Resource Allocation in Relay Enhanced Broadband Wireless Access Networks

The use of relay nodes to improve the performance of broadband wireless access (BWA) networks has been the subject of intense research activities in recent years. Relay enhanced BWA networks are anticipated to support multimedia traffic (i.e., voice, video, and data traffic). In order to guarantee service to network users, efficient resource distribution is imperative. Wireless multihop networks are characterized by two inherent dynamic characteristics: 1) the existence of wireless interference and 2) mobility of user nodes. Both mobility and interference greatly influence the ability of users to obtain the necessary resources for service. In this dissertation we conduct a comprehensive research study on the topic of resource allocation in the presence of interference and mobility. Specifically, this dissertation investigates the impact interference and mobility have on various aspects of resource allocation, ranging from fairness to spectrum utilization. We study four important resource allocation algorithms for relay enhanced BWA networks. The problems and our research achievements are briefly outlined as follows. First, we propose an interference aware rate adaptive subcarrier and power allocation algorithm using maximum multicommodity flow optimization. We consider the impact of the wireless interference constraints using Signal to Interference Noise Ratio (SINR). We exploit spatial reuse to allocate subcarriers in the network and show that an intelligent reuse of resources can improve throughput while mitigating the impact of interference. We provide a sub-optimal heuristic to solve the rate adaptive resource allocation problem. We demonstrate that aggressive spatial reuse and fine tuned-interference modeling garner advantages in terms of throughput, end-to-end delay and power distribution. Second, we investigate the benefits of decoupled optimization of interference aware routing and scheduling using SINR and spatial reuse to improve the overall achievable throughput. We model the routing optimization problem as a linear program using maximum concurrent flows. We develop an optimization formulation to schedule the link traffic such that interference is mitigated and time slots are reused appropriately based on spatial TDMA (STDMA). The scheduling problem is shown to be NP-hard and is solved using the column generation technique. We compare our formulations to conventional counterparts in the literature and show that our approach guarantees higher throughput by mitigating the effect of interference effectively. Third, we investigate the problem of multipath flow routing and fair bandwidth allocation under interference constraints for multihop wireless networks. We first develop a novel isotonic routing metric, RI3M, considering the influence of interflow and intraflow interference. Second, in order to ensure QoS, an interference-aware max-min fair bandwidth allocation algorithm, LMX:M3F, is proposed where the lexicographically largest bandwidth allocation vector is found among all optimal allocation vectors while considering constraints of interference on the flows. We compare with various interference based routing metrics and interference aware bandwidth allocation algorithms established in the literature to show that RI3M and LMX:M3F succeed in improving network performance in terms of delay, packet loss ratio and bandwidth usage. Lastly, we develop a user mobility prediction model using the Hidden Markov Model(HMM) in which prediction control is transferred to the various fixed relay nodes in the network. Given the HMM prediction model, we develop a routing protocol which uses the location information of the mobile user to determine the interference level on links in its surrounding neighborhood. We use SINR as the routing metric to calculate the interference on a specific link (link cost). We minimize the total cost of routing as a cost function of SINR while guaranteeing that the load on each link does not exceed its capacity. The routing protocol is formulated and solved as a minimum cost flow optimization problem. We compare our SINR based routing algorithm with conventional counterparts in the literature and show that our algorithm reinforces routing paths with high link quality and low latency, therefore improving overall system throughput. The research solutions obtained in this dissertation improve the service reliability and QoS assurance of emerging BWA networks

