Roadside Units (RSUs) or Access Points (APs), the Multi-hop network serves has a redundant path to send the data collected from DCUs to the Urban Sense cloud database. To plan this highly dynamic network, the Wi-Fi Planner Tool was developed. This tool allowed taking measurements on the field that led to an optimized location of the Multi-hop network nodes with the use of radio propagation models. This tool also allowed rendering a temperature-map style overlay for Google Earth [2] application. For the DCU for garbage street containers the parner company provided the access to a HUB (device that communicates with the sensor inside the garbage containers). The Future Cities use the Raspberry pi as a platform for the DCUs. To collect the data from the HUB a RS485 to RS232 converter was used at the physical level and the Modbus protocol at the application level. To determine the location and status of the vehicles whinin the vehicular network a TCP Server was developed. This application was developed for the OBUs providing the vehicle Global Positioning System (GPS) location as well as information of when the vehicle is stopped, moving, on idle or even its slope. To implement the Multi-hop network on the field some scripts were developed such as pingLED and ���shark���. These scripts helped upon node deployment on the field as well as to perform all the tests on the network. Two setups were implemented on the field, an urban setup was implemented for a Multi-hop network coverage survey and a sub-urban setup was implemented to test the Multi-hop network routing protocols, Optimized Link State Routing Protocol (OLSR) and Babel.

Amostragem Adaptativa em Redes de Sensores

Uma nova ��rea tecnol��gica est�� em crescente desenvolvimento. Esta ��rea, denominada de internet das coisas, surge na necessidade de interligar v��rios objetos para uma melhoria a n��vel de servi��os ou necessidades por parte dos utilizadores. Esta disserta����o concentra-se numa ��rea espec��fica da tecnologia internet das coisas que �� a sensoriza����o. Esta rede de sensoriza����o �� implementada pelo projeto europeu denominado de Future Cities [1] onde se cria uma infraestrutura de investiga����o e valida����o de projetos e servi��os inteligentes na cidade do Porto. O trabalho realizado nesta disserta����o insere-se numa das plataformas existentes nessa rede de sensoriza����o: a plataforma de sensores ambientais intitulada de UrbanSense. Estes sensores ambientais que est��o incorporados em Data Collect Unit (DCU), tamb��m denominados por n��s, medem vari��veis ambientais tais como a temperatura, humidade, ozono e mon��xido de carbono. No entanto, os n��s t��m recursos limitados em termos de energia, processamento e mem��ria. Apesar das grandes evolu����es a n��vel de armazenamento e de processamento, a n��vel energ��tico, nomeadamente nas baterias, n��o existe ainda uma evolu����o t��o not��vel, limitando a sua operacionalidade [2]. Esta tese foca-se, essencialmente, na melhoria do desempenho energ��tico da rede de sensores UrbanSense. A principal contribui����o �� uma adapta����o do protocolo de redes Ad Hoc OLSR (Optimized Link State Routing Protocol) para ser usado por n��s alimentados a energia renov��vel, de forma a aumentar a vida ��til dos n��s da rede de sensoriza����o. Com esta contribui����o �� poss��vel obter um maior n��mero de dados durante per��odos de tempo mais longos, aproximadamente 10 horas relativamente ��s 7 horas anteriores, resultando numa maior recolha e envio dos mesmos com uma taxa superior, cerca de 500 KB/s. Existindo deste modo uma aproxima����o anal��tica dos v��rios par��metros existentes na rede de sensoriza����o. Contudo, o aumento do tempo de vida ��til dos n��s sensores com recurso �� energia renov��vel, nomeadamente, energia solar, incrementa o seu peso e tamanho que limita a sua mobilidade. Com o referido acr��scimo a determinar e a limitar a sua mobilidade exigindo, por isso, um planeamento pr��vio da sua localiza����o. Numa primeira fase do trabalho analisou-se o consumo da DCU, visto serem estes a base na infraestrutura e comunicando entre si por WiFi ou 3G. Ap��s uma an��lise dos protocolos de routing com iv suporte para parametriza����o energ��tica, a escolha recaiu sobre o protocolo OLSR devido �� maturidade e compatibilidade com o sistema atual da DCU, pois apesar de existirem outros protocolos, a implementa����o dos mesmos, n��o se encontram dispon��vel como software aberto. Para a valida����o do trabalho realizado na presente disserta����o, �� realizado um ensaio pr��vio sem a energia renov��vel, para permitir caracteriza����o de limita����es do sistema. Com este ensaio, tornou-se poss��vel verificar a compatibilidade entre os v��rios materiais e ajustamento de estrat��gias. Num segundo teste de valida����o �� concretizado um ensaio real do sistema com 4 n��s a comunicar, usando o protocolo com efici��ncia energ��tica. O protocolo �� avaliado em termos de aumento do tempo de vida ��til do n�� e da taxa de transfer��ncia. O desenvolvimento da an��lise e da adapta����o do protocolo de rede Ad Hoc oferece uma maior longevidade em termos de tempo de vida ��til, comparando ao que existe durante o processamento de envio de dados. Apesar do tempo de longevidade ser inferior, quando o par��metro energ��tico se encontra por omiss��o com o fator 3, a realiza����o da adapta����o do sistema conforme a energia, oferece uma taxa de transfer��ncia maior num per��odo mais longo. Este �� um fator favor��vel para a abertura de novos servi��os de envio de dados em tempo real ou envio de ficheiros com um tamanho mais elevado.

