A PROTOCOL SUITE FOR WIRELESS PERSONAL AREA NETWORKS

A Wireless Personal Area Network (WPAN) is an ad hoc network that consists of devices that surround an individual or an object. Bluetooth® technology is especially suitable for formation of WPANs due to the pervasiveness of devices with Bluetooth® chipsets, its operation in the unlicensed Industrial, Scientific, Medical (ISM) frequency band, and its interference resilience. Bluetooth® technology has great potential to become the de facto standard for communication between heterogeneous devices in WPANs. The piconet, which is the basic Bluetooth® networking unit, utilizes a Master/Slave (MS) configuration that permits only a single master and up to seven active slave devices. This structure limitation prevents Bluetooth® devices from directly participating in larger Mobile Ad Hoc Networks (MANETs) and Wireless Personal Area Networks (WPANs). In order to build larger Bluetooth® topologies, called scatternets, individual piconets must be interconnected. Since each piconet has a unique frequency hopping sequence, piconet interconnections are done by allowing some nodes, called bridges, to participate in more than one piconet. These bridge nodes divide their time between piconets by switching between Frequency Hopping (FH) channels and synchronizing to the piconet\u27s master. In this dissertation we address scatternet formation, routing, and security to make Bluetooth® scatternet communication feasible. We define criteria for efficient scatternet topologies, describe characteristics of different scatternet topology models as well as compare and contrast their properties, classify existing scatternet formation approaches based on the aforementioned models, and propose a distributed scatternet formation algorithm that efficiently forms a scatternet topology and is resilient to node failures. We propose a hybrid routing algorithm, using a bridge link agnostic approach, that provides on-demand discovery of destination devices by their address or by the services that devices provide to their peers, by extending the Service Discovery Protocol (SDP) to scatternets. We also propose a link level security scheme that provides secure communication between adjacent piconet masters, within what we call an Extended Scatternet Neighborhood (ESN)

A survey on Bluetooth multi-hop networks

Bluetooth was firstly announced in 1998. Originally designed as cable replacement connecting devices in a point-to-point fashion its high penetration arouses interest in its ad-hoc networking potential. This ad-hoc networking potential of Bluetooth is advertised for years - but until recently no actual products were available and less than a handful of real Bluetooth multi-hop network deployments were reported. The turnaround was triggered by the release of the Bluetooth Low Energy Mesh Profile which is unquestionable a great achievement but not well suited for all use cases of multi-hop networks. This paper surveys the tremendous work done on Bluetooth multi-hop networks during the last 20 years. All aspects are discussed with demands for a real world Bluetooth multi-hop operation in mind. Relationships and side effects of different topics for a real world implementation are explained. This unique focus distinguishes this survey from existing ones. Furthermore, to the best of the authors’ knowledge this is the first survey consolidating the work on Bluetooth multi-hop networks for classic Bluetooth technology as well as for Bluetooth Low Energy. Another individual characteristic of this survey is a synopsis of real world Bluetooth multi-hop network deployment efforts. In fact, there are only four reports of a successful establishment of a Bluetooth multi-hop network with more than 30 nodes and only one of them was integrated in a real world application - namely a photovoltaic power plant. © 2019 The Author

Message forwarding techniques in Bluetooth enabled opportunistic communication environment

