Delay Contributing Factors and Strategies Towards Its Minimization in IoT

Internet of Things (IoT) refers to various interconnected devices, typically supplied with limited computational and communication resources. Most of the devices are designed to operate with limited memory and processing capability, low bandwidth, short range and other characteristics of low cost hardware. The resulting networks are exposed to traffic loss and prone to other vulnerabilities. One of the major concerns is to ensure that the network communication among these deployed devices remains at required level of Quality of Service (QoS) of different IoT applications. The purpose of this paper is to highlight delay contributing factors in Low Power and Lossy Networks (LLNs) since providing low end-to-end delay is a crucial issue in IoT environment especially for mission critical applications. Various research efforts in relevance to this aspect are then presente

On the use of fuzzy logic in a hybrid scheme for tolerating mobilesupport station failure

Mobile computing systems are used in different applications, some of which may be sensitive to be interrupted. However, these systems are susceptible to fault. One such fault is the failure of mobile support station. The main role of these stations is to help providing reliable and uninterrupted communication and computing facilities to mobile hosts. A scheme, known as the hybrid scheme, has recently been proposed that can tolerate failures of mobile support stations. The hybrid scheme combines the characteristics of two other schemes, known as pessimistic and optimistic schemes. There are two objectives that need to be optimized. These objectives are acknowledgement delay and storage capacity. We use fuzzy logic to find the best ratio of pessimistic to optimistic secondary stations to get the optimized values of the two objectives in the hybrid scheme. Simulation results show that fuzzy logic is a suitable choice for addressing the multiobjective nature of the proble

On the use of fuzzy logic in a hybrid scheme for tolerating mobilesupport station failure

Mobile computing systems are used in different applications, some of which may be sensitive to be interrupted. However, these systems are susceptible to fault. One such fault is the failure of mobile support station. The main role of these stations is to help providing reliable and uninterrupted communication and computing facilities to mobile hosts. A scheme, known as the hybrid scheme, has recently been proposed that can tolerate failures of mobile support stations. The hybrid scheme combines the characteristics of two other schemes, known as pessimistic and optimistic schemes. There are two objectives that need to be optimized. These objectives are acknowledgement delay and storage capacity. We use fuzzy logic to find the best ratio of pessimistic to optimistic secondary stations to get the optimized values of the two objectives in the hybrid scheme. Simulation results show that fuzzy logic is a suitable choice for addressing the multiobjective nature of the proble

Energy-efficient wireless communication

In this chapter we present an energy-efficient highly adaptive network interface architecture and a novel data link layer protocol for wireless networks that provides Quality of Service (QoS) support for diverse traffic types. Due to the dynamic nature of wireless networks, adaptations in bandwidth scheduling and error control are necessary to achieve energy efficiency and an acceptable quality of service. In our approach we apply adaptability through all layers of the protocol stack, and provide feedback to the applications. In this way the applications can adapt the data streams, and the network protocols can adapt the communication parameters

Intrusion Tolerant Routing Protocols for Wireless Sensor Networks

This MSc thesis is focused in the study, solution proposal and experimental evaluation of security solutions for Wireless Sensor Networks (WSNs). The objectives are centered on intrusion tolerant routing services, adapted for the characteristics and requirements of WSN nodes and operation behavior. The main contribution addresses the establishment of pro-active intrusion tolerance properties at the network level, as security mechanisms for the proposal of a reliable and secure routing protocol. Those properties and mechanisms will augment a secure communication base layer supported by light-weigh cryptography methods, to improve the global network resilience capabilities against possible intrusion-attacks on the WSN nodes. Adapting to WSN characteristics, the design of the intended security services also pushes complexity away from resource-poor sensor nodes towards resource-rich and trustable base stations. The devised solution will construct, securely and efficiently, a secure tree-structured routing service for data-dissemination in large scale deployed WSNs. The purpose is to tolerate the damage caused by adversaries modeled according with the Dolev-Yao threat model and ISO X.800 attack typology and framework, or intruders that can compromise maliciously the deployed sensor nodes, injecting, modifying, or blocking packets, jeopardizing the correct behavior of internal network routing processing and topology management. The proposed enhanced mechanisms, as well as the design and implementation of a new intrusiontolerant routing protocol for a large scale WSN are evaluated by simulation. For this purpose, the evaluation is based on a rich simulation environment, modeling networks from hundreds to tens of thousands of wireless sensors, analyzing different dimensions: connectivity conditions, degree-distribution patterns, latency and average short-paths, clustering, reliability metrics and energy cost