An SNMP-based audio distribution service architecture

Dissertação de mestrado em Engenharia de Redes e Serviços TelemáticosThe constant growth of integration and popularity of “Internet of Things” devices is affecting home automation systems, where new technologies were introduced, in the recent years for this particular sector. These automation systems integrate devices that can be anywhere in the house, connected to a home network, either through a wire or wireless connection. A home automation system can be used to control air conditioning, lighting, pool control systems, home-entertainment systems and much more. Within the field of home-entertainment systems, the best known technologies are the Digital Living Network Alliance and the Digital Audio Access Protocol, which provide interoperability to allow sharing of digital media content between devices across a home network. However, these technologies have the disadvantage of being proprietary, maintaining restrict documentation access, complex architectures and concepts and not optimal to specific purposes, like audio distribution. The main goal of this project was to prove that is possible to use standardized protocols, such as the Simple Network Manager Protocol and open source tools in order to develop a music distribution service that allows the implementation of similar features than the ones already existing proprietary technologies. As such, the implementation prototype system allows a user to manage and play audio from a music collection that is stored in a single home audio server. The system architecture enables audio streaming between the server and the various devices in the same local network. Further more, the music collection, can integrate virtual audio files that are available from external music sources, like iTunes, etc.O constante crescimento de integração e popularidade da “Internet das coisas” tem atualmente afetado sistemas de domótica, onde cada vez mais tecnologias têm vindo a ser desenvolvidas nos últimos anos para este sector em particular. Estes sistemas de domótica integram dispositivos que podem estar em qualquer parte de uma casa, ligados à rede seja através de um cabo ou por wireless. Um sistema de domótica pode ser usado para controlar: ar condicionado, iluminação, sistemas de controlo de piscinas, sistemas de entretenimento, entre outros. Na área de sistemas de entretenimento, as tecnologias mais conhecidas são Digital Living Network Alliance e Digital Audio Access Protocol, que fornecem interoperabilidade de modo a permitir a partilha de conteúdos digitais multimédia entre dispositivos que se encontram na mesma rede local. Contudo, possuem a desvantagem de serem tecnologias proprietárias, com documentação e manuais restritos, arquiteturas e conceitos complexos, e não otimizados para fins específicos, tal distribuição de áudio. O principal objetivo deste projeto foi provar que é possível usar protocolos normalizados, como o Simple Network Manager Protocol e ferramentas open source de forma a desenvolver um serviço de distribuição de música que permite a implementação de funcionalidades semelhantes às tecnologias proprietárias já existentes. Assim, o protótipo implementado permite a um utilizador gerir e reproduzir áudio de uma coleção de música que se esteja armazenada num servidor de áudio domestico. A arquitetura permite streaming de áudio entre o servidor e os diferentes dispositivos que se encontram na mesma rede local. Consequentemente, a coleção de música pode integrar ficheiros de áudio visuais que estejam acessíveis através de fontes externas de música, como por exemplo: iTunes, etc

Building energy metering and environmental monitoring - A state-of-the-art review and directions for future research

Buildings are responsible for 40% of global energy use and contribute towards 30% of the total CO2 emissions. The drive to reduce energy consumption and associated greenhouse gas emissions from buildings has acted as a catalyst in the increasing installation of meters and sensors for monitoring energy use and indoor environmental conditions in buildings. This paper reviews the state-of-the-art in building energy metering and environmental monitoring, including their social, economic, environmental and legislative drivers. The integration of meters and sensors with existing building energy management systems (BEMS) is critically appraised, especially with regard to communication technologies and protocols such as ModBus, M-Bus, Ethernet, Cellular, ZigBee, WiFi and BACnet. Findings suggest that energy metering is covered in existing policies and regulations in only a handful of countries. Most of the legislations and policies on energy metering in Europe are in response to the Energy Performance of Buildings Directive (EPBD), 2002/91/EC. However, recent developments in policy are pointing towards more stringent metering requirements in future, moving away from voluntary to mandatory compliance. With regards to metering equipment, significant developments have been made in the recent past on miniaturisation, accuracy, robustness, data storage, ability to connect using multiple communication protocols, and the integration with BEMS and the Cloud – resulting in a range of available solutions, selection of which can be challenging. Developments in communication technologies, in particular in low-power wireless such as ZigBee and Bluetooth LE (BLE), are enabling cost-effective machine to machine (M2M) and internet of things (IoT) implementation of sensor networks. Privacy and data protection, however, remain a concern for data aggregators and end-users. The standardization of network protocols and device functionalities remains an active area of research and development, especially due to the prevalence of many protocols in the BEMS industry. Available solutions often lack interoperability between hardware and software systems, resulting in vendor lock-in. The paper provides a comprehensive understanding of available technologies for energy metering and environmental monitoring; their drivers, advantages and limitations; factors affecting their selection and future directions of research and development – for use a reference, as well as for generating further interest in this expanding research area

Exploiting the power of multiplicity: a holistic survey of network-layer multipath

