Self-Synchronization in Duty-cycled Internet of Things (IoT) Applications

In recent years, the networks of low-power devices have gained popularity. Typically these devices are wireless and interact to form large networks such as the Machine to Machine (M2M) networks, Internet of Things (IoT), Wearable Computing, and Wireless Sensor Networks. The collaboration among these devices is a key to achieving the full potential of these networks. A major problem in this field is to guarantee robust communication between elements while keeping the whole network energy efficient. In this paper, we introduce an extended and improved emergent broadcast slot (EBS) scheme, which facilitates collaboration for robust communication and is energy efficient. In the EBS, nodes communication unit remains in sleeping mode and are awake just to communicate. The EBS scheme is fully decentralized, that is, nodes coordinate their wake-up window in partially overlapped manner within each duty-cycle to avoid message collisions. We show the theoretical convergence behavior of the scheme, which is confirmed through real test-bed experimentation.Comment: 12 Pages, 11 Figures, Journa

Feasibility of Using Passive Monitoring Techniques in Mesh Networks for the Support of Routing

In recent years, Wireless Mesh Networks (WMNs) have emerged as a promising solution to provide low cost access networks that extend Internet access and other networking services. Mesh routers form the backbone connectivity through cooperative routing in an often unstable wireless medium. Therefore, the techniques used to monitor and manage the performance of the wireless network are expected to play a significant role in providing the necessary performance metrics to help optimize the link performance in WMNs. This thesis initially presents an assessment of the correlation between passive monitoring and active probing techniques used for link performance measurement in single radio WMNs. The study reveals that by combining multiple performance metrics obtained by using passive monitoring, a high correlation with active probing can be achieved. The thesis then addresses the problem of the system performance degradation associated with simultaneous activation of multiple radios within a mesh node in a multi-radio environment. The experiments results suggest that the finite computing resource seems to be the limiting factor in the performance of a multi-radio mesh network. Having studied this characteristic of multi-radio networks, a similar approach as used in single radio mesh network analysis was taken to investigate the feasibility of passive monitoring in a multi-radio environment. The accuracy of the passive monitoring technique was compared with that of the active probing technique and the conclusion reached is that passive monitoring is a viable alternative to active probing technique in multi-radio mesh networks

Banco de pruebas de una red inalámbrica Mesh basada en el protocolo IEEE 802.11s

La tecnología inalámbrica Mesh es una de las tecnologías que van a jugar un importante papel dentro de las redes de comunicaciones inalámbricas en la próxima década. Con el uso de esta tecnología será posible llevar a cabo un sueño dentro de las redes de comunicaciones: poder conectarse a la red desde cualquier sitio a cualquier hora muy fácilmente y con un coste muy bajo. Las mejoras que ofrece este tipo de tecnología son debido a la capacidad de auto organización de la que dispone, ya que reduce significativamente la complejidad y el mantenimiento de la red, lo que repercute en que la inversión a realizar es mínima. El objetivo principal de este proyecto es la creación de una Red Inalámbrica Mesh (WMN, Wireless Mesh Network) basada en el proyecto Open80211s, que sirva como banco de pruebas para analizar el rendimiento y comportamiento de esta nueva tecnología. Este Proyecto Fin de Carrera ha sido realizado en la Universidad Tecnológica de Luleå dentro de su Grupo de Investigación de Redes de Comunicación, con el propósito de avanzar en el desarrollo e implantación de esta tecnología emergente. Los objetivos de este proyecto son construir y verificar dos paquetes de instalación para evaluar diferentes topologías de una Red Inalámbrica Mesh basada en el protocolo 802.11s. El primer paquete de instalación será desarrollado bajo el sistema operativo Ubuntu-Linux, utilizando la implementación del proyecto open80211s, y el segundo será desarrollado en el simulador de redes NS-3. La evaluación incluye pruebas de calidad y rendimiento de la red para diferentes topologías y tráfico de datos, comparando los resultados obtenidos en ambos sistemas. Con la realización de este proyecto obtenemos dos sistemas en los que se puede analizar la tecnología inalámbrica Mesh. Por un lado, tenemos un sistema real donde podemos analizar la red bajo condiciones reales y por otra parte tenemos un sistema donde podemos simular la red con las mismas condiciones que en la realidad. Se han podido comparar los resultados y se ha determinado que se ajustan a la realidad, pero con algunos matices a la hora de implementar las interferencias del medio. Con los resultados obtenidos podemos modificar, mejorar y ampliar las implementaciones utilizadas obteniendo un sistema más eficaz y robusto