Clustering objectives in wireless sensor networks: A survey and research direction analysis

Wireless Sensor Networks (WSNs) typically include thousands of resource-constrained sensors to monitor their surroundings, collect data, and transfer it to remote servers for further processing. Although WSNs are considered highly flexible ad-hoc networks, network management has been a fundamental challenge in these types of net- works given the deployment size and the associated quality concerns such as resource management, scalability, and reliability. Topology management is considered a viable technique to address these concerns. Clustering is the most well-known topology management method in WSNs, grouping nodes to manage them and/or executing various tasks in a distributed manner, such as resource management. Although clustering techniques are mainly known to improve energy consumption, there are various quality-driven objectives that can be realized through clustering. In this paper, we review comprehensively existing WSN clustering techniques, their objectives and the network properties supported by those techniques. After refining more than 500 clustering techniques, we extract about 215 of them as the most important ones, which we further review, catergorize and classify based on clustering objectives and also the network properties such as mobility and heterogeneity. In addition, statistics are provided based on the chosen metrics, providing highly useful insights into the design of clustering techniques in WSNs.publishedVersio

Control logic distribution trade-offs in software-defined wireless networks

The SDN (Software-Defined Networks) architecture separates the data and the control planes of the networks. It logically centralizes the control of a network in a central point that is an SDN controller, which acts as a brain of the network and is in charge of telling each network node how to forward incoming packets by installing the appropriate forwarding rules. One of the main advantages it brings is programmability through this single entity (the logical controller) with which network management applications must interact to apply their policies. Through agreed-upon APIs, the network managers can exploit the full potential of SDN. SDN generally assumes ideal control channels between the SDN controller and the network nodes, which may not be the case in challenging environments that are becoming more common due to dense deployment of small cells (SCs) with reduced coverage in 5G and beyond 5G deployments. In 5G and beyond 5G use cases, cost-effective wireless transport networks are required to connect the SCs. In this context, mmWave technology is a good player to connect the SCs as mmWave provides larger radio spectrum chunks that in turn provide larger bandwidth and higher data rate. To manage the dense deployment of SCs in the mobile networks, on the network management/control front, network programmability and virtualization are also an integral part of 5G and beyond 5G networks. In this regard, to provide end-to-end connectivity, management and orchestration of all the segments of the networks ranging from RAN (Radio Access Network), transport network to the core is vital. On the transport networks side (the main focus of the dissertation), SDN plays an important role as SDN enables programmability and virtualization in the network. Though SDN Provides huge flexibility in network management by splitting the control plane from the data plane, it has some limitations in wireless networks context as separation of the control plane from the data plane introduce the extra points of failure in the SDN paradigm (e.g., control communication channel failure, SDN controller failure). In the wide-area networks (WAN) scenarios where in-band channels (e.g., microwave or mmWave links) are responsible to carry control traffic between the forwarding nodes and the SDN controller, the assumption of the availability of a reliable network may not be possible as the performance of the wireless link changes with the environmental conditions, which leads to a high risk of experiencing channel impairments, which might cause centralized SDN operation failure by affecting communication between the transport component of SCs and the SDN controller. To overcome SDN from failure, the dissertation presents a hybrid SDN scheme that explores the benefits of centralized and distributed operations depending on control communication channel conditions. Our hybrid SDN approach combines both centralized and distributed modes in the same node to form a hybrid control plane architecture. We introduce a local agent in the node that is composed