29,367 research outputs found
Large-Scale Distributed Internet-based Discovery Mechanism for Dynamic Spectrum Allocation
Scarcity of frequencies and the demand for more bandwidth is likely to
increase the need for devices that utilize the available frequencies more
efficiently. Radios must be able to dynamically find other users of the
frequency bands and adapt so that they are not interfered, even if they use
different radio protocols. As transmitters far away may cause as much
interference as a transmitter located nearby, this mechanism can not be based
on location alone. Central databases can be used for this purpose, but require
expensive infrastructure and planning to scale. In this paper, we propose a
decentralized protocol and architecture for discovering radio devices over the
Internet. The protocol has low resource requirements, making it suitable for
implementation on limited platforms. We evaluate the protocol through
simulation in network topologies with up to 2.3 million nodes, including
topologies generated from population patterns in Norway. The protocol has also
been implemented as proof-of-concept in real Wi-Fi routers.Comment: Accepted for publication at IEEE DySPAN 201
Coalition Formation and Combinatorial Auctions; Applications to Self-organization and Self-management in Utility Computing
In this paper we propose a two-stage protocol for resource management in a
hierarchically organized cloud. The first stage exploits spatial locality for
the formation of coalitions of supply agents; the second stage, a combinatorial
auction, is based on a modified proxy-based clock algorithm and has two phases,
a clock phase and a proxy phase. The clock phase supports price discovery; in
the second phase a proxy conducts multiple rounds of a combinatorial auction
for the package of services requested by each client. The protocol strikes a
balance between low-cost services for cloud clients and a decent profit for the
service providers. We also report the results of an empirical investigation of
the combinatorial auction stage of the protocol.Comment: 14 page
A Multi-perspective Analysis of Carrier-Grade NAT Deployment
As ISPs face IPv4 address scarcity they increasingly turn to network address
translation (NAT) to accommodate the address needs of their customers.
Recently, ISPs have moved beyond employing NATs only directly at individual
customers and instead begun deploying Carrier-Grade NATs (CGNs) to apply
address translation to many independent and disparate endpoints spanning
physical locations, a phenomenon that so far has received little in the way of
empirical assessment. In this work we present a broad and systematic study of
the deployment and behavior of these middleboxes. We develop a methodology to
detect the existence of hosts behind CGNs by extracting non-routable IP
addresses from peer lists we obtain by crawling the BitTorrent DHT. We
complement this approach with improvements to our Netalyzr troubleshooting
service, enabling us to determine a range of indicators of CGN presence as well
as detailed insights into key properties of CGNs. Combining the two data
sources we illustrate the scope of CGN deployment on today's Internet, and
report on characteristics of commonly deployed CGNs and their effect on end
users
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