Packet aggregation for voice over internet protocol on wireless mesh networks

>Magister Scientiae - MScThis thesis validates that packet aggregation is a viable technique to increase call ca-pacity for Voice over Internet Protocol over wireless mesh networks. Wireless mesh networks are attractive ways to provide voice services to rural communities. Due to the ad-hoc routing nature of mesh networks, packet loss and delay can reduce voice quality.Even on non-mesh networks, voice quality is reduced by high overhead, associated with the transmission of multiple small packets. Packet aggregation techniques are proven to increase VoIP performance and thus can be deployed in wireless mesh networks. Kernel level packet aggregation was initially implemented and tested on a small mesh network of PCs running Linux, and standard baseline vs. aggregation tests were conducted with a realistic voice tra c pro le in hop-to-hop mode. Modi cations of the kernel were then transferred to either end of a nine node 'mesh potato' network and those tests were conducted with only the end nodes modi ed to perform aggregation duties. Packet ag- gregation increased call capacity expectedly, while quality of service was maintained in both instances, and hop-to-hop aggregation outperformed the end-to-end con guration. However, implementing hop-to-hop in a scalable fashion is prohibitive, due to the extensive kernel level debugging that must be done to achieve the call capacity increase.Therefore, end-to-end call capacity increase is an acceptable compromise for eventual scalable deployment of voice over wireless mesh networks

Modeling and Performance Analysis of Throughput-Received Power Relationship for Indoor Wireless Mesh Network

In Wireless Mesh Network (WMN) the mesh nodes (APs) are configured with the same frequency channel creates a phenomenon called as co-channel interference. The purpose of selecting the same frequency channel is to make sure all the mesh nodes can talk each other within the frequency range. In order to study the effects of this phenomenon together with multipath fading for indoor environment, we have setup a wireless mesh network operating at 2.4GHz inside a 4-floors faculty building. Extensive measurement campaigns have been conducted at each floor. To observe the effects of these phenomena at the application layer perspective, we measure the network throughput and mapped it to the physical layer performance parameter; received power. The relationship between the application and physical layers performance parameters is modeled numerically and the results are analyzed. One interesting finding is that the empirical relationship model for wireless mesh network does not follow the common exponential models as known in Wireless Local Area Network (WLAN). We can say that the throughput drop is too small and can be neglected and the average throughput is at 1.53Mbps over all received powers. The result shows that the effects of both co-channel interference and multipath are very severe and need to be tackled properly in wireless mesh network design and deployment

Performance Evaluation of Multi-Channel Wireless Mesh Networks with Embedded Systems

Many commercial wireless mesh network (WMN) products are available in the marketplace with their own proprietary standards, but interoperability among the different vendors is not possible. Open source communities have their own WMN implementation in accordance with the IEEE 802.11s draft standard, Linux open80211s project and FreeBSD WMN implementation. While some studies have focused on the test bed of WMNs based on the open80211s project, none are based on the FreeBSD. In this paper, we built an embedded system using the FreeBSD WMN implementation that utilizes two channels and evaluated its performance. This implementation allows the legacy system to connect to the WMN independent of the type of platform and distributes the load between the two non-overlapping channels. One channel is used for the backhaul connection and the other one is used to connect to the stations to wireless mesh network. By using the power efficient 802.11 technology, this device can also be used as a gateway for the wireless sensor network (WSN)

Throughput-Received Power Relationship for File Transfer Protocol (FTP) Service in Wireless Mesh Network (WMN)

In Wireless Mesh Network (WMN) the mesh nodes (APs) are configured with the same frequency channel creates a phenomenon called as co-channel interference. The purpose of selecting the same frequency channel is to make sure all the mesh nodes can talk each other within the frequency range. In order to study the effects of this phenomenon together with multipath fading for indoor environment, we have setup a wireless mesh network operating at 2.4GHz inside a 4-floors faculty building. Extensive measurement campaigns have been conducted at each floor. To observe the effects of these phenomena at the application layer perspective, we measure the network throughput of difference services such as the send and receive e-mail (SMTP and POP3) services, file transfer protocol (FTP) services and hyper text transfer protocol (HTTP) services, and mapped it to the physical layer performance parameter; received power. The relationship between the application and physical layers performance parameters is modelled numerically and the results are analyzed. One interesting finding is that the empirical relationship model for wireless mesh network does not follow the common exponential models as known in Wireless Local Area Network (WLAN). We can say that the throughput drop is too small and can be neglected and the average throughput is at 0.02Mbps, 1.0875Mbps, 0.885Mbps and 0.18Mbps for send and received or SMTP and POP3, FTP Get, FTP Put and HTTPtext services over all received powers. The result shows that the effects of both co-channel interference and multipath are very severe and need to be tackled properly in wireless mesh network design and deployment

Exploring the benefits of multipath TCP In wireless networks

The revolution of the information society has created a completely new situation in the telecommunications markets. As the average user data demands in today's society grow bigger, since users nowadays are demanding a faster, wider and more reliable communication service from the operators so they can watch more videos, listen to more music or access the Internet in general with a better quality, a lower latency and seamlessly to the network access they are using, the network operators face the challenge to fit this demands into their existing networks. This has forced the operators to think in terms of how optimal they are on providing their services if they want to fulfil the customer requirements in this new environment. At the same time we need to keep in mind that simultaneously to this new user's habits smartphones revolution has created, it has also made it possible to have accessible communication devices which have the necessary hardware and horsepower to keep different network interfaces up, and so it has become a common thing to reach the Internet via different kind of networks along the day. Even more it has enabled a rich communications environment where different connection possibilities are available to the user at the same time. In this context, the idea of multipath communication emerges. The idea of taking advantage of a dense wireless communication offer through the use of multipath (sending and receiving information through different network interfaces simultaneously) looks promising to overcome a situation where user's communications services demand grows and at the same time the mobile network load becomes stronger. The newfangled protocol Multipath TCP (MPTCP) is a technology which is enabling in practice this king of multipath communication, and it is the focus of this project to dig into possible benefits the protocol may bring to the table by defining a set of use cases, test-bed implementations and experiments with MPTCP which we present and analyse in this document.La revolución de la sociedad de la información ha creado una situación que es completamente nueva en los mercados de telecomunicaciones. A medida que el usuario medio aumenta su demanda de datos, ya que hoy en día los hábitos de estos pasan por conexiones más rápidas y fiables que les permitan reproducir contenido (video, música, páginas web) con mejor calidad, menor latencia y transparentemente a la red que estén utilizando, los operadores de red afrontan nuevos retos a la hora de encajar estas expectativas del usuario dentro de las posibilidades que ofrece la red. Esto está forzando a los operadores a buscar una manera más óptima de gestionar el tráfico de sus clientes para así poder satisfacer la demanda de unos servicios de mayor calidad que estos realizan. Al mismo tiempo hay que tener en mente que, de la misma manera que el impacto que esta esta revolución de los smartphones ha tenido en los hábitos de consumo del usuario ha creado nuevos y complejos problemas, también ha hecho posible que existan dispositivos económicamente accesibles para el público con el hardware y la capacidad de procesamiento necesarias para incorporar múltiples adaptadores de red, y esto a su vez ha llevado a al escenario actual en el que comúnmente coexisten en el mismo lugar diferentes posibilidades para conectarse a internet (típicamente Wi-Fi y conexión móvil, pero también podríamos nombrar tecnologías como el Bluetooth o la clásica conexión de Ethernet en ordenadores portátiles) Es en este contexto en el que surge la idea de la comunicación multi-trayecto. La idea de aprovechar un entorno con una densa pero heterogénea oferta de conexión a través del uso del multi-trayecto (enviar y recibir información a través de múltiples interfaces de red simultáneamente) aparece como una posibilidad prometedora para los operadores para mejorar la experiencia del usuario al mismo tiempo que se gestiona el tráfico en la red de una manera más eficiente. El protocolo experimental Multipath TCP es una extensión del TCP clásico que hace posible este uso simultáneo de múltiples interfaces para la comunicación, y es objetivo de este proyecto diseñar, implementar y testear el protocolo en diferentes casos de uso en los que el multi-trayecto ofrece, a priori, algunas ventajas. En las siguientes páginas explicaremos que casos de uso hemos elegido para probar el protocolo y por qué, cómo hemos diseñado e implementado los bancos de pruebas y que resultados hemos obtenido en nuestro experimentos sobre el rendimiento del protocolo, realizando al mismo tiempo un análisis crítico de los resultados de los resultados.Ingeniería de Telecomunicació