The Internet is inherently a multipath network: For an underlying network with only a single path, connecting various nodes would have been debilitatingly fragile. Unfortunately, traditional Internet technologies have been designed around the restrictive assumption of a single working path between a source and a destination. The lack of native multipath support constrains network performance even as the underlying network is richly connected and has redundant multiple paths. Computer networks can exploit the power of multiplicity, through which a diverse collection of paths is resource pooled as a single resource, to unlock the inherent redundancy of the Internet. This opens up a new vista of opportunities, promising increased throughput (through concurrent usage of multiple paths) and increased reliability and fault tolerance (through the use of multiple paths in backup/redundant arrangements). There are many emerging trends in networking that signify that the Internet's future will be multipath, including the use of multipath technology in data center computing; the ready availability of multiple heterogeneous radio interfaces in wireless (such as Wi-Fi and cellular) in wireless devices; ubiquity of mobile devices that are multihomed with heterogeneous access networks; and the development and standardization of multipath transport protocols such as multipath TCP. The aim of this paper is to provide a comprehensive survey of the literature on network-layer multipath solutions. We will present a detailed investigation of two important design issues, namely, the control plane problem of how to compute and select the routes and the data plane problem of how to split the flow on the computed paths. The main contribution of this paper is a systematic articulation of the main design issues in network-layer multipath routing along with a broad-ranging survey of the vast literature on network-layer multipathing. We also highlight open issues and identify directions for future work

Methodological foundation ofintegrated aircraft positioning by multiple navigational aids under risk condition

Дисертаційна робота спрямована на вирішення актуальної науково-технічної проблеми підвищення точності визначення координат місцеположення літального апарату в умовах незапланованої відмови основної системи позиціонування з метою забезпечення виконання сучасних вимог навігації заснованої на характеристиках. Розроблено та запатентовано методи позиціонування літального апарату за сукупністю навігаційної інформації отриманої за результатами вимірювань датчиків та прогнозованих за регресією значень на основі попередніх вимірювань. Зокрема, розроблено методи позиціонування за сукупністю інформації від далекомірного обладнання, сукупністю кутової інформації від всенапрямлених радіомаяків, та їх комбінації, що дозволяє підвищити точність кожного з методів шляхом вибору оптимальної геометрії взаємного місцерозташування у порівнянні з існуючими методами позиціонування за парами навігаційних засобів. Запропоновано методи позиціонування за інформацією системи попередження зіткнень літаків у повітрі та інформацією про повітряний рух навколо, отриманої за концепцією автоматичного залежного спостереження, що дозволяє оцінювати координати літального апарату з урахуванням зони невизначеності. Розробленометод пасивного позиціонування, що використовує сигнали далекомірного обладнання, наявні у просторі, у якості опорного навігаційного сигналу для отримання часової різниці фіксації сигналів на борту літака, що дозволяє визначати власне місцеположення у просторі на основі різністно-далекомірного принципу без випромінювання електромагнітних хвиль, що зменшить завантаженість наземних радіонавігаційних засобів. Удосконалено метод оцінювання доступності радіонавігаційних засобів, що враховує індивідуальні особливості наземного обладнання, вплив тропосфери, рельєфу місцевості і штучних споруд на поширення сигналів радіонавігаційних засобів та дозволяє більш точно визначати зону дії наземних радіонавігаційних засобів у повітряному просторі. Вперше запропоновані моделі ймовірнісного класифікатора для контролю за витримуванням навігаційних характеристик, що гарантують розпізнавання відповідності специфікаційним вимогам зональної навігації з максимальною ймовірністю. Сформульовано та вирішено оптимізаційну задачу вибору оптимальногонабору радіонавігаційних засобів у термінах цілочисленного лінійного програмування, що дозволяє оптимально використовувати наземний сегмент радіонавігаційного обладнання. В роботі уперше розроблено модель оцінювання характеристик поля навігаційних сигналів сформованих радіонавігаційними засобами у тривимірному просторі, що дозволяє отримувати точну тривимірну модель просторових зон відповідності специфікаційним вимогам зональної навігації для задач планування повітряного руху. Модель ґрунтується на ітеративному підході оцінювання характеристик позиціонування за різними методами з використанням розбиття повітряного простору на елементарні частинки та інтегрального оцінювання контурів просторових об’єктів. Розроблену модель використано для оцінювання тривимірних зон простору відповідності різним вимогам зональної навігації для різних методів навігації у межах повітряного простору України. У сукупності розроблені методи надають якісно нове рішення задачі забезпечення систем літального апарату навігаційною інформацією у випадку відмови основного джерела даних позиціонування. Застосування розроблених методів відповідає напрямам розвитку авіаційної галузі та підвищує безпеку авіаційних перевезень.Thesis is dedicated to solve scientific-technic problem of aircraft coordinates’ accuracy improvement in the case of primary positioning system malfunction in order to guarantee performance-based navigation requirements. New methods of aircraft positioning by advanced integration of measured data from air navigation sensors and valuespredicted by regression model obtained with a help of previous measurements were developed. In particular, positioning methods by aggregate data from distance measuring equipment, angular information from omni-directional beacons, and their combinations have been developed, which allows to increase the accuracy of each of the methods by choosing the optimal geometry of the relative positioning in comparison with the existing methods of positioning by pairs of navigation means. The methods of airplane positioning by data of traffic collision and avoidance system and information about the air traffic, obtained by automatic dependent surveillance-broadcast, which allows to estimate the coordinates of the aircraft taking into account the areas of uncertainty, are offered. Developed passive positioning method uses navigational signals of distance measuring equipment available in space as a reference signal to obtain a temporal difference in the signals fixation on-board the aircraft, that reduce the load of ground-based infrastructure. The method of estimating the availability of navigation aids has been improved, by taking into account the individual characteristics of ground equipment, the influence of the troposphere, terrain and artificial structures on the propagation of signals, that helps to identify operational volume of navigational aids. Models of probabilistic classifier for controlling the holding of navigation characteristics, which guarantee recognition of compliance with the air navigation specifications with maximum probability, were first proposed. The optimization problem of choosing the optimal set of radio navigation aids in terms of integer linear programming is formulated and solved, which allows optimal use of the terrestrial segment of navigation equipment. In this paper, we first developed a model for estimating the characteristics of a field of navigation signals generated by navigational aids in three-dimensional space, which allows to obtain an accurate three-dimensional model of volume in accordance with the specifications of area navigation for air traffic planning tasks. The modelis based on an iterative approach to evaluate the positioning characteristics of various methods using the partitioning of air space into elementary particles and the integral estimation of the contours of spatial objects. The developed modelwas used to evaluate three-dimensional volume of air space compliance with different area navigational requirements within Ukrainian airspace. In complex, the developed methods provide new solution to the problem of providing aircraft systems with navigation information in case of failure of the main source of positioning data. Application of the developed methods corresponds to the directions of development of aviation industry and improves safety of aviation transportation