These days, most of the mobile phones are smart enough with computer like intelligence and equipped with multiple communication technologies such as Bluetooth, wireless LAN, GPRS and GSM. Different communication medium on single device have unlocked the new horizon of communication means. Modern mobile phones are not only capable of using traditional way of communication via GSM or GPRS; but, also use wireless LANs using access points where available. Among these communication means, Bluetooth technology is very intriguing and unique in nature. Any two devices equipped with Bluetooth technology can communicate directly due to their unique IDs in the world. This is opposite to GSM or Wireless LAN technology; where devices are dependent on infrastructure of service providers and have to pay for their services. Due to continual advancement in the field of mobile technology, mobile ad-hoc network seems to be more realised than ever using Bluetooth. In traditional mobile ad-hoc networks (MANETs), before information sharing, devices have partial or full knowledge of routes to the destinations using ad-hoc routing protocols. This kind of communication can only be realised if nodes follow the certain pattern. However, in reality mobile ad-hoc networks are highly unpredictable, any node can join or leave network at any time, thus making them risky for effective communication. This issue is addressed by introducing new breed of ad-hoc networking, known as opportunistic networks. Opportunistic networking is a concept that is evolved from mobile ad-hoc networking. In opportunistic networks nodes have no prior knowledge of routes to intended destinations. Any node in the network can be used as potential forwarder with the exception of taking information one step closer to intended destination. The forwarding decision is based on the information gathered from the source node or encountering node. The opportunistic forwarding can only be achieved if message forwarding is carried out in store and forward fashion. Although, opportunistic networks are more flexible than traditional MANETs, however, due to little insight of network, it poses distinct challenges such as intermittent connectivity, variable delays, short connection duration and dynamic topology. Addressing these challenges in opportunistic network is the basis for developing new and efficient protocols for information sharing. The aim of this research is to design different routing/forwarding techniques for opportunistic networks to improve the overall message delivery at destinations while keeping the communication cost very low. Some assumptions are considered to improved directivity of message flow towards intended destinations. These assumptions exploit human social relationships analogies, approximate awareness of the location of nodes in the network and use of hybrid communication by combining several routing concept to gain maximum message directivity. Enhancement in message forwarding in opportunistic networks can be achieved by targeting key nodes that show high degree of influence, popularity or knowledge inside the network. Based on this observation, this thesis presents an improved version of Lobby Influence (LI) algorithm called as Enhanced Lobby Influence (ELI). In LI, the forwarding decision is based on two important factors, popularity of node and popularity of node’s neighbour. The forwarding decision of Enhanced Lobby Influence not only depends on the intermediate node selection criteria as defined in Lobby Influence but also based on the knowledge of previously direct message delivery of intended destination. An improvement can be observed if nodes are aware of approximate position of intended destinations by some communication means such as GPS, GSM or WLAN access points. With the knowledge of nodes position in the network, high message directivity can be achieved by using simple concepts of direction vectors. Based on this observation, this research presents another new algorithm named as Location-aware opportunistic content forwarding (LOC). Last but not least, this research presents an orthodox yet unexplored approach for efficient message forwarding in Bluetooth communication environment, named as Hybrid Content Forwarding (HCF). The new approach combines the characteristics of social centrality based forwarding techniques used in opportunistic networks with traditional MANETs protocols used in Bluetooth scatternets. Simulation results show that a significant increase in delivery radio and cost reduction during content forwarding is observed by deploying these proposed algorithms. Also, comparison with existing technique shows the efficiency of using the new schemes

Device Discovery in Frequency Hopping Wireless Ad Hoc Networks

This research develops a method for efficient discovery of wireless devices for a frequency hopping spread spectrum, synchronous, ad hoc network comprised of clustered sub-networks. The Bluetooth wireless protocol serves as the reference protocol. The development of a discovery, or outreach, method for scatternets requires the characterization of performance metrics of Bluetooth piconets, many of which are unavailable in literature. Precise analytical models characterizing the interference caused to Bluetooth network traffic by inquiring devices, the probability mass function of packet error rates between arbitrary pairs of Bluetooth networks, and Bluetooth discovery time distribution are developed. Based on the characterized performance metrics, three scatternet outreach methods are developed and compared. Outreach methods which actively inquire on a regular basis, as proposed in literature, are shown to produce lower goodput, have greater mean packet delay, require more power, and cause significant delays in discovery. By passively remaining available for outreach, each of these disadvantages is avoided

Improving forwarding mechanisms for mobile personal area networks

This thesis presents novel methods for improving forwarding mechanisms for personal area networks. Personal area networks are formed by interconnecting personal devices such as personal digital assistants, portable multimedia devices, digital cameras and laptop computers, in an ad hoc fashion. These devices are typically characterised by low complexity hardware, low memory and are usually batterypowered. Protocols and mechanisms developed for general ad hoc networking cannot be directly applied to personal area networks as they are not optimised to suit their specific constraints. The work presented herein proposes solutions for improving error control and routing over personal area networks, which are very important ingredients to the good functioning of the network. The proposed Packet Error Correction (PEC) technique resends only a subset of the transmitted packets, thereby reducing the overhead, while ensuring improved error rates. PEC adapts the number of re-transmissible packets to the conditions of the channel so that unnecessary retransmissions are avoided. It is shown by means of computer simulation that PEC behaves better, in terms of error reduction and overhead, than traditional error control mechanisms, which means that it is adequate for low-power personal devices. The proposed C2HR routing protocol, on the other hand, is designed such that the network lifetime is maximised. This is achieved by forwarding packets through the most energy efficient paths. C2HR is a hybrid routing protocol in the sense that it employs table-driven (proactive) as well as on-demand (reactive) components. Proactive routes are the primary routes, i.e., packets are forwarded through those paths when the network is stable; however, in case of failures, the protocol searches for alternative routes on-demand, through which data is routed temporarily. The advantage of C2HR is that data can still be forwarded even when routing is re-converging, thereby increasing the throughput. Simulation results show that the proposed routing method is more energy efficient than traditional least hops routing, and results in higher data throughput. C2HR relies on a network leader for collecting and distributing topology information, which in turn requires an estimate of the underlying topology. Thus, this thesis also proposes a new cooperative leader election algorithm and techniques for estimating network characteristics in mobile environments. The proposed solutions are simulated under various conditions and demonstrate appreciable behaviour

Distributed Topology Organization and Transmission Scheduling in Wireless Ad Hoc Networks

