1,405 research outputs found
An Approximate Inner Bound to the QoS Aware Throughput Region of a Tree Network under IEEE 802.15.4 CSMA/CA and Application to Wireless Sensor Network Design
We consider a tree network spanning a set of source nodes that generate
measurement packets, a set of additional relay nodes that only forward packets
from the sources, and a data sink. We assume that the paths from the sources to
the sink have bounded hop count. We assume that the nodes use the IEEE 802.15.4
CSMA/CA for medium access control, and that there are no hidden terminals. In
this setting, starting with a set of simple fixed point equations, we derive
sufficient conditions for the tree network to approximately satisfy certain
given QoS targets such as end-to-end delivery probability and delay under a
given rate of generation of measurement packets at the sources (arrival rates
vector). The structures of our sufficient conditions provide insight on the
dependence of the network performance on the arrival rate vector, and the
topological properties of the network. Furthermore, for the special case of
equal arrival rates, default backoff parameters, and for a range of values of
target QoS, we show that among all path-length-bounded trees (spanning a given
set of sources and BS) that meet the sufficient conditions, a shortest path
tree achieves the maximum throughput
Co-evolution of Content Popularity and Delivery in Mobile P2P Networks
Mobile P2P technology provides a scalable approach to content delivery to a
large number of users on their mobile devices. In this work, we study the
dissemination of a \emph{single} content (e.g., an item of news, a song or a
video clip) among a population of mobile nodes. Each node in the population is
either a \emph{destination} (interested in the content) or a potential
\emph{relay} (not yet interested in the content). There is an interest
evolution process by which nodes not yet interested in the content (i.e.,
relays) can become interested (i.e., become destinations) on learning about the
popularity of the content (i.e., the number of already interested nodes). In
our work, the interest in the content evolves under the \emph{linear threshold
model}. The content is copied between nodes when they make random contact. For
this we employ a controlled epidemic spread model. We model the joint evolution
of the copying process and the interest evolution process, and derive the joint
fluid limit ordinary differential equations. We then study the selection of the
parameters under the content provider's control, for the optimization of
various objective functions that aim at maximizing content popularity and
efficient content delivery.Comment: 21 pages, 16 figure
Deep CNN Framework for Audio Event Recognition using Weakly Labeled Web Data
The development of audio event recognition models requires labeled training
data, which are generally hard to obtain. One promising source of recordings of
audio events is the large amount of multimedia data on the web. In particular,
if the audio content analysis must itself be performed on web audio, it is
important to train the recognizers themselves from such data. Training from
these web data, however, poses several challenges, the most important being the
availability of labels : labels, if any, that may be obtained for the data are
generally {\em weak}, and not of the kind conventionally required for training
detectors or classifiers. We propose that learning algorithms that can exploit
weak labels offer an effective method to learn from web data. We then propose a
robust and efficient deep convolutional neural network (CNN) based framework to
learn audio event recognizers from weakly labeled data. The proposed method can
train from and analyze recordings of variable length in an efficient manner and
outperforms a network trained with {\em strongly labeled} web data by a
considerable margin
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