36,115 research outputs found
Thirty Years of Machine Learning: The Road to Pareto-Optimal Wireless Networks
Future wireless networks have a substantial potential in terms of supporting
a broad range of complex compelling applications both in military and civilian
fields, where the users are able to enjoy high-rate, low-latency, low-cost and
reliable information services. Achieving this ambitious goal requires new radio
techniques for adaptive learning and intelligent decision making because of the
complex heterogeneous nature of the network structures and wireless services.
Machine learning (ML) algorithms have great success in supporting big data
analytics, efficient parameter estimation and interactive decision making.
Hence, in this article, we review the thirty-year history of ML by elaborating
on supervised learning, unsupervised learning, reinforcement learning and deep
learning. Furthermore, we investigate their employment in the compelling
applications of wireless networks, including heterogeneous networks (HetNets),
cognitive radios (CR), Internet of things (IoT), machine to machine networks
(M2M), and so on. This article aims for assisting the readers in clarifying the
motivation and methodology of the various ML algorithms, so as to invoke them
for hitherto unexplored services as well as scenarios of future wireless
networks.Comment: 46 pages, 22 fig
Model Order Selection for Collision Multiplicity Estimation
The collision multiplicity (CM) is the number of users involved in a collision. The CM estimation is an essential step in multi-packet reception (MPR) techniques and in collision resolution (CR) methods. We propose two techniques to estimate collision multiplicities in the context of IEEE 802.11 networks. These two techniques have been initially designed in the context of source separation. The first estimation technique is based on eigenvalue statistics. The second technique is based on the exponentially embedded family (EEF). These two techniques outperform current estimation techniques in terms of underestimation rate (UNDER). The reason for this is twofold. First, current techniques are based on a uniform distribution of signal samples whereas the proposed methods rely on a Gaussian distribution. Second, current techniques use a small number of observations whereas the proposed methods use a number of observations much greater than the number of signals to be separated. This is in accordance with typical source separation techniques
CMD: A Multi-Channel Coordination Scheme for Emergency Message Dissemination in IEEE 1609.4
In the IEEE 1609.4 legacy standard for multi-channel communications in
vehicular ad hoc networks(VANETs), the control channel (CCH) is dedicated to
broadcast safety messages while the service channels (SCH's) are dedicated to
transmit infotainment service content. However, the SCH can be used as an
alternative to transmit high priority safety messages in the event that they
are invoked during the service channel interval (SCHI). This implies that there
is a need to transmit safety messages across multiple available utilized
channels to ensure that all vehicles receive the safety message. Transmission
across multiple SCH's using the legacy IEEE 1609.4 requires multiple channel
switching and therefore introduces further end-to-end delays. Given that safety
messaging is a life critical application, it is important that optimal
end-to-end delay performance is derived in multi-channel VANET scenarios to
ensure reliable safety message dissemination. To tackle this challenge, three
primary contributions are in this article: first, a channel coordinator
selection approach based on the least average separation distance (LAD) to the
vehicles that expect to tune to other SCH's and operates during the control
channel interval (CCHI) is proposed. Second, a model to determine the optimal
time intervals in which CMD operates during the CCHI is proposed. Third, a
contention back-off mechanism for safety message transmission during the SCHI
is proposed. Computer simulations and mathematical analysis show that CMD
performs better than the legacy IEEE 1609.4 and a selected state-of-the-art
multi-channel message dissemination schemes in terms of end-to-end delay and
packet reception ratio.Comment: 15 pages, 10 figures, 7 table
Dynamic Radio Cooperation for Downlink Cloud-RANs with Computing Resource Sharing
A novel dynamic radio-cooperation strategy is proposed for Cloud Radio Access
Networks (C-RANs) consisting of multiple Remote Radio Heads (RRHs) connected to
a central Virtual Base Station (VBS) pool. In particular, the key capabilities
of C-RANs in computing-resource sharing and real-time communication among the
VBSs are leveraged to design a joint dynamic radio clustering and cooperative
beamforming scheme that maximizes the downlink weighted sum-rate system utility
(WSRSU). Due to the combinatorial nature of the radio clustering process and
the non-convexity of the cooperative beamforming design, the underlying
optimization problem is NP-hard, and is extremely difficult to solve for a
large network. Our approach aims for a suboptimal solution by transforming the
original problem into a Mixed-Integer Second-Order Cone Program (MI-SOCP),
which can be solved efficiently using a proposed iterative algorithm. Numerical
simulation results show that our low-complexity algorithm provides
close-to-optimal performance in terms of WSRSU while significantly
outperforming conventional radio clustering and beamforming schemes.
Additionally, the results also demonstrate the significant improvement in
computing-resource utilization of C-RANs over traditional RANs with distributed
computing resources.Comment: 9 pages, 6 figures, accepted to IEEE MASS 201
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