1,137 research outputs found
Efficient Media Access Protocols for Wireless LANs with Smart Antennas
The use of smart antennas in extending coverage range and capacity of wireless networks dictates the employment of novel media access control protocols, with which the base station (BS) or access point (AP) provides access to users by learning their locations. We consider the class of protocols that employ beamforming and use contention-based or contention-free polling methods to locate users residing in or out of coverage range of the AP. Such protocols allow rapid media access and can be embedded in existing MAC protocols
MAC Protocols for Wireless Mesh Networks with Multi-beam Antennas: A Survey
Multi-beam antenna technologies have provided lots of promising solutions to
many current challenges faced in wireless mesh networks. The antenna can
establish several beamformings simultaneously and initiate concurrent
transmissions or receptions using multiple beams, thereby increasing the
overall throughput of the network transmission. Multi-beam antenna has the
ability to increase the spatial reuse, extend the transmission range, improve
the transmission reliability, as well as save the power consumption.
Traditional Medium Access Control (MAC) protocols for wireless network largely
relied on the IEEE 802.11 Distributed Coordination Function(DCF) mechanism,
however, IEEE 802.11 DCF cannot take the advantages of these unique
capabilities provided by multi-beam antennas. This paper surveys the MAC
protocols for wireless mesh networks with multi-beam antennas. The paper first
discusses some basic information in designing multi-beam antenna system and MAC
protocols, and then presents the main challenges for the MAC protocols in
wireless mesh networks compared with the traditional MAC protocols. A
qualitative comparison of the existing MAC protocols is provided to highlight
their novel features, which provides a reference for designing the new MAC
protocols. To provide some insights on future research, several open issues of
MAC protocols are discussed for wireless mesh networks using multi-beam
antennas.Comment: 22 pages, 6 figures, Future of Information and Communication
Conference (FICC) 2019, https://doi.org/10.1007/978-3-030-12388-8_
Design and evaluation of wireless dense networks : application to in-flight entertainment systems
Le rĂ©seau sans fil est l'un des domaines de rĂ©seautage les plus prometteurs avec des caractĂ©ristiques uniques qui peuvent fournir la connectivitĂ© dans les situations oĂč il est difficile d'utiliser un rĂ©seau filaire, ou lorsque la mobilitĂ© des nĆuds est nĂ©cessaire. Cependant, le milieu de travail impose gĂ©nĂ©ralement diverses contraintes, oĂč les appareils sans fil font face Ă diffĂ©rents dĂ©fis lors du partage des moyens de communication. De plus, le problĂšme s'aggrave avec l'augmentation du nombre de nĆuds. DiffĂ©rentes solutions ont Ă©tĂ© introduites pour faire face aux rĂ©seaux trĂšs denses. D'autre part, un nĆud avec une densitĂ© trĂšs faible peut crĂ©er un problĂšme de connectivitĂ© et peut conduire Ă l'optension de nĆuds isolĂ©s et non connectes au rĂ©seau. La densitĂ© d'un rĂ©seau est dĂ©finit en fonction du nombre de nĆuds voisins directs au sein de la portĂ©e de transmission du nĆud. Cependant, nous croyons que ces mĂ©triques ne sont pas suffisants et nous proposons une nouvelle mesure qui considĂšre le nombre de voisins directs et la performance du rĂ©seau. Ainsi, la rĂ©ponse du rĂ©seau, respectant l'augmentation du nombre de nĆuds, est considĂ©rĂ©e lors du choix du niveau de la densitĂ©. Nous avons dĂ©fini deux termes: l'auto-organisation et l'auto-configuration, qui sont gĂ©nĂ©ralement utilisĂ©s de façon interchangeable dans la littĂ©rature en mettant en relief la diffĂ©rence entre eux. Nous estimons qu'une dĂ©finition claire de la terminologie peut Ă©liminer beaucoup d'ambiguĂŻtĂ© et aider Ă prĂ©senter les concepts de recherche plus clairement. Certaines applications, telles que Ies systĂšmes "In-Flight Entertainment (IFE)" qui se trouvent Ă l'intĂ©rieur des cabines d'avions, peuveut ĂȘtre considĂ©rĂ©es comme des systĂšmes sans fil de haute densitĂ©, mĂȘme si peu de nĆuds sont relativement prĂ©sents. Pour rĂ©soudre ce problĂšme, nous proposons une architecture hĂ©tĂ©rogĂšne de diffĂ©rentes technologies Ă fin de surmonter les contraintes spĂ©cifiques de l'intĂ©rieur de la cabine. Chaque technologie vise Ă rĂ©soudre une partie du problĂšme. Nous avons rĂ©alisĂ© diverses expĂ©rimentations et simulations pour montrer la faisabilitĂ© de l'architecture proposĂ©e. Nous avons introduit un nouveau protocole d'auto-organisation qui utilise des antennes intelligentes pour aider certains composants du systĂšme IFE; Ă savoir les unitĂ©s d'affichage et leurs systĂšmes de commande, Ă s'identifier les uns les autres sans aucune configuration prĂ©liminaire. Le protocole a Ă©tĂ© conçu et vĂ©rifiĂ© en utilisant le langage UML, puis, un module de NS2 a Ă©tĂ© crĂ©Ă© pour tester les diffĂ©rents scĂ©narios.Wireless networking is one of the most challenging networking domains with unique features that can provide connectivity in situations where it is difficult to use wired networking, or when ! node mobility is