A RELIABILITY-BASED ROUTING PROTOCOL FOR VEHICULAR AD-HOC NETWORKS

Vehicular Ad hoc NETworks (VANETs), an emerging technology, would allow vehicles to form a self-organized network without the aid of a permanent infrastructure. As a prerequisite to communication in VANETs, an efficient route between communicating nodes in the network must be established, and the routing protocol must adapt to the rapidly changing topology of vehicles in motion. This is one of the goals of VANET routing protocols. In this thesis, we present an efficient routing protocol for VANETs, called the Reliable Inter-VEhicular Routing (RIVER) protocol. RIVER utilizes an undirected graph that represents the surrounding street layout where the vertices of the graph are points at which streets curve or intersect, and the graph edges represent the street segments between those vertices. Unlike existing protocols, RIVER performs real-time, active traffic monitoring and uses this data and other data gathered through passive mechanisms to assign a reliability rating to each street edge. The protocol then uses these reliability ratings to select the most reliable route. Control messages are used to identify a node’s neighbors, determine the reliability of street edges, and to share street edge reliability information with other nodes

Proceedings of 2013 Kentucky Water Resources Annual Symposium

This symposium was planned and conducted as a part of the state water resources research institute annual program that is supported by Grant/Cooperative Agreement Number G11AP20081 from the United States Geological Survey. The contents of this proceedings document and the views and conclusions presented at the symposium are solely the responsibility of the individual authors and presenters and do not necessarily represent the official views of the USGS or of the symposium organizers and sponsors. This publication is produced with the understanding that the United States Government is authorized to reproduce and distribute reprints for government purposes