Obstacle-free geocasting protocol for ad hoc wireless networks

[[abstract]]Mobile ad hoc networks (MANET) comprise mobile hosts in a network bereft of base stations and characterized by a highly dynamic network topology. The MANET environment contains unpredictable obstacles, such as mountains, lakes, buildings, or regions without any hosts, impeding or blocking message relay. This study proposes geocasting protocol for sending short message from a source host to a geocasting region in ad hoc networks. The proposed protocol keeps messages away from unpredictable obstacles and creates a small flooding region. Experimental results show that a source host can send a short message to all hosts located in geographical area with a high success rate and low flooding overhead.[[conferencetype]]國際[[conferencedate]]20030320~20030320[[iscallforpapers]]Y[[conferencelocation]]New Orleans, LA, US

Application-level Data Dissemination in Multi-hop Wireless Networks

Abstract-We investigate different schemes for data dissemination in multi-hop ad-hoc networks using network coding. We study the performance of these schemes in terms of the completion time when a set of data packets must be disseminated from a single source to all nodes in a multi-hop network, i.e. a network where at least one node is several hops away from the source. Therefore some network nodes must relay information to other nodes that are farther away from the source. In this setting, a relay node does not send a particular data packet, but a linear combination of the packets that it has previously received. The selection of such relays has a significant impact on performance. We present a graphical simulator based on OpenGL that allows to study performance and illustrate the status of network nodes in real time during the dissemination of an image file. Features of real-life ad-hoc networks such as packet losses and collisions are taken into consideration in our simulator. Numerical results are presented for simple linear meshed networks and for arbitrary topologies. Results indicate that schemes promoting parallel non-interfering transmissions complete the dissemination process faster

Probabilistic Broadcast for Flooding in Wireless Mobile Ad hoc Networks

Although far from optimal, flooding is an in- dispensable message dissemination technique for network- wide broadcast within mobile ad hoc networks (MANETs). As such, the plain flooding algorithm provokes a high number of unnecessary packet rebroadcasts, causing contention, packet collisions and ultimately wasting precious limited bandwidth. We explore the phase transition phenomenon observed in percolation theory and random graphs as a basis for defining probabilistic flooding algorithms. By considering ideal and realistic models, we acquire a better understanding of the factors that determine phase transition, the consequences of the passage to realistic MANET conditions and to what extent we may benefit from probabilistic flooding in real MANET networks

Mobility Friendly Publish/Subscribe

This paper describes an event dissemination algorithm that implements a topic-based publish/subscribe abstraction in mobile ad-hoc networks (MANETs). Our algorithm relies on (1) the mobility of the processes and (2) the validity period of the events to ensure the reliability of the dissemination (under reasonable conditions) with a thrifty usage of the memory. The algorithm is inherently portable and does not assume any specific routing protocol. Old events are collected to save the memory and the energy consumption is, in some sense, related to the size of the event scope a subscriber is interested in. We give simulation results in different mobility models and highlight the advantages/drawbacks of our approach as well as we expose some interesting relations between validity periods and reliability

Providing reliable and fault-tolerant broadcast delivery in mobile ad hoc networks

Mobile ad-hoc networks are making a new class of mobile applications feasible. They benefit from the fast deployment and reconfiguration of the networks, are mainly characterized by the need to support many-to-many interaction schema within groups of cooperating mobile hosts and are likely to use replication of data objects to achieve performances and high data availability. This strong group orientation requires specialized solutions that combine adaptation to the fully mobile environment and provide the adequate level of fault tolerance. In this paper, we present the reliable broadcast protocol that has been purposely designed for mobile ad-hoc networks. The reliable broadcast service ensures that all the hosts in the network deliver the same set of messages to the upper layer. It represents the building block to obtain higher broadcast and multicast services with stronger guarantees and is an efficient and reliable alternative to flooding. The protocol is constructed on top of the wireless MAC protocol, which in turn sits over the clustering protocol. It provides an exactly once message delivery semantics and tolerates communication failures and host mobility. Temporary disconnections and network partitions are also tolerated under the assumption that they are eventually repaired, as specified by a Liveness property. The termination of the protocol is proved and complexity and performance analyses are also provided