of a monitoring framework to detect reliability of the control communication channel and a decision module that conceive a novel control logic switching algorithm to make a decision whether to operate in a centralized or distributed mode. We evaluate the proposed solution under a variety of unreliable network conditions (e.g., link impairments, control packet loss) to investigate the operational performance of the hybrid SDN during high loss conditions. The experimental results show that the proposed hybrid SDN solution substantially improves the aggregated throughput, particularly when control channel packet loss ratios increase, which in turn keeps the network operational in hard conditions where the centralized SDN would result in a non-operational network.La arquitectura SDN (Software-Defined Networks) separa los planos de datos y control de las redes. Centraliza lógicamente el control de una red en un controlador SDN. Una de las principales ventajas que aporta es la programabilidad a través de esta única entidad (el controlador lógico) con la que las aplicaciones de gestión de red deben interactuar para aplicar sus políticas. SDN generalmente asume canales de control ideales entre el controlador SDN y los nodos de la red, lo que puede no ser el caso en entornos inalámbricos (o menos estables) que se están volviendo más comunes debido al despliegue denso de celdas pequeñas (SC) con cobertura reducida en 5G (y más allá). En los casos de uso de futuras redes, se requieren redes de transporte inalámbricas rentables para conectar los SC. En este contexto, la tecnología mmWave es apropiada para conectar las SC, ya que mmWave proporciona fragmentos de espectro más grandes que, a su vez, proporcionan un mayor ancho de banda y una mayor velocidad de datos. Para administrar el despliegue denso de SC en redes móviles, se requiere administración/control de la red, de la virtualización y de la programabilidad de la red, ay que son parte integral de las redes 5G/6G. En este sentido, para proporcionar conectividad de extremo a extremo, es vital la gestión y la orquestación de todos los segmentos de red que van desde la RAN (Red de acceso radio), la red de transporte hasta el núcleo de la red. Por lo que respecte a las redes de transporte (el enfoque principal de la tesis), SDN juega un papel importante ya que SDN permite la programabilidad y la virtualización en la red. Aunque SDN proporciona una gran flexibilidad en la gestión de redes al dividir el plano de control del plano de datos, tiene algunas limitaciones en el contexto de las redes inalámbricas, ya que la separación del plano de control del plano de datos introduce puntos adicionales de fallo en el paradigma SDN (p. ej., fallo del canal de comunicación, fallo del controlador SDN). En los escenarios de redes de área extendida (WAN) donde los canales en-banda (p. ej., enlaces de microondas o mmWave) son responsables de transportar el tráfico de control entre los nodos de red y el controlador SDN, la suposición de la disponibilidad de una red confiable puede no ser posible, ya que el rendimiento del enlace inalámbrico cambia con las condiciones ambientales, lo que conduce a un alto riesgo de experimentar deterioros en el canal, lo que podría causar errores en la operación SDN centralizada al afectar la comunicación entre el componente de transporte de los SC y el controlador SDN. Para superar estos problemas de SDN, la tesis presenta un esquema de SDN híbrido que explora los beneficios de las operaciones centralizadas y distribuidas según sean las condiciones del canal de comunicación de control. Nuestro enfoque SDN híbrido combina los modos centralizados y distribuidos en el mismo nodo para formar una arquitectura de plano de control híbrido. Introducimos un agente local en el nodo que se compone de un marco de monitorización para detectar la confiabilidad del canal de comunicación de control y un módulo de decisión que concibe un algoritmo de conmutación de lógica de control novedoso para tomar la decisión de operar en un modo centralizado o distribuido. Evaluamos la solución propuesta bajo una variedad de condiciones de red poco confiables (p. ej., deterioros de enlace, pérdida de paquetes de control) para investigar el rendimiento operativo de la SDN híbrida durante condiciones de alta pérdida. Los resultados experimentales muestran que la solución SDN híbrida propuesta mejora sustancialmente el rendimiento agregado, particularmente cuando aumentan las tasas de pérdida de paquetes del canal de control, lo que a su vez mantiene la red operativa en condiciones difíciles donde la SDN centralizada daría como resultado una red no operativa.Postprint (published version