required. However, the working environment us! ually im poses various constrains, where wireless devices face various challenges when sharing the communication media. Furthermore, the problem becomes worse when the number of nodes increase. Different solutions were introduced to cope with highly dense networks. On the other hand, a very low density can create a poor connectivity problem and may lead to have isolated nodes with no connection to the network. It is common to define network density according to the number of direct neighboring nodes within the node transmission range. However, we believe that such metric is not enough. Thus, we propose a new metric that encompasses the number of direct neighbors and the network performance. In this way, the network response, due to the increasing number of nodes, is considered when deciding the density level. Moreover, we defined two terms, self-organization and self-configuration, which are usually used interchangeably in the literature through highlighting the difference ! between them. We believe that having a clear definition for terminology can eliminate a lot of ambiguity and help to present the research concepts more clearly. Some applications, such as In-Flight Entertainment (IFE) systems inside the aircraft cabin, can be considered as wirelessly high dense even if relatively few nodes are present. To solve this problem, we propose a heterogeneous architecture of different technologies to overcome the inherited constrains inside the cabin. Each technology aims at solving a part of the problem. We held various experimentation and simulations to show the feasibility of the proposed architecture
Wireless communication, identification and sensing technologies enabling integrated logistics: a study in the harbor environment
In the last decade, integrated logistics has become an important challenge in
the development of wireless communication, identification and sensing
technology, due to the growing complexity of logistics processes and the
increasing demand for adapting systems to new requirements. The advancement of
wireless technology provides a wide range of options for the maritime container
terminals. Electronic devices employed in container terminals reduce the manual
effort, facilitating timely information flow and enhancing control and quality
of service and decision made. In this paper, we examine the technology that can
be used to support integration in harbor's logistics. In the literature, most
systems have been developed to address specific needs of particular harbors,
but a systematic study is missing. The purpose is to provide an overview to the
reader about which technology of integrated logistics can be implemented and
what remains to be addressed in the future
Cooperative communication in wireless networks: algorithms, protocols and systems
Current wireless network solutions are based on a link abstraction where a
single co-channel transmitter transmits in any time duration. This model severely
limits the performance that can be obtained from the network. Being inherently an
extension of a wired network model, this model is also incapable of handling the
unique challenges that arise in a wireless medium. The prevailing theme of this
research is to explore wireless link abstractions that incorporate the broadcast and
space-time varying nature of the wireless channel. Recently, a new paradigm for
wireless networks which uses the idea of 'cooperative transmissions' (CT) has garnered
significant attention. Unlike current approaches where a single transmitter transmits
at a time in any channel, with CT, multiple transmitters transmit concurrently after
appropriately encoding their transmissions. While the physical layer mechanisms for
CT have been well studied, the higher layer applicability of CT has been relatively
unexplored. In this work, we show that when wireless links use CT, several network
performance metrics such as aggregate throughput, security and spatial reuse can
be improved significantly compared to the current state of the art. In this context,
our first contribution is Aegis, a framework for securing wireless networks against
eavesdropping which uses CT with intelligent scheduling and coding in Wireless Local
Area networks. The second contribution is Symbiotic Coding, an approach to encode
information such that successful reception is possible even upon collisions. The third
contribution is Proteus, a routing protocol that improves aggregate throughput in
multi-hop networks by leveraging CT to adapt the rate and range of links in a flow.
Finally, we also explore the practical aspects of realizing CT using real systems.PhDCommittee Chair: Sivakumar, Raghupathy; Committee Member: Ammar, Mostafa; Committee Member: Ingram, Mary Ann; Committee Member: Jayant, Nikil; Committee Member: Riley, Georg
Wireless body sensor networks for health-monitoring applications
This is an author-created, un-copyedited version of an article accepted for publication in
Physiological Measurement. The publisher is
not responsible for any errors or omissions in this version of the manuscript or any version
derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0967-3334/29/11/R01
- âŠ