9,921 research outputs found
Performance Comparison of Cooperative and Distributed Spectrum Sensing in Cognitive Radio
In this paper, we compare the performances of cooperative and distributed
spectrum sensing in wireless sensor networks. After introducing the basic
problem, we describe two strategies: 1) a cooperative sensing strategy, which
takes advantage of cooperation diversity gain to increase probability of
detection and 2) a distributed sensing strategy, which by passing the results
in an inter-node manner increases energy efficiency and fairness among nodes.
Then, we compare the performances of the strategies in terms of three criteria:
agility, energy efficiency, and robustness against SNR changes, and summarize
the comparison. It shows that: 1) the non-cooperative strategy has the best
fairness of energy consumption, 2) the cooperative strategy leads to the best
agility, and 3) the distributed strategy leads to the lowest energy consumption
and the best robustness against SNR changes.Comment: submitte
Restoration of pseudo-spin symmetry in and isotones described by relativistic Hartree-Fock theory
Restoration of pseudo-spin symmetry (PSS) along the and isotonic
chains and the physics behind are studied by applying the relativistic
Hartree-Fock theory with effective Lagrangian PKA1. Taking the proton
pseudo-spin partners as candidates, systematic
restoration of PSS along both isotonic chains is found from sulphur (S) to
nickel (Ni), while distinct violation from silicon (Si) to sulphur is
discovered near the drip lines. The effects of the tensor-force components
introduced naturally by the Fock terms are investigated, which can only partly
interpret the systematics from calcium to nickel, but fail for the overall
trends. Further analysis following the Schr\"{o}dinger-like equation of the
lower component of Dirac spinor shows that the contributions from the Hartree
terms dominate the overall systematics of the PSS restoration, and such effects
can be self-consistently interpreted by the evolution of the proton central
density profiles along both isotonic chains. Specifically the distinct PSS
violation is found to tightly relate with the dramatic changes from the
bubble-like density profiles in silicon to the central-bumped ones in sulphur.Comment: 4 figures, to be published in Chinese Physics
HyCell: Enabling GREEN Base Station Operations in Software-Defined Radio Access Networks
The radio access networks (RANs) need to support massive and diverse data
traffic with limited spectrum and energy. To cope with this challenge,
software-defined radio access network (SDRAN) architectures have been proposed
to renovate the RANs. However, current researches lack the design and
evaluation of network protocols. In this paper, we address this problem by
presenting the protocol design and evaluation of hyper-cellular networks
(HyCell), an SDRAN framework making base station (BS) operations globally
resource-optimized and energy-efficient (GREEN). Specifically, we first propose
a separation scheme to realize the decoupled air interface in HyCell. Then we
design a BS dispatching protocol which determines and assigns the optimal BS
for serving mobile users, and a BS sleeping protocol to improve the network
energy efficiency. Finally, we evaluate the proposed design in our HyCell
testbed. Our evaluation validates the feasibility of the proposed separation
scheme, demonstrates the effectiveness of BS dispatching, and shows great
potential in energy saving through BS sleeping control.Comment: 6 pages, 4 figures, accepted by IEEE ICC 2015 Workshop on Next
Generation Green IC
Towards Service-oriented 5G: Virtualizing the Networks for Everything-as-a-Service
It is widely acknowledged that the forthcoming 5G architecture will be highly
heterogeneous and deployed with a high degree of density. These changes over
the current 4G bring many challenges on how to achieve an efficient operation
from the network management perspective. In this article, we introduce a
revolutionary vision of the future 5G wireless networks, in which the network
is no longer limited by hardware or even software. Specifically, by the idea of
virtualizing the wireless networks, which has recently gained increasing
attention, we introduce the Everything-as-a-Service (XaaS) taxonomy to light
the way towards designing the service-oriented wireless networks. The concepts,
challenges along with the research opportunities for realizing XaaS in wireless
networks are overviewed and discussed.Comment: 18 pages, 5 figure
Organization mechanism and counting algorithm on Vertex-Cover solutions
Counting the solution number of combinational optimization problems is an
important topic in the study of computational complexity, especially on the
#P-complete complexity class. In this paper, we first investigate some
organizations of Vertex-Cover unfrozen subgraphs by the underlying connectivity
and connected components of unfrozen vertices. Then, a Vertex-Cover Solution
Number Counting Algorithm is proposed and its complexity analysis is provided,
the results of which fit very well with the simulations and have better
performance than those by 1-RSB in a neighborhood of c = e for random graphs.
Base on the algorithm, variation and fluctuation on the solution number
statistics are studied to reveal the evolution mechanism of the solution
numbers. Besides, marginal probability distributions on the solution space are
investigated on both random graph and scale-free graph to illustrate different
evolution characteristics of their solution spaces. Thus, doing solution number
counting based on graph expression of solution space should be an alternative
and meaningful way to study the hardness of NP-complete and #P-complete
problems, and appropriate algorithm design can help to achieve better
approximations of solving combinational optimization problems and the
corresponding counting problems.Comment: 17 pages, 6 figure
ERA: Towards Privacy Preservation and Verifiability for Online Ad Exchanges
Ad exchanges are kind of the most popular online advertising marketplaces for
trading ad spaces over the Internet. Ad exchanges run auctions to sell diverse
ad spaces on the publishers' web-pages to advertisers, who want to display ads
on ad spaces. However, the parties in an ad auction cannot verify whether the
auction is carried out correctly or not. Furthermore, the advertisers are
usually unwilling to reveal their sensitive bids and identities. In this paper,
we jointly consider the auction verifiability and the advertisers' privacy
preservation, and thus propose ERA, which is an Efficient, pRivacy-preserving,
and verifiAble online auction mechanism for ad exchanges. ERA exploits an order
preserving encryption scheme to guarantee privacy preservation, and achieves
verifiability by constructing a novel protocol of privacy preserving integer
comparison, which is built on the Paillier homomorphic encryption scheme. We
extensively evaluate the performance of ERA, and our evaluation results show
that ERA satisfies several desirable properties with low computation,
communication, and storage overheads, so ERA can be easily deployed in today's
ad exchanges
Solving the inverse problem of noise-driven dynamic networks
Nowadays massive amount of data are available for analysis in natural and
social systems. Inferring system structures from the data, i.e., the inverse
problem, has become one of the central issues in many disciplines and
interdisciplinary studies. In this Letter, we study the inverse problem of
stochastic dynamic complex networks. We derive analytically a simple and
universal inference formula called double correlation matrix (DCM) method.
Numerical simulations confirm that the DCM method can accurately depict both
network structures and noise correlations by using available kinetic data only.
This inference performance was never regarded possible by theoretical
derivation, numerical computation and experimental design.Comment: 4 pages, 2 figure
Research on Solution Space of Bipartite Graph Vertex-Cover by Maximum Matchings
Some rigorous results and statistics of the solution space of Vertex-Covers
on bipartite graphs are given in this paper. Based on the 's
theorem, an exact solution space expression algorithm is proposed and
statistical analysis of the nodes' states is provided. The statistical results
fit well with the algorithmic results until the emergence of the unfrozen core,
which makes the fluctuation of statistical quantities and causes the replica
symmetric breaking in the solutions. Besides, the entropy of bipartite
Vertex-Cover solutions is calculated with the clustering entropy using a cycle
simplification technique for the unfrozen core. Furthermore, as generalization
of bipartite graphs, bipartite core graph is proposed, the solution space of
which can also be easily determined; and based on these results, how to
generate a subgraph is studied by a growth
process of adding edges. The investigation of solution space of bipartite graph
Vertex-Cover provides intensive understanding and some insights on the solution
space complexity, and will produce benefit for finding maximal
subgraphs, solving general graph Vertex-Cover
and recognizing the intrinsic hardness of NP-complete problems.Comment: 19 pages, 8 figure
Towards Conversational Recommendation over Multi-Type Dialogs
We propose a new task of conversational recommendation over multi-type
dialogs, where the bots can proactively and naturally lead a conversation from
a non-recommendation dialog (e.g., QA) to a recommendation dialog, taking into
account user's interests and feedback. To facilitate the study of this task, we
create a human-to-human Chinese dialog dataset \emph{DuRecDial} (about 10k
dialogs, 156k utterances), which contains multiple sequential dialogs for every
pair of a recommendation seeker (user) and a recommender (bot). In each dialog,
the recommender proactively leads a multi-type dialog to approach
recommendation targets and then makes multiple recommendations with rich
interaction behavior. This dataset allows us to systematically investigate
different parts of the overall problem, e.g., how to naturally lead a dialog,
how to interact with users for recommendation. Finally we establish baseline
results on DuRecDial for future studies. Dataset and codes are publicly
available at
https://github.com/PaddlePaddle/models/tree/develop/PaddleNLP/Research/ACL2020-DuRecDial.Comment: Accepted by ACL 202
Attention-based Temporal Weighted Convolutional Neural Network for Action Recognition
Research in human action recognition has accelerated significantly since the
introduction of powerful machine learning tools such as Convolutional Neural
Networks (CNNs). However, effective and efficient methods for incorporation of
temporal information into CNNs are still being actively explored in the recent
literature. Motivated by the popular recurrent attention models in the research
area of natural language processing, we propose the Attention-based Temporal
Weighted CNN (ATW), which embeds a visual attention model into a temporal
weighted multi-stream CNN. This attention model is simply implemented as
temporal weighting yet it effectively boosts the recognition performance of
video representations. Besides, each stream in the proposed ATW framework is
capable of end-to-end training, with both network parameters and temporal
weights optimized by stochastic gradient descent (SGD) with backpropagation.
Our experiments show that the proposed attention mechanism contributes
substantially to the performance gains with the more discriminative snippets by
focusing on more relevant video segments.Comment: 14th International Conference on Artificial Intelligence Applications
and Innovations (AIAI 2018), May 25-27, 2018, Rhodes, Greec
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