An ad hoc network is a set of nodes that spontaneously form a multi-hop all-wireless infrastructure without centralized administration. We study two fundamental issues arising in this setting: topology organization and transmission scheduling. In topology organization we consider a system where nodes need to coordinate their transmissions on a non-broadcast frequency hopping channel to discover each other. We devise a symmetric technique where two nodes use a randomized schedule to synchronize and connect in minimum time. This forms the basis for a topology construction protocol where a set of initially unsynchronized nodes are quickly grouped in multiple interconnected communication channels such that the resulting topology is connected subject to channel membership constraints imposed by the physical layer. In the transmission scheduling problem we consider Time Division Multiple Access (TDMA)the network operates with a schedule where at each slot transmissions can be scheduled without conflicts at the intended receivers. TDMA can provide deterministic allocations but typically relies on two restrictive assumptions: network-wide slot synchronization and global knowledge of network topology and traffic requirements. We first introduce an asynchronous TDMA communication model where slot reference for each link is provided locally by the clock of one of the node endpoints. We study the overhead introduced when nodes switch among multiple time references and propose algorithms for its minimization. We then introduce a distributed asynchronous TDMA protocol where nodes dynamically adjust the rates their adjacent links via local slot reassignments to reach a schedule that realizes a set of optimal link rates. We introduce fairness models for both links and multi-hop sessions sharing the network and devise convergent distributed algorithms for computing the optimal rates for each model. These rates are enforced by a distributed algorithm that decides the slots reassigned during each link rate adjustment. For tree topologies we introduce an algorithm that incrementally converges to the optimal schedule in finite time; for arbitrary topologies an efficient heuristic is proposed. Both topology organization and transmission scheduling protocols are implemented over Bluetooth, a technology enabling ad hoc networking applications. Through extensive simulations they demonstrate excellent performance in both static and dynamic scenarios

Evaluación de tecnologías inalámbricas de área personal.

La enorme evolución que se ha producido en la última década en el campo de las comunicaciones inalámbricas y de las plataformas de computación para electrónica de consumo, ha convertido el denominado Internet de las cosas (IoT) en una realidad tangible cuya eclosión parece inminente. En este marco, las tecnologías inalámbricas de área personal se configuran como el tejido base que va a permitir la conexión de diversos objetos inteligentes, muchos de ellos con limitaciones de consumo y capacidad de proceso, a una red única de área global. Así pues, la capacidad de las tecnologías WPAN existentes para ofrecer una respuesta adecuada a las diferentes necesidades puede condicionar el éxito de la IoT y ser determinante en el desarrollo de su potencial para el soporte de aplicaciones novedosas. En esta Tesis se lleva a cabo un estudio y evaluación de las prestaciones en términos de consumo y retardo de varias tecnologías inalámbricas para redes de área personal. En concreto, se analizan las tecnologías estándares que en el momento actual cuentan con un amplio despliegue e implantación en dispositivos y sistemas comerciales, y son estándares abiertos cuya especificación se puede consultar y para los que hay diversas herramientas de desarrollo disponibles: Bluetooth, Bluetooth low energy y ZigBee. Las aportaciones de esta tesis no han estado encaminadas a una comparativa entre las tecnologías estudiadas, ya que en la situación actual cada una de ellas tiene su nicho de aplicación y en la práctica no deben considerarse como rivales. Para cada una de ellas se realiza un análisis de las distintas versiones de las especificaciones a nivel de arquitectura de protocolos y topologías de red, así como un estudio del estado del arte. Este análisis establece la base para poder desarrollar modelos analíticos del comportamiento energético de las citadas tecnologías, lo que constituye uno de los principales objetivos de la Tesis. Estos modelos han sido validados experimentalmente mediante la caracterización de diversas implementaciones de dispositivos comerciales para las tecnologías evaluadas. Durante el desarrollo de las pruebas experimentales, se ha hecho uso de herramientas ya disponibles para las pilas de protocolos de cada una de las tecnologías, así como de otras herramientas personalizadas creadas ex profeso. La metodología de trabajo desarrollada, basada en pruebas sobre sistemas reales, permite también comprobar hasta qué punto se aproxima su comportamiento al previsto en casos más ideales, así como determinar las principales limitaciones que pueden encontrarse en el funcionamiento de la tecnología actual. Además, constituye una de las aportaciones frente a otros estudios realizados sobre las mismas tecnologías y presentes en la literatura científica. En este sentido cabe destacar que el estudio del estado del arte llevado a cabo para las diferentes tecnologías muestra que aunque los estudios teóricos y las evaluaciones realizadas mediante simulación siguen siendo necesarios, convenientes, y ampliamente utilizados, existe un creciente interés por contrastar los resultados mediante pruebas en plataformas basadas en dispositivos comerciales en los casos en los que es posible. La evaluación de las tecnologías ZigBee y Bluetooth low energy ha demostrado que poseen cierto potencial para ofrecer el soporte necesario para conectar objetos inteligentes a la Internet de las cosas. No obstante, ambas tecnologías presentan todavía ciertas limitaciones que están intentando vencer mediante la incorporación de nuevas características a sus especificaciones, lo que deja abierta la puerta a nuevos estudios tal y como se plantea en las líneas futuras de esta Tesis