Seguretat en xarxes i aplicacions distribu��des: MANET routing

L���objectiu del projecte ��s tractar de donar soluci�� al problema d���interconnexi�� de dispositius m��bils, en concret de PDAs Nokia 810, en una situaci�� on no es disposa d���un punt d���acc��s fixe. Per a fer-ho possible es forma una xarxa MANET, ��s a dir una xarxa Ad-hoc m��bil, on els nodes s��n els propis dispositius. Un cop establerta la connexi��, s���obt�� un llistat actualitzat amb les adreces IP de tots els nodes visibles de la xarxa.

Sotilaan paikkatiedon siirt��minen tietoverkoissa

Paikkatietoj��rjestelm��n avulla voidaan seurata maastossa olevien sotilaiden sijaintia karttasovellukselta. Paikkatietoj��rjestelmien k��ytt��minen lis���� tilannetietoisuutta ja palvelusturvallisuutta. Tutkimuksen tavoitteena on kehitt���� sotilaan paikkatietoj��rjestelm��n k��ytett��vyytt�� Puolustusvoimissa. Tutkimuksessa esitell����n paikkatietoj��rjestelm�� sotilastoiminnassa ja yleiset paikantamismenetelm��t. Tutkimuksessa selvitet����n paikkatietoj��rjestelm����n soveltuvat tietoverkot ja tekniikat. Tutkimuksessa esitell����n paikkatietoj��rjestelm����n kehitteill�� oleva sanomanv��litysj��rjestelm��.

Impact of transmission errors in enhanced relay-enabled distributed coordination function

This paper analyzes the performance of Enhanced relay-enabled Distributed Coordination Function (ErDCF) for wireless ad hoc networks under transmission errors. The idea of ErDCF is to use high data rate nodes to work as relays for the low data rate nodes. ErDCF achieves higher throughput and reduces energy consumption compared to IEEE 802.11 Distributed Coordination Function (DCF) in an ideal channel environment. However, there is a possibility that this expected gain may decrease in the presence of transmission errors. In this work, we modify the saturation throughput model of ErDCF to accurately reflect the impact of transmission errors under different rate combinations. It turns out that the throughput gain of ErDCF can still be maintained under reasonable link quality and distance.

Performance evaluation of enhanced relay-enabled distributed coordination function

In this paper we evaluate the performance of our earlier proposed enhanced relay-enabled distributed coordination function (ErDCF) for wireless ad hoc networks. The idea of ErDCF is to use high data rate nodes to work as relays for the low data rate nodes. ErDCF achieves higher throughput and reduced energy consumption compared to IEEE 802.11 distributed coordination function (DCF). This is a result of. 1) using relay which helps to increase the throughput and lower overall blocking time of nodes due to faster dual-hop transmission, 2) using dynamic preamble (i.e. using short preamble for the relay transmission) which further increases the throughput and lower overall blocking time and also by 3) reducing unnecessary overhearing (by other nodes not involved in transmission). We evaluate the throughput and energy performance of the ErDCF with different rate combinations. ErDCF (11,11) (ie. R1=R2=11 Mbps) yields a throughput improvement of 92.9% (at the packet length of 1000 bytes) and an energy saving of 72.2% at 50 nodes.

Analysis of enhanced relay-enabled distributed coordination function under transmission errors

This paper analyzes the performance of enhanced relay-enabled distributed coordination function (ErDCF) for wireless ad hoc networks under transmission errors. The idea of ErDCF is to use high data rate nodes to work as relays for the low data rate nodes. ErDCF achieves higher throughput and reduces energy consumption compared to IEEE 802.11 distributed coordination function (DCF) in an ideal channel environment. However, there is a possibility that this expected gain may decrease in the presence of transmission errors. In this work, we modify the saturation throughput model of ErDCF to accurately reflect the impact of transmission errors under different rate combinations. It turns out that the throughput gain of ErDCF can still be maintained under reasonable link quality and distance.

Delay analysis of enhanced relay-enabled distributed coordination function

This paper analyzes the delay performance of Enhanced relay-enabled Distributed Coordination Function (ErDCF) for wireless ad hoc networks under ideal condition and in the presence of transmission errors. Relays are nodes capable of supporting high data rates for other low data rate nodes. In ideal channel ErDCF achieves higher throughput and reduced energy consumption compared to IEEE 802.11 Distributed Coordination Function (DCF). This gain is still maintained in the presence of errors. It is also expected of relays to reduce the delay. However, the impact on the delay behavior of ErDCF under transmission errors is not known. In this work, we have presented the impact of transmission errors on delay. It turns out that under transmission errors of sufficient magnitude to increase dropped packets, packet delay is reduced. This is due to increase in the probability of failure. As a result the packet drop time increases, thus reflecting the throughput degradation.