1,107 research outputs found
Contributions to QoS and energy efficiency in wi-fi networks
The Wi-Fi technology has been in the recent years fostering the proliferation of attractive mobile computing devices with broadband capabilities. Current
Wi-Fi radios though severely impact the battery duration of these devices thus limiting their potential applications.
In this thesis we present a set of contributions that address the challenge of increasing energy efficiency in Wi-Fi networks. In particular, we consider
the problem of how to optimize the trade-off between performance and energy effciency in a wide variety of use cases and applications. In this context, we introduce novel energy effcient algorithms for real-time and data applications, for distributed and centralized Wi-Fi QoS and power saving protocols and for Wi-Fi stations and Access Points.
In addition, the diÂżerent algorithms presented in this thesis adhere to the following design guidelines: i) they are implemented entirely at layer two, and
can hence be easily re-used in any device with a Wi-Fi interface, ii) they do not require modiÂżcations to current 802.11 standards, and can hence be readily deployed in existing Wi-Fi devices, and iii) whenever possible they favor client side solutions, and hence mobile computing devices implementing them can benefit from an increased energy efficiency regardless of the Access Point they connect to. Each of our proposed algorithms is thoroughly evaluated by means of both theoretical analysis and packet level simulations. Thus, the contributions presented in this thesis provide a realistic set of tools to improve energy efficiency in current Wi-Fi networks
Cross-layer design of multi-hop wireless networks
MULTI -hop wireless networks are usually defined as a collection of nodes
equipped with radio transmitters, which not only have the capability to
communicate each other in a multi-hop fashion, but also to route each othersâ data
packets. The distributed nature of such networks makes them suitable for a variety of
applications where there are no assumed reliable central entities, or controllers, and
may significantly improve the scalability issues of conventional single-hop wireless
networks.
This Ph.D. dissertation mainly investigates two aspects of the research issues
related to the efficient multi-hop wireless networks design, namely: (a) network
protocols and (b) network management, both in cross-layer design paradigms to
ensure the notion of service quality, such as quality of service (QoS) in wireless mesh
networks (WMNs) for backhaul applications and quality of information (QoI) in
wireless sensor networks (WSNs) for sensing tasks. Throughout the presentation of
this Ph.D. dissertation, different network settings are used as illustrative examples,
however the proposed algorithms, methodologies, protocols, and models are not
restricted in the considered networks, but rather have wide applicability.
First, this dissertation proposes a cross-layer design framework integrating
a distributed proportional-fair scheduler and a QoS routing algorithm, while using
WMNs as an illustrative example. The proposed approach has significant performance
gain compared with other network protocols. Second, this dissertation proposes
a generic admission control methodology for any packet network, wired and
wireless, by modeling the network as a black box, and using a generic mathematical
0. Abstract 3
function and Taylor expansion to capture the admission impact. Third, this dissertation
further enhances the previous designs by proposing a negotiation process,
to bridge the applicationsâ service quality demands and the resource management,
while using WSNs as an illustrative example. This approach allows the negotiation
among different service classes and WSN resource allocations to reach the optimal
operational status. Finally, the guarantees of the service quality are extended to
the environment of multiple, disconnected, mobile subnetworks, where the question
of how to maintain communications using dynamically controlled, unmanned data
ferries is investigated
Dynamic bandwidth allocation in multi-class IP networks using utility functions.
PhDAbstact not availableFujitsu Telecommunications Europe Lt
Spectrum Trading: An Abstracted Bibliography
This document contains a bibliographic list of major papers on spectrum
trading and their abstracts. The aim of the list is to offer researchers
entering this field a fast panorama of the current literature. The list is
continually updated on the webpage
\url{http://www.disp.uniroma2.it/users/naldi/Ricspt.html}. Omissions and papers
suggested for inclusion may be pointed out to the authors through e-mail
(\textit{[email protected]})
An In-Depth Analysis of the Slingshot Interconnect
The interconnect is one of the most critical components in large scale
computing systems, and its impact on the performance of applications is going
to increase with the system size. In this paper, we will describe Slingshot, an
interconnection network for large scale computing systems. Slingshot is based
on high-radix switches, which allow building exascale and hyperscale
datacenters networks with at most three switch-to-switch hops. Moreover,
Slingshot provides efficient adaptive routing and congestion control
algorithms, and highly tunable traffic classes. Slingshot uses an optimized
Ethernet protocol, which allows it to be interoperable with standard Ethernet
devices while providing high performance to HPC applications. We analyze the
extent to which Slingshot provides these features, evaluating it on
microbenchmarks and on several applications from the datacenter and AI worlds,
as well as on HPC applications. We find that applications running on Slingshot
are less affected by congestion compared to previous generation networks.Comment: To be published in Proceedings of The International Conference for
High Performance Computing Networking, Storage, and Analysis (SC '20) (2020
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