Design and analysis of distributed primitives for mobile ad hoc networks

This dissertation focuses on the design and analysis of distributed primitives for mobile ad hoc networks, in which mobile hosts are free to move arbitrarily. Arbitrary mobility adds unpredictability to the topology changes experienced by the network, which poses a serious challenge for the design and analysis of reliable protocols. In this work, three different approaches are used to handle mobility. The first part of the dissertation employs the simple technique of ignoring the mobility and showing a lower bound for the static case, which also holds in the mobile case. In particular, a lower bound on the worstcase running time of a previously known token circulation algorithm is proved. In the second part of the dissertation, a self-stabilizing mutual exclusion algorithm is proposed for mobile ad hoc networks, which is based on dynamic virtual rings formed by circulating tokens. The difficulties resulting from mobility are dealt with in the analysis by showing which properties hold for several kinds of mobile behavior; in particular, it is shown that mutual exclusion always holds and different levels of progress hold depending on how the mobility affects the token circulation. The third part of the dissertation presents two broadcasting protocols which propagate a message from a source node to all of the nodes in the network. Instead of relying on the frequently changing topology, the protocols depend on a less frequently changing and more stable characteristic â the distribution of mobile hosts. Constraints on distribution and mobility of mobile nodes are given which guarantee that all the nodes receive the broadcast data

Design and Implementation of a Communication Protocol to Improve Multimedia QoS and QoE in Wireless Ad Hoc Networks

[EN] This dissertation addresses the problem of multimedia delivery over multi-hop ad hoc wireless networks, and especially over wireless sensor networks. Due to their characteristics of low power consumption, low processing capacity and low memory capacity, they have major difficulties in achieving optimal quality levels demanded by end users in such communications. In the first part of this work, it has been carried out a study to determine the behavior of a variety of multimedia streams and how they are affected by the network conditions when they are transmitted over topologies formed by devices of different technologies in multi hop wireless ad hoc mode. To achieve this goal, we have performed experimental tests using a test bench, which combine the main codecs used in audio and video streaming over IP networks with different sound and video captures representing the characteristic patterns of multimedia services such as phone calls, video communications, IPTV and video on demand (VOD). With the information gathered in the laboratory, we have been able to establish the correlation between the induced changes in the physical and logical topology and the network parameters that measure the quality of service (QoS) of a multimedia transmission, such as latency, jitter or packet loss. At this stage of the investigation, a study was performed to determine the state of the art of the proposed protocols, algorithms, and practical implementations that have been explicitly developed to optimize the multimedia transmission over wireless ad hoc networks, especially in ad hoc networks using clusters of nodes distributed over a geographic area and wireless sensor networks. Next step of this research was the development of an algorithm focused on the logical organization of clusters formed by nodes capable of adapting to the circumstances of real-time traffic. The stated goal was to achieve the maximum utilization of the resources offered by the set of nodes that forms the network, allowing simultaneously sending reliably and efficiently all types of content through them, and mixing conventional IP data traffic with multimedia traffic with stringent QoS and QoE requirements. Using the information gathered in the previous phase, we have developed a network architecture that improves overall network performance and multimedia streaming. In parallel, it has been designed and programmed a communication protocol that allows implementing the proposal and testing its operation on real network infrastructures. In the last phase of this thesis we have focused our work on sending multimedia in wireless sensor networks (WSN). Based on the above results, we have adapted both the architecture and the communication protocol for this particular type of network, whose use has been growing hugely in recent years.[ES] Esta tesis doctoral aborda el problema de la distribución de contenidos multimedia a través de redes inalámbricas ad hoc multisalto, especialmente las redes inalámbricas de sensores que, debido a sus características de bajo consumo energético, baja capacidad de procesamiento y baja capacidad de memoria, plantean grandes dificultades para alcanzar los niveles de calidad óptimos que exigen los usuarios finales en dicho tipo de comunicaciones. En la primera parte de este trabajo se ha llevado a cabo un estudio para determinar el comportamiento de una gran variedad de flujos multimedia y como se ven afectados por las condiciones de la red cuando son transmitidos a través topologías formadas por dispositivos de diferentes tecnologías que se comunican en modo ad hoc multisalto inalámbrico. Para ello, se han realizado pruebas experimentales sobre una maqueta de laboratorio, combinando los principales códecs empleados en la transmisión de audio y video a través de redes IP con diversas capturas de sonido y video que representan patrones característicos de servicios multimedia tales como las llamadas telefónicas, videoconferencias, IPTV o video bajo demanda (VOD). Con la información reunida en el laboratorio se ha podido establecer la correlación entre los cambios inducidos en la topología física y lógica de la red con los parámetros que miden la calidad de servicio (QoS) de una transmisión multimedia, tales como la latencia el jitter o la pérdida de paquetes. En esta fase de la investigación se realiza un estudio para determinar el estado del arte de las propuestas de desarrollo e implementación de protocolos y algoritmos que se han generado de forma explícita para optimizar la transmisión de tráfico multimedia sobre redes ad hoc inalámbricas, especialmente en las redes inalámbricas de sensores y redes ad hoc utilizando clústeres de nodos distribuidos en un espacio geográfico. El siguiente paso en la investigación ha consistido en el desarrollo de un algoritmo propio para la organización lógica de clústeres formados por nodos capaces de adaptarse a las circunstancias del tráfico en tiempo real. El objetivo planteado es conseguir un aprovechamiento máximo de los recursos ofrecidos por el conjunto de nodos que forman la red, permitiendo de forma simultánea el envío de todo tipo de contenidos a través de ellos de forma confiable y eficiente, permitiendo la convivencia de tráfico de datos IP convencional con tráfico multimedia con requisitos exigentes de QoS y QoE. A partir de la información conseguida en la fase anterior, se ha desarrollado una arquitectura de red que mejora el rendimiento general de la red y el de las transmisiones multimedia de audio y video en particular. De forma paralela, se ha diseñado y programado un protocolo de comunicación que permite implementar el modelo y testear su funcionamiento sobre infraestructuras de red reales. En la última fase de esta tesis se ha dirigido la atención hacia la transmisión multimedia en las redes de sensores inalámbricos (WSN). Partiendo de los resultados anteriores, se ha adaptado tanto la arquitectura como el protocolo de comunicaciones para este tipo concreto de red, cuyo uso se ha extendido en los últimos años de forma considerable[CA] Esta tesi doctoral aborda el problema de la distribució de continguts multimèdia a través de xarxes sense fil ad hoc multi salt, especialment les xarxes sense fil de sensors que, a causa de les seues característiques de baix consum energètic, baixa capacitat de processament i baixa capacitat de memòria, plantegen grans dificultats per a aconseguir els nivells de qualitat òptims que exigixen els usuaris finals en eixos tipus de comunicacions. En la primera part d'este treball s'ha dut a terme un estudi per a determinar el comportament d'una gran varietat de fluxos multimèdia i com es veuen afectats per les condicions de la xarxa quan són transmesos a través topologies formades per dispositius de diferents tecnologies que es comuniquen en mode ad hoc multi salt sense fil. Per a això, s'han realitzat proves experimentals sobre una maqueta de laboratori, combinant els principals códecs empleats en la transmissió d'àudio i vídeo a través de xarxes IP amb diverses captures de so i vídeo que representen patrons característics de serveis multimèdia com son les cridades telefòniques, videoconferències, IPTV o vídeo baix demanda (VOD). Amb la informació reunida en el laboratori s'ha pogut establir la correlació entre els canvis induïts en la topologia física i lògica de la xarxa amb els paràmetres que mesuren la qualitat de servei (QoS) d'una transmissió multimèdia, com la latència el jitter o la pèrdua de paquets. En esta fase de la investigació es realitza un estudi per a determinar l'estat de l'art de les propostes de desenvolupament i implementació de protocols i algoritmes que s'han generat de forma explícita per a optimitzar la transmissió de tràfic multimèdia sobre xarxes ad hoc sense fil, especialment en les xarxes sense fil de sensors and xarxes ad hoc utilitzant clusters de nodes distribuïts en un espai geogràfic. El següent pas en la investigació ha consistit en el desenvolupament d'un algoritme propi per a l'organització lògica de clusters formats per nodes capaços d'adaptar-se a les circumstàncies del tràfic en temps real. L'objectiu plantejat és aconseguir un aprofitament màxim dels recursos oferits pel conjunt de nodes que formen la xarxa, permetent de forma simultània l'enviament de qualsevol tipus de continguts a través d'ells de forma confiable i eficient, permetent la convivència de tràfic de dades IP convencional amb tràfic multimèdia amb requisits exigents de QoS i QoE. A partir de la informació aconseguida en la fase anterior, s'ha desenvolupat una arquitectura de xarxa que millora el rendiment general de la xarxa i el de les transmissions multimèdia d'àudio i vídeo en particular. De forma paral¿lela, s'ha dissenyat i programat un protocol de comunicació que permet implementar el model i testejar el seu funcionament sobre infraestructures de xarxa reals. En l'última fase d'esta tesi s'ha dirigit l'atenció cap a la transmissió multimèdia en les xarxes de sensors sense fil (WSN). Partint dels resultats anteriors, s'ha adaptat tant l'arquitectura com el protocol de comunicacions per a aquest tipus concret de xarxa, l'ús del qual s'ha estés en els últims anys de forma considerable.Díaz Santos, JR. (2016). Design and Implementation of a Communication Protocol to Improve Multimedia QoS and QoE in Wireless Ad Hoc Networks